Xanthomonas

J Biochem (Tokyo), 1996 Sep, 120(3), 564 - 72
Cloning and expression of an isovaleryl pepstatin-insensitive carboxyl proteinase gene from Xanthomonas sp . T-22; Oda K et al.; Xanthomonas carboxyl proteinase (XCP), isolated from Xanthomonas sp . T-22, is the second example of the unique carboxyl proteinases {EC 3.4.23.33} which are insensitive to the classical aspartic proteinase inhibitor . The gene coding for XCP was cloned, sequenced, and expressed in Escherichia coli . The XCP gene contains an open reading frame of 2,481 base pairs encoding a protein of 827 amino acid residues with a M(r) of 83,677 . The XCP was synthesized as a large precursor consisting of three regions: NH2-terminal prepro (N-Prepro) (237 amino acid residues); mature XCP (398 a.a.residues); and COOH-terminal pro (C-Pro) (192 a.a . residues) . The N-Prepro and mature XCP regions had no sequence similarity to any other proteins reported so far, except the carboxyl proteinase from Pseudomonas sp . 101 {Oda, K., Takahashi, T., Tokuda, Y., Shibano, Y., and Takahashi, S . (1994) J . Biol . Chem . 269, 26518-26524} . The C-Pro region showed high similarity to COOH-terminal regions of other microbial proteinase precursors . E . coli carrying a plasmid containing the cloned wild-type XCP gene produced an 84-kDa protein . This protein was processed into a mature, active form under acidic conditions . This process was completely blocked by tyrostatin, an XCP-specific inhibitor from Kitasatosporia sp . 55, indicating an autocatalytic processing . The purified recombinant XCP had the same characteristics as authentic XCP except for the NH2-terminal amino acid sequence . When the mutant XCP gene truncated in the C-Pro region was expressed in E . coli, an expected 64-kDa protein was detected in the cells, and also processed into the 42-kDa active form under the acidic conditions . Thus, the C-Pro region was not essential for the formation of active mature XCP.

Mol Plant Microbe Interact, 1996 Sep, 9(7), 664 - 6
Cloning and characterization of the rpfC gene of Xanthomonas oryzae pv . oryzae: involvement in exopolysaccharide production and virulence to rice; Tang JL et al.; rpfC is one of a cluster of genes which coordinately regulate the synthesis of extracellular enzymes and exopolysaccharide and pathogenicity in Xanthomonas campestris pv . campestris, the black rot pathogen of brassicas . An rpfC homolog which could functionally complement an rpfC mutant of X . campestris pv . campestris was identified in Xanthomonas oryzae pv . oryzae and the gene was characterized . Mutation of this gene in X . oryzae pv . oryzae had no effect on extracellular enzymes, but exopolysaccharide synthesis and virulence to rice were substantially reduced.

Mol Plant Microbe Interact, 1996 Sep, 9(7), 584 - 93
A gene for superoxide dismutase from Xanthomonas campestris pv . campestris and its expression during bacterial-plant interactions; Smith SG et al.; A recombinant plasmid selected from a library of Xanthomonas campestris pv . campestris genomic DNA by functional complementation of a superoxide dismutase (SOD)-deficient strain of Escherichia coli contained a gene encoding the major SOD activity of X . campestris pv . campestris . Inhibition and renaturation studies suggested that manganese was the metal cofactor for this SOD . Examination of the nucleotide sequence of an active subclone revealed a 612-bp open reading frame that encodes a protein with high amino acid sequence homology to a range of SOD enzymes . The sod gene was mutagenized with Tn5-lacZ . None of the insertions that abolished SOD-conferring activity were in the correct orientation for lacZ expression . Repeated attempts to introduce these insertions into the chromosome of X . campestris pv . campestris were unsuccessful and it was concluded that the sod gene may be essential for viability . In order to monitor the expression of the sod gene, a sod-gus transcriptional fusion was constructed . Expression of the sod gene varied according to the growth stage of the organism in culture . In planta, the sod gene was induced within 3 to 4 h of inoculation, with similar kinetics during compatible and incompatible interactions with turnip and pepper, respectively.

Mol Gen Genet, 1996 Aug 27, 252(1-2), 162 - 8
Two cold-inducible genes encoding lipid transfer protein LTP4 from barley show differential responses to bacterial pathogens; Molina A et al.; The barley genes HvLtp4.2 and HvLtp4.3 both encode the lipid transfer protein LTP4 and are less than 1 kb apart in tail-to-tail orientation . They differ in their non-coding regions from each other and from the gene corresponding to a previously reported Ltp4 cDNA (now Ltp4.1) . Southern blot analysis indicated the existence of three or more Ltp4 genes per haploid genome and showed considerable polymorphism among barley cultivars . We have investigated the transient expression of genes HvLtp4.2 and HvLtp4.3 following transformation by particle bombardment, using promoter fusions to the beta-glucuronidase reporter sequence . In leaves, activities of the two promoters were of the same order as those of the sucrose synthase (Ss1) and cauliflower mosaic virus 35S promoters used as controls . Their expression patterns were similar, except that Ltp4.2 was more active than Ltp4.3 in endosperm, and Ltp4.3 was active in roots, while Ltp4.2 was not . The promoters of both genes were induced by low temperature, both in winter and spring barley cultivars . Northern blot analysis, using the Ltp4-specific probe, indicated that Xanthomonas campestris pv . translucens induced an increase over basal levels of Ltp4 mRNA, while Pseudomonas syringae pv . japonica caused a decrease . The Ltp4.3-Gus promoter fusion also responded in opposite ways to these two compatible bacterial pathogens, whereas the Ltp4.2-Gus construction did not respond to infection.

Mol Microbiol, 1996 Aug, 21(3), 449 - 57
Genetic analysis of the transcriptional arrangement of Azotobacter vinelandii alginate biosynthetic genes: identification of two independent promoters; Lloret L et al.; The study of alginate biosynthesis, the exopolysaccharide produced by Azotobacter vinelandii and Pseudomonas aeruginosa, might lead to different biotechnological applications . Here we report the cloning of A . vinelandii algA, the gene coding for the bifunctional enzyme phosphomannose isomerase-guanosine diphospho-o-mannose pyrophosphorylase (PMI-GMP) . This gene was selected by the complementation for xanthan gum production of Xanthomonas campestris pv . campestris xanB-mutants, which lack this enzymatic activity . The complementing cosmid clones selected, besides containing algA, presented a gene coding for an alginate lyase activity (algL), and some of them also contained algD which codes for GDP-mannose dehydrogenase . We present here the characterization of the A . vinelandii chromosomal region comprising algD and its promoter region, algA and algL, showing that, as previously reported for P . aeruginosa, A . vinelandii has a cluster of the biosynthetic alginate genes . We provide evidence for the presence of an algD-independent promoter in this region which transcribes at least algL and algA, and which is regulated in a manner that differs from that of the algD promoter.

J Bacteriol, 1996 Aug, 178(16), 4814 - 21
Isolation and nucleotide sequence of the GDP-mannose:cellobiosyl-diphosphopolyprenol alpha-mannosyltransferase gene from Acetobacter xylinum; Petroni EA et al.; A genetic locus from Acetobacter xylinum involved in acetan polysaccharide synthesis has been characterized . The chromosomal region was identified by screening a genomic library of A . xylinum in a Xanthomonas campestris mutant defective in xanthan polysaccharide synthesis . The A . xylinum cosmid clone can functionally complement a xanthan-negative mutant . The polymer produced by the recombinant strain was found to be indistinguishable from xanthan . Insertion mutagenesis and subcloning of the cosmid clone combined with complementation studies allowed the identification of a 2.3-kb fragment of A . xylinum chromosomal DNA . The nucleotide sequence of this fragment was analyzed and found to contain an open reading frame (aceA) of 1,182 bp encoding a protein of 43.2 kDa . Results from biochemical and genetic analyses strongly suggest that the aceA gene encodes the GDP-mannose:cellobiosyl-diphosphopolyprenol alpha-mannosyltransferase enzyme, which is responsible for the transfer of an alpha-mannosyl residue from GDP-Man to cellobiosyl-diphosphopolyprenol . A search for similarities with other known mannosyltransferases revealed that all bacterial alpha-mannosyltransferases have a short COOH-terminal amino acid sequence in common.

J Bacteriol, 1996 Aug, 178(15), 4590 - 6
At least two separate gene clusters are involved in albicidin production by Xanthomonas albilineans; Rott PC et al.; Transposon mutagenesis was used to obtain mutations affecting production of the toxin albicidin in Xanthomonas albilineans, which causes leaf scald disease of sugarcane and is also pathogenic to corn . Transposon Tn5-gusA inserted randomly into genomic DNA of X . albilineans Xa23R1 at a frequency of 10(-4) to 10(-5) per recipient after conjugal transfer from Escherichia coli . Fifty prototrophic mutants defective in albicidin production were isolated from 7,100 Tn5-gusA insertional derivatives tested for toxin production by an antibiosis bioassay . EcoRI fragments containing Tn5 flanking sequences from two mutants (AM15 and AM40) were cloned and used to probe a wild-type Xa23R1 DNA library by colony hybridization . Nine cosmids showed homology to the AM15 probe, and six showed homology to the AM40 probe . Four cosmid clones hybridized to both probes . Forty-five of the 50 defective mutants were restored to albicidin production with two overlapping cosmid clones . Restriction mapping showed that these mutants span a genomic region of about 48 kb . At least one other gene cluster is also involved in albicidin production in Xa23R1 . DNA fragments from the 48-kb cluster proved to be very specific to X . albilineans . Some mutants affected in albicidin production retain their ability to colonize sugarcane cultivated in vitro.

Eur J Clin Microbiol Infect Dis, 1996 Jul, 15(7), 607 - 10
A new selective differential medium for isolation of Stenotrophomonas maltophilia; Kerr KG et al.; A new selective differential medium for the isolation of Stenotrophomonas (formerly Xanthomonas) maltophilia was developed . The medium, VIA agar, contained vancomycin, imipenem, and amphotericin B as selective agents and incorporated a mannitol/bromothymol blue indicator system . Compared with Xanthomonas maltophilia Selective Medium (XMSM), VIA agar was less inhibitory to Stenotrophomonas maltophilia and was more selective than XMSM in preventing the growth of unwanted bacteria from contaminated specimens . Although vancomycin-resistant strains of Enterococcus faecium may grow on VIA agar, these can be easily distinguished from Stenotrophomonas maltophilia because of mannitol fermentation.

J Bacteriol, 1996 Jul, 178(14), 4313 - 8
Promoter analysis of the Xanthomonas campestris pv . campestris gum operon directing biosynthesis of the xanthan polysaccharide; Katzen F et al.; The Xanthomonas campestris gum gene cluster is composed of 12 genes designated gumB, -C, -D, -E, -F, -G, -H, -I, -J, -K, -L, and -M . The transcriptional organization of this gene cluster was analyzed by the construction of gum-lacZ transcriptional fusions in association with plasmid integration mutagenesis . This analysis, coupled with primer extension assays, indicated that the gum region was mainly expressed as an operon from a promoter located upstream of the first gene, gumB.

Microbiology, 1996 Jun, 142 ( Pt 6), 1505 - 12
Expression of periplasmic alpha-amylase of Xanthomonas campestris K-11151 in Escherichia coli and its action on maltose; Abe J et al.; A gene encoding the periplasmic alpha-amylase of Xanthomonas campestris K-11151 was cloned into Escherichia coli using pUC19 as a vector . An ORF of 1578 bp was deduced to be the amylase structural gene . The primary structure of the enzyme had little identity with other alpha-amylases, except with the enzyme from Bacillus megaterium . The enzyme was expressed in E . coli from the lac promoter of pUC19 and was found to be transported to the periplasmic space . The expressed enzyme showed the same thermal stability, optimum temperature and substrate specificity as the enzyme from X . campestris . The enzyme formed maltotetraose, but not 6(1)- nor 6(2)-maltosyl-maltose, from maltose by the reverse reaction, and the tetraose was then hydrolysed to maltotriose and glucose . The addition of maltotriose enhanced the production of glucose from maltose . In addition, maltose was formed by the condensation of glucose by the enzyme . Thus, the periplasmic alpha-amylase of X . campestris was shown to produce glucose from maltose by hydrolysing maltotetraose and possibly higher maltooligosaccharides, which were the products of a condensation reaction, as a major pathway, and by direct hydrolysis of maltose as a minor pathway.

J Bacteriol, 1996 Jun, 178(12), 3578 - 84
Heterologous growth phase- and temperature-dependent expression and H2O2 toxicity protection of a superoxide-inducible monofunctional catalase gene from Xanthomonas oryzae pv . oryzae; Mongkolsuk S et al.; Catalase is an important protective enzyme against H2O2 toxicity . Here, we report the characterization of a Xanthomonas oryzae pv . oryzae catalase gene (katX) . The gene was localized and its nucleotide sequence was determined . The gene codes for a 77-kDa polypeptide . The deduced katX amino acid sequence shares regions of high identity with other monofunctional catalases in a range of organisms from bacteria to eukaryotes . The transcriptional regulation of katX was atypical of bacterial monofunctional kat genes . Northern (RNA) analysis showed that katX transcription was highly induced by treatments with low concentrations of menadione, a superoxide generator, and methyl methanesulfonate, a mutagen . It was only weakly induced by H2O2 . Unlike in other bacteria, a high level of catalase in Xanthomonas spp . provided protection from the growth-inhibitory and killing effects of H2O2 but not from those of organic peroxides and superoxide generators . Unexpectedly, heterologous expression of katX in Escherichia coli was both growth phase and temperature dependent . Catalase activity in E . coli kat mutants harboring katX on an expression vector was detectable only when the cells entered the stationary phase of growth and at 28 degrees C . The patterns of transcription regulation, heterologous expression, and physiological function of katX are different from previously studied bacterial kat genes.

Am Surg, 1996 Jun, 62(6), 478 - 80
Characteristics of Xanthomonas infections in critically ill surgical patients; Cornwell EE 3rd et al.; The aim of our study was to describe the characteristics of Xanthomonas infections in a population of critically ill surgical patients . The clinical records and microbiological data on 93 patients in a surgical intensive care unit (SICU) developing Xanthomonas infections were reviewed . Xanthomonas was isolated in 125 sites in the 93 patients . Their average age was 48 years (range, 14-94) . Mortality occurred in 25 patients (26.9%) versus 10.3 per cent of SICU patients in general (P < 0.05) . Patients were in the SICU for an average of 11.9 days before developing a positive Xanthomonas culture, and 87 per cent (81/93) of patients developed an infection at some other site before isolation of Xanthomonas . Trimethoprim sulfamethoxazole was the only drug to which the isolates were commonly sensitive (123/125 = 98.4%) . We conclude that Xanthomonas 1) is associated with increased mortality; 2) is resistant to many of the drugs that usually cover Gram-negative infections; and 3) commonly complicates a prolonged intensive care stay, thus serving as a marker for severity of illness.

Mikrobiologiia, 1996 May-Jun, 65(3), 326 - 32
{Lytic action of lysoamidase from Xanthomonas sp . correlates with the presence of the target ribitol teichoic acids in the cell wall of gram-positive bacteria}; Kulaev IS et al.; Lysoamidase, a bacteriolytic complex from the culture liquid of Xanthomonas sp., hydrolyzed the cells walls of Staphylococcus aureus, Streptomyces chrysomallus, and Streptomyces azureus, which contain ribitol teichoic acids in addition to peptidoglycan . The cell walls of Streptomyces roseoflavus, Glycomyces harhinensis, and Nocardiopsis dassonvillei, containing glycerol teichoic acids, were not hydrolyzed by lysoamidase . The extent of the hydrolysis of 20-h Str . chrysomallus cells and cell walls, containing 40% ribitol teichoic acids, was considerably higher than that of 40-h cells and cell walls, containing 15% teichoic acids . Homogeneous bacteriolytic enzymes of the lysoamidase complex (muramidase and two bacteriolytic peptidases) most efficiently hydrolyzed S . aureus and Str . chrysomallus cell walls, characterized by the highest content of ribitol teichoic acids, and did not hydrolyze purified peptidoglycan.

Graefes Arch Clin Exp Ophthalmol, 1996 May, 234(5), 311 - 4
The effect of concurrent Pseudomonas or Xanthomonas exposure on adherence of Acanthamoeba castellanii to soft contact lenses; Kelly LD et al.; BACKGROUND: Approximately 85% of Acanthamoeba-contaminated contact lens systems in asymptomatic patients have concurrent bacterial contamination . Pseudomonas aeruginosa and Xanthomonas maltophilia are common contact lens contaminants; we investigated the effect of coincubation of Acanthamoeba adherence to contact lenses . METHODS: A . castellanii, 1 x 10(5) organisms/ml, was coincubated with P . aeruginosa or X . maltophilia, 1 x 10(8) CFU/ml in phosphate-buffered saline . Sterile, unworn polymacon, etafilcon A or lidofilcon contact lens were investigated . The experimental groups were: (I) lenses exposed to bacteria for 1 h, then Acanthamoeba for 2 h; (II) lenses exposed concurrently to bacteria and Acanthamoeba for 2 h; (III) Acanthamoeba coincubated with bacteria for 24 h, then lenses exposed for 2 h; (IV) lenses exposed to Acanthamoeba for 2 h (control) . RESULTS: For all experimental groups, Acanthamoeba adherence was greater to lidofilcon than to polymacon and etafilcon . For both P . aeruginosa and X . maltophilia, neither group I nor group II displayed greater Acanthamoeba adherence than group IV . Group III exhibited significantly less adherence than group IV for lidofilcon and polymacon . The decrease in group III adherence reflected an overall decrease in Acanthamoeba trophozoite concentration . CONCLUSION: Short bacteria/Acanthamoeba coincubation times did not result in increased Acanthamoeba adherence . Twenty-four-hour coincubation resulted in decreased adherence for Pseudomonas and unchanged adherence rates for Xanthomonas . This model suggests that Pseudomonas or Xanthomonas co-contamination does not necessarily facilitate quantitative Acanthamoeba contact lens adherence.

Biochem Biophys Res Commun, 1996 Apr 16, 221(2), 459 - 65
Isolation and characterization of the recA gene of Xanthomonas campestris pv . campestris; Lee TC et al.; A 1.8-kb NsiI-StuI fragment containing the recA gene of Xanthomonas campestris pv . campestris was cloned by a PCR-based approach and complementation of Escherichia coli HB 101 . Sequence analysis of this fragment revealed an ORF (orf343) of 1,032 bp able to encode a protein of 343 amino acids with a calculated MW of 37,021 Da, a size similar to the values detected by in vitro system and Western blotting . It showed 69.6% identity to the E . coli RecA in amino acid sequence . Amino acid residues of the E coli RecA associated with functional activities are conserved in this Xc17 RecA . The recA mutant, L1, constructed by gene replacement, was sensitive to ultraviolet irradiation and methyl methanesulfonate, and deficient in homologous recombination.

J Antimicrob Chemother, 1996 Apr, 37(4), 665 - 76
Temperature-dependent aminoglycoside resistance in Stenotrophomonas (Xanthomonas) maltophilia; alterations in protein and lipopolysaccharide with growth temperature; Rahmati-Bahram A et al.; Clinical strains of Stenotrophomonas (Xanthomonas) maltophilia often show large, growth temperature-dependent, variations in their susceptibility (TDVS) to aminoglycoside antibiotics . Strains showing more than a fourfold increase in susceptibility between 30 degrees and 37 degrees C (TDVS+ strains; n = 23) were contrasted with those showing lesser variation (TDVS- strains; n = 15) in studies of growth temperature-dependent variation in protein and cell-wall lipopolysaccharide (LPS) electrophoresis patterns in an attempt to determine the mechanism of TDVS . Several proteins showed increased intensity with increasing growth temperature . These comprised bands at c . 65, 55, 42.5, 26 and 21.5 kDa in the whole cell proteins, an outer membrane protein band at c . 21.5 kDa, and cytoplasmic membrane protein bands at c . 42.5 and 27 kDa . Two whole cell protein bands at c . 30 and 24 kDa and three outer membrane protein bands at c . 45, 30 and 24 kDa decreased in intensity with increasing growth temperature . However, there was no correlation with the extent of variation in susceptibility, either in the extent of temperature dependent changes in protein banding patterns, or the presence or absence of specific protein bands . By contrast, temperature-dependent variation in LPS patterns correlated well with TDVS . TDVS+ strains yielded intense ladder patterns of more than 30 discrete bands, and the mean molecular weight of the ladder pattern was markedly higher at growth temperatures < or = 30 degrees C, than at > or = 37 degrees C . TDVS- strains gave a clearly distinct high mol . wt LPS banding pattern showing fewer, less intense bands and a smaller and less consistent shift in mean molecular weight with temperature . Strains which were clearly resistant at 30 degrees and 37 degrees C, had a high mol . wt . polysaccharide component but an absence of the typical LPS-ladder pattern . We conclude that the temperature-dependent variation in the aminoglycoside susceptibility of this species was not correlated with any detectable change in protein composition, but correlated well with changes in LPS structure.

FEMS Microbiol Lett, 1996 Mar 15, 137(1), 115 - 21
Identification, cloning and sequencing the aceA gene involved in acetan biosynthesis in Acetobacter xylinum; Griffin AM et al.; The aceA gene from Acetobacter xylinum was identified and cloned from a genomic DNA library . The complete DNA sequence was determined and computer analysis of the translated gene sequence revealed homology with the deduced amino acid sequence of gumD from Xanthomonas campestris . Therefore aceA is likely to encode the phosphate-prenyl glucose l-phosphate transferase catalyzing the first step in acetan biosynthesis in A . xylinum.

Clin Infect Dis, 1996 Mar, 22(3), 508 - 12
Bacteremia due to Stenotrophomonas (Xanthomonas) maltophilia: a prospective, multicenter study of 91 episodes; Muder RR et al.; We identified 91 cases of bacteremia due to Stenotrophomonas (Xanthomonas) maltophilia in a prospective, multicenter observational study . The patients were highly compromised; the majority had an underlying malignancy, had received immunosuppressive therapy, and had indwelling venous catheters . Although 94% of patients received an antimicrobial agent to which the blood isolate was susceptible, the mortality among these patients 14 days after the onset of bacteremia was 21% . Mortality was significantly correlated with the presence of a hematologic malignancy or neutropenia or transplantation, immunosuppressive therapy, and a severity-of-illness score of > 4 . S . maltophilia infection is associated with substantial morbidity and mortality among highly compromised patients . The organism is typically resistant to expanded spectrum beta-lactam agents and aminoglycoside antibiotics . Trimethoprim-sulfamethoxazole should be administered if the isolate is susceptible to this combination; addition of another agent to which the isolate is susceptible should be considered in treating patients who are neutropenic, immunocompromised, or critically ill.

Carbohydr Res, 1996 Feb 28, 282(1), 149 - 56
Structure of the O3 antigen of Stenotrophomonas (Xanthomonas or Pseudomonas) maltophilia; Winn AM et al.; The O antigen isolated from the lipopolysaccharide of a strain of Stenotrophomonas (Xanthomonas or Pseudomonas) maltophilia serogroup O3 was found to contain 4-acetamido-4,6-dideoxy-D-galactose, D-fucose, and N-acetyl-D-glucosamine . By means of chemical degradations and NMR spectroscopy the repeating unit of the O-specific polymer was determined to be a branched trisaccharide repeating-unit of the structure shown.

J Biol Chem, 1996 Feb 2, 271(5), 2703 - 8
XpsD, an outer membrane protein required for protein secretion by Xanthomonas campestris pv . campestris, forms a multimer; Chen LY et al.; XpsD is an outer membrane lipoprotein, required for the secretion of extracellular enzymes by Xanthomonas campestris pv . campestris . Our previous studies indicated that when the xpsD gene was interrupted by transposon Tn5, extracellular enzymes were accumulated in the periplasm (Hu, N.-T., Hung, M.-N., Chiou, S.-J., Tang, F., Chiang, D.-C . Huang, H.-Y . and Wu, C.-Y . (1992) J . Bacteriol . 174, 2679-2687) . In this study, we constructed a series of substitutions and deletion mutant xpsD genes to investigate the roles of NH2- and COOH-terminal halves of XpsD in protein secretory function . Among these secretion defective xpsD mutations, one group (encoded by pCD105, pYLA, pKdA6, and pKD2) caused secretion interference when co-expressed with wild type xpsD, but the other (encoded by pMH7, pKdPs, and pKDT) did not . Cross-linking studies and gel filtration chromatography analysis indicated that the wild type XpsD protein forms a multimer in its native state . Similar gel filtration analysis of xpsD mutants revealed positive correlations between multimer formation and secretion interfering properties exerted by the mutant XpsD proteins in the parental strain XC1701 . Those mutant XpsD proteins (encoded by pCD105, pYL4, pKdA6, and pKD2) that caused secretion interference formed multimers that are similar to the wild type XpsD multimers and those (encoded by pMH7, pKdPs, and pKDT) that did not formed smaller ones . Furthermore, gel filtration and anion exchange chromatography analyses indicated that the wild type XpsD protein co-fractionated with XpsD (delta 29-428) or XpsD (delta 448-650) protein but not with XpsD (delta 74-303) or XpsD (delta 553-759) protein . We propose that the mutant XpsD (delta 29-428) protein caused secretion interference primarily by forming mixed nonfunctional multimers with the wild type XpsD protein in XC1701 (pCD105), whereas the mutant XpsD (delta 74-303) did so by competing for unknown factor(s) in XC1701(pYL4).

APMIS, 1996 Feb, 104(2), 108 - 14
In vitro susceptibility of 124 Xanthomonas maltophilia (Stenotrophomonas maltophilia) isolates: comparison of the agar dilution method with the E-test and two agar diffusion methods; Arpi M et al.; The in vitro susceptibility of 124 Xanthomonas maltophilia isolates was tested by four methods: Agar dilution (reference method), E-test, a disk diffusion and a tablet diffusion method . Trimethoprim-sulfamethoxazole had the highest activity against X . maltophilia, followed by a combination of aztreonam-clavulanic acid at different ratios, the ratio 1:1 being the most active with a susceptibility rate of 85% as compared to 2% for aztreonam alone . Addition of the beta-lactamase inhibitor tazobactam to piperacillin enhanced the rate of susceptible isolates from 31% to 53%, Relatively few isolates were susceptible to ciprofloxacin (27%) and gentamicin (9%) . Generally, the disk diffusion method had a considerably higher frequency of "very major" discrepancies when compared with the agar dilution method than with the other methods . The susceptibility of X . maltophilia to trimethoprim-sulfamethoxazole and ciprofloxacin could reliably be determined by all the diffusion methods tested, but otherwise the agar dilution method is to be preferred . A standardized and reliable diffusion method for susceptibility testing of X . maltophilia remains to be found . Trimethoprim-sulfamethoxazole must be considered the drug of choice in the treatment of severe X . maltophilia infections . The combination aztreonam-clavulanic acid is promising, but must be proved in a clinical setting.

J Bacteriol, 1996 Feb, 178(4), 1061 - 9
Expression and localization of HrpA1, a protein of Xanthomonas campestris pv . vesicatoria essential for pathogenicity and induction ofthe hypersensitive reaction; Wengelnik K et al.; The hrp cluster of the pepper and tomato pathogen Xanthomonas campestris pv . vesicatoria is required for both pathogenicity on susceptible host plants and induction of the hypersensitive reaction on resistant plants . The hrpA locus is located at the left end of the 25-kb hrp region and encodes a single 64-kDa Hrp protein, HrpA1, which belongs to the PulD superfamily of proteins involved in type II and type III protein secretion . In this study, we developed a defined medium without any plant-derived molecules that induces expression of hrpA in vitro . The hrpA transcription start site was mapped in the coding region of the hrpB8 gene, which is the last gene of the hrpB operon . The inducible hrpA promoter shows no homology to known promoter elements or other hrp loci of X . campestris pv . vesicatoria . hrpA expression was shown to be independent of the hrp regulatory gene hrpX . The amino acid sequence of the HrpA1 protein is predicted to contain an N-terminal signal sequence and no further transmembrane domains and to be rich in beta-sheet stretches . Expression of HrpA1 in Escherichia coli cells causes induction of the psp operon like some of its counterparts, suggesting some commonality of function and that HrpA1 forms multimers . The protein product of hrpA1 was identified by using a specific polyclonal antibody . Cell fractionation studies demonstrated that the HrpA1 protein is localized in the outer membrane of X . campestris pv . vesicatoria . HrpA1 is the first component of the Hrp secretion system whose localization has been determined in the original organism.

Biochem Biophys Res Commun, 1996 Jan 5, 218(1), 12 - 6
A region of the filamentous phage phi Lf genome that can support autonomous replication and miniphage production; Lin NT et al.; A 2028-bp fragment from the RF DNA of phi Lf, a filamentous phage of Xanthomonas campestris pv . campestris, was maintained autonomously as a minireplicon . Upon superinfection of the cells harboring the minireplicon with phi Lf, transducing miniphage particles were released . The minireplicon contained an open reading frame (ORF346) able to encode a polypeptide of MW39144, which possessed consensus motifs found in the Rep proteins from various sources . These findings suggested ORF346 to be the gene encoding replication initiation protein, gene II (gII) of phi Lf . Upstream to ORF346 were sequences with potential to form hairpin structures and a sequence similar to the integration host factor (IHF) binding site, structures similar to the intergenic region (IR) of the Ff phages . A 15 bp AT-rich core for phi Lf integration was found 37 bp downstream to the IHF binding site.

J Hosp Infect, 1996 Jan, 32(1), 39 - 50
Use of random amplified polymorphic DNA for epidemiological typing of Stenotrophomonas maltophilia; Davin-Regli A et al.; We used the technique of random amplification of polymorphic DNA (RAPD) to type 130 isolates of Stenotrophomonas (Xanthomonas) maltophilia, using four arbitrary short primers . Of the 130 isolates, 51 were from the hospital environment, 48 from clinical specimens and 31 were geographically diverse environmental isolates . DNA amplification with the four sets of primers generated 112 RAPD patterns that differed by two or more bands in one of the four primers . Sixteen pairs of isolates were of the same RAPD pattern and some of these pairs represented clinical strains obtained from patients hospitalized at the same time in the same ward . In three patients, two to three strains of S . maltophilia which gave different RAPD fingerprints were isolated on the same day from different specimens . RAPD fingerprinting demonstrated great genomic diversity within the species S . maltophilia and provided an effective method for the study of the epidemiology of both clinical and environmental strains.

Indian J Exp Biol, 1996 Jan, 34(1), 27 - 31
Cloning of extracellular lipase gene from Xanthomonas campestris pathovar sesami on to Escherichia coli; Sheela P et al.; A lipase gene from X . campestris pv . sesami (strain XcS 1) causal agent of leaf spot disease of Sesamum indicum, was cloned onto E . colt . XcS showed the presence of lip+ transformants on Dye's medium with 1% glycerol as sole carbon source . The recombinant plasmids were isolated and when digested with Eco R1, yielded 2 fragments with molecular weights 4.0 and 4.8 kb . Thus a 8.8 kb insert DNA fragment was obtained which showed lipase activity.

Yi Chuan Xue Bao, 1996, 23(2), 110 - 6
{A PCR marker-based selection for resistance to bacterial blight in rice}; Lu C et al.; Molecular marker-based selection in plant breeding requires not only suitable molecular markers closely linked to the known genes, but a simple, economic and reliable analyzing technique . We report here a useful PCR marker for genetic diagnostics in breeding for resistance to rice bacterial blight . Xa21 is a newly found gene of rice which confers resistance to bacterial blight caused by Xanthomonas oryzae pv . oryzae . We produced two F2 populations between one resistant line IRBB21 containing Xa21 and two susceptible varieties, respectively . One PCR marker, PB78, detected polymorphism between the susceptible varieties and the resistant line . Cosegregation between Xa21 and PB78 was studied in the two F2 populations . The results showed that Xa21 was closely linked to the molecular marker, the crossing over value was 2.48% . Marker-based selection revealed that 100% of the plants with homozygous resistant genotype of PB78 showed resistance to bacterial blight . The available approaches detecting molecular markers in plant breeding are also discussed.

Carbohydr Res, 1995 Dec 20, 278(2), 205 - 25
A conformational model for cyclic beta-(1-->2)-linked glucans based on NMR analysis of the beta-glucans produced by Xanthomonas campestris; York WS; A cyclic hexadecaglucoside containing 15 beta-(1-->2)-linkages and one alpha-(1-->6)-linkage (A . Amemura and J . Cabrera-Crespo, J . Gen . Microbiol . 132 (1986) 2443-2452) was purified from cultures of Xanthomonas campestris . The homogeneity of this glucan preparation facilitated the complete assignment of its 1H NMR spectrum and the assignment of all of the C-1 and C-2 resonances in its 13C NMR spectrum to specific residues within the glucan . The resonances (i.e., H-1, H-2, C-1 and C-2) that are closely associated with the beta-(1-->2) glucosidic bonds of this glucan are dispersed over a relatively broad chemical shift range . This chemical shift dispersion is attributed to the differences in the time-averaged geometry of individual beta-(1-->2)-linked glycosidic bonds in this glucan and is consistent with the hypothesis that these glycosidic bonds have less conformational freedom than do the glycosidic bonds in a linear beta-(1-->2)-linked glucan . The chemical shifts of H-1, H-2, C-1, and C-2 exhibit an alternating pattern when plotted as a function of their locations within the macrocyclic ring, suggesting that the glycosidic bond geometry also alternates in the glucan . A new conformational model for cyclic beta-(1-->2)-linked glucans was developed on the basis of these observations . This model is consistent with the observed spectroscopic features of all cyclic beta-(1-->2)-linked glucans known to be produced by Gram-negative bacteria.

FEMS Microbiol Lett, 1995 Dec 15, 134(2-3), 189 - 94
Rapid inhibition of protein histidine phosphorylation by UV-irradiation in Xanthomonas oryzae pv . oryzae; Huang HJ et al.; Exposure of Xanthomonas oryzae pv . oryzae cells to 254 nm UV radiation resulted in an alteration of protein phosphorylation . Labelling of the phosphohistidine-containing proteins with molecular masses of 81 and 32 kDa, named p81 and p32, was rapidly reduced following UV irradiation in the early exponential cells, but the decrease was not detected in mid-exponential cells . Mitomycin C, a DNA replication inhibitor, and rifampicin, a drug generally used to inhibit RNA synthesis and DNA replication, were also found to reduce the histidyl phosphorylation . However, this alteration of protein phosphorylation was not hindered by chloramphenicol treatment . A possible role for these histidyl phosphoproteins in sensing UV light is proposed.

Science, 1995 Dec 15, 270(5243), 1804 - 6
A receptor kinase-like protein encoded by the rice disease resistance gene, Xa21; Song WY et al.; The rice Xa21 gene, which confers resistance to Xanthomonas oryzae pv . oryzae race 6, was isolated by positional cloning . Fifty transgenic rice plants carrying the cloned Xa21 gene display high levels of resistance to the pathogen . The sequence of the predicted protein, which carries both a leucine-rich repeat motif and a serine-threonine kinase-like domain, suggests a role in cell surface recognition of a pathogen ligand and subsequent activation of an intracellular defense response . Characterization of Xa21 should facilitate understanding of plant disease resistance and lead to engineered resistance in rice.

Microbiologia, 1995 Dec, 11(4), 471 - 84
{Kinetic model of micro-organism growth: the case of Xanthomonas campestris}; Garcia-Ochoa F et al.; Microbial growth is studied and kinetic models to describe the process rate useful in the scale-up are proposed . The growth of Xanthomonas campestris NRRL B-1459, a bacterium producing xanthan, a major industrial gum, is studied . Experimental data are arranged by means of different methods, and linear and non-linear regression techniques are applied in several ways (i.e . fixing or not fixing the values of certain parameters) and they are compared . To obtain parameter values with statistical meaning, two parameters must be calculated (namely, the maximum specific growth rate and the maximum biomass concentration available) by means of a non-linear regression technique employing the logistic equation . The maximum specific growth rate is related to temperature by means of different equations, but that of Ratkowsky et al . is the most suitable for X . campestris growth . Studied variables present no tendency to error and the reproduction of experimental data is very good.

Microbiology, 1995 Dec, 141 ( Pt 12), 3229 - 39
tRNA intergenic spacers reveal polymorphisms diagnostic for Xanthomonas albilineans; Honeycutt RJ et al.; A PCR-based detection system was developed for Xanthomonas albilineans, a pathogen of sugarcane, and other related xanthomonads, using the conserved sequence of two adjacent tRNA genes and the variable length and sequence of the spacer region between them . An appropriate region was identified as follows: tRNA genes with the same anticodon from a wide variety of bacteria were aligned and the most frequent base at each position was chosen to derive primers that would anneal to the gene in either orientation . Pairs of such primers were screened against various Xanthomonas species and members of related genera using PCR at low to moderate annealing stringency . A subset of these pairs of tRNA consensus primers gave one or more PCR products which generally displayed interspecific length variability . The primer pair 5'-3' tRNA(ala) and 3'-5' tRNA(ile) showed interspecific length polymorphisms between X . albilineans and all other Xanthomonas species examined . These PCR products were cloned and sequenced from four isolates of X . albilineans and four isolates from different pathovars of X . campestris, and the spacer length variation confirmed . Specific tRNA gene primers were derived from the tRNA gene sequences . These primers yielded a PCR product of a characteristic length within most Xanthomonas species and pathovars tested . When a primer that projected from tRNA(ala) into the 3' end of the variable intergenic spacer was used with a tRNA(ile)-specific primer, PCR was a very sensitive diagnostic test for X . albilineans-infected sugarcane and gave no product or only a faint product with other species of bacteria . The specificity of this PCR-based detection system was further enhanced by a nested PCR reaction that took advantage of the fact that the tRNA(ala)-tRNA(ile) region was found to be embedded in a 16S rRNA-23S rRNA gene spacer . By amplifying the region between the 16S rRNA gene and tRNA(ile) or between the tRNA(ala) and the 23S rRNA gene, the subsequent nested PCR product was shown to be X . albilineans-specific.

Mol Microbiol, 1995 Nov, 18(4), 769 - 77
The type IV pre-pilin leader peptidase of Xanthomonas campestris pv . campestris is functional without conserved cysteine residues; Hu NT et al.; Type IV pre-pilin leader peptidase was demonstrated to be required for protein secretion, in addition to its involvement in biogenesis of type IV pIII . The type IV pre-pilin leader peptidase gene of Xanthomonas campestris pv . campestris was located on a 3 kb Accl fragment on account of its hybridization with the DNA fragment containing the type IV pre-pilin leader-peptidase gene pilD/xcpA of Pseudomonas aeruginosa . Sequencing of the cloned fragment revealed an open reading frame (ORF) (designated xpsO) of 287 amino acid residues . A protein with an apparent molecular mass of approximately 32.5 kDa was synthesized in vitro from a DNA fragment containing the xpsO gene . The amino acid sequence shares 50% identity with that of PilD throughout the entire sequence . Among other type IV pre-pilin leader peptidases, XpsO is unique in not having the two conserved -CXXC-motifs in a cytoplasmic domain . Instead, new motifs were noted when the protein was compared with XpsE, which is another member of the extracellular protein-secretion machinery . When the xpsO gene was introduced into the pilD mutant of P . aeruginosa, both the sensitivity against infection with the pilus-specific phage PO4 and the ability to secrete extracellular protein were recovered . Furthermore, immunoblot analysis indicated that the P . aeruginosa pilin was apparently processed in vivo by the xpsO gene product.

Biosci Biotechnol Biochem, 1995 Nov, 59(11), 2087 - 90
Prolidase from Xanthomonas maltophilia: purification and characterization of the enzyme; Suga K et al.; Prolidase (iminodipeptidase, EC 3.4.13.9) was purified from an extract of Xanthomonas maltophilia, by ammonium sulfate fractionation and sequential chromatographies on DEAE-Toyopearl, Toyopearl HW65C, FPLC-Hiload Superdex 200 pg, and FPLC-Hitrap Q columns, which an activity recovery of 2.3% . The enzyme was the most active at pH 7.5 with Leu-Pro as substrate . It was stable between pH 6.0 and 8.5 for 60 min at 37 degrees C and retained half of activity after 60 min at 37 degrees C . The isoelectric point of the enzyme was 3.7 . Its molecular weight was estimated to be 100,000 by gel filtration on FPLC-Hiload Superdex 200 and 51,000 by SDS-PAGE, suggesting that it is a dimer . It hydrolyzed dipeptides only if proline is located at the carboxyl terminal position . The enzyme was inhibited by PCMB and o-phenanthroline, and was activated by Mn2+.

Genetics, 1995 Oct, 141(2), 675 - 82
Genomic localization of tomato genes that control a hypersensitive reaction to Xanthomonas campestris pv . vesicatoria (Doidge) dye; Yu ZH et al.; Xanthomonas campestris pv . vesicatoria causes bacterial spot, one of the most serious diseases of tomatoes . The lycopersicon esculentum accession 'Hawaii 7998' is the only reliable source of resistance to race 1 strains of the pathogen . This resistance is associated with a hypersensitive reaction controlled by multiple nondominant genes . The inoculated area becomes fully necrotic 24 hr after inoculation in 'Hawaii 7998,' whereas full necrosis is observed 5 and 4 days after inoculation in the susceptible species L . pennellii (LA 716) and their F1, respectively . An interspecific backcross population, using 'Hawaii 7998' as the recurrent parent, was analyzed to determine the linkage relationships between the resistance genes and 135 molecular marker loci . The range of responses of the BC1 population included those of the parents . Linkage to a hypersensitive response factor was assessed by comparing the rates of necrosis development between homozygous and heterozygous plants at 8 hr-intervals . Three factors that affect the hypersensitive response of 'Hawaii 7998' were detected . One factor is on the short arm of chromosome I, another on the long arm of chromosome I, and a third on the long arm of chromosome 5 . These factors appeared to act independently and to have additive effects.

Antimicrob Agents Chemother, 1995 Oct, 39(10), 2220 - 3
In vitro activities of antimicrobial combinations against Stenotrophomonas (Xanthomonas) maltophilia; Poulos CD et al.; Stenotrophomonas (Xanthomonas) maltophilia is inherently resistant to multiple antimicrobial agents . In order to investigate the in vitro potential of combinations of antimicrobial agents, we obtained 230 epidemiologically unrelated clinical isolates from seven hospitals across Canada and from Northwestern Memorial Hospital in Chicago . Ticarcillin-clavulanate combined with ciprofloxacin or trimethoprim-sulfamethoxazole were assayed for synergy against 31 ticarcillin-resistant strains of S . maltophilia by using microtiter checkerboard panels and against 20 strains by using time-kill methodology . The combination of ciprofloxacin with ceftazidime was also evaluated by time-kill studies . Ticarcillin-clavulanate plus trimethoprim-sulfamethoxazole demonstrated synergy by checkerboard panels, with fractional inhibitory concentration indices ranging from 0.033 to 0.49, and by time-kill studies for all 20 strains tested . Synergy between ticarcillin-clavulanate plus ciprofloxacin was found by the checkerboard method for 24 of 31 strains (77%), with fractional inhibitory concentration indices ranging from 0.188 to 0.75 . A correlation between synergy by the checkerboard method and the reference time-kill study method was not observed for ticarcillin-clavulanate plus ciprofloxacin, with results for 3 of 10 strains being nonconcordant . Synergy with both ticarcillin-clavulanate plus ciprofloxacin and ceftazidime plus ciprofloxacin by the time-kill method was found to correlate with ciprofloxacin MICs of <32 micrograms/ml and zone diameters of >15 mm on Mueller-Hinton agar . Evaluation of these combinations in vivo may be warranted.

J Antibiot (Tokyo), 1995 Oct, 48(10), 1081 - 5
Isolation and structure determination of two novel phenazines from a Streptomyces with inhibitory activity against metallo-enzymes, including metallo-beta-lactamase; Gilpin ML et al.; Two novel metabolites, SB 212021 and SB 212305, have been isolated from a Streptomyces and shown to have molecular formulae of C15H10N2O5 and C20H17N3O8S, respectively . The structures were deduced by a combination of NMR techniques and mass spectral fragmentation patterns and shown to be novel members of the phenazine group of antibiotics . In the absence of added zinc, both compounds had IC50's of 1-75 microM for the Bacteroides fragilis 262 CfiA and Xanthomonas maltophilia L-1 metallo-beta-lactamases . The compounds also inhibited ACE with IC50's of 55 and 68 microM, respectively . Mode of action studies illustrate that the compounds inhibit some metalloenzymes by chelation of the active site metal ion . They exhibit poor antibacterial activity.

J Infect, 1995 Sep, 31(2), 89 - 92
Xanthomonas maltophilia and Pseudomonas cepacia in lower respiratory tracts of patients in critical care units; Maningo E et al.; Xanthomonas maltophilia and Pseudomonas cepacia are Gram-negative bacilli that are considered to opportunistic pathogens . These bacteria may cause colonization and infection, especially in acutely ill patients . Between 1 July 1990 and 30 June 1992 sputum {correction of suptum} culture results from patients in the critical care units were surveyed daily . During the 2 year period, sputum from 27 patients grew X . maltophilia . It was hospital-acquired in 26 patients . A total of 26 patients were mechanically ventilated for between 1 day and 8 months (median 19 days) before sputum cultures grew X . maltophilia . Various antimicrobial agents were prescribed for 25 of the 27 patients before they acquired X . maltophilia infection . The case fatality was 44.4% . Sputum from 79 patients grew P . cepacia . It was hospital-acquired in all who were ventilated for between 1 day and 50 days (median 9 days) before sputum cultures grew P . cepacia . Several antimicrobial agents were given to 77 patients before P . cepacia was isolated from them . The case fatality rate was 51.9% . In the majority of cases, the positive cultures indicated colonization . Patients with APACHE II scores >15 experienced a higher fatality (55.6% vs . 22.2%, P<0.05 for X . maltophilia and 56.9% vs.28.6%, P<0.05 for P . cepacia).

Glycobiology, 1995 Sep, 5(6), 603 - 10
A novel beta-galactosidase gene isolated from the bacterium Xanthomonas manihotis exhibits strong homology to several eukaryotic beta-galactosidases; Taron CH et al.; The gene encoding a beta-galactosidase from Xanthomonas manihotis was cloned into Escherichia coli . The gene resides on a 2.4 kb DNA fragment which was isolated from a partial Sau3A library in the cloning vector pUC19 using 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-gal) as the selection . The enzyme produced by the clone has a specificity for beta 1-3- > beta 1-4-linked galactose . The nucleotide sequence of the gene was determined . The deduced protein sequence contained 597 amino acids yielding a monomeric molecular mass of 66 kDa . The cloned beta-galactosidase showed no similarity to any known prokaryotic beta-galactosidase . However, extensive similarity was observed with eukaryotic beta-galactosidases from animals, plants and fungi . The strongest similarity was with the beta-galactosidases found in the human and mouse lysosomes (42 and 41% identity, respectively) . Alignment of the X.manihotis and eukaryotic beta-galactosidase sequences revealed seven highly conserved domains common to each protein . Additionally, Domain 1 in X.manihotis showed similarity to regions within catalytic domains from seven xylanases and cellulases belonging to family 10 of glucosyl hydrolases . A region spanning Domain 2 showed similarity to the catalytic domain of endo beta 1-3 glucanases from tobacco and barley.

J Bacteriol, 1995 Sep, 177(17), 4963 - 8
Intragenic recombination of a single plant pathogen gene provides a mechanism for the evolution of new host specificities; Yang Y et al.; Gene pthA is required for virulence of Xanthomonas citri on citrus plants and has pleiotropic pathogenicity and avirulence functions when transferred to many different xanthomonads . DNA sequencing revealed that pthA belongs to a family of Xanthomonas avirulence/pathogenicity genes characterized by nearly identical 102-bp tandem repeats in the central region . By inserting an nptI-sac cartridge into the tandemly repeated region of pthA as a selective marker, intragenic recombination among homologous repeats was observed in both Xanthomonas spp . and Escherichia coli . Intragenic recombination within pthA created new genes with novel host specificities and altered pathogenicity and/or avirulence phenotypes . Many pthA recombinants gained or lost avirulence function in pathogenicity assays on bean, citrus, and cotton cultivars . Although the ability to induce cell division (hyperplastic cankers) on citrus could be lost, this ability was not acquired on cotton or bean plants . Intragenic recombination therefore provides a genetic mechanism for the generation of multiple, different, and gratuitous avirulence genes from a single, required, host-specific pathogenicity gene.

Mol Plant Microbe Interact, 1995 Sep-Oct, 8(5), 778 - 80
Lipopolysaccharide from Xanthomonas campestris induces defense-related gene expression in Brassica campestris; Newman MA et al.; Purified lipopolysaccharide (LPS) from Xanthomonas campestris pv . campestris induced accumulation of transcript for beta-1,3-glucanase in turnip at concentrations of 1 micrograms/ml . The lipid A-inner core structure was required for activity but the O-antigen had no role . We suggest that release of LPS in planta triggers expression of at least some defense-related genes.

Mol Plant Microbe Interact, 1995 Sep-Oct, 8(5), 768 - 77
A locus determining pathogenicity of Xanthomonas campestris is involved in lipopolysaccharide biosynthesis; Dow JM et al.; A pathogenicity locus in Xanthomonas campestris pv . campestris has been shown to comprise two genes which mediate biosynthesis of the bacterial lipopolysaccharide (LPS) but not extracellular polysaccharide . Mutants with Tn5 insertions in either gene showed alterations in the electrophoretic patterns of both water-soluble and phenol-soluble LPS forms, which suggested defects in the biosynthesis of the core oligosaccharide component . On gel chromatography, core oligosaccharides of the mutants were of apparently lower molecular weight than those from the wild type . Furthermore, the content of mannose and glucose, sugars characteristic of the core oligosaccharide, were significantly lower in the water-soluble LPS of the mutants . Because of their role in LPS core biosynthesis, the two genes were called rfaX and rfaY . rfaX mutants show altered behavior in a range of host and non-host plants such that the number of recoverable bacteria drop within the first 24 h after inoculation . In contrast, the behavior of rfaY mutants only differed from the wild type in Datura, a non-host plant in which the growth of the wild type is severely attenuated . The predicted protein RfaY showed significant sequence homology to a sub-family of RNA polymerase sigma factors which are involved in extracytoplasmic functions.

Microbiology, 1995 Sep, 141 ( Pt 9), 2253 - 60
Fructose phosphotransferase system of Xanthomonas campestris pv . campestris: characterization of the fruB gene; de Crecy-Lagard V et al.; In the plant pathogen Xanthomonas campestris pv . campestris, fructose is transported by a specific phosphotransferase system (PTS) . This PTS involves a multiphosphoryl transfer protein (MTP) encoded by the fruB gene, which was cloned and sequenced . fruB is part of a transcriptional unit together with the fruK gene, coding for 1-phosphofructokinase, which is located upstream from the fruA gene, coding for the fructose-specific permease (EIIB'BCFru) . The amino acid sequence of the X . campestris MTP deduced from the fruB sequence shared 46% identical residues with an MTP identified in Rhodobacter capsulatus . The X . campestris MTP (837 amino acid residues) consists of three moieties: a fructose-specific enzyme-IIA-like N-terminal moiety (residues 1-148), followed by an HPr-like moiety (161-251) and an enzyme-I-like C-terminal moiety (274-837) . The three domains are separated by two flexible hinge regions rich in proline and alanine residues . The construction of a fruB mutant confirmed the role of the MTP in fructose transport and phosphorylation in X . campestris.

Carbohydr Res, 1995 Aug 11, 272(2), 225 - 30
Structure of the O6 antigen of Stenotrophomonas (Xanthomonas or Pseudomonas) maltophilia; Winn AM et al.; A polysaccharide containing D-xylose, L-rhamnose, and N-acetyl-D-glucosamine was released on mild acid hydrolysis of the lipopolysaccharide extracted from defatted cell walls of Stenotrophomonas (Xanthomonas or Pseudomonas) maltophilia strain 557, the reference strain for serotype O6 . By means of NMR spectroscopy and chemical degradations, the repeating unit of the polymer was identified as a branched trisaccharide with the structure shown . {formula: see text}

Antonie Van Leeuwenhoek, 1995 Aug, 68(2), 161 - 4
Xanthomonas campestris pv . parthenii pathovar nov . incitant of leaf blight of parthenium; Chand R et al.; A new bacterial leaf blight disease of parthenium (Parthenium hysterophorus L.) is described for the first time . The disease-causing bacterium was isolated and its morphological, physiological and biochemical characters were determined . The pathogenicity of bacterium is apparently limited only to parthenium . The pathogen was identified as Xanthomonas campestris pv . parthenii pathovar nov . on the basis of morphological, physiological, biochemical and pathogenic characteristics.

J Antimicrob Chemother, 1995 Aug, 36(2), 317 - 26
Growth temperature-dependent variation of cell envelope lipids and antibiotic susceptibility in Stenotrophomonas (Xanthomonas) maltophilia; Rahmati-Bahram A et al.; Clinical isolates of Stenotrophomonas (Xanthomonas) maltophilia showed growth temperature-dependent variation in susceptibility (TDVS) to aminoglycoside antibiotics between 30 degrees C and 37 degrees C, but little or no TDVS effect for polymixin B, colistin, ceftazidime, chloramphenicol and piperacillin . When phenylethanol was added at sub-inhibitory concentrations, the TDVS effect was eliminated . Gas liquid chromatography showed that 13-methyl tetradecanoate (i-15;0), was the predominant fatty acid, and was present in lower proportions in cells grown at 30 degrees C than 37 degrees C, by contrast to the unsaturated acids, which were found in increased proportions in cells grown at 30 degrees C . However, the extent of these shifts in composition did not correlate with the extent of the TDVS effect in individual strains . Membrane analysis by spin label-electron spin resonance spectroscopy showed that strains exhibiting TDVS had significantly decreased membrane fluidity compared with susceptible strains at 30 degrees C . Furthermore, analysis of the outer and cytoplasmic membranes from the strains with TDVS revealed that in organisms grown at 30 degrees C, the outer membrane remained in a more rigid conformation than the cytoplasmic membrane . We conclude that resistance of S . maltophilia to aminoglycoside antibiotics at 30 degrees C correlates with changes in the conformation of the outer membrane so that binding and/or uptake of the antibiotic is inhibited.

J Clin Microbiol, 1995 Aug, 33(8), 2195 - 8
Molecular typing of Stenotrophomonas (Xanthomonas) maltophilia by DNA macrorestriction analysis and random amplified polymorphic DNA analysis; Yao JD et al.; Stenotrophomonas (Xanthomonas) maltophilia is a multidrug-resistant, nosocomial pathogen for which optimal typing methods in epidemiologic investigations of nosocomial outbreaks have not been defined . We compared DNA macrorestriction analysis by pulsed-field gel electrophoresis (PFGE) with random amplified polymorphic DNA (RAPD) analysis by arbitrarily primed PCR for molecular typing of 109 multidrug-resistant strains of S . maltophilia from multiple outbreaks at our institution over a 10-month period in 1993 . PFGE after digestion with restriction endonuclease DraI revealed 62 unique DNA restriction profiles among the 109 strains, with 23, 11, 6, 6, and 3 strains having concordant profiles in each of five types . There were four concordant profiles among 8 strains (2 strains with each profile), while unique profiles were present in each of the remaining 52 strains . Further RAPD analysis with a decanucleotide primer showed the same number of distinct strain types as PFGE but more subtype diversity within each clonal type . We concluded that DNA macrorestriction analysis and RAPD analysis are sufficiently discriminatory and useful for differentiation of S . maltophilia strains in epidemiologic investigations of nosocomial outbreaks . However, RAPD analysis by arbitrarily primed PCR is faster and less laborious method of molecular typing.

J Hosp Infect, 1995 Aug, 30(4), 309 - 13
Nosocomial and community-acquired Xanthomonas maltophilia infection in tropical Australia; Heath T et al.; Xanthomonas maltophilia infection is recognized as a serious problem in association with immunosuppressive and invasive therapies, and with the use of broad-spectrum antibiotics . In Darwin Hospital in Australia's Northern Territory preliminary evidence of nosocomial transmission of X . maltophilia prompted this retrospective examination of all X . maltophilia isolates over a 30 month period . X . maltophilia was most frequently isolated in the 'wet season' corresponding to times of increased antibiotic treatment of the serious community-acquired pneumonias encountered in this tropical region . A relatively high proportion of community-acquired isolates (4/18; 22%) was documented . This study demonstrates that X . maltophilia infection is an emerging cause of morbidity in tropical regions where endemic infections require the use of broad-spectrum beta-lactams.

FEBS Lett, 1995 Jul 10, 368(1), 113 - 6
Structure of an acidic polysaccharide present in the bacteriolytic complex lysoamidase; Likhosherstov LM et al.; The structure of an acidic polysaccharide component of a bacteriolytic complex (lysoamidase), isolated from a bacterium of the genus Xanthomonas, was studied . On the basis of sugar analysis and one- and two-dimensional 1H and 13C NMR spectroscopic study of the initial polysaccharide and its O-deacetylated and carboxyl-reduced derivatives, the following structure of the trisaccharide repeating unit of the polysaccharide was established {formula: see text} where ManNAcA and GalNAcA are 2-acetamido-2-deoxymannuronic acid and 2-acetamido-2-deoxygalacturonic acid, respectively.

Rev Argent Microbiol, 1995 Jul-Sep, 27(3), 146 - 55
{Isolation of xanthan from Xanthomonas campesteris B-1459 in mechanically agitated fermentors}; Lorda GS et al.; Xanthan production from Xanthomonas campestris was studied by a mechanically shaken fermentor . Influence of glucose concentration, aeration of culture media, rheology of broths and pH control was evaluated . Different aeration conditions based on variation of stirring rates were assayed . Substrate concentration was determined according to the Miller method, and polymer production was performed by the Cadmus method . The higher xanthan levels (i.e . 2.3%) were obtained at 750 rpm, with 1 v/v . min . In such conditions, viscosity ranges about 7000 cPoise and a low level of dissolved oxygen were detected in the culture medium . Xanthan production was influenced by the glucose concentration and the presence of amaranth within the culture medium . In the processes wherein an automatic control of pH was performed, the polymer concentration did not increase regarding to processes involving regular pH evolution.

J Bacteriol, 1995 Jul, 177(14), 3932 - 9
A specific PulD homolog is required for the secretion of paracrystalline surface array subunits in Aeromonas hydrophila; Thomas SR et al.; Aeromonas hydrophila is an important pathogen of fish, and its high-virulence strains display a two-dimensional paracrystalline layer (S-layer) on their outermost surfaces . The nucleotide sequence of a 4.1-kb region located 700 bp upstream of the A . hydrophila TF7 S-layer protein gene (ahsA) has been determined . A sequence analysis of the region revealed the presence of three complete open reading frames ending in a gene encoding a 79.8-kDa polypeptide that shows high homology to the PulD family of secretion proteins . The sequenced region displays both organizational and sequence homology to the Xanthomonas campestris pv . campestris Xps secretory system . Insertional inactivation of the spsD (S-protein secretion D) gene showed that the loss of expression of the PulD homolog coincided with the localization of the S-protein in the periplasm and the loss of the S-layer from the surface of the bacterium . However, the secretion of the enzymes hemolysin, amylase, and protease was unaffected in the mutant with the nonfunctional spsD gene, as was the export of flagella and fimbrial proteins . Southern blot analysis showed that the spsD gene was not conserved among all strains of S-protein-producing A . hydrophila or Aeromonas veronii biotype sobria . Use of the promoterless chloramphenicol acetyltransferase gene showed that unlike pulD and its homologs, spsD contains its own promoter . A . hydrophila has been shown to contain the exe operon, which is responsible for the secretion of a number of extracellular enzymes in this bacterium . A fragment of DNA was generated from the exeD gene of A . hydrophilia Ah65 by PCR and was subsequently used in hybridization studies to probe the chromosome of A . hydrophila TF7 . The presence of an exeD homolog in A . hydrophila TF7 was found; therefore, the spsD gene encodes a second pulD homolog that displays a high specificity for the secretion of the S-protein . This gene appears to be part of a second terminal branch of the general secretory pathway in A . hydrophila.

Clin Diagn Lab Immunol, 1995 Jul, 2(4), 448 - 53
Oligonucleotide primers designed to differentiate pathogenic pseudomonads on the basis of the sequencing of genes coding for 16S-23S rRNA internal transcribed spacers; Tyler SD et al.; Universal primers targeting conserved sequences flanking the 3' end of the 16S and the 5' end of the 23S rRNA genes (rDNAs) were used to amplify the 16S-23S rDNA internal transcribed spacers (ITS) from eight species of pseudomonads which have been associated with human infections . Amplicons from reference strains of Pseudomonas aeruginosa, Pseudomonas cepacia, Pseudomonas gladioli, Pseudomonas mallei, Pseudomonas mendocina, Pseudomonas pickettii, Pseudomonas pseudomallei, and Xanthomonas maltophilia were cloned from each species, and sequence analysis revealed a total of 19 distinct ITS regions, each defining a unique sequevar with ITS sizes ranging from 394 (P . cepacia) to 641 (P . pseudomallei) bp . Five distinct ITS sequevars in P . cepacia, four in P . mendocina, three in P . aeruginosa, two each in P . gladioli and P . pseudomallei, and one each in P . mallei, P . pickettii, and X . maltophilia were identified . With the exception of one P . cepacia ITS, all ITS regions contained potential tRNA sequences for isoleucine and/or alanine . On the basis of these ITS sequence data, species-specific oligonucleotide primers were designed to differentiate P . aeruginosa, P . cepacia, and P . pickettii . The specificities of these primers were investigated by testing 220 clinical isolates, including 101 strains of P . aeruginosa, 103 strains of P . cepacia, and 16 strains of P . pickettii, in addition to 24 American Type Culture Collection (ATCC) Pseudomonas strains . The results showed that single primer pairs directed at particular ITSs were capable of specifically identifying the ATCC reference strains and all of the clinical isolates of P . aeruginosa and P . pickettii, but this was not the case with several ITS-based primer pairs tested for P . cepacia . This pathogen, on the other hand, could be specifically identified by primer pairs directed against the 23S rDNA.

Microbiology, 1995 Jun, 141 ( Pt 6), 1395 - 406
Subcellular location of XpsD, a protein required for extracellular protein secretion by Xanthomonas campestris pv . campestris; Hu NT et al.; The last ORF of an xps gene cluster, designated xpsD, is required for the secretion of extracellular enzymes across the outer membrane in Xanthomonas campestris pv . campestris . It could encode a protein of 759 amino acid residues . A consensus N-terminal lipoprotein signal peptide was revealed from its deduced amino acid sequence . A {3H}palmitate labelling experiment indicated that XpsD was fatty-acylated . Differential extraction with Triton X-100 disclosed that XpsD was fractionated with the outer membrane . Sucrose gradient sedimentation analysis of total membranes also indicated that XpsD was mainly located in the outer membrane . At least part of XpsD is exposed to the cell surface as suggested by trypsin experiment results . Intact cells pretreated with antibody against XpsD could indirectly be labelled with fluorescent agent . When the N-terminal lipoprotein signal peptide was replaced with a nonlipoprotein signal peptide cleavable by signal peptidase I, non-fatty-acylated XpsD was synthesized . Its subcellular location was indistinguishable from that of the fatty-acylated XpsD . Complementation of an xpsD::Tn5 mutant of X . campestris pv . campestris indicated that this non-fatty-acylated XpsD remains functional in extracellular protein secretion . A stable, C-terminal truncated protein, XpsD delta 414-759, was synthesized from a mutated xpsD gene . Although it stayed associated with the outer membrane and exposed to the cell surface, it no longer could complement the xpsD::Tn5 mutant of X . campestris pv . campestris.

Gene, 1995 May 26, 158(1), 73 - 6
Characterization of an open reading frame involved in site-specific integration of filamentous phage Cf1t from Xanthomonas campestris pv . citri; Shieh GJ et al.; Cf1t is a single-stranded DNA filamentous phage; a 1.9-kb segment of DNA from Cf1t was found to be responsible for site-specific integration into Xanthomonas campestris pv . citri (XW47), in the absence of any Xanthomonas origin of replication . Deletion analysis and introduction of amber stop codons into this fragment from Cf1t revealed an open reading frame (ORF344) which was involved in the integration function . The predicted amino-acid sequence of ORF344 bears no homology with conserved sequences of the integrase family.

J Clin Microbiol, 1995 May, 33(5), 1289 - 91
Genomic fingerprinting of epidemic and endemic strains of Stenotrophomonas maltophilia (formerly Xanthomonas maltophilia) by arbitrarily primed PCR; VanCouwenberghe CJ et al.; Arbitrarily primed PCR (AP-PCR) was used to type 64 clinical isolates of Stenotrophomonas maltophilia from 60 patients and the hands of one nurse . Forty-seven different patterns were observed, most patients having isolates with unique genomic fingerprints . A single pattern, however, was obtained from six of eight patients involved in an intensive care nursery outbreak, confirming the suspected nosocomial transmission of this microorganism . This strain was also found in four other patients hospitalized at the same time but in different units . AP-PCR typing results had a good correlation with the 49 patterns obtained when the isolates were typed by contour-clamped homogeneous electric field gel electrophoresis . Although AP-PCR is slightly less discriminatory than contour-clamped homogeneous electric field gel electrophoresis, it offers several advantages and should be considered as a practical option for molecular typing during investigations of outbreaks.

J Clin Microbiol, 1995 May, 33(5), 1428 - 30
Comparison of E test and agar dilution for antimicrobial susceptibility testing of Stenotrophomonas (Xanthomonas) maltophilia; Yao JD et al.; Currently recommended dilution test methods for the determination of antimicrobial susceptibility of Stenotrophomonas (Xanthomonas) maltophilia are labor-intensive and often impractical in many clinical laboratories . We compared the E test with the agar dilution method for susceptibility testing of 176 clinical isolates of S . maltophilia against 16 antimicrobial agents . The MICs obtained by E test correlated well with those determined by the agar dilution method, with an overall agreement of 94% . Very major and major errors occurred infrequently (0.6 to 2.9%) when testing beta-lactam agents, tobramycin, trimethoprim-sulfamethoxazole, and fluoroquinolones . The E test was found to be accurate and easy to perform . For most antimicrobial agents tested against S . maltophilia, the E test is an acceptable alternative susceptibility test method.

Gene, 1995 Apr 14, 156(1), 75 - 8
Complete sequence of the gene encoding a chorionic gonadotropin-like protein from Xanthomonas maltophilia; Grover S et al.; Our laboratory has previously reported that: (i) Xanthomonas maltophilia (Xm) produces a protein which has immunological resemblance to the beta-subunit of human chorionic gonadotropin (hCG) and (ii) possesses a high-affinity receptor which binds holo hCG, and the endogenous ligand, Xm chorionic gonadotropin (xCG), but does not bind human luteinizing hormone (hLH) . We have also previously published a 492-bp partial nucleotide sequence of the gene (xcg) coding for xCG . We report herein the entire xcg sequence of 1362 bp, which codes for a 48-kDa protein . This sequence confirmed the 492-bp sequence, as well as two partial amino acid (aa) sequences which we have previously reported . The sequence has a region which is homologous to aa 56-139 of the beta-subunit of hCG, and a second region homologous to the C-terminal tail of hCG . This is the first report of a prokaryotic gene homologous to the hCG beta-subunit-encoding gene.

Plant Physiol, 1995 Apr, 107(4), 1333 - 41
Rice cationic peroxidase accumulates in xylem vessels during incompatible interactions with Xanthomonas oryzae pv oryzae; Young SA et al.; A cationic peroxidase, PO-C1 (molecular mass 42 kD, isoelectric point 8.6), which is induced in incompatible interactions between the vascular pathogen Xanthomonas oryzae pv oryzae and rice (Oryza sativa L.), was purified . Amino acid sequences from chemically cleaved fragments of PO-C1 exhibited a high percentage of identity with deduced sequences of peroxidases from rice, barley, and wheat . Polyclonal antibodies were raised to an 11-amino acid oligopeptide (POC1a) that was derived from a domain where the sequence of the cationic peroxidase diverged from other known peroxidases . The anti-POC1a antibodies reacted only with a protein of the same mobility as PO-C1 in extracellular and guttation fluids from plants undergoing incompatible responses collected at 24 h after infection . In the compatible responses, the antibodies did not detect PO-C1 until 48 h after infection . Immunoelectron microscopy was used to demonstrate that PO-C1 accumulated within the apoplast of mesophyll cells and within the cell walls and vessel lumen of xylem elements of plants undergoing incompatible interactions.

Chemotherapy, 1995 Mar-Apr, 41(2), 121 - 4
Clinical isolate of a Xanthomonas maltophilia strain producing L-1-deficient and L-2-inducible beta-lactamases; Bonfiglio G et al.; Xanthomonas maltophilia produces two inducible beta-lactamases, L-1 and L-2, and resists the antimicrobial activity of beta-lactam antibiotics including carbapenems . L-1 has carbapenemase activity and L-2 is a cephalosporinase . It has been suggested that these beta-lactamases share regulatory components . We isolated a recent clinical X . maltophilia strain susceptible to carbapenems and resistant to almost all the other beta-lactam antibiotics tested . beta-Lactamase induction with cefotaxime showed that the clinical isolate had low-level expression of L-1 beta-lactamase but remained inducible for L-2 enzyme . The possible relationship of this enzyme to carbapenem sensitivity is considered.

J Clin Microbiol, 1995 Mar, 33(3), 513 - 8
Molecular epidemiology of Xanthomonas maltophilia colonization and infection in the hospital environment; Laing FP et al.; Between April 1992 and December 1993, 80 Xanthomonas maltophilia isolates were collected from 63 patients in three acute-care hospitals in Calgary, Alberta, Canada . On the basis of Centers for Disease Control and Prevention definitions, 48 patients had nosocomial and 15 had community-acquired X . maltophilia . Thirty-eight of the patients were colonized and 25 were infected . Sixty-four percent of patients who acquired X . maltophilia in the intensive care unit (ICU) became infected, whereas 32% of patients in a non-ICU setting became infected . ICU patients tended to be hospitalized for a shorter period of time than non-ICU patients before the onset of X . maltophilia infection . Regardless of being colonized or infected, all patients had debilitating conditions, with respiratory disease being the most common underlying illness (35%) . Forty-two patients (88%) with hospital-acquired X . maltophilia received prior antibiotic therapy which included gentamicin, tobramycin, ceftazidime, piperacillin, and imipenem . Agar dilution MICs showed that patient isolates were resistant to these antimicrobial agents that patients had received . Pulsed-field gel electrophoresis of SpeI-digested genomic DNA revealed that six epidemiologically linked patient isolates from the ICU of one acute-care hospital had identical DNA profiles . In contrast, isolates from patients from the other two hospitals had unique genotype profiles (n = 57) regardless of the presence or absence of an epidemiologic association . In these patients there was genetic evidence against the acquisition of a resident hospital clone . These results indicate that pulsed-field gel electrophoresis can resolve genotypically distinct strains of X . maltophilia and, consequently, is a useful tool for evaluating nosocomial infections caused by X . maltophilia.

Biochem Biophys Res Commun, 1995 Feb 6, 207(1), 223 - 30
Nucleotide sequence and expression of UDP-glucose dehydrogenase gene required for the synthesis of xanthan gum in Xanthomonas campestris; Lin CS et al.; Xanthomonas campestris pv . campestris, producing large amounts of exopolysaccharide xanthan gum, has a mucoid phenotype . Strain SD7 was a non-mucoid mutant deficient in UDP-glucose dehydrogenase . A DNA fragment able to complement the mutation of SD7 was cloned from the parental wild-type strain Xc11 . Sequence analysis of the region required for the complementation revealed an open reading frame which could encode a polypeptide of 445 amino acids with a calculated molecular weight of 48,432, a size similar to that of the product produced by maxicell . The amino acid sequence had significant homology to that of the GDP-mannose dehydrogenase from Pseudomonas aeruginosa.

Glycobiology, 1995 Feb, 5(1), 19 - 28
Purification and characterization of novel glycosidases from the bacterial genus Xanthomonas; Wong-Madden ST et al.; Enzymatic analysis of oligosaccharides using exoglycosidases has become a powerful tool for determining the sequence and structure of sugar chains . The principal limitation to these methods has been the lack of highly purified and well-characterized enzymes . Using fluorescently labelled carbohydrate substrates and TLC, we have developed a method to identify glycosidases with novel specificities . This screening method led to the discovery that bacteria of the genus Xanthomonas are a rich source of exoglycosidases . From Xanthomonas manihotis, eight novel exoglycosidases have been isolated and characterized . A novel beta-N-acetylglucosaminidase has been purified that, unlike those previously described, will cleave N-acetylglucosamine without cleaving N-acetylgalactosamine residues . A novel beta-galactosidase has been isolated that preferentially hydrolyses beta(1-->3) galactosyl linkages . Three alpha-mannosidases have been isolated that serve as useful reagents in the analysis of high-mannose oligosaccharide structures: alpha 1-3,6 mannosidase, alpha 1-6 mannosidase and alpha 1-2,3 mannosidase . An alpha 1-3,6 galactosidase has been purified that does not hydrolyse terminal alpha 1-4 galactose residues . Two fucosidases, alpha 1-3,4 fucosidase and alpha 1-2 fucosidase, are similar to enzymes purified from other sources . Together, these glycosidases provide powerful reagents for determining the sequence of complex carbohydrates . Equally important is their usefulness in selectively removing specific sugar residues and thereby creating novel carbohydrates for analysing the biological roles of oligosaccharides.

Biosci Biotechnol Biochem, 1995 Feb, 59(2), 298 - 301
Prolylcarboxypeptidase (angiotensinase C): purification and characterization of the enzyme from Xanthomanas maltophilia; Suga K et al.; Prolylcarboxypeptidase (Angiotensinase C, EC 3.4.16.2) was purified to homogeneity from cell free extracts of Xanthomonas maltophilia by ammonium sulfate fractionation and sequential chromatographies on DEAE-Toyopearl, Sephadex G-150, FPLC-Hiload Superdex 200 pg, and FPLC-Hitrap SP columns, with an activity recovery of 15% . The molecular weight of the enzyme was found to be 330,000 by gel filtration and 83,000 by SDS-PAGE, suggesting a tetrameric form for the native enzyme . It had an optimum pH of 8.5 and stability between pH 8.0 and 11.0 . The isoelectric point of the enzyme was 6.6 . The enzyme hydrolyzed Pro-X bonds when proline was in the penultimate position from the carboxyl terminal . The enzyme was strongly inhibited by diisopropylfluorophosphate (DFP), while phenylmethylsulfonyl fluoride (PMSF), p-chloromercuribenzoic acid (PCMB), iodoacetamide, and metal chelators had no effect.

Eur J Clin Microbiol Infect Dis, 1995 Feb, 14(2), 137 - 40
Diversity of nosocomial Xanthomonas maltophilia (Stenotrophomonas maltophilia) as determined by ribotyping; Gerner-Smidt P et al.; Seventy-seven clinical isolates of Xanthomonas maltophilia (Stenotrophomonas maltophilia) were consecutively collected from the Rigshospitalet, Copenhagen, ribotyped and compared with the ribotypes of 25 other clinical and reference strains of Xanthomonas maltophilia . Using restriction enzyme EcoRI, 20 different ribotypes were observed, with 78 isolates displaying the five most common types . Using another enzyme, BamHI, these 78 isolates were further subdivided into 16 different ribotypes . Three patients harboured two strains with different ribotypes . No type was found related to only one department and no single-strain outbreak was detected . The origin of this wealth of different strains in hospital patients needs to be established.

Clin Infect Dis, 1995 Feb, 20(2), 445 - 8
Xanthomonas maltophilia misidentified as Pseudomonas cepacia in cultures of sputum from patients with cystic fibrosis: a diagnostic pitfall with major clinical implications; Burdge DR et al.; Pseudomonas cepacia infection in patients with cystic fibrosis (CF) has major significance in terms of infection control, psychosocial issues, and medical treatment . We describe three instances in which the diagnostic laboratory misidentified Xanthomonas maltophilia as P . cepacia in cultures of sputum from patients with CF . These errors were recognized when 3 (9%) of 32 isolates, which had all been identified as P . cepacia and had been submitted to the Canadian Pseudomonas Repository Laboratory (Vancouver, BC), were correctly identified there as X . maltophilia . Each of the three isolates grew well on P . cepacia media, turned a characteristic vivid pink color, were polymyxin-resistant, and were lysine-positive . All three were initially characterized incorrectly as oxidase-positive and DNase-negative . The diagnostic laboratory then reexamined 24 other isolates that had been identified as P . cepacia; complete biochemical testing confirmed that all were indeed P . cepacia . Because infection due to P . cepacia has major implications for patients with CF, when a possible strain of P . cepacia is isolated, careful and complete characterization should be performed.

Carbohydr Res, 1995 Feb 1, 267(1), 127 - 33
Structure of the O10 antigen of Stenotrophomonas (Xanthomonas) maltophilia; Winn AM et al.; A polysaccharide containing L-rhamnose and L-xylose was isolated from the lipopolysaccharide extracted from the cell walls of the reference strain for Stenotrophomonas (Xanthomonas) maltophilia serogroup O10 . By means of NMR studies and methylation analysis, the repeating unit of the polymer was identified as a branched tetrasaccharide of the structure shown . {formula: see text}

Adv Exp Med Biol, 1995, 390, 71 - 80
A low-copy number plasmid mediating beta-lactamase production by Xanthomonas maltophilia; Kelly MD et al.; To delineate the mechanisms contributing to the high level of antimicrobial resistance often demonstrated by Xanthomonas maltophilia, plasmid DNA was isolated from 5 clinical isolates and analyzed . Purified plasmid DNA from a single isolate contained a 6.5 kb plasmid (pXM222) and a 5.6 kb plasmid, (pTHB) . Transformation of pTHB into E . coli HB101 resulted in the expression of resistance to all penicillins tested and cefazolin.

J Antimicrob Chemother, 1995 Jan, 35(1), 167 - 71
The role of lipopolysaccharide anionic binding sites in aminoglycoside uptake in Stenotrophomonas (Xanthomonas) maltophilia; Vanhoof R et al.; Aminoglycoside resistance was investigated in six clinical isolates of Stenotrophomonas (Xanthomonas) maltophilia by studying the uptake kinetics and by using a radiochemical method to detect aminoglycoside modifying enzymes . Furthermore, the lipopolysaccharides (LPS) were extracted and characterized by SDS-PAGE and chemical analysis . Dansyl-polymyxin displacement experiments confirmed the availability of anionic binding sites . Growing cells of the isolates bound dansyl-polymyxin but were not lysed.

Antimicrob Agents Chemother, 1995 Jan, 39(1), 192 - 9
Kinetic analysis of extension of substrate specificity with Xanthomonas maltophilia, Aeromonas hydrophila, and Bacillus cereus metallo-beta-lactamases; Felici A et al.; Twenty beta-lactam molecules, including penicillins, cephalosporins, penems, carbapenems, and monobactams, were investigated as potential substrates for Xanthomonas maltophilia ULA-511, Aeromonas hydrophila AE036, and Bacillus cereus 5/B/6 metallo-beta-lactamases . A detailed analysis of the kinetic parameters examined confirmed these enzymes to be broad-spectrum beta-lactamases with different ranges of catalytic efficiency . Cefoxitin and moxalactam, substrates for the beta-lactamases from X . maltophilia ULA-511 and B . cereus 5/B/6, behaved as inactivators of the A . hydrophila AE036 metallo-beta-lactamase, which appeared to be unique among the enzymes tested in this study . In addition, we report a new, faster, and reliable purification procedure for the B . cereus 5/B/6 metallo-beta-lactamase, cloned in Escherichia coli HB101.

DNA Seq, 1995, 5(5), 299 - 305
A homolog of an Escherichia coli phosphate-binding protein gene from Xanthomonas oryzae pv . oryzae; Hopkins CM et al.; A Xanthomonas oryzae pv . oryzae gene with sequence similarity to an Escherichia coli phosphate-binding protein gene (phoS) produces a periplasmic protein of apparent M(r) 35,000 when expressed in E . coli . Amino terminal sequencing revealed that a signal peptide is removed during transport to the periplasm in E . coli.

Ann Intern Med, 1994 Dec 15, 121(12), 969 - 73
Mucocutaneous and soft tissue infections caused by Xanthomonas maltophilia . A new spectrum; Vartivarian SE et al.; OBJECTIVE: To describe the mucocutaneous and soft tissue infections caused by Xanthomonas maltophilia in patients with cancer . DESIGN: A retrospective 15-month clinical study . SETTING: Academic, referral-based cancer center . PATIENTS: Of 237 patients with X . maltophilia isolated from all sites during the 15-month study period, 114 patients were judged to have true X . maltophilia infections . Only patients with mucocutaneous and soft tissue infections were included in the study . RESULTS: 17 (15%) of the 114 patients with X . maltophilia infection had mucocutaneous and soft tissue infections: Six patients had metastatic cellulitis, 5 had primary cellulitis usually associated with catheter use, and 6 had infected mucocutaneous ulcers . The metastatic cellulitis consisted of previously undescribed multiple, hard, tender nodules with surrounding and distant cellulitis (5 patients) or ecthyma gangrenosum (1 patient) . Four of these patients died of the infection . Metastatic cellulitis and mucocutaneous infections occurred in hospitalized, neutropenic patients who received broad-spectrum antibiotics (beta-lactams, quinolones), often with in vitro activity against the infecting organisms . Response usually correlated with recovery from myelosuppression and administration of trimethoprim-sulfamethoxazole with or without ticarcillin-clavulanate . Catheter removal contributed to response in the treatment of primary cellulitis . CONCLUSIONS: Mucocutaneous and soft tissue infections caused by X . maltophilia are not uncommon, and X . maltophilia can cause metastatic nodular skin lesions that mimic disseminated fungal infections . It also causes serious morbidity and high mortality in patients with metastatic skin nodules and can cause superinfections in patients receiving broad-spectrum beta-lactam or quinolone antibiotics to which the organisms are susceptible when the infections develop . Catheter removal contributes to a favorable outcome in patients with catheter-associated cellulitis without bacteremia . Xanthomonas maltophilia infection should be added to the differential diagnosis of mucocutaneous or soft tissue infection in patients with cancer . Trimethoprim-sulfamethoxazole with or without ticarcillin-clavulanate is the current treatment of choice for culture-proven infections, but early empiric therapy may improve outcome.

Biosci Biotechnol Biochem, 1994 Dec, 58(12), 2269 - 70
Enhancing effect of 4-hydroxy-3-nitrophenylacetic acid on transcription of the ice nucleation-active gene of Xanthomonas campestris; Watanabe M et al.; Cultivation of an ice nucleation-active strain of Xanthomonas campestris in the presence (1 ppm) of 4-hydroxy-3-nitrophenylacetic acid resulted in enhancement of its ice-nucleation activity . Both the ice-nucleation-active protein, InaX, and its mRNA were effectively expressed in the bacterial cells cultured in the presence of this compound . This indicates that this compound stimulated the biosynthesis of the ice-nucleation-active protein.

Ugeskr Laeger, 1994 Nov 28, 156(48), 7229 - 30
{Xanthomonas maltophilia . A cause of epidural abscess in a patient with epidural catheterization}; Wagn P et al.; A case of epidural abscess following continuous spinal epidural catheterization is presented . The clinical signs included spinal ache, root pain, weakness and paralysis but no fever . Xanthomonas maltophilia, an organism closely related to Pseudomonas species, was the causative agent . This has not previously been described as the causative agent of epidural abscesses.

Appl Environ Microbiol, 1994 Nov, 60(11), 4094 - 9
Sensitive and specific detection of Xanthomonas campestris pv . pelargonii with DNA primers and probes identified by random amplified polymorphic DNA analysis; Manulis S et al.; The random amplified polymorphic DNA method was used to distinguish strains of Xanthomonas campestris pv . pelargonii from 21 other Xanthomonas species and/or pathovars . Among the 42 arbitrarily chosen primers evaluated, 3 were found to reveal diagnostic polymorphisms when purified DNAs from compared strains were amplified by the PCR . The three primers revealed DNA amplification patterns which were conserved among all 53 strains tested of X . campestris pv . pelargonii isolated from various locations worldwide . The distinctive X . compestris pv . pelargonii patterns were clearly different from those obtained with any of 46 other Xanthomonas strains tested . An amplified 1.2-kb DNA fragment, apparently unique to X . campestris pv . pelargonii by these random amplified polymorphic DNA tests, was cloned and evaluated as a diagnostic DNA probe . It hybridized with total DNA from all 53 X . campestris pv . pelargonii strains tested and not with any of the 46 other Xanthomonas strains tested . The DNA sequence of the terminal ends of this 1.2-kb fragment was obtained and used to design a pair of 18-mer oligonucleotide primers specific for X . campestris pv . pelargonii . The custom-synthesized primers amplified the same 1.2-kb DNA fragment from all 53 X . campestris pv . pelargonii strains tested and failed to amplify DNA from any of the 46 other Xanthomonas strains tested . DNA isolated from saprophytes associated with the geranium plant also did not produce amplified DNA with these primers . The sensitivity of the PCR assay using the custom-synthesized primers was between 10 and 50 cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasmid, 1994 Nov, 32(3), 328 - 32
Replicon typing of plasmids of phytopathogenic xanthomonads; Amuthan G et al.; Replicon types of plasmids of phytopathogenic Xanthomonads have been identified . Plasmids of Xanthomonas oryzae pathovar oryzae belonged to types RepP, RepW, RepY, RepU, and RepF1 and 50% of the plasmids of different isolates of X.o.pv.oryzae belonged to type RepP . X.c.pv.citri contained plasmids belonging to RepF1 and RepF11 . Of the 19 replicon probes used, only 9 (repP, repF1, repF11, repY, repQ, repW, repX, and repU) hybridized with various plasmids of Xanthomonas.

Mol Plant Microbe Interact, 1994 Nov-Dec, 7(6), 799 - 804
AVRXa10 protein is in the cytoplasm of Xanthomonas oryzae pv . oryzae; Young SA et al.; AVRXa10 from Xanthomonas oryzae pv . oryzae was tagged with a unique hydrophilic octapeptide (FLAG) to permit antibody-mediated identification and purification of the gene product . X . o . pv . oryzae that produced tagged AVRXa10 elicited a hypersensitive response (HR) on rice cultivars containing the resistance gene Xa-10, but not on cultivars lacking Xa-10 . The tagged AVRXa10 protein purified from Escherichia coli or X . o . pv . oryzae did not elicit a hypersensitive response in rice with the Xa-10 resistance gene . Anti-FLAG monoclonal antibodies reacted with a 119-kDa protein in both E . coli and X . o . pv . oryzae cells expressing the tagged avrXa10 gene . Polyclonal antibodies raised against purified AVRXa10 protein reacted with the 119-kDa protein and several additional proteins from X . o . pv . oryzae, which probably are the products of genes related to avrXa10 . Biochemical fractionation and immunoelectronmicroscopy analysis was used to demonstrate that AVRXa10 was located in the cytoplasm of X . o . pv . oryzae cells when grown in planta or in culture medium.

Infect Control Hosp Epidemiol, 1994 Nov, 15(11), 691 - 6
Analysis of epidemic and endemic isolates of Xanthomonas maltophilia by contour-clamped homogeneous electric field gel electrophoresis; VanCouwenbergh C et al.; BACKGROUND: Xanthomonas maltophilia is increasingly a cause of nosocomial infections . The mode of transmission of this organism is not well known . OBJECTIVE: To investigate clonality of X maltophilia isolates in epidemic and endemic settings . METHODS: An outbreak of X maltophilia was noted in the Intensive Care Nursery (ICN) . Over the ensuing 9 months, hospital wide isolates of X maltophilia were analyzed using contour-clamped homogeneous electric field (CHEF) gel electrophoresis of chromosomal DNA . This method was compared with the antibiogram for detecting differences and similarities among strains . RESULTS: X maltophilia was recovered from 76 sites in 72 patients; 65 isolates from 61 patients and the hands of one nurse were available for analysis . CHEF demonstrated differences between most epidemiologically unrelated strains and similarity between most epidemiologically related strains . Several strains, initially presumed to be related because of temporal and spatial proximity of the patients involved, were determined by CHEF analysis to be independent infections . One pair of isolates whose XbaI CHEF patterns differed by a single band were differentiated clearly by SspI . There was enough variation in the minimum inhibitory concentrations of selected antibiotics to allow typing of some strains . The antibiogram, however, did not group all of the ICN outbreak isolates with others found to be genetically identical by CHEF, and it grouped 39 of 56 isolates with others not genetically the same . CONCLUSIONS: Although it is a convenient and economical tool, the antibiogram has limitations . Analysis by CHEF should help to elucidate the epidemiological spread of X maltophilia in the hospital.

J Clin Microbiol, 1994 Nov, 32(11), 2856 - 7
Pneumonia caused by Stenotrophomonas maltophilia with a mucoid phenotype; Irifune K et al.; We describe the first known case of pneumonia caused by a mucoid Stenotrophomonas maltophilia (Xanthomonas maltophilia) strain in a patient with bronchiectasis . The patient was admitted because of mild hemoptysis and productive cough with infiltrative shadow in the right lower lung field on chest X ray . The clinical symptoms were mild, and treatment with minocycline was effective.

Microbiology, 1994 Nov, 140 ( Pt 11), 3007 - 13
Gellan lyases--novel polysaccharide lyases; Kennedy L et al.; A number of bacterial strains capable of degrading the bacterial exopolysaccharide gellan have been isolated by standard enrichment procedures . They include several pink-pigmented Gram-negative rod-shaped bacteria . A red-pigmented Gram-positive bacillus earlier found to degrade the exopolysaccharide xanthan from Xanthomonas campestris also showed slight gellanase activity . All the Gram-negative bacteria are non-fermentative, motile and amylase-producing . The gellan degradation in each case is due to eliminase-type enzymes (lyases) which appear to be extracellular enzymes cleaving the sequence.. . beta-D-glucosyl-(1-->4)-beta-D-glucuronosyl.. . in the tetrasaccharide repeat unit of the substrate polysaccharides . Although in some isolates these enzymes appear to be exo-acting, it appears from the loss in viscosity of the alternative substrate deacetylated rhamsan that they are predominantly endoenzymes . The enzyme activity is inducible: it is almost absent from glucose-grown cells . Associated with the 'gellanase' activity, all the Gram-negative bacterial isolates possess intracellular alpha-L-rhamnosidase and beta-D-glucosidase activities apparently located in the periplasm . The enzymes are highly specific and fail to cause significant degradation of most of the other bacterial exopolysaccharides which have been shown to be structurally related to gellan . As well as acting on gellan, they exert similar degradative activity against the chemically deacylated form of polysaccharide S194 (rhamsan gum), which is effectively a gentiobiosylated form of gellan . The enzymes only have relatively slight activity against the natural, acylated gellan-like polysaccharides from the bacteria now designated as strains of Sphingomonas paucimobilis.

J Appl Bacteriol, 1994 Nov, 77(5), 509 - 18
Production of monoclonal antibodies against Xanthomonas campestris pv . mangiferaeindicae and their use to investigate differences in virulence; Sanders GM et al.; Four Xanthomonas campestris pv . mangiferaeindicae isolates from mango black spot lesions were grouped according to differences in virulence and used to raise monoclonal antibodies (mAbs) . Two immunization approaches were followed . In the first, four groups of mice were immunized, each with a different isolate and the spleens from each group homogenized together for cell fusion . The second approach entailed immunization of a single group of mice with bacteria pooled from all four isolates . The resultant mAbs were characterized with regard to the antigen binding specificity and antibody class . A relationship between mAb binding specificity and virulence of the bacteria was shown by Western blot analysis.

J Bacteriol, 1994 Oct, 176(20), 6229 - 37
Mechanism of bacitracin resistance in gram-negative bacteria that synthesize exopolysaccharides; Pollock TJ et al.; Four representative species from three genera of gram-negative bacteria that secrete exopolysaccharides acquired resistance to the antibiotic bacitracin by stopping synthesis of the exopolysaccharide . Xanthomonas campestris, Sphingomonas strains S-88 and NW11, and Escherichia coli K-12 secrete xanthan gum, sphingans S-88 and NW11, and colanic acid, respectively . The gumD gene in X . campestris is required to attach glucose-P to C55-isoprenyl phosphate, the first step in the assembly of xanthan . A recombinant plasmid carrying the gumD gene of X . campestris restored polysaccharide synthesis to bacitracin-resistant exopolysaccharide-negative mutants of X . campestris and Sphingomonas strains . Similarly, a newly cloned gene (spsB) from strain S-88 restored xanthan synthesis to the same X . campestris mutants . However, the intergeneric complementation did not extend to mutants of E . coli that were both resistant to bacitracin and nonproducers of colanic acid . The genetic results also suggest mechanisms for assembling the sphingans which have commercial potential as gelling and viscosifying agents.

J Gen Virol, 1994 Sep, 75 ( Pt 9), 2543 - 7
Characterization of two novel filamentous phages of Xanthomonas; Lin NT et al.; Two filamentous phages of Xanthomonas campestris pv . vesicatoria and Xanthomonas oryzae pv . oryzae were isolated and designated phi Xv and phi Xo, respectively . They were similar to other filamentous phages of Xanthomonas in (i) shape, (ii) restrictive host specificity, (iii) high stability, (iv) an ssDNA genome, (v) a dsDNA as the replicative form (RF), (vi) propagation without lysis of host cells and (vii) ability to integrate into the host chromosome . These phages showed sequence homology to filamentous phage phi Lf of X . c . pv . campestris . phi Xv was inactivated by antisera against phi Xv, phi Xo and phi Lf, whereas phi Xo and phi Lf were inactivated only by their respective antisera and the anti-phi Xv serum . Both the single-stranded phage DNAs and the RF DNAs of phi Xv, phi Xo and phi Lf were able to transfect X . c . pv . vesicatoria, X . o . pv . oryzae and X . c . pv . campestris . Physical maps of phi Xv and phi Xo were constructed for the RF DNAs . Genome sizes were estimated, based on mapping data, to be 6.8 kb for phi Xv and 7.6 kb for phi Xo, larger than that of the phi Lf genome (6.0 kb) . The difference in genome sizes appeared to result from insertions of large DNA fragments . These fragments and the regions mediating integration were localized in the physical maps.

Mol Plant Microbe Interact, 1994 Sep-Oct, 7(5), 677 - 9
Avirulence gene avrPphC from Pseudomonas syringae pv . phaseolicola 3121: a plasmid-borne homologue of avrC closely linked to an avrD allele; Yucel I et al.; Cosmid clone pPsp01 from race 1 Pseudomonas syringae pv . phaseolicola isolate 3121 conferred a unique pattern of soybean cultivar reactions when expressed in P . s . pv . glycinea R4 . The avirulence phenotype was shown to result from the presence in clone pPsp01 of an avrD allele as well as an additional avirulence gene located approximately 5-kb upstream . The new gene, called avrPphC, shows high identity to and is phenotypically identical to avrC, previously cloned from P . s . pv . glycinea race 0 . avrD and avrPphC occur on an approximately 120-kb indigenous plasmid in P . s . pv . phaseolicola 3121 . Although commonly observed in Xanthomonas campestris, this is the first noted occurrence of multiple avirulence genes on a single plasmid in Pseudomonas syringae . Unlike avrD, however, avrPphC does not appear to occur widely in pathovars of Pseudomonas syringae.

Mol Plant Microbe Interact, 1994 Sep-Oct, 7(5), 553 - 63
Defense-related gene induction in Brassica campestris in response to defined mutants of Xanthomonas campestris with altered pathogenicity; Newman MA et al.; We have studied the induction of beta-1,3-glucanase (BGL) in turnip following inoculation with pathovars of Xanthomonas campestris and derived mutants . BGL transcript accumulated more rapidly in leaves in the incompatible interactions with X . c . pv . armoraciae and X . c . pv . raphani than in the compatible interaction with X . c . pv . campestris . No accumulation was seen in response to wounding or inoculation with water, salicylic acid, or Escherichia coli . Deletion of the hrp cluster from the X . campestris pathovars caused a reduction in the level of transcript accumulation; these effects were much more pronounced in the incompatible than in the compatible interaction, in which bacterial growth was also affected . In the compatible interaction, bacterial growth and BGL transcript accumulation were not altered by mutation of bacterial genes involved in the regulation of the synthesis of extracellular enzymes or their export from the cell, or by mutation of the structural genes for extracellular endoglucanase and serine protease . Mutation of genes involved in the synthesis of extracellular polysaccharide or lipopolysaccharide reduced bacterial survival in planta, so that the numbers were between two and three orders of magnitude lower than the number of wild-type bacteria . However, total BGL transcript accumulation after inoculation with these mutants was about 80% of that seen after inoculation with the wild-type bacteria, suggesting that one aspect of the role of extracellular polysaccharide and lipopolysaccharide in pathogenesis is to mask the presence of bacteria in the plant . Our results are discussed in the context of work on other plant-microbe interactions.

Antimicrob Agents Chemother, 1994 Sep, 38(9), 2143 - 9
Biochemical properties of inducible beta-lactamases produced from Xanthomonas maltophilia; Paton R et al.; Four different beta-lactamases have been found in several strains of Xanthomonas maltophilia isolated from blood cultures during 1984 to 1991 at the Edinburgh Royal Infirmary . One was a metallo-beta-lactamase with predominantly penicillinase activity and an isoelectric point of 6.8 . Its molecular size as determined by gel filtration was 96 kDa but was only 26 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), suggesting a tetramer of four equal subunits . The enzyme hydrolyzed all classes of beta-lactams except the monobactam aztreonam . This enzyme was not inhibited by potassium clavulanate or BRL 42715 but was inhibited by p-chloromercuribenzoate, mercuric chloride, and EDTA . The beta-lactamase was unstable in 50 mM sodium phosphate buffer (pH 8.0) but stable in 50 mM Tris HCl (pH 8.0) . The other beta-lactamases focused as a series of different isoelectric points, ranging from pI 5.2 to 6.6 . Together, these enzymes exhibited a broad spectrum of activity, hydrolyzing most classes of beta-lactams but not imipenem or aztreonam . Their molecular size was 48 kDa by Sephadex gel filtration and 24 kDa by SDS-PAGE, indicating that they were enzymes consisting of two equal subunits . They were inhibited by p-chloromercuribenzoate, mercuric chloride, potassium clavulanate, and BRL 42715 but not EDTA . This study demonstrated that X . maltophilia produces more than just the L1 and L2 beta-lactamases.

Gene, 1994 Aug 19, 146(1), 73 - 8
The sequence of the mer operon of pMER327/419 and transposon ends of pMER327/419, 330 and 05; Hobman J et al.; Three different, independently isolated mercury-resistance-conferring plasmids, pMER327/419, pMER330 and pMER05, from cultures originating from the river Mersey (UK), contain identical regulatory merR genes and transposon ends . The mer determinant from pMER327/419 contains an additional potential ORF (ORF F) located between merP and merA when compared with the archetypal Tn501 . Although these plasmids confer narrow-spectrum resistance (resistance to Hg2+, but not organomercurials) their merR genes encode a potential organomercurial-sensing protein . Transposition of the mer of pMER05 into plasmid RP4 was demonstrated and, as with Tn502 and Tn5053, insertion occurred at a specific region . The sequence of pMER05 is identical at the 'left' and 'right' termini and across merR to Tn5053, which was independently isolated from the chromosome of a Xanthomonas sp . bacteria from the Khaidarkan mercury mine in Kirgizia, former Soviet Union {Kholodii et al., J . Mol . Biol . 230 (1993a) 1103-1107} . The transpositional unit of pMER05 is, like that of Tn5053, bounded by DNA homologous to the imperfect 25-bp inverted repeats (IR) of the In2 integron, which brackets antibiotic-resistance cassettes in Tn21 subgroup transposons . At one end of the transposable element, and internal to the In2-like IR, is a 38-bp IR which closely resembles the IR that bounds Tn21.

Mol Gen Genet, 1994 Aug 15, 244(4), 383 - 90
Identification of the XorII methyltransferase gene and a vsr homolog from Xanthomonas oryzae pv . oryzae; Choi SH et al.; The gene encoding the XorII methyltransferase (M.XorII) was cloned from Xanthomonas oryzae pv . oryzae and characterized in Escherichia coli . The M.XorII activity was localized to a 3.1 kb BamHI-BstXI fragment, which contained two open reading frames (ORFs) of 1272 nucleotides (424 amino acids) and 408 nucleotides (136 amino acids) . Ten polypeptide domains conserved in other M5 cytosine methyltransferases (MTases) were identified in the deduced amino acid sequence of the 1272 ORF . E . coli Mrr+ strains were transformed poorly by plasmids containing the XorII MTase gene, indicating the presence of at least one MCG in the recognition sequence for M.XorII (CGATCG) . The 408 nucleotide ORF was 36% identical at the amino acid level to sequences of the E . coli dem-vsr gene, which is required for very short patch repair . X . oryzae pv . oryzae genomic DNA that is resistant to digestion by PvuI and XorII hybridizes with a 7.0 kb fragment containing the XorII MTase gene and vsr homolog, whereas DNA from strains that lack M.XorII activity do not hybridize with the fragment.

Clin Infect Dis, 1994 Aug, 19(2), 325 - 6
Meningitis due to Xanthomonas maltophilia: case report and review; Nguyen MH et al.; Xanthomonas maltophilia is being increasingly recognized as an opportunistic pathogen in debilitated patients . We report a case of postoperative meningitis due to X . maltophilia and review the cases of X . maltophilia meningitis reported in the literature . Because X . maltophilia is often resistant to multiple beta-lactam agents, including cephalosporins and imipenem, trimethoprim-sulfamethoxazole appears to be the drug of choice for treatment of X . maltophilia meningitis.

FEMS Microbiol Rev, 1994 Aug, 14(4), 381 - 6
Molecular mechanisms of copper resistance and accumulation in bacteria; Cooksey DA; An unusual mechanism of metal resistance is found in certain plant pathogenic strains of Pseudomonas syringae that are exposed to high levels of copper compounds used in disease control on agricultural crops . These bacteria accumulate blue Cu2+ ions in the periplasm and outer membrane . At least part of this copper sequestering activity is determined by copper-binding protein products of the copper resistance operon (cop) . Potential copper-binding sites of the periplasmic CopA protein show conservation with type-1, type-2, and type-3 copper sites of several eukaryotic multi-copper oxidases . In addition to compartmentalization of copper in the periplasm, two components of the cop operon, copC and copD, appear to function in copper uptake into the cytoplasm . Copper resistance operons related to cop have been described in the related plant pathogen Xanthomonas campestris and in Escherichia coli, but these resistance systems may differ functionally from the Pseudomonas syringae system.

Wei Sheng Wu Xue Bao, 1994 Aug, 34(4), 271 - 8
{Cloning and expression of beta-glucosidase gene in Xanthomonas campestris XA5-5}; Zou W et al.; A beta-glucosidase gene from Xanthomonas campestris XA5-5 was cloned in Escherichia coli with the broad-host-range plasmid pRK404 . The beta-glucosidase encoding plasmid designated pLZS1 contained a 1.1kb PstI DNA fragment deriving from XA5-5 . The plasmid pLZS1 was transconjugated by filter mating into XA5-5 producing homologous clones XA5-5(pLZS1) . Plasmid stability analysis revealed that pLZS1 was more stable in XA5-5 than in E . coli JM83 . The level of beta-glucosidase expressed in XA5-5 (pLZS1) was much higher than in E . coli JM83 (pLZS1) using salicin as the substrate . From the results obtained, it seems that the gene product of this cloned DNA fragment has higher affinity to salicin substrate, and in some sense reduces the affinity between the enzyme and pNPG substrate in XA5-5.

Appl Environ Microbiol, 1994 Jul, 60(7), 2286 - 95
Specific genomic fingerprints of phytopathogenic Xanthomonas and Pseudomonas pathovars and strains generated with repetitive sequences and PCR; Louws FJ et al.; DNA primers corresponding to conserved motifs in bacterial repetitive (REP, ERIC, and BOX) elements and PCR were used to show that REP-, ERIC-, and BOX-like DNA sequences are widely distributed in phytopathogenic Xanthomonas and Pseudomonas strains . REP-, ERIC, and BOX-PCR (collectively known as rep-PCR) were used to generate genomic fingerprints of a variety of Xanthomonas and Pseudomonas isolates and to identify pathovars and strains that were previously not distinguishable by other classification methods . Analogous rep-PCR-derived genomic fingerprints were generated from purified genomic DNA, colonies on agar plates, liquid cultures, and directly from lesions on infected plants . REP, ERIC, and BOX-PCR-generated fingerprints of specific Xanthomonas and Pseudomonas strains were found to yield similar conclusions wtih regard to the identity of and relationship between these strains . This suggests that the distribution of REP-, ERIC, and BOX-like sequences in these strains is a reflection of their genomic structure . Thus, the rep-PCR technique appears to be a rapid, simple, and reproducible method to identify and classify Xanthomonas and Pseudomonas strains, and it may be a useful diagnostic tool for these important plant pathogens.

Infection, 1994 Jul-Aug, 22(4), 258 - 63
Bacterial colonisation with Xanthomonas maltophilia--a retrospective study in a cystic fibrosis patient population; Karpati F et al.; Xanthomonas maltophilia was isolated from 25 of 150 patients with cystic fibrosis during a period of 10 years (1983-1992) . Twelve patients harboured X . maltophilia chronically, i.e . repeatedly for more than 6 months . No predisposing factors for the colonisation could be identified by studying the clinical and laboratory data of the patients, including preceding and concurrent bacterial colonisation with other bacteria, antibacterial treatments, pulmonary function and biochemical markers . Up to 2 years after the chronic colonisation was established no clinical deterioration could be verified, but the patients with X . maltophilia generally had a worse lung function at the latest follow-up (2-7 years after colonisation) than controls colonised with Pseudomonas aeruginosa (p < 0.05) . Our data imply that X . maltophilia is a pathogen and the colonisation appears to follow the same pattern as the colonisation by P . aeruginosa . The development of resistance to different antibiotics, as revealed by analysis of the inhibition zones, was related to antibacterial treatment courses . X . maltophilia showed reduced sensitivity to the most commonly used antibiotics, ceftazidime and tobramycin.

Pathology, 1994 Jul, 26(3), 321 - 4
The antibiotic susceptibilities of Xanthomonas maltophilia and their relation to clinical management; Smit WJ et al.; An increase in recovery of Xanthomonas maltophilia from clinical specimens at our institutions prompted, amongst other measures, an investigation of the antibiotic susceptibility patterns of the organism . Fifty-five consecutive first isolates of Xanthomonas maltophilia were obtained and antimicrobial susceptibility tests were carried out by the agar dilution method . Trimethoprim/sulfamethoxazole was the most active antimicrobial agent (94% susceptible), with 71% susceptible to ticarcillin/clavulanic acid, 56% susceptible to ciprofloxacin and 49% susceptible to ceftazidime . Amoxycillin/clavulanic acid and imipenem were inactive (0% susceptible), while aminoglycosides were effective against only 7% of isolates . Potentiation was observed with both the combination of trimethoprim and sulfamethoxazole and the combination of ticarcillin and clavulanic acid . Familiarity with the antibiotic susceptibility pattern of Xanthomonas maltophilia as well as the potential shortcomings of the in vitro susceptibility data are important in the effective clinical management of Xanthomonas maltophilia infections.

Nihon Kyobu Shikkan Gakkai Zasshi, 1994 Jul, 32(7), 638 - 43
{Nosocomial respiratory infection caused by Xanthomonas maltophilia in immunocompromised hosts}; Fujita J et al.; Between January 1988 and December 1992, 68 patients admitted to our Department of Internal Medicine with hematological malignancies or solid tumors showed colonization of the respiratory tract with Xanthomonas maltophilia (X . maltophilia) . To characterize the significance of respiratory tract colonization by X . maltophilia, we retrospectively reviewed the medical records of the 68 patients colonized with this organism . Twenty-seven of these 68 patients developed pneumonia, with X . maltophilia being implicated in 10 cases . The majority of the 10 patients showed lobular infiltration on chest X-ray . Pleural effusion was observed in 2 (20%) of the 10 patients . All 68 strains of X . maltophilia were resistant to imipenem/cilastatin . Most strains (98.5%) were sensitive to latamoxef, while all strains were sensitive to minocycline . This report describes the clinical features of nosocomial X . maltophilia pneumonia in immunocompromised patients.

Rev Argent Microbiol, 1994 Jul-Sep, 26(3), 133 - 8
{Bacterial leaf blight affecting Syngonium podophyllum in Argentina}; Alippi AM et al.; Bacterial leaf blight of Syngonium podophyllum caused by Xanthomonas campestris pv . syngonii is recorded for the first time in Argentina . The first symptom of the disease was an interveinal watersoaking of leaves, the tissues became chlorotic and finally necrotic over areas of about 4 cm . The identification of the causal microorganism was based on disease symptoms, morphological, physiological and biochemical characteristics and pathogenicity test.

Biochim Biophys Acta, 1994 Jun 21, 1218(2), 199 - 201
Sequence analysis of the L1 metallo-beta-lactamase from Xanthomonas maltophilia; Walsh TR et al.; The amino acid sequence deduced from the L1 beta-lactamase gene of Xanthomonas maltophilia shows a significant variation from that of the CphA and Blm metallo-beta-lactamases of Aeromonas hydrophila and Bacillus cereus, respectively . Whilst the N-terminus of the L1 protein shows some similarity, particularly at the histidine residues previously suggested as a zinc-binding motif, the C-terminus of the protein demonstrates very little similarity . Such differences amongst this group of enzymes would argue for at least three subclasses within the Group 3 beta-lactamases . However, in order to predict their phylogenetic ancestry more sequence data are required from other possible metallo-beta-lactamases.

J Bacteriol, 1994 Jun, 176(12), 3584 - 8
Purification and characterization of periplasmic alpha-amylase from Xanthomonas campestris K-11151; Abe J et al.; Xanthomonas campestris K-11151, isolated from soil, produced a periplasmic alpha-amylase of a new type . The enzyme was purified to homogeneity, as shown by several criteria . The purified enzyme showed almost the same activities on alpha-, beta-, and gamma-cyclodextrins, soluble starch, and amylose . Moreover, it was active on branched cyclodextrins, pullulan, and maltose but not on glycogen . Kinetic analysis showed that alpha-cyclodextrin was the best substrate among the cyclodextrins . The substrate specificity suggested that this enzyme had the combined activities of alpha-amylase, cyclodextrinase, and neopullulanase.

J Bacteriol, 1994 Jun, 176(11), 3354 - 9
Isolation and characterization of a generalized transducing phage for Xanthomonas campestris pv . campestris; Weiss BD et al.; We have isolated and characterized a lytic double-stranded DNA Xanthomonas campestris pv . campestris bacteriophage (XTP1) capable of mediating generalized transduction . The phage transduces chromosomal markers at frequencies of 10(-5) to 10(-6) transductants per PFU . We demonstrated its genetic utility by the isolation and cotransduction of linked transposon insertions to a nonselectable locus, xgl, required for the cleavage of 5-bromo-3-chloro-indoyl-beta-D-galactoside and showed that rif and str alleles in X . campestris are 75% linked . One-step growth experiments showed that the latent and rise periods were each 2 h and the average burst size was 35 . The DNA genome is approximately 180 kb, presumably modified in a sequence-specific manner, and may be covalently attached to protein(s) . Electron micrographs show the phage particle to have an icosahedral head and contractile tail with tail fibers uniquely attached to a location 40 nm proximal from the end of the tail.

Mol Phylogenet Evol, 1994 Jun, 3(2), 135 - 45
Characterization of random amplified polymorphic DNA (RAPD) products from Xanthomonas campestris and some comments on the use of RAPD products in phylogenetic analysis; Smith JJ et al.; As part of our research to determine phylogenetic relationships of organisms within the phytobacterial species Xanthomonas campestris, we have examined the use of the random amplified polymorphic DNA (RAPD) technique . The objective of this aspect of our research was to determine if a valid cladistic character analysis could be carried out by direct comparison of RAPD products separated on ethidium bromide-stained agarose gels . RAPD products were amplified from 47 Xanthomonas campestris DNA templates using a single oligonucleotide primer . These RAPD products were compared and variation was characterized by Southern analysis of both RAPD products and genomic DNA of the 47 bacterial strains using two cloned RAPD products as probes . Analysis of the data set revealed that the RAPD products were not necessarily homologous or independent, crucial prerequisites for characters to be analyzed in a cladistic phylogenetic analysis . It has been commonly assumed that RAPD variation occurs due to insertion/deletion events or alterations in the primer binding site . Within our data set, we demonstrate absence phenotypes arising from the apparent absence of corresponding loci and also due to the preferred synthesis of alternative RAPD products from unrelated loci . These different types of variation are a reflection of different types of genotypic variation, and direct examination of RAPD products did not allow us to distinguish by which mechanism a particular absence phenotype arose . Although this may not be important for phenetic analyses, for analyses of homologous characters using a cladistic approach it is critical . We also detected unrelated, co-migrating RAPD products and multiple related RAPD products within reaction mixtures . These could both contribute to errors in estimates of similarity, important in any phylogenetic analysis . All of these characteristics of RAPD products should be taken into consideration when RAPD products are used for phylogenetic comparisons.

J Antimicrob Chemother, 1994 Jun, 33(6), 1147 - 54
Antibacterial activity of PD 131628 and proposed disc diffusion susceptibility test criteria; Fuchs PC et al.; The antibacterial activity of PD 131628 was compared with that of ciprofloxacin against 401 clinical isolates . The two drugs had comparable MICs for most Gram-negative species . PD 131628 was two to eight times more active against Gram-positive species and against Xanthomonas maltophilia . Both drugs were bactericidal, Among Gram-positive isolates, resistant mutants were not detected in vitro . Among Gram-negative bacilli, spontaneously occurring mutants resistant to PD 131628 were readily demonstrated more frequently than for ciprofloxacin . Resistance to PD 131628 was more readily induced by serially transferring the Gram-negative species, and resistant organisms emerged more rapidly on prolonged incubation in time-kill studies . Correlating the PD 131628 5 micrograms disc diffusion zone diameters with PD 131628 MICs, the following breakpoints are tentatively proposed: susceptible, MIC < or = 1 mg/L or zone > or = 19 mm; intermediate, MIC 2.0 mg/L or zones 16-18 mm; and resistant, MIC > or = 4.0 mg/L or zones < or = 15 mm.

Schweiz Med Wochenschr, 1994 May 28, 124(21), 900 - 5
{Fulminant purpura in Still's disease and bacteremia with Xanthomonas maltophilia and coagulase-negative staphylococci}; Meier S et al.; We describe the case of a 31-year-old man with a long history of juvenile rheumatoid arthritis who was admitted to the hospital because of painful purple skin lesions on hands and feet . On admission he presented the classical picture of "purpura fulminans" with extensive acrocyanosis and large blisters on the lower limbs which evolved into symmetrical peripheral gangrene . Laboratory findings revealed activated intravascular coagulation and bacteremia with coagulase-negative staphylococci and Xanthomonas maltophilia which was thought to be catheter-related . His condition improved markedly under therapy with antibiotics, intravenous heparin, iloprost and intensive local debridement including amputation of several toes . Coagulation studies two months after the acute phase of the disease revealed chronic activated coagulation with a significant protein S deficiency . Clinical findings, etiology, significance of impaired coagulation and therapeutic action in "purpura fulminans" are discussed.

Antimicrob Agents Chemother, 1994 May, 38(5), 991 - 6
Rapid identification of metallo- and serine beta-lactamases; Payne DJ et al.; Simple methods to detect, identify, and differentiate metallo- and serine beta-lactamases were developed and used to differentiate enzymes produced by 17 clinical isolates of Xanthomonas maltophilia . All isolates exhibited beta-lactamase activity, and in 16 strains this was induced by imipenem . All but one isolate hydrolyzed imipenem (and meropenem), and in all cases this activity was inhibited by 1 mM EDTA . The metallo- and serine beta-lactamases in the cell extracts were distinguished on isoelectric focusing (IEF) gels by using the following procedures . (i) Cell lysates were preincubated with 83 mM EDTA prior to IEF and subsequent visualization with nitrocefin, and (ii) after IEF, the gels were overlaid with either 1 mM zinc sulfate or 100 microM BRL 42715 before staining with nitrocefin . Bands of beta-lactamase activity which were removed by BRL 42715 but unaffected by EDTA or zinc sulfate were categorized as serine beta-lactamases . Bands which were unaffected by BRL 42715 but inhibited by EDTA or enhanced by zinc sulfate were classified as metallo-beta-lactamases . By using this approach, seven metallo-beta-lactamases were differentiated with pI values of 4.8 (two strains), 5.5 (four strains), 5.7 (one strain), 6.0 (one strain), 6.4 (four strains), 6.6 (one strain), and 6.8 (three strains) . The metallo-beta-lactamase band with a pI of 6.4 aligned with the recently characterized metallo-beta-lactamase from X . maltophilia 511 . Heterogeneity was also observed for the serine beta-lactamases: 14 isolates elaborated serine beta-lactamase activity which focused with major bands with at least eight different pIs . The remaining three strains produced serine beta-lactamases which focused with five distinct bands with pIs of 6.4, 6.2, 5.7, 5.5, and 5.2 . We conclude that X . maltophilia produces many types of metallo- and serine beta-lactamases distinguishable by these new methods and that the previously reported L-1 and L-2 enzymes are not solely representative of the beta-lactamases produced by this species.

Plant Mol Biol, 1994 May, 25(2), 229 - 39
A new, pathogen-inducible gene of Arabidopsis is expressed in an ecotype-specific manner; Aufsatz W et al.; In this study we describe a novel gene, which was isolated in an attempt to search for specific plant resistance genes of Arabidopsis against isolates of the phytopathogenic bacterium Xanthomonas campestris pv . campestris . The gene was cloned by differential screening of a genomic library of the Xcc 750-resistant ecotype Col-0, using cDNA populations derived from ecotype Col-0 and the Xcc 750-susceptible ecotype Oy-0 . The isolated gene, CXc750, is differentially expressed in ecotypes of Arabidopsis thaliana . In addition, although highly expressed in uninfected plants, gene expression increases in response to pathogen attack . CXc750 potentially codes for a small, basic protein of about 10 kDa . The predicted protein product contains a potential signal leader peptide at the amino-terminal end but no ER retention sequence and no further transmembrane domain . This indicates that the gene product is transported to other compartments or out of the cell . The possible function of CXc750 as a member of the plant defense response system is discussed.

Mol Plant Microbe Interact, 1994 May-Jun, 7(3), 334 - 44
Partial characterization of fimbriae of Xanthomonas campestris pv . hyacinthi; van Doorn J et al.; Xanthomonas campestris pv . hyacinthi is a plant-pathogenic bacterium that causes yellow disease in Hyacinthus . X . c . pv.hyacinthi produces monopolarly attached fimbriae with a diameter of approximately 5 nm and a length of at least 6 micron . Fimbriae were purified by acid precipitation and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis . No hemagglutinating activity of purified fimbriae was found when the fimbriae were tested with several types of erythrocytes . The fimbrial protein subunit had a relative molecular mass of 17 kDa; an isoelectric point was found at pH 4.1 . Analysis of the N-terminal amino acid sequence of the fimbrial subunit indicated that X . c . pv . hyacinthi expresses type 4 fimbriae . A polyclonal rabbit antiserum was raised against the purified fimbriae . This antiserum recognized fimbriae of X . c . pv . hyacinthi in immunogold electron microscopy and immunoblotting experiments . Immunofluorescence studies showed that X . c . pv . hyacinthi cells as well as purified native fimbriae were attached to stomata of hyacinth leaves, suggesting a role for these surface antigens in the first stages of yellow disease.

Appl Environ Microbiol, 1994 Apr, 60(4), 1078 - 86
Genetic analysis of hrp-related DNA sequences of Xanthomonas campestris strains causing diseases of citrus; Leite RP Jr et al.; The hrp gene cluster of strains of Xanthomonas campestris that cause diseases of citrus was examined by Southern hybridization of genomic DNA and by restriction endonuclease analysis of enzymatically amplified DNA fragments of the hrp gene cluster . The hrp genes were present in all strains of the pathovars of X . campestris tested in this study, including strains of the three aggressiveness groups of the citrus bacterial spot pathogen, X . campestris pv . citrumelo . X . campestris pv . citri strains in groups A, B, and C, which cause citrus canker A, B, and C, respectively, each produced characteristic restriction banding patterns of amplified hrp fragments . The restriction banding patterns of all strains within each group were identical . In contrast, restriction fragment length polymorphism was evident among strains of the moderately and weakly aggressive groups of X . campestris pv . citrumelo . X . campestris pv . citrumelo strains in the highly aggressive group had a homogeneous restriction banding pattern . The characteristic banding patterns obtained for each bacterial group indicate that X . campestris strains causing disease in citrus can be reliably differentiated and identified by restriction analysis of amplified DNA fragments of the hrp gene cluster . In addition, the phylogenetic analysis based on the restriction banding patterns of amplified fragments suggests a polyphyletic relationship of the hrp genes among the strains of X . campestris that cause disease in citrus.

Plant Cell, 1994 Apr, 6(4), 511 - 20
Tomato mutants altered in bacterial disease resistance provide evidence for a new locus controlling pathogen recognition; Salmeron JM et al.; We have employed a genetic approach to study the resistance of tomato to the phytopathogenic bacterium Pseudomonas syringae pv tomato . Resistance to P . s . tomato depends upon expression of the Pto locus in tomato, which encodes a protein with similarity to serine/threonine protein kinases and recognizes pathogen strains expressing the avirulence gene avrPto . Eleven tomato mutants were isolated with altered resistance to P . s . tomato strains expressing avrPto . We identified mutations both in the Pto resistance locus and in a new locus designated Prf (for Pseudomonas resistance and fenthion sensitivity) . The genetic approach allowed us to dissect the roles of these loci in signal transduction in response to pathogen attack . Lines carrying mutations in the Pto locus vary 200-fold in the degree to which they are susceptible to P . s . tomato strains expressing avrPto . The pto mutants retain sensitivity to the organophosphate insecticide fenthion; this trait segregates with Pto in genetic crosses . This result suggested that contrary to previous hypotheses, the Pto locus controls pathogen recognition but not fenthion sensitivity . Interestingly, mutations in the prf locus result in both complete susceptibility to P . s . tomato and insensitivity to fenthion, suggesting that Prf plays a role in tomato signaling in response to both pathogen elicitors and fenthion . Because pto and prf mutations do not alter recognition of Xanthomonas campestris strains expressing avrBsP, an avirulence gene recognized by all tested tomato cultivars, Prf does not play a general role in disease resistance but possibly functions specifically in resistance against P . s . tomato . Genetic analysis of F2 populations from crosses of pto and prf homozygotes indicated that the Pto and Prf loci are tightly linked.

Antimicrob Agents Chemother, 1994 Mar, 38(3), 624 - 7
A changing pattern of susceptibility of Xanthomonas maltophilia to antimicrobial agents: implications for therapy; Vartivarian S et al.; The in vitro susceptibilities of 130 Xanthomonas maltophilia isolates to 12 antibiotics--trimethoprim-sulfamethoxazole, minocycline, ticarcillin-clavulanate, ceftazidime, cefoperazone, cefoperazone-sulbactam, imipenem, ciprofloxacin, and the investigational quinolones PD 117558, PD 117596, PD 127391, and sparfloxacin--were determined by a microtiter broth dilution technique . Other than the investigational quinolones, the most active antibiotics were minocycline, trimethoprim-sulfamethoxazole, and ticarcillin-clavulanate, in order . However, the first two were not bactericidal, while about half of the isolates exhibited intermediate susceptibility to ticarcillin-clavulanate . Patterns of susceptibility to trimethoprim-sulfamethoxazole and ciprofloxacin relative to the years of isolation of these strains reflected the development of resistance to the antibiotic prophylaxis practices in the hospital . We recommend that a combination of antibiotics, such as trimethoprim-sulfamethoxazole, minocycline, and ticarcillin-clavulanate, at or close to the maximum tolerated doses be in the treatment of serious X . maltophilia infections.

Antimicrob Agents Chemother, 1994 Feb, 38(2), 369 - 70
Susceptibilities of 123 Xanthomonas maltophilia strains to clinafloxacin, PD 131628, PD 138312, PD 140248, ciprofloxacin, and ofloxacin; Pankuch GA et al.; The susceptibilities of 123 clinically isolated strains of Xanthomonas maltophilia to six fluoroquinolones (clinafloxacin, PD 131628, PD 138312, PD 140248, ciprofloxacin, and ofloxacin) were examined by microdilution MIC methodology . Clinafloxacin and PD 131628 were the most active compounds tested (MICs for 50% of the strains tested {MIC50s} of 0.5 and 1.0 microgram/ml and MIC90s of 2.0 and 4.0 micrograms/ml, respectively) . PD 138312, PD 140248, ciprofloxacin, and ofloxacin were less active, with MIC50s ranging from 4.0 to 8.0 micrograms/ml and MIC90s of 16.0 micrograms/ml for all four compounds . Only clinafloxacin and PD 131628 were active against ciprofloxacin-resistant strains, with MIC50s of 0.5 and 1.0 microgram/ml and MIC90s of 2.0 and 4.0 micrograms/ml, respectively.

Endocr Res, 1994 Feb, 20(1), 1 - 19
Characterization and purification of the chorionic gonadotropin-like protein binding site in Candida albicans; Caticha O et al.; Recent studies from our laboratory have shown that human chorionic gonadotropin (hCG), human luteinizing hormone (hLH), and CG-like proteins from Xanthomonas maltophilia (xCG) and Candida albicans (CaCGLP) induce Candida albicans transition from blastospores to hyphal forms . Xanthomonas maltophilia CG-like protein (xCG), hCG, and hLH also bind to Candida albicans blastospores with a high-affinity nM Kd, indicating that these substances can control Candida albicans pathogenicity . The work reported herein describes the purification of the binding site for these CG-like proteins from Candida albicans . The purification developed involved alcohol extraction followed by affinity chromatography . The product obtained was a protein of 64-69 kDa, as analyzed by sodium dodecyl sulfate-polyacrylamide electrophoresis (SDS-PAGE), Western blot and Sephadex G-100 column chromatography . This binding site reacted in a Western blot with both 125I-hCG and 125I-CaCGLP . Purified CaCGLP was able to displace specifically 125I-hCG bound to Candida albicans blastospores . Scatchard plot analysis showed that the Kd of this reaction was of high affinity in the nM range, and also indicated the presence of one single binding site . These results lead us to conclude: 1) Candida albicans possesses a binding site which is able to bind hCG, hLH and CG-like proteins from Xanthomonas maltophilia and Candida albicans; 2) This binding site is a hydrophobic protein of approximately 64 kDa and; 3) We postulate that CaCGLP is the natural ligand for this binding site and this system is used to control Candida albicans transition and, therefore, pathogenicity.

J Med Microbiol, 1994 Feb, 40(2), 148 - 54
Differential binding capacity and internalisation of bacterial substrates as factors in growth rate of Acanthamoeba spp; Bottone EJ et al.; Acanthamoeba spp . are free-living predators that selectively feed on bacteria . Adherence of the bacterial food source to the trophozoite membrane is followed by internalisation and digestion . Through co-cultivation of A . castellanii and A . polyphaga, individually, with Xanthomonas maltophilia, Escherichia coli, Staphylococcus epidermidis and Pseudomonas aeruginosa (despite the amoebicidal properties of the latter organism), specificity with regard to the preferred bacterial substrate was judged . X . maltophilia and P . aeruginosa adhered almost immediately forming a multilayered mantle of bacilli around trophozoites of both species of amoebae . E . coli adhered to fewer trophozoites and in smaller numbers . X . maltophilia was readily internalised after co-cultivation for 8 h, whereas P . aeruginosa, E . coli and S . epidermidis were not internalised even after co-cultivation for 24 h . These data suggest that the suitability of a bacterial food source for the Acanthamoeba spp . studied is associated not only with the proclivity with which the bacterial species binds to the trophozoite surface, but also with the rate of its internalisation.

Appl Microbiol Biotechnol, 1994 Feb, 40(6), 846 - 50
Cloning and characterization of the hemA gene for synthesis of delta-aminolevulinic acid in Xanthomonas campestris pv . phaseoli; Asahara N et al.; The gene from Xanthomonas campestris pv . phaseoli that is involved in the C5 pathway of delta-amino-levulinic acid (ALA) of Escherichia coli . Subcloning of deletion fragments from the initial 2.5-kilobase (kb) chromosomal fragment allowed the isolation of a 1.6-kb fragment that could complement the hemM mutation . Nucleotide sequence analysis of the 1.6-kb DNA fragment revealed an open reading frame that encodes a polypeptide of 426 amino acid residues, and the deduced molecular mass of this polypeptide is 46768 Da . The amino acid sequence shows a high degree of homology of the HemA protein, which is glutamyl-tRNA reductase, to other organisms . Thus, we examined the complementation test of the cloned gene from Xanthomonas with a hemA mutation of E . coli and found that the gene complemented the hemA mutation . These results suggest that the cloned gene is hemA and the gene from Xanthomonas also complements both hemA and hemM mutations, as in the case of the E . coli hemA.

J Bacteriol, 1994 Jan, 176(1), 173 - 88
Molecular cloning, chromosomal mapping, and sequence analysis of copper resistance genes from Xanthomonas campestris pv . juglandis: homology with small blue copper proteins and multicopper oxidase; Lee YA et al.; Copper-resistant strains of Xanthomonas campestris pv . juglandis occur in walnut orchards throughout northern California . The copper resistance genes from a copper-resistant strain C5 of X . campestris pv . juglandis were cloned and located on a 4.9-kb ClaI fragment, which hybridized only to DNA of copper-resistant strains of X . campestris pv . juglandis, and was part of an approximately 20-kb region which was conserved among such strains of X . campestris pv . juglandis . Hybridization analysis indicated that the copper resistance genes were located on the chromosome . Plasmids conferring copper resistance were not detected in copper-resistant strains, nor did mating with copper-sensitive strains result in copper-resistant transconjugants . Copper resistance genes from X . campestris pv . juglandis shared nucleotide sequence similarity with copper resistance genes from Pseudomonas syringae pv . tomato, P . syringae, and X . campestris pv . vesicatoria . DNA sequence analysis of the 4.9-kb fragment from strain C5 revealed that the sequence had an overall G+C content of 58.7%, and four open reading frames (ORF1 to ORF4), oriented in the same direction . All four ORFs were required for full expression of copper resistance, on the basis of Tn3-spice insertional inactivation and deletion analysis . The predicted amino acid sequences of ORF1 to ORF4 showed 65, 45, 47, and 40% identity with CopA, CopB, CopC, and CopD, respectively, from P . syringae pv . tomato . The most conserved regions are ORF1 and CopA and the C-terminal region (166 amino acids from the C terminus) of ORF2 and CopB . The hydrophobicity profiles of each pair of predicted polypeptides are similar except for the N terminus of ORF2 and CopB . Four histidine-rich polypeptide regions in ORF1 and CopA strongly resembled the copper-binding motifs of small blue copper proteins and multicopper oxidases, such as fungal laccases, plant ascorbate oxidase, and human ceruloplasmin . Putative copper ligands of the ORF1 polypeptide product are proposed, indicating that the polypeptide of ORF1 might bind four copper ions: one type 1, one type 2, and two type 3.

J Gen Virol, 1994 Jan, 75 ( Pt 1), 15 - 22
Nucleotide sequence determination, characterization and purification of the single-stranded DNA-binding protein and major coat protein of filamentous phage phi Lf of Xanthomonas campestris pv . campestris; Wen FS et al.; phi Lf is a filamentous bacteriophage of Xanthomonas campestris pv . campestris, which can integrate its genome into the host chromosome . The nucleotide sequence of an EcoRV-SphI fragment (1018 bp) from the phi Lf replicative form DNA was determined . Four contiguous open reading frames (ORFs), orf98-orf43-orf38-orf42, were revealed . ORFs 98 and 42 were identified as the genes encoding a single-stranded DNA-binding protein (Sbp) and a major coat protein, respectively . Sbp was purified and found to bind with a high affinity to ssDNA prepared from phi Lf phage particles . The major coat protein showed sequence features similar to those of the typical major coat proteins of other filamentous phages . However, it appears to be synthesized as a mature product, similar to the situation with Pf3 but different from that with other filamentous phage major coat proteins which are synthesized as pre-coats and are subject to post-translational processing . The M(r)s, estimated by SDS-PAGE, of both the Sbp (10.9K) and the major coat protein (4.1K) coincide with the values deduced from the nucleotide sequences . ORFs 43 and 38 are proposed to be the genes encoding two minor coat proteins . The order of these four genes is similar to that found in the Escherichia coli filamentous phages.

Scand J Infect Dis, 1994, 26(2), 163 - 70
Xanthomonas maltophilia bacteremia in immunocompromised hematological patients; Victor MA et al.; Epidemiological, microbiological and clinical characteristics of 14 episodes of Xanthomonas maltophilia bacteremia in 12 seriously immunocompromised hematological patients, admitted to Rigshospitalet in Copenhagen over the 3-year period 1989-91, were evaluated . The results were compared with a randomly selected control group of 25 patients with Escherichia coli bacteremia . Hospital acquired bacteremia was more common among the patients with X . maltophilia bacteremia (p < 0.01) . Treatment with broad-spectrum antibiotics before the bacteremic episode was markedly more common among the patients with X . maltophilia bacteremia (p < 0.001) . The presence of a central venous catheter and previous treatment with corticosteroids were more frequent in patients with X . maltophilia bacteremia (p < 0.05) . The X . maltophilia blood culture isolates were generally resistant to aminoglycosides and most beta-lactams . The mortality rates related to bacteremia caused by X . maltophilia and E . coli were 14% and 20%, respectively.

Arch Microbiol, 1994, 161(4), 281 - 5
Specific protein phosphorylation induced in Xanthomonas campestris pv . oryzae by bacteriophage Xp12; Cheng CM et al.; We have investigated the endogenous phosphorylation patterns of phosphorylated proteins of Xanthomonas campestris pv . oryzae induced by its bacteriophages . For bacteriophage Xp12-infected cells, at least three phosphoproteins with apparent molecular weights of 28, 28.5 and 45 kDa were detected by in vitro labeling with {gamma-32P}-ATP . These Xp12-specific phosphoproteins only occurred with Xp12 infection, and were not shown in uninfected or Xp10-infected cells . The protein kinase(s) responsible could use either ATP or GTP as the nucleotide substrate with nearly the same efficiency . Magnesium was proved to be an essential factor for the phosphorylation . EGTA treatment excluding the possibility that the presumed protein kinase was calcium-dependent . Under our reaction conditions, the optimal phosphorylation occurred at pH 7 to 8, for 30 to 40 min at 25 to 37 degrees C . The Xp12-specific protein phosphorylation hint the existence of a physiological regulation mechanism involved in the life cycle of bacteriophage Xp12 . Furthermore, the presumed protein kinase was shown to be encoded by the genome of Xp12 rather than indirectly induced by Xp12 infection.

Arch Virol, 1994, 135(3-4), 253 - 64
A long lytic cycle in filamentous phage Cf1tv infecting Xanthomonas campestris pv . citri; Kuo TT et al.; In this study the lytic cycle of a filamentous phage is reported . Under normal laboratory cultivation conditions a virulent form could spontaneously and easily arise from a temperate phage . The virulent one could superinfect cells containing Cf1t lysogen . Therefore, we have named it Cf1tv . In a colony formation assay using cells from an infected culture, two types of colonies were observed, small and large . It could be proven that the formation of small colonies is the result of killing during Cf1tv infection . The number of small colony forming units (cfu) increased with infection time and reached a maximum at 16 h after infection, then dropped to the initial cell concentration at 28 h after infection; 28 h were required to kill all infected cells . Large colonies contained uninfected or phage-resistant cells, but no lysogenic cells . Bacterial death was further confirmed by a microculture assay . At 2 h after infection, normal-dividing cells (cfu giving large colonies) contained about 40% of Cf1tv-infected cells, then the percentage decreased with infection time . Slow-dividing cells (infected cfu giving small colonies) initially contained 55% of cells; this percentage increased slightly at 4 h after infection, then decreased at 8 h after infection . Non-dividing cells initially contained 5% of infected cells, then their numbers rapidly increased with time after infection . The cell division was seriously affected and finally stopped . During one-step growth, the latent period was 30 min and there was no burst; phages were released at 30 min after infection and the rate of release increased gradually with time after infection . Phage DNA integration into host chromosome could not be observed.

Rev Argent Microbiol, 1994 Jan-Mar, 26(1), 9 - 20
{Xanthan production by Xanthomonas campestris B-1459}; Lorda GS et al.; The production of xantano from Xanthomonas campestris B-1459 was analyzed . The experiments were performed in shaked flasks at 250 rpm and 2.5 cm eccentricity . Using a base modified medium it was possible to achieve xantano concentration of 35 g/l in 72 h of process . The modified medium contained glucose as carbon source, and yeast extract, meat peptone, malt extract and amaranth meal as growth factors and nitrogen sources, in a KH2PO4/K2HPO4 buffer.

Appl Environ Microbiol, 1994 Jan, 60(1), 377 - 84
Isolation of an insertion sequence (IS1051) from Xanthomonas campestris pv . dieffenbachiae with potential use for strain identification and characterization; Berthier Y et al.; A new insertion sequence was isolated from Xanthomonas campestris pv . dieffenbachiae . Sequence analysis showed that this element is 1,158 bp long and has 15-bp inverted repeat ends containing two mismatches . Comparison of this sequence with sequences in data bases revealed significant homology with Escherichia coli IS5 . IS1051, which detected multiple restriction fragment length polymorphisms, was used as a probe to characterize strains from the pathovar dieffenbachiae.

Rev Med Interne, 1994, 15(12), 808 - 12
{Xanthomonas maltophilia nosocomial infections . A new threat . Apropos of 30 cases}; Rispal P et al.; In an attempt to further characterize infections due to Xanthomonas maltophilia, we reviewed 20 colonisations and 30 infections observed in our institution from january 1990 to december 1992, Xanthomonas maltophilia is emerging as an important nosocomial pathogen in immunocompromised patients, especially those receiving broad spectrum antimicrobial antibiotherapy . Distinction between colonisation and infection is often difficult . Xanthomonas maltophilia presents a therapeutic challenge because of its tendency to exhibit multiple resistance.

Chemotherapy, 1994, 40(6), 391 - 8
Comparative antimicrobial activity of FK037, cefpirome, ceftazidime and cefepime against aminoglycoside-sensitive and aminoglycoside-resistant Pseudomonas aeruginosa and Pseudomonas spp; Baltch AL et al.; The activities of FK037, cefpirome, ceftazidime and cefepime against 71 aminoglycoside-resistant, 35 aminoglycoside-sensitive, 29 cystic fibrosis Pseudomonas aeruginosa isolates, and 31 Pseudomonas spp . strains were studied using the agar dilution technique (final inoculum 10(4) c.f.u./spot) . The MIC90 for aminoglycoside-sensitive P . aeruginosa against FK037, cefpirome, ceftazidime and cefepime was 32, 16, 8 and 16 mg/l, respectively . The MIC90 for P . aeruginosa strains resistant to one or more aminoglycosides was similar for FK037, cefpirome and ceftazidime (128 mg/l) and two dilutions lower for cefepime (32 mg/l) . The MIC90 for P . aeruginosa isolates highly resistant to all three aminoglycosides (MIC > or = 128 mg/l) was 64 mg/l for FK037 and cefpirome, and 32 mg/l for ceftazidime and cefepime . The MIC90 for P . aeruginosa from patients with cystic fibrosis was 32 mg/l for all four cephalosporins tested, and 8, 32 and 64 for tobramycin, gentamicin and amikacin, respectively . Xanthomonas maltophilia was resistant to all four cephalosporins and three aminoglycosides . The activity of ceftazidime and cefepime was one to two dilutions greater against P . cepacia and P . picketti than of FK037 and cefpirome . The activity of ceftazidime was two dilutions greater than the other three cephalosporins against P . fluorescens . In kinetic time kill curves against P . aeruginosa, all four cephalosporins demonstrated similar activity at 6 and 24 h when tested at 1 x MIC . At 2 x MIC, regrowth was less at 24 h for cefepime, cefpirome and FK037 than for ceftazidime . In time kill curves for P . aeruginosa, synergy was clearly demonstrated at 1/4 MIC and 1/2 MIC concentrations for FK037 and tobramycin.

Nephrol Dial Transplant, 1994, 9(12), 1774 - 7
Clinical significance of exit-site infections due to Xanthomonas in CAPD patients: a comparison with Pseudomonas infection; Dapena F et al.; We have assessed the clinical significance of exit-site infections secondary to Xanthomonas maltophilia in continuous ambulatory peritoneal dialysis (CAPD) patients, and compared them with episodes due to Pseudomonas . The study was a retrospective survey of all episodes of Xanthomonas and Pseudomonas-related exit-site infections (ESI) in all patients treated in our unit between 1984 and 1992 . Thirteen episodes of Xanthomonas-related ESI were observed in eight patients and 17 episodes of Pseudomonas-related ESI were seen in 15 patients . Xanthomonas-related ESI was frequently associated with other microorganisms, while Pseudomonas-related ESI was not (66% versus 5%, P < 0.02) . Only one episode of Xanthomonas-related ESI resulted in peritonitis and subsequent catheter removal, after 15 months of resistant colonization . Another case was considered to be chronic and indolent, as the Xanthomonas-related ESI continued after 23 months of local treatment . The other 11 episodes were resolved either without treatment or with an antibiotic cream after 7-120 days . However, all but two episodes of Pseudomonas-related ESI required intravenous antibiotics (usually ceftazidime); seven patients developed peritonitis, and 11 required surgical catheter manipulation (five external cuff extrusion, and six catheter removal) (1/13 Xanthomonas-related versus 11/17 Pseudomonas-related ESI, P < 0.03) . Most Xanthomonas-related ESI do not lead to peritonitis, and constitute a mild condition, easily treatable without parenteral antibiotics or catheter replacement . The appearance of other associated organisms and the favourable evolution with local treatment suggest a saprophytic behaviour for Xanthomonas in our CAPD patients . On the contrary, Pseudomonas-related ESI is usually severe, requires parenteral antibiotics, frequently leads to peritonitis, and requires catheter replacement.

Biotechnol Appl Biochem, 1993 Dec, 18 ( Pt 3), 299 - 309
Interrelated approach to optimization of biosynthesis and chemical isolation of biologically active substances: the production of penicillinamidase by Escherichia coli and peptidohydrolase by Xanthomonas sp; Zaslavskaya PL et al.; The solution to the problem of optimizing conditions for the isolation of biologically active substances (BAS) from microbial cells should be based on investigations of the structural and functional characteristics of cultures . Models of two bacterial cultures, of Escherichia coli and a Xanthomonas species, producing enzymes the localization of which differ, is described . The isolation of membrane-bound penicillinamidase from E . coli was optimal in the 'preautolysis' period, when the components of the cytoplasm autolysed but the membranes remained intact . In contrast, the isolation of the cytoplasmic enzyme peptidohydrolase from Xanthomonas sp . was optimal during the period when the cell membranes markedly changed . Thus the physiological state of the cultures and the localization of the BAS within the cells are important determinants for optimization of the isolation process . It follows that all stages of a technological process for the production of BAS, i.e . biosynthesis, chemical isolation, etc., should be interrelated for a successful outcome.

Appl Environ Microbiol, 1993 Dec, 59(12), 3996 - 4003
Differential expression of conserved protease genes in crucifer-attacking pathovars of Xanthomonas campestris; Dow JM et al.; Strains of Xanthomonas campestris pathovars armoraciae and raphani, which cause leaf spotting diseases in brassicas, produce a major extracellular protease in liquid culture which was partially purified . The protease (PRT 3) was a zinc-requiring metalloenzyme and was readily distinguishable from the two previously characterized proteases (PRT 1 and PRT 2) of X . campestris pv . campestris by the pattern of degradation of beta-casein and sensitivity to inhibitors . PRT 3 was produced at a low level in the vascular brassica pathogen X . campestris pv . campestris (five strains tested), in which PRT 1 and PRT 2 predominate . In contrast, expression of PRT 1, a serine protease, could not be detected in the six tested strains of the leaf spotting mesophyll pathogens . However, all these strains had DNA fragments which hybridized to a prtA probe and which probably carry a functional prtA (the structural gene for PRT 1) . The structural gene for PRT 3 (prtC) was cloned by screening a genomic library of X . campestris pv . raphani in a protease-deficient X . campestris pv . campestris strain . Subcloning and Tn5 mutagenesis located the structural gene to 1.2 kb of DNA . DNA fragments which hybridized to the structural gene were found in all strains of the crucifer-attacking X . campestris pathovars tested as well as in a number of other pathovars . Experiments in which the pattern of protease production of the pathovars was manipulated by introduction of cloned genes into heterologous pathovars suggested that no determinative relationship exists between the pattern of protease gene expression and the (vascular or mesophyllic) mode of pathogenesis.

Clin Infect Dis, 1993 Nov, 17 Suppl 2, S378 - 84
Empirical antibiotic therapy for fever in neutropenic patients; Bodey GP; The necessity for administering empirical antibiotic therapy to febrile neutropenic patients has been well-established; however, no single regimen has been uniformly accepted . During the past decade, gram-positive organisms, often methicillin-resistant, have emerged as significant pathogens . The routine use of vancomycin may be appropriate at some institutions, but its widespread use may lead to resistance . The role of aminoglycosides as part of routine empirical regimens is controversial, and single extended-spectrum beta-lactam agents are often adequate therapy . Not all beta-lactam agents are equally effective, and some gram-negative pathogens, such as Xanthomonas maltophilia, are resistant to many of them . Pneumonia is frequent, the infecting pathogen is often undetermined, and therapy is unsatisfactory . Outpatient antibiotic therapy can be used in selected neutropenic patients . Empirical antibiotic regimens should be selected on the basis of knowledge about predominant pathogens and antibiotic susceptibilities at each institution as much as on the basis of studies from other institutions reported in the literature.

Enzyme Microb Technol, 1993 Nov, 15(11), 965 - 73
Synthesis of beta-lactam antibiotics containing alpha-aminophenylacetyl group in the acyl moiety catalyzed by D-(-)-phenylglycyl-beta-lactamide amidohydrolase; Blinkovsky AM et al.; D-(-)-Phenylglycyl-beta-lactamide amidohydrolase was isolated from Xanthomonas sp., purified, and characterized . A characteristic feature of the enzyme is its high specificity for substrates containing an alpha-aminophenylacetic group in the acyl moiety . Cephalexin and D-C-(-)-phenylglycine methyl ester (MEPG), being nonspecific penicillin acylase (EC 3.5.1.11) substrates, have the highest values of bimolecular constant kcat/Km (2.8 x 10(5) and 2.0 x 10(5) M-1 x s-1, respectively) in the case of amidohydrolase . On the contrary, benzylpenicillin is not hydrolyzed by D-(-)-phenylglycyl-beta-lactamide amidohydrolase . The other peculiarity of the enzyme is its affinity for the charged forms of substrates . Using the amidohydrolase, it was found that the values of delta Go'pH7.0 for hydrolysis of the amide bond in cephalexin and ampicillin are -3.3 and -2.3 kJ mol-1, respectively . They are less by a minimum of 2.7 kJ mol-1 than those for other beta-lactam antibiotics . Detailed thermodynamic and kinetic studies of the synthesis of cephalexin from MEPG and 7-aminodeacetoxycephalosporanic acid (7-ADCA) catalyzed by D-(-)-phenylglycyl-beta-lactamide amidohydrolase were undertaken . A kinetic scheme is proposed which describes well the experimental curves . The value of conversion of "nucleus" was found to be 76% when the synthesis was carried out from a 31.5 mM solution of 7-ADCA and an 88.5 mM solution of MEPG at pH 6.2 (optimum conditions) . A 75% conversion of 7-aminocephalosporanic acid (7-ACA) was achieved in the synthesis of cephaloglycine catalyzed by D-(-)-phenylglycyl-beta-lactamide amidohydrolase.

Infect Immun, 1993 Oct, 61(10), 4338 - 43
Inhibition of adherence of mucoid Pseudomonas aeruginosa by alginase, specific monoclonal antibodies, and antibiotics; Mai GT et al.; The adherence of pseudomonal species was investigated by using a newly developed radiometric dacron fiber microcolumn assay . Pseudomonas aeruginosa, P . stutzeri, and Xanthomonas maltophilia were more adherent (approximately 20%) than P . pseudomallei, P . fluorescens, and P . cepacia (approximately 10%) . Mucoid strains of P . aeruginosa were consistently more adherent than nonmucoid strains (30% versus 20%) . Alginase was shown to inhibit the adherence of mucoid but not nonmucoid P . aeruginosa . Monoclonal antibodies to alginate were also shown to inhibit the adherence of mucoid but not nonmucoid P . aeruginosa . In addition, antibiotics active against P . aeruginosa were shown to inhibit the adherence of both mucoid and nonmucoid strains . Furthermore, synergism between dyadic combinations of monoclonal antibodies and antibiotic (ciprofloxacin), as well as alginase and antibiotic, was also observed . These results indicate that bacterial alginate has an intrinsic role in the adherence of mucoid P . aeruginosa and may have evolved not only for protection against dehydration in the water and soil ecosystem of this bacterium, but also as a means of attaching to soil substrates in the same ecosystem to enhance survival . They also suggest that synergistic combinations of antibiotics with alginase or monoclonal antibodies to alginate may be of value in the therapy of some pseudomonal infections.

Gene, 1993 Sep 30, 132(1), 113 - 8
Isolation and expression in Escherichia coli of a Xanthomonas oryzae recA-like gene; Rabibhadana S et al.; The recA gene from the bacterium Xanthomonas oryzae pv . oryzae (Xoo), a rice pathogen, was cloned based on its ability to complement DNA repair defects of Escherichia coli recA- mutants . The Xoo recA was localized to a 1.3-kb Sau3AI-XhoI fragment and, when cloned into pBR322, specifies increased methylmethanesulfonate and mitomycin C resistance to E . coli recA mutants and allows lambda red- gam- to plaque on an E . coli recA- host . An E . coli recA- strain harboring a plasmid containing the Xoo recA-like gene was shown to produce a 40-kDa protein which cross-reacted with an anti-E . coli RecA antibody . A similar molecular mass protein to RecA has been detected in several Xanthomonas pathovars using an anti-E . coli RecA antibody . Furthermore, the cloned Xoo recA was shown to hybridize to genomic DNA from various Xanthomonas pathovars, but not to genomic DNA from other bacteria species under high-stringency hybridization conditions . These results indicate the isolation of the Xoo recA gene.

Carbohydr Res, 1993 Sep 2, 247, 249 - 54
Structure of the O19 antigen of Xanthomonas maltophilia; Winn AM et al.; The O-specific polymer from a strain of Xanthomonas maltophilia O19 contains D-glucose, L-rhamnose, and D-fucose . By means of chemical degradations and NMR studies, the repeating unit of the polymer was determined to be a branched tetrasaccharide of the structure shown . {formula: see text}

Mol Plant Microbe Interact, 1993 Sep-Oct, 6(5), 655 - 64
Pathological and molecular characterizations of alfalfa interactions with compatible and incompatible bacteria, Xanthomonas campestris pv . alfalfae and Pseudomonas syringae pv . pisi; Esnault R et al.; We report on the interactions of alfalfa with Xanthomonas campestris pv . alfalfae and Pseudomonas syringae pv . pisi . A hypersensitive response was observed when leaves were infiltrated with P . s . pv . pisi, which remained strictly limited to the injected zone . The compatible interaction with X . c . pv . alfalfae was characterized by water-soaking symptoms and the spreading of the bacterium into the leaf blade . Analyses of transcript accumulation were conducted with cDNAs encoding enzymes involved in phytoalexin synthesis: chalcone synthase (CHS), chalcone isomerase (CHI), and isoflavone reductase (IFR) . In incompatible interactions the maximum accumulation of the CHS, CHI, and IFR transcripts was observed 6 hr postinfection . In the compatible interaction, the induction of these transcripts was delayed until 25-30 hr postinfection, and the level of their accumulation was considerably lower . Extending this molecular analysis to the root system showed that the reaction of roots during an incompatible interaction was quite comparable to that of leaves . To complete these analyses, expression of genes encoding pathogenesis-related (PR) proteins in leaves was also analyzed by polymerase chain reaction . High-level accumulation of a 0.8-kb transcript encoding a PR protein was observed 6 to 30 hr postinfection in the incompatible interaction.

Mol Plant Microbe Interact, 1993 Sep-Oct, 6(5), 616 - 27
Avirulence gene avrRxv from Xanthomonas campestris pv . vesicatoria specifies resistance on tomato line Hawaii 7998; Whalen MC et al.; The molecular and genetic control of the interaction between tomato races of Xanthomonas campestris pv . vesicatoria (XcvT) and tomato was studied . Based on inoculation phenotype and analysis of in planta bacterial growth, tomato line Hawaii 7998 is resistant to XcvT race 1 75-3 but not to XcvT race 2 89-1 . Two cosmid clones from a genomic library of XcvT race 1 75-3 converted the normally virulent race 2 89-1 to avirulence on Hawaii 7998 . The two clones contained the previously isolated, nonhost avirulence gene avrRxv, and their activity was localized to a 2.1-kbp subclone of avrRxv . avrRxv inhibits growth of race 2 89-1 in the resistant line Hawaii 7998 and an insertional mutation in avrRxv prevents this inhibition . In addition, a dramatic increase in electrolyte leakage of leaves of Hawaii 7998 occurred after 12-hr postinfiltration with race 2 89-1 carrying avrRxv . The nucleotide sequence of avrRxv revealed one major open reading frame (ORF) that accords well with activity analysis of nested deletions . ORF 2-2 encodes a putative protein of 374 amino acids with a molecular weight of 42.1 kDa and a pI of 10.7 . Inheritance of the avrRxv-specific resistance in Hawaii 7998 was studied in a total of 587 F2 individuals from crosses between Hawaii 7998 and susceptible lines . The inheritance of avrRxv-specific resistance in Hawaii 7998 appears to be governed by more than one locus.

Int J Syst Bacteriol, 1993 Jul, 43(3), 606 - 9
Stenotrophomonas, a new bacterial genus for Xanthomonas maltophilia (Hugh 1980) Swings et al . 1983; Palleroni NJ et al.; In consideration of the criticisms of the transfer of Pseudomonas maltophilia to the genus Xanthomonas proposed by J . Swings, P . De Vos, M . Van den Mooter, and J . De Ley (Int . J . Syst . Bacteriol . 33:409-413, 1983), a new generic name is created for this taxon . The name Stenotrophomonas is here proposed for the new genus, which includes a single species, Stenotrophomonas maltophilia . This proposal restores the genus Xanthomonas to its former definition (J . Bradbury, p . 199-210, in N . R . Krieg and J . G . Holt, ed., Bergey's Manual of Systematic Bacteriology, 1984) The arguments on which this proposal is based are presented.

J Postgrad Med, 1993 Jul-Sep, 39(3), 153 - 5
Meningitis due to Xanthomonas maltophilia; Girijaratnakumari T et al.; During 1st week of post-operative period, a 28 year old female patient operated for left cerebellopontine angle tumor, continued to get fever . Lumbar puncture did not reveal any organisms . She responded to ciprofloxacin . Two months later, she was readmitted with signs and symptoms of meningitis . The CSF tapped on lumbar puncture grew Xanthomonas maltophilia, Gram negative bacilli, sensitive to various antibiotics, ciprofloxacin being one of them . The patient was given ciprofloxacin for 3 weeks . On follow up, a year later she was found to be asymptomatic.

Biochem Biophys Res Commun, 1993 Jun 30, 193(3), 841 - 7
A bacterial protein has homology with human chorionic gonadotropin (hCG); Grover S et al.; Studies from our laboratory have demonstrated the presence of a 48.5 kD cell wall protein in the bacterium, Xanthomonas maltophilia, which immunologically resembles the beta subunit of human chorionic gonadotropin . Primers were designed from the amino acid sequences of enzymatically cleaved peptide fragments of this protein . These primers were used to obtain PCR amplified products, which were subsequently cloned in a PCR11TA cloning vector, and a 492 base pair nucleotide sequence was obtained with a 164 amino acid open reading frame . When this nucleotide sequence was aligned with exon 2 of genes 5 and 6 of the beta hCG gene, a 53% homology was observed . The translated protein sequence had a 35% homology with hCG and a 25% homology with human luteinizing hormone.

Mol Microbiol, 1993 Jun, 8(6), 1053 - 61
Genetic stability and xanthan gum production in Xanthomonas campestris pv . campestris NRRL B1459; Martinez-Salazar JM et al.; A transposon (Tn5-SC) was constructed that can be used to quantify genetic deletions or amplifications . This transposon was used to evaluate the genomic stability of Xanthomonas campestris pv . campestris NRRL B1459 and we found that the genome of this bacterium is as stable as other Gram-negative bacteria or even more stable . Homologous recombination between plasmid sequences was determined in strain NRRL B1459 and was found to occur at a similar level to that reported for other Gram-negative bacteria . We report here that in X.c.c . NRRL B1459 there is no straightforward correlation between the occurrence of genetic rearrangements and frequency of homologous recombination . These data are discussed with respect to the reported instability of strain NRRL B1459 for xanthan gum production.

J Antibiot (Tokyo), 1993 May, 46(5), 833 - 9
Synthesis and antibacterial activity of cephalosporins having a catechol in the C3 side chain; Okita T et al.; Cephalosporins having a catechol through a variety of linkages to the C3 position and a different C7 side chain were prepared . Among them, 3-(catechol-4- ylcarbonyloxy)methylcephalosporin (14) and 3-{(E)-3-(catechol-4-ylcarbonyloxy)-1-propen-1-yl}cephalospo rin (10) showed excellent activity against Gram-negative activity including ceftazidime-resistant Escherichia coli, Pseudomonas aeruginosa, Xanthomonas maltophilia and Pseudomonas cepacia.

Biorheology, 1993 May-Aug, 30(3-4), 217 - 27
Polysaccharide strong and weak gels; Ross-Murphy SB et al.; Small deformation oscillatory shear measurements have enabled a distinction to be made between so-called "strong" and "weak" gels, in particular those formed from biologically significant polysaccharides . At small enough strains, both systems give essentially the same mechanical spectrum, with G' > G", and with both moduli largely independent of frequency . However, the deformation dependence of the two classes of materials is very different . Strong gels are essentially strain independent (linearly viscoelastic) for strains of greater than about 0.25, whereas weak gels show such a response only for strains of less than about 0.05 . At large deformations strong gels will rupture and fail, and will never "heal" without melting and resetting . Conversely, weak gels will recover and can flow without fracture, giving a power law response, with an exponent approaching -1, so-called "yield stress" behavior . The rheological properties of a strong gel, agarose, derived from the Rhodophyceae (marine algae) and a weak gel xanthan, an exocellular slime exuded by bacteria of the genus Xanthomonas, are measured in vitro, and related to in vivo requirements.

J Bacteriol, 1993 May, 175(9), 2490 - 500
Sequential assembly and polymerization of the polyprenol-linked pentasaccharide repeating unit of the xanthan polysaccharide in Xanthomonas campestris; Ielpi L et al.; Lipid-linked intermediates are involved in the synthesis of the exopolysaccharide xanthan produced by the bacterium Xanthomonas campestris (L . Ielpi, R . O . Couso, and M . A . Dankert, FEBS Lett . 130:253-256, 1981) . In this study, the stepwise assembly of the repeating pentasaccharide unit of xanthan is described . EDTA-treated X . campestris cells were used as both enzyme preparation and lipid-P acceptor, and UDP-Glc, GDP-Man, and UDP-glucuronic acid were used as sugar donors . A linear pentasaccharide unit is assembled on a polyprenol-P lipid carrier by the sequential addition of glucose-1-P, glucose, mannose, glucuronic acid, and mannose . The in vitro synthesis of pentasaccharide-P-P-polyprenol was also accompanied by the incorporation of radioactivity into a polymeric product, which was characterized as xanthan, on the basis of gel filtration and permethylation studies . Results from two-stage reactions showed that essentially pentasaccharide-P-P-polyprenol is polymerized . In addition, the direction of chain elongation has been studied by in vivo experiments . The polymerization of lipid-linked repeat units occurs by the successive transfer of the growing chain to a new pentasaccharide-P-P-polyprenol . The reaction involves C-1 of glucose at the reducing end of the polyprenol-linked growing chain and C-4 of glucose at the nonreducing position of the newly formed polyprenol-linked pentasaccharide, generating a branched polymer with a trisaccharide side chain.

J Mol Biol, 1993 Apr 20, 230(4), 1103 - 7
Tn5053, a mercury resistance transposon with integron's ends; Kholodii GY et al.; We describe a novel type of mercury resistance transposon, Tn5053, which was found in the chromosome of a mercury-resistant Xanthomonas strain isolated from a mercury mine . An 8400 base-pair Tn5053 is bracketed by 25 base-pair inverted repeats that have no sequence homology with inverted repeats of classical mercury resistance transposons Tn501 and Tn21 . Instead they show high homology with inverted repeats bracketing the antibiotic resistance segment of Tn21 (integron In2) . A 38 base-pair element, which is highly homologous to the inverted repeats of classical mercury resistance transposons has been found within Tn5053 near one of its ends . This internal inverted repeat is fused to the mer operon of Tn5053 in exactly the same way as in the Tn501 mercury resistance transposon . This finding suggests that the mer operon was integrated into the Tn5053 transposition module not through integron-specific pathway but rather via insertion of a classical mercury resistance transposon.

Mol Gen Genet, 1993 Apr, 238(1-2), 261 - 9
Resistance in tomato to Xanthomonas campestris pv vesicatoria is determined by alleles of the pepper-specific avirulence gene avrBs3; Bonas U et al.; Bacterial spot disease of tomato and pepper caused by Xanthomonas campestris pv vesicatoria is prevented by resistance genes in the plant that match genes for avirulence in the bacterium . Based on DNA homology to the avirulence gene avrBs3, which induces the resistance response on pepper, we have isolated another avirulence gene from X . c . vesicatoria, designated avrBs3-2 . This gene differs in specificity from avrBs3 in inducing the hypersensitive response on tomato but not on pepper . Sequence analysis of the avrBs3-2 gene revealed a high degree of conservation: the 3480 bp open reading frame contains an internal region of 17.5 nearly identical 102 bp repeat units that differ in their order from those present in the avrBs3 gene . The coding region is 97% identical to avrBs3 and expresses constitutively a 122 kDa protein, thus representing a natural allele of this gene . The previously isolated 1.7 kb avrBsP gene from X . c . vesicatoria is 100% identical to the corresponding avrBs3-2 sequence, indicating that these genes might be identical . Interestingly, derivatives of avrBs3-2 lacking the C-terminal region and part of the repetitive region are still able to confer incompatibility in tomato . The avrBs3-2 gene is compared with the sequence of avrBs3 derivatives generated by deletion of repeat units that also have avirulence activity on tomato . Both genes, avrBs3 and avrBs3-2, are flanked by a 62 bp long inverted repeat, which prompts speculations about the origin of the members of the avrBs3 gene family.

Appl Environ Microbiol, 1993 Apr, 59(4), 1143 - 8
Detection of Xanthomonas campestris pv . citri by the polymerase chain reaction method; Hartung JS et al.; pFL1 is a pUC9 derivative that contains a 572-bp EcoRI insert cloned from plasmid DNA of Xanthomonas campestris pv . citri XC62 . The nucleotide sequence of pFL1 was determined, and the sequence information was used to design primers for application of the polymerase chain reaction (PCR) to the detection of X . campestris pv . citri, the causal agent of citrus bacterial canker disease . Seven 18-bp oligonucleotide primers were designed and tested with DNA from X . campestris pv . citri strains and other strains of X . campestris associated with Citrus spp . as templates in the PCR . Four primer pairs directed the amplification of target DNA from X . campestris pv . citri strains but not from strains of X . campestris associated with a different disease, citrus bacterial spot . Primer pair 2-3 directed the specific amplification of target DNA from pathotype A but not other pathotypes of X . campestris pv . citri . A pH 9.0 buffer that contained 1% Triton X-100 and 0.1% gelatin was absolutely required for the successful amplification of the target DNA, which was 61% G+C . Limits of detection after amplification and gel electrophoresis were 25 pg of purified target DNA and about 10 cells when Southern blots were made after gel electrophoresis and probed with biotinylated pFL1 . This level of detection represents an increase in sensitivity of about 100-fold over that of dot blotting with the same hybridization probe . PCR products of the expected sizes were amplified from DNA extracted from 7-month-old lesions from which viable bacteria could not be isolated . These products were confirmed to be specific for X . campestris pv . citri by Southern blotting . This PCR-based detection protocol will be a useful addition to current methods of detection of this pathogen, which is currently the target of international quarantine measures.

Appl Environ Microbiol, 1993 Apr, 59(4), 1018 - 24
Ecological and genetic analysis of copper and streptomycin resistance in Pseudomonas syringae pv . syringae; Sundin GW et al.; Strains of Pseudomonas syringae pv . syringae resistant to copper, streptomycin, or both compounds were recovered from symptomless and diseased tissue of four woody hosts in three nurseries in Oklahoma . In strains resistant to copper and streptomycin (Cur Smr), resistance to both compounds was cotransferred with a single plasmid which was either 68, 190, or 220 kilobase pairs (kb) . All Cus Smr strains contained a 68-kb conjugative plasmid . Cur Sms strains contained one plasmid which varied in size from 60 to 73 kb . All conjugative plasmids which transferred streptomycin resistance contained sequences homologous to the strA and strB Smr genes from the broad-host-range plasmid RSF1010 . The Smr determinant was subsequently cloned from a 68-kb Cur Smr plasmid designated pPSR1 . A restriction map detailing the organization of the homologous Smr genes from pPSR1 and RSF1010 and cloned Smr genes from P . syringae pv . papulans and Xanthomonas campestris pv . vesicatoria revealed the conservation of all sites studied . The Cur genes cloned from P . syringae pv . tomato PT23 and X . campestris pv . vesicatoria XV10 did not hybridize to the Cur plasmids identified in the present study, indicating that copper resistance in these P . syringae pv . syringae strains may be conferred by a distinct genetic determinant.

J Bacteriol, 1993 Apr, 175(7), 2017 - 25
Restoration of pathogenicity of avirulent Xanthomonas oryzae pv . oryzae and X . campestris pathovars by reciprocal complementation with the hrpXo and hrpXc genes and identification of HrpX function by sequence analyses; Kamdar HV et al.; The molecular basis of pathogenesis by Xanthomonas oryzae pv . oryzae has been partly elucidated by the identification of a gene, hrpXo, required for bacterial blight on rice . A mutation in hrpXo results in the loss of pathogenicity on rice and the loss of hypersensitivity on nonhosts such as Datura stramonium and radishes . Pathogenicity and its ability to cause the hypersensitive reaction is restored by complementing the mutant with the heterologous hrpXc gene derived from X . campestris pv . campestris . Conversely, hrpXo complements nonpathogenic mutants of X . campestris pv . campestris and X . campetstris pv, armoraciae . Mutants bearing the heterologous hrpX gene are restored in their abilities to cause diseases typical of their chromosomal background and not the hypersensitive reaction on their respective hosts . The hrpXo and hrpXc genes are therefore functionally equivalent, and this functional equivalence extends into X . campestris pv . armoraciae and possibly into other X . campestris pathovars, since this gene is highly conserved among eight other pathovars tested . Sequence analyses of hrpXo revealed an open reading frame of 1,452 bp with a coding capacity for a protein of 52.3 kDa . The protein contains a consensus domain for possible protein myristoylation whose consequence may result in a loss of recognition by host defense and surveillance systems.

J Antimicrob Chemother, 1993 Apr, 31(4), 523 - 32
In-vitro susceptibilities of Pseudomonas aeruginosa and Pseudomonas spp . to the new fluoroquinolones clinafloxacin and PD 131628 and nine other antimicrobial agents; Ford AS et al.; The in-vitro activities of two new fluoroquinolones, clinafloxacin (CI-960, PD 127391, AM-1091) and PD 131628 (the active component of the pro-drug CI-990, PD 131112) and nine other antibiotics were tested against 107 clinical isolates of Pseudomonas aeruginosa, 12 isolates of Xanthomonas maltophilia, and 19 isolates of other Pseudomonas spp . Of the 107 P . aeruginosa isolates, 33 were resistant to gentamicin, tobramycin and amikacin, 17 were resistant to only one or two of these aminoglycosides and 24 were aminoglycoside sensitive . Thirty-three were isolates from cystic fibrosis patients . Susceptibility studies were performed using the agar dilution technique and kinetic time kill curves . With the exception of aminoglycoside-sensitive P . aeruginosa isolates where ciprofloxacin had similar activity to clinafloxacin and PD 131628, the two new fluoroquinolones were the most active agents against all isolates tested (MIC90 0.25-2.0 mg/L) . Cross-resistance was identified with ciprofloxacin and ofloxacin-resistant strains, but the superior activity of clinafloxacin and PD 131628 resulted in 90% of the isolates having MICs < 2 mg/L . Kinetic kill curves with aminoglycoside-sensitive P . aeruginosa revealed ciprofloxacin to have the most rapid and sustained killing . However, with amino-glycoside-resistant P . aeruginosa isolates, clinafloxacin and PD 131628 were more rapidly bactericidal than ciprofloxacin.

Biochem Mol Biol Int, 1993 Apr, 29(6), 989 - 98
Amino acid sequence of extracellular acidic protease V5 of Dichelobacter nodosus, the causative organism of ovine footrot; Kortt AA et al.; Dichelobacter nodosus, a Gram-negative obligate anaerobe and the causative organism of ovine footrot, secretes a family of extracellular serine proteases with pI's in the range of 5.2 to 5.6 and a serine basic protease with a pI of approximately 9.5 . The primary structure of acidic protease V5 (pI approximately 5.2) from D . nodosus virulent strain 198 was determined by direct amino acid sequencing . This protease consists of a single polypeptide chain of 347 amino acids, contains two disulfide bonds and has a M(r) of 35960 . Comparison of the D . nodosus acidic protease V5 sequence with that of other serine proteases showed that it is a member of the subtilisin family of proteases with strong conservation of identity around the catalytic residues . The sequence of protease V5 showed 64% identity to D . nodosus basic protease (pI approximately 9.5) and 53% identity to the extracellular serine protease of Xanthomonas campestris, a plant pathogen but only 25-35% identity to other proteases of the subtilisin family . The D . nodosus proteases are similar in length to X . campestris protease (but some 70 residues shorter than the subtilisins) and they share two conserved disulfide bonds with the X . campestris protease, a feature not observed for other members of the subtilisin family.

Mol Plant Microbe Interact, 1993 Mar-Apr, 6(2), 225 - 37
Gene-for-genes interactions between cotton R genes and Xanthomonas campestris pv . malvacearum avr genes; De Feyter R et al.; Six plasmid-borne avirulence (avr) genes were previously cloned from strain XcmH of the cotton pathogen, Xanthomonas campestris pv . malvacearum . We have now localized all six avr genes on the cloned fragments by subcloning and Tn5-gusA insertional mutagenesis . None of these avr genes appeared to exhibit exclusively gene-for-gene patterns of interactions with cotton R genes, and avrB4 was demonstrated to confer avr gene-for-R genes (plural) avirulence to X . c . pv . malvacearum on congenic cotton lines carrying either of two different resistance loci, B1 or B4 . Furthermore, the B1 locus appeared to confer R gene-for-avr genes resistance to cotton against isogenic X . c . pv . malvacearum strains carrying any one of three avr genes: avrB4, avrb6, or avrB102 . Restriction enzyme, Southern blot hybridization, and DNA sequence analyses showed that the XcmH avr genes are all highly similar to each other, to avrBs3 and avrBsP from the pepper pathogen X . c . pv . vesicatoria, and to the host-specific virulence gene pthA from the citrus pathogen X . citri . The XcmH avr genes differed primarily in the multiplicity of a tandemly repeated 102-base pair motif within the central portions of the genes, repeated from 14 to 23 times in members of this gene family . The complete nucleotide sequence of avrb6 revealed that it is 97% identical in DNA sequence to avrB4, avrBs3, avrBsP, and pthA and that 62-bp inverted terminal repeats mark the boundaries of homology between avrb6 and all members of this Xanthomonas virulence/avirulence gene family sequenced to date . The terminal 38 bp of both inverted repeats are highly similar to the 38-bp consensus terminal sequence of the Tn3 family of transposons . Up to 11 members of the avr gene family appear to be present in North American strains of X . c . pv . malvacearum, including XcmH . The high level of homology observed among these avr genes and their presence in multiple copies may explain the gene-for-genes interactions and also the observed high frequencies (10(-3) to 10(-4) per locus) of X . c . pv . malvacearum race change mutations . Five spontaneous race change mutants of XcmH suffered avr locus deletions, strongly indicating intergenic recombination as the primary mechanism for generating new races in X . c . pv . malvacearum.

Endocrinology, 1993 Mar, 132(3), 1085 - 9
Evidence for an autocrine/paracrine function of chorionic gonadotropin in Xanthomonas maltophilia; Carrell DT et al.; In the human and all other mammalian systems studied, LH and hCG bind to a common high affinity receptor with equal affinity . We have recently reported that a unique high affinity binding site in Xanthomonas maltophilia preferentially binds hCG and a native CG-like ligand over LH or other glycoprotein hormones . In the current studies, we have analyzed the effect of hCG or the native ligand on culturing Xanthomonas maltophilia . Both the human and native ligand caused a dose-dependent alteration in the pattern of the growth cycle and a change in the morphology of the bacteria during the stationary phase of the growth cycle . The protein concentration reached during the stationary phase was significantly (P < 0.005) higher in cultures supplemented with hCG or the native ligand . When an aliquot of the culture was diluted and plated on Earl's Martin Balanced agar plates, the number of subsequent colonies was increased (P < 0.02) in the fractions supplemented with the ligands . The increased growth was significant (P < 0.05) to the lowest concentration of 50 ng/ml ligand . When grown under partially anaerobic conditions, the effects of hCG were observed earlier in the growth cycle . The active hormones, hCG and native ligand, also changed bacterial morphology . These data indicate that hCG may have an autocrine and/or paracrine function in bacteria.

Wei Sheng Wu Xue Bao, 1993 Feb, 33(1), 7 - 12
{A study on classification of Xanthomonas by isoelectric focusing}; Xu B et al.; Studying Xanthomonas strains of 4 species and 29 pathovars by isoelectric focusing, it was shown that the protein patterns were very different among the species and pathovars . Through cluster analysis of IEF date, it was found that the protein pattern differences among certain pathovars were no fewer than that among the species . It revealed that some pathovars could become to be species . There were few differences of 6 protein bands among X . campestris pv . cerealis, X . campestris pv . undulosa and X . campestris pv . hordei which cause bacterial black cheff, so the classification of the three pathovars need to be re-considered . It also showed that isoelectric focusing could be used to classify Xanthomonas below species.

Can J Microbiol, 1993 Feb, 39(2), 207 - 12
Degradation of acrylamide by immobilized cells of a Pseudomonas sp . and Xanthomonas maltophilia; Nawaz MS et al.; Two bacterial isolates capable of utilizing acrylamide as the sole source of carbon and nitrogen were isolated from herbicide-contaminated soil samples and identified as Pseudomonas sp . and Xanthomonas maltophilia . Batch cultures of Pseudomonas sp . and X . maltophilia completely degraded 62.8 mM acrylamide to acrylic acid and ammonia in 24 and 48 h, respectively . Pseudomonas sp . and X . maltophilia, when immobilized in calcium alginate, markedly increased the rate of degradation of acrylamide over batch cultures . Cells of the isolates immobilized in calcium alginate degraded acrylamide to acrylic acid and ammonia in less than 6 h . Initial metabolism of acrylamide by immobilized cells of Pseudomonas sp . followed by inoculation with nonimmobilized cells after 6 h totally removed acrylamide and its metabolites in 72 h . A similar procedure with X . maltophilia resulted in the total metabolism of acrylamide in 96 h . An inducible, intracellular amidase was responsible for the hydrolysis of acrylamide to acrylic acid and ammonia . The specific activity of Pseudomonas sp . amidase was higher than the specific activity of X . maltophilia amidase.

Endocrinology, 1993 Feb, 132(2), 667 - 73
Characterization of a human chorionic gonadotropin-like protein from Candida albicans; Caticha O et al.; Studies from our laboratory have demonstrated that human CG (hCG), human LH, (hLH), and an hCG-like protein extracted from Xanthomonas maltophilia were able to induce Candida albicans transition from the blastospore to the germ tube stage . In the present study, we describe the characterization of an hCG-like material extracted from Candida albicans blastospores (CaCGLP), which is potent in inducing transition and presumably represents the endogenous transition-inducing substance . This material was extracted from Candida albicans blastospores with glacial acetic acid and purified by affinity chromatography using a polyclonal rabbit anti-hCG antibody . The product obtained is a 68-kilodalton single band protein, as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis . Under reduced conditions a protein smear is seen . Amino acid analysis showed a predominance of glycine (22%), followed by serine (12%), and glutamate (12%) . This protein reacted in the following hCG immunoassays: 1) a polyclonal rabbit anti-hCG equilibrium assay, 2) a carboxyl-tail hCG equilibrium assay, 3) two hCG equilibrium assays using monoclonal antibodies (CG no . 4 and CG no . 9), 4) a free alpha-subunit equilibrium assay using a monoclonal antibody, and 5) an ultrasensitive immunoradiometric assay for hCG which does not cross-react with hLH, nor the free beta-subunit of hCG . The CaCGLP showed no reaction in a specific hLH immunoradiometric assay . When CaCGLP was tested in the transition assay, in the presence of 4% rat serum, it was found that this protein was 100 times more potent than hCG in producing Candida albicans transition . We conclude that Candida albicans produces a protein that has certain tertiary structure similarities to hCG and that this material is able to induce germ tube formation . We postulate that CaCGLP has an autocrine/paracrine effect in Candida albicans as a transition factor to control its own pathogenicity.

Biochem Biophys Res Commun, 1993 Jan 29, 190(2), 371 - 6
Partial nucleotide sequence of the Xanthomonas maltophilia chorionic gonadotropin-like receptor; Grover S et al.; Xanthomonas maltophilia possesses a unique high-affinity binding site which binds human chorionic gonadotropin (hCG), but not human luteinizing hormone (hLH) or other glycoprotein hormones . We designed primers from the known nucleotide sequence of the human LH/CG receptor, spanning an area extending from transmembrane region 2 to transmembrane region 6 . Genomic DNA extracted from Xanthomonas maltophilia was used to obtain a PCR amplified product using the above primers . The primary amplification product was cloned in a pCR11 TA cloning vector, and the partial nucleotide sequence of the gene determined . This determined sequence showed 73% identity with the human, as well as the rat LH/CG receptor . Comparison of the translated protein sequence with the human, rat and porcine receptor protein sequences showed a 52% similarity.

J Antimicrob Chemother, 1993 Jan, 31(1), 47 - 55
Effect of divalent cations in bacteriological media on the susceptibility of Xanthomonas maltophilia to imipenem, with special reference to zinc ions; Hawkey PM et al.; The susceptibility of Xanthomonas maltophilia strains to beta-lactams is known to vary according to the type of growth media used . We have assayed the divalent cation content of various susceptibility testing media and correlated this with the susceptibility to imipenem of 30 strains of X . maltophilia, by calculating the IC50 . No correlation was found with Ca++ and Mg++ content (r = 0.005, P = 0.99), but a highly significant correlation with the Zn++ content (7.7-42.7 mumol/L) of the medium was found (r = 0.93, P = 0.003) . The effect of Zn++ on the susceptibility of X . maltophilia to imipenem was further investigated by adding varying amounts of zinc sulphate to Oxoid Mueller-Hinton agar which has a low Zn++ content (14.2 mumol/L) . A highly significant correlation between the Zn++ content and the IC50 was observed (r = 0.95, P = 0.001) . Some variability was seen from one series of IC50 determinations to another and samples of ultra-pure water were processed in exactly the same fashion as the agar media and then assayed for cation content . No significant increase in Ca++ or Mg++ content of the water were observed but water autoclaved in universal containers with metal caps and rubber washers acquired up to 40 mumol/L of Zn++ . Studies of the correlation between in-vitro sensitivity tests and the clinical performance of beta-lactams used against X . maltophilia will need to take account of the Zn++ content of the susceptibility testing media used.

Int J Syst Bacteriol, 1993 Jan, 43(1), 120 - 4
Telluria mixta (Pseudomonas mixta Bowman, Sly, and Hayward 1988) gen . nov., comb . nov., and Telluria chitinolytica sp . nov., soil-dwelling organisms which actively degrade polysaccharides; Bowman JP et al.; Pseudomonas mixta (type strain, ACM 1762 {= ATCC 49108}, an actively dextranolytic species that possesses both lateral and polar flagella, was compared with the strictly aerobic, rod-shaped, chitinolytic bacterium "Pseudomonas chitinolytica" ACM 3522T (= CNCM I-804) (T = type strain), which has a similar flagellation pattern, by performing phenotypic characterization and DNA-DNA hybridization studies and by analyzing DNA base compositions and 16S rRNA sequences . Our results indicated that "P . chitinolytica" ACM 3522T was phenotypically and genotypically distinct from P . mixta and other phenotypically analogous Pseudomonas spp., Xanthomonas maltophilia, and other aerobic chitin degraders . The 16S rRNA sequences of strains ACM 1762T and ACM 3522T were found to be very similar (97%) to each other and indicated that these organisms are proteobacteria that belong to the beta subclass . The strains were deeply branched in the beta subclass and were distinct from other pseudomonads, including Pseudomonas cepacia, and from Comamonas testosteroni . On the basis of phenotypic, genotypic, and phylogenetic evidence, it is proposed that P . mixta and "P . chitinolytica" ACM 3522T represent two distinct species in a new genus called Telluria . Thus, the genus Telluria gen . nov . contains Telluria mixta comb . nov . and Telluria chitinolytica sp . nov., which are strictly aerobic, rod-shaped, soil-dwelling bacteria that are active polysaccharide degraders.

Chin J Biotechnol, 1993, 9(2), 85 - 8
Evidence of the specific molecular interactions between naringenin, NODD and nod-promoter; Hong G et al.; This paper presents evidence that specific molecular interactions occur between three nod regulation elements: naringenin, NODD and nod-promoter . No such interactions were observed when the concentration of naringenin was less than 0.4 mM . However, remarkable molecular interactions were observed when naringenin was at 4.0 mM . The interactions were highly specific because no such interactions have been observed when naringenin was exposed at various concentrations to other promoter-regulatory protein system (e.g., the protease regulatory system of Xanthomonas campestris, although, like NODD-nod-promoter system, specific binding occurs between the protease promoter and the corresponding regulatory protein).

Rev Med Interne . 1993;14(10):986.
{A new threat: Xanthomonas maltophilia infection . Apropos of 50 cases}; Rispal P et al.; In an attempt to further characterize infections due to Xanthomonas maltophilia (XM), we reviewed 50 case reports observed in our institution . XM is emerging as an important nosocomial pathogen in immunocompromised patients, especially those receiving broad spectrum antimicrobial antibiotherapy . Distinction between colonisation and infection is often difficult . XM presents a therapeutic challenge because of its tendency to exhibit multiple resistance.

Appl Microbiol Biotechnol, 1993 Jan, 38(4), 502 - 6
Cloning and characterization of the glutamate 1-semialdehyde aminomutase gene from Xanthomonas campestris pv . phaseoli; Murakami K et al.; The gene from Xanthomonas campestris pv . phaseoli for glutamate 1-semialdehyde (GSA) aminomutase, which is involved in the C5 pathway for synthesis of delta-aminolevulinic acid (ALA), was cloned onto a multicopy plasmid, pUC18, by the complementation of an ALA-deficient mutant (hemL) of Escherichia coli . Subcloning of deletion fragments from the initial 3.5-kb chromosomal fragment allowed the isolation of a 1.7-kb fragment which could complement the hemL mutation . Nucleotide sequence analysis of the 1.7-kb DNA fragment revealed an open reading frame (ORF) that is located downstream from a potential promoter sequence and a ribosome-binding site . The ORF encodes a polypeptide of 429 amino acid residues, and the deduced molecular mass of this polypeptide is 45,043 Da . The amino acid sequence shows a high degree of homology to the HemL proteins from other organisms, and a putative binding site for pyridoxal 5'-phosphate is conserved.

Endocr Res, 1993, 19(2-3), 147 - 62
Characterization of the 48.5 kDa chorionic gonadotropin-like protein from Xanthomonas maltophilia; Grover S et al.; Our laboratory has previously reported the isolation of a 48.5 kDa membrane protein from Xanthomonas maltophilia (ATCC 13637) which immunologically cross-reacts with the beta-subunit of human chorionic gonadotropin (hCG) in both polyclonal and monoclonal radioimmunoassays (RIA) (1) . The protein showed no reaction in RIAs for human LH, TSH, or the free alpha subunit of hCG . We have now improved the protein purification procedure and have obtained adequate bacterial protein to characterize the pure protein (designated xCG) in RIAs and also to obtain amino acid composition and partial sequence . We present these data and compare homology to hCG . An RIA for the bacterial protein has also been developed.

Nucleic Acids Res, 1992 Dec 11, 20(23), 6267 - 73
Structure and evolution of the XcyI restriction-modification system; Withers BE et al.; The XcyI restriction-modification system from Xanthomonas cyanopsidis recognizes the sequence, CCCGGG . The XcyI endonuclease and methylase genes have been cloned and sequenced and were found to be aligned in a head to tail orientation with the methylase preceding and overlapping the endonuclease by one base pair . The nucleotide sequence codes for an N4 cytosine methyltransferase with a predicted molecular weight of 33,500 and an endonuclease comprised of 333 codons and a molecular weight of 36,600 . Sequence comparisons revealed significant similarity between the XcyI, CfrI and SmaI methylisomers . In contrast, no similarity was detected between the primary structures of the XcyI and SmaI endonucleases . The XcyI restriction-modification system is highly homologous to the XmaI genes, although the DNA sequences flanking the genes rapidly diverge . The sequence of the XcyI endonuclease contains two motifs which have recently been identified as essential to the activity of the EcoRV endonuclease.

J Formos Med Assoc, 1992 Dec, 91(12), 1170 - 6
Xanthomonas maltophilia bacteremia: an analysis of 32 cases; Jang TN et al.; Thirty-two cases of Xanthomonas maltophilia bacteremia have been identified over the last two years at the Veterans General Hospital, Taipei . Among them, 27 cases (84%) were due to hospital-acquired infections, and 14 cases (44%) were polymicrobial bacteremia . One case was confirmed as prosthetic valve endocarditis and one case was complicated by recurrent attacks of ecthyma gangrenosum . Most cases had severe debilitating conditions . Twelve cases (38%) had a malignancy, 19 cases (59%) were resident in the Intensive Care Unit and 16 cases (50%) had undergone major surgery . The main predisposing factors included central venous catheterization, endotracheal intubation or tracheostomy, prior antibiotic therapy and prolonged hospitalization . Moxalactam, chloramphenicol and trimethoprim-sulfamethoxazole were the most effective agents in vitro against X . maltophilia . Twenty-two cases (69%) died during hospitalization; 13 cases (41%) were directly attributed to septicemia . Factors that adversely influenced mortality included inappropriate antimicrobial therapy and prior antibiotic treatment . Of particular interest is the fact that none of the patients who did not receive appropriate antimicrobial therapy survived . Early diagnosis and appropriate antibiotic therapy are critical for improving the prognosis of X . maltophilia infection.

J Hosp Infect, 1992 Dec, 22(4), 307 - 16
Bacteraemia caused by non-aeruginosa Pseudomonas species in a cancer centre; Aoun M et al.; Fifty-one episodes of bacteraemia due to Pseudomonas species other than Pseudomonas aeruginosa occurring between 1980 and 1990 in a Belgian cancer centre were reviewed . This corresponded to an incidence of 0.62/1000 admissions, or 1.5% of all bacteraemic episodes . Twenty-nine episodes, each with several positive blood culture sets were considered clinically significant, including six patients belonging to a well-documented outbreak of pseudobacteraemia with Xanthomonas maltophilia and associated with contaminated blood sampling tubes . The respiratory tract was the source in six (20.7%), an infected intravenous catheter in 10 (34.5%) and the source was unknown in seven (24.1%) . Seven patients died from infection (24.1%) . Twenty-three episodes with a single positive blood culture set were considered clinically not significant, although four of them were considered significant by the Centers for Disease Control (CDC) criteria because of the presence of symptoms and specific antibiotic treatment being administered . None of the patients with a single isolate died from infection despite the fact that 17 of 22 did not receive an effective antimicrobial agent . All isolates were susceptible to co-trimoxazole.

Mol Gen Genet, 1992 Dec, 236(1), 113 - 20
Genetic and physical analysis of the rice bacterial blight disease resistance locus, Xa21; Ronald PC et al.; Nearly isogenic lines (NILs) of rice (Oryza sativa) differing at a locus conferring resistance to the pathogen Xanthomonas oryzae pv . oryzae were surveyed with 123 DNA markers and 985 random primers using restriction fragment length plymorphism (RFLP) and random amplified polymorphic DNA (RAPD) analysis . One chromosome 11 marker (RG103) detected polymorphism between the NILs that cosegregated with Xa21 . All other chromosome 11 DNA markers tested were monomorphic between the NILs, localizing the Xa21 introgressed region to an 8.3 cM interval on chromosome 11 . Furthermore, we identified two polymerase chain reaction (PCR) products (RAPD2148 and RAPD818) that detected polymorphisms between the NILs . Genomic sequences hybridizing with RAPD818, RAPD248 and RG103 were duplicated specifically in the Xa21 NIL . All three markers cosegregated with the resistance locus, Xa21, in a F2 population of 386 progeny . Based on the frequency with which we recovered polymorphic Xa21-linked markers, we estimated the physical size of the introgressed region to be approximately 800 kb . This estimation was supported by physical mapping (using pulsed field gel electrophoresis) of the sequences hybridizing with the three Xa21-linked DNA markers . The results showed that the three Xa21-linked markers are physically close to each other, with one copy of the RAPD818 sequences located within 60 kb of RAPD248 and the other copy within 270 kb of RG103 . None of the enzymes tested generated a DNA fragment that hybridized with all three of the markers indicating that the introgressed region containing the resistance locus Xa21 is probably larger than 270 kb.

Eur J Biochem, 1992 Nov 15, 210(1), 13 - 21
Amino acid and DNA sequences of an extracellular basic protease of Dichelobacter nodosus show that it is a member of the subtilisin family of proteases; Lilley GG et al.; A DNA fragment encoding an extracellular basic protease (pI approximately 9.5) from Dichelobacter nodosus, a Gram-negative obligate anaerobe and the causative agent of ovine footrot, has been cloned and expressed in Escherichia coli and sequenced . E . coli harbouring a plasmid with a 3-kb DNA fragment containing the D . nodosus basic-protease gene exhibited proteolytic activity when tested on skim-milk plates . The sequence of the native basic protease isolated from D . nodosus was also determined by direct amino acid sequencing . Comparison of the deduced sequence of the primary translation product (603 residues) and that of the native protease (344 residues) indicates that the protease is synthesized as a precursor molecule, containing a signal peptide (21 residues), a 111 amino acid pro-peptide and a 127 residue C-terminal extension which is subsequently processed to the mature active form . Comparison of the D . nodosus basic protease sequence with that of other serine proteases showed that it is related to the subtilisin family of proteases with strong conservation of sequence identity around the catalytic site residues . A remarkable similarity in structure was found to the serine protease of Xanthomonas campestris, a plant pathogen, with respect to the length of the precursor segments, conservation of disulfide bridges and approximately 50% sequence identity of the mature proteases.

Mol Plant Microbe Interact, 1992 Nov-Dec, 5(6), 451 - 9
Identification of a family of avirulence genes from Xanthomonas oryzae pv . oryzae; Hopkins CM et al.; Races of Xanthomonas oryzae pv . oryzae, the causal agent of bacterial blight of rice, interact with cultivars of rice in a gene-for-gene specific manner . Multiple DNA fragments of various sizes from all strains of X . o . pv . oryzae hybridized with avrBs3, an avirulence gene from Xanthomonas campestris pv . vesicatoria, in Southern blots; this suggests the presence of several homologs and possibly a gene family . A genomic library of a race 2 strain of X . o . pv . oryzae, which is avirulent on rice cultivars carrying resistance genes xa-5, Xa-7, and Xa-10, was constructed . Six library clones, which hybridized to avrBs3, altered the interaction phenotype with rice cultivars carrying either xa-5, Xa-7, or Xa-10 when present in a virulent race 6 strain . Two avirulence genes, avrXa7 and avrXa10, which correspond to resistance genes Xa-7 and Xa-10, respectively, were identified and partially characterized from the hybridizing clones . On the basis of transposon insertion mutagenesis, sequence homology, restriction mapping, and the presence of a repeated sequence, both genes are homologs of avirulence genes from dicot xanthomonad pathogens . Two BamHI fragments that are homologous to avrBs3 and correspond to avrXa7 and avrXa10 contain a different number of copies of a 102-bp direct repeat . The DNA sequence of avrXa10 is nearly identical to avrBs3 . We suggest that avrXa7 and avrXa10 are members of an avirulence gene family from xanthomonads that control the elicitation of resistance in mono- and dicotyledonous plants.

Gene, 1992 Oct 12, 120(1), 99 - 103
Analysis of the genes and gene products of Xanthomonas transposable elements ISXc5 and ISXc4; Liu CC et al.; A series of deletion mutants have been constructed for the gene analyses of transposable elements, ISXc5 and ISXc4, derived from Xanthomonas . At least two element-encoded polypeptides of 48 kDa and 40 kDa have been identified in the minicell-producing Escherichia coli strain, TC410 . A study of the element transposition and cointegrate resolution revealed that the 48-kDa and 40-kDa polypeptide are both involved in translocation of the elements, the 48-kDa product being involved in transposition of the elements and the 40-kDa product being involved in cointegrate resolution.

Mol Plant Microbe Interact, 1992 Sep-Oct, 5(5), 372 - 8
Disease development in ethylene-insensitive Arabidopsis thaliana infected with virulent and avirulent Pseudomonas and Xanthomonas pathogens; Bent AF et al.; The plant hormone ethylene has been hypothesized to play roles both in disease resistance and in disease susceptibility . These processes were examined by using isogenic virulent and avirulent bacterial pathogens and mutants of Arabidopsis thaliana that were altered in ethylene physiology . Ethylene-insensitive ein1 and ein2 mutants of Arabidopsis were resistant to Pseudomonas syringae pv . tomato made avirulent by the addition of the cloned avirulence genes avrRpt2, avrRpm1, or avrB; this suggests that ethylene is not required for active resistance against avirulent bacteria . In a second set of experiments, susceptibility was monitored with virulent P . s . pv . tomato, P . s . pv . maculicola, or Xanthomonas campestris pv . campestris strains . Wild-type Arabidopsis and ein1 mutants were susceptible to these strains, but ein2 mutants developed only minimal disease symptoms . Despite these reduced symptoms, virulent P . s . pv . tomato grew extensively within ein2 leaves . The Pseudomonas phytotoxin coronatine induces ethylene biosynthesis and diseaselike symptoms on many plant species, but the reduced symptomology of ein2 mutants could not be attributed to insensitivity to coronatine . The enhanced disease tolerance of ein2 plants suggests that ethylene may mediate pathogen-induced damage, but the absence of tolerance in ein1 mutants has yet to be explained.

J Gen Microbiol, 1992 Aug, 138 ( Pt 8), 1647 - 55
Molecular cloning, characterization and nucleotide sequence of the gene for secreted alpha-amylase from Xanthomonas campestris pv . campestris; Hu NT et al.; alpha-Amylase (1,4-alpha-D-glucan glucanohydrolase, EC 3.2.1.1) of apparent molecular mass 45 kDa was secreted by Xanthomonas campestris pv . campestris grown in medium containing starch or maltose . We isolated its structural gene from a recombinant lambda library and located it on a 2.7 kb DNA fragment . Nucleotide sequencing of the fragment revealed a potential ORF encoding a protein of 475 amino acid residues, including a potential signal sequence of 35 amino acids . The signal processing site was confirmed by N-terminal amino acid sequence analysis of the exported alpha-amylase . The deduced amino acid sequence of the mature protein is very similar to that of the alpha-amylase of Aeromonas hydrophila . It also contains all four amino acid sequences highly conserved in the alpha-amylases from a wide range of organisms . Expression of the amy gene in Escherichia coli was poor from its own promoter, but was enhanced by the upstream promoter on the vector . The alpha-amylase synthesized in E . coli was located in the periplasm.

J Bacteriol, 1992 Aug, 174(16), 5457 - 61
DNA binding specificity and sequence of Xanthomonas campestris catabolite gene activator protein-like protein; Dong Q et al.; The Xanthomonas campestris catabolite gene activator protein-like protein (CLP) can substitute for the Escherichia coli catabolite gene activator protein (CAP) in transcription activation at the lac promoter (V . de Crecy-Lagard, P . Glaser, P . Lejeune, O . Sismeiro, C . Barber, M . Daniels, and A . Danchin, J . Bacteriol . 172:5877-5883, 1990) . We show that CLP has the same DNA binding specificity as CAP at positions 5, 6, and 7 of the DNA half site . In addition, we show that the amino acids at positions 1 and 2 of the recognition helix of CLP are identical to the amino acids at positions 1 and 2 of the recognition helix of CAP:i.e., Arg at position 1 and Glu at position 2.

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