Soc Sci Med, 1996 Jan, 42(1), 141 - 52 Prostitutes, prostitution and STD/HIV transmission in mainland China; Gil VE et al.; China's opening to the world has enabled massive social and economic transformations and the liberalization of many policies, but also the rise of coincident social problems and diseases . A revival of wide-scale female prostitution since the 1980s has now accelerated to a nationwide dilemma . Prostitutes have long been considered to be reservoirs, if not 'vectors' for the transmission of sexual diseases . A well established STD epidemic in the last decade, plus the presence of growing HIV infections in China now, underscore the need to evaluate the prostitute's role in STD and HIV propagation . This report examines unobtrusive data on female prostitutes in the People's Republic of China through an analysis of prison records from eight sexually segregated prisons (six in Sichuan Province and two in Guizhou Province), two female re-education institutions, and arrest records for convicted prostitutes from four counties in Sichuan Province and Chengdu City (also in Sichuan) . Collectively, these data represent 2057 female prostitution cases, and span the years 1988-1990 . Demographics are examined to enable a profile of the prostitute as based on data reviewed, and this is contrasted to the stereotype of the prostitute as described in government propaganda against prostitution . STD prevalence rates in the samples are examined and contrasted to two other studies on STDs in nonprostitution populations made available to the authors . Prostitute arrest records reveal a majority had active STD infection{s} at the time of their apprehension, with gonorrhea being the most common bacterium; in many instances, prostitutes also had a history of other sexually transmitted diseases . Thus, data examined support the notion of prostitution as an agent in STD transmission . Presence of HIV infection in prostitutes could not be corroborated through sampled records, nor could prostitution itself be confirmed as an agent in HIV transmission at present . However, given the type of clients serviced by prostitutes in China, a prostitute's own risk of HIV infection is discussed . Control measures by the Chinese government to curb prostitution are examined at both national and provincial levels . Questions are raised as to the effectiveness of present tactics as adjunctive strategies in reducing STD infection and HIV risk in the prostitution population. Crit Rev Microbiol, 1996, 22(1), 27 - 56 Ecology, metabolism, and genetics of ruminal selenomonads; Ricke SC et al.; Selenomonas ruminantium is one of the more prominent and functionally diverse bacteria present in the rumen and can survive under a wide range of nutritional fluctuations . Selenomonas is not a degrader of complex polysaccharides associated with dietary plant cell wall components, but is important in the utilization of soluble carbohydrates released from initial hydrolysis of these polymers by other ruminal bacteria . Selenomonads have multiple carbon flow routes for carbohydrate catabolism and ATP generation, and subspecies differ in their ability to use lactate . Some soluble carbohydrates (glucose, sucrose) appear to be transported via the phosphoenolpyruvate phosphotransferase system, while arabinose and xylose are transported by proton symport . High cell yields and the presence of electron transport components in Selenomonas strains has been documented repeatedly and this may partially account for the energy partitioning observed between energy consumed for growth and maintenance functions . Most strains can utilize ammonia, protein, and/or amino acids as a nitrogen source . Some strains can hydrolyze urea and/or reduce nitrate and use the ammonia for the biosynthesis of amino acids . Experimental evidence suggests that ammonia assimilatory enzymes in some strains may possess unique properties with respect to other presumably similar bacteria . Little is known about the genetics of ruminal selenomonads . Plasmid DNA has been isolated from some strains, but it is unknown what physiological functions may be encoded on these extrachromosomal elements . Due to the predominance of S . ruminantium in the rumen, it is an ideal candidate for genetic manipulation . Once the genetics of this bacterium are better understood, it may be possible to amplify its role in the rumen. Scand J Gastroenterol Suppl, 1996, 215, 48 - 51 Helicobacter pylori and gastric cancer; Forman D; The International Agency for Research on Cancer, sponsored by the World Health Organization, has recently categorized Helicobacter pylori infection as a class I carcinogen, based on evidence that this infection increases the risk of gastric cancer . The classification was intentionally qualitative in nature and not associated with any public health recommendations . In addition, no specific causal mechanism was proposed to explain the relationship between H . pylori and gastric cancer . In this paper, the magnitude of the risk, implications of the relationship for the prevention of gastric cancer and nature of the causal mechanisms are considered . Relative risk of gastric cancer may be substantial; even with conservative assumptions, the proportion of new cases of gastric cancer worldwide attributable to H . pylori infection is approximately one third of a million annually . This figure is likely to increase with changes in the age structure of the population, and the eradication of H . pylori as a means of prevention of gastric cancer should be considered . A strategy of screening populations in middle age and treating those infected could be relatively inexpensive to administer, but the efficacy is totally unknown and requires evaluation in a randomized controlled trial . Studies designed to address this issue in the general population would need to be large and long-term if gastric cancer is used as an end-point . With respect to carcinogenic mechanisms, a number of constitutive properties of H . pylori may be of relevance to cancer without being specifically carcinogenic . Thus ammonia, which is produced in abundance as a result of urease activity, may promote cell division . Other relevant properties result from the immune response of the host to the bacterium . For example, the excessive production of reactive oxygen metabolites can lead to extensive DNA damage and molecular mutations. Scand J Gastroenterol Suppl, 1996, 215, 32 - 7 Helicobacter pylori and disturbance of gastric function associated with duodenal ulcer disease and gastric cancer; McColl KE et al.; Helicobacter pylori is now recognized as the major acquired factor in the pathogenesis of duodenal ulcer disease (DU) . There is also an association between H . pylori infection and the subsequent development of gastric cancer . The mechanisms by which such infection predisposes the host to these diseases are incompletely understood, but disorders induced by the bacterium in gastric function play a pivotal role . In most patients, H . pylori infection stimulates acid secretion, leading to a predisposition to DU development . However, in some patients, the infection is associated with a significant decrease in acid secretion, a predisposition to gastric cancer . These divergent effects of H . pylori on gastric acid secretion explain the early conflicting reports on changes in acid secretion associated with the infection . The reason why H . pylori infection produces divergent effects on gastric acid secretion is unclear, but may be related to differences in bacterial strains or genetic, dietary or other environmental factors. Farmaco, 1996 Jan, 51(1), 49 - 52 3-Diazopyrroles . Part 6 . Mutagenic activity of 3-diazopyrroles in Streptomyces coelicolor A3(2) during various phases of growth; Cirrincione G et al.; 3-Diazopyrroles, a class of compounds particularly interesting from a chemical and biological point of view, were assayed for their ability to induce gene mutations employing back mutation (his+ reversion) test in the philamentous bacterium Streptomyces coelicolor at various time during life cycle . Our results suggest that in evaluating the mutagenicity and toxicity of chemicals in Streptomyces system it is important to consider factors such as growth phase . Furthermore in this series of diazopyrroles a relationship between toxicity, mutagenicity and chemical structure was found . The observed mutagenic activity can be the molecular basis for the appearance of antitumor activity. J Biomol NMR, 1996 Jan, 7(1), 35 - 47 1H NMR investigation of the secondary structure, tertiary contacts and cluster environment of the four-iron ferredoxin from the hyperthermophilic archaeon Thermococcus litoralis; Donaire A et al.; The solution molecular structure of the four-iron ferredoxin (Fd) from the hyperthermophilic archaeon Thermococcus litoralis (Tl) has been investigated by 1H NMR spectroscopy . TOCSY and NOESY experiments in H2O, tailored to detect both weakly and strongly relaxed resonances, together with steady-state NOEs in both H2O and D2O, allowed the identification of 58 of the 59 residues, with one residue near the paramagnetic center undetected . It is shown that the contact shifted and strongly relaxed signals for all four cysteines ligated to the paramagnetic cluster can be assigned by standard backbone connectivities that do not require any assumptions about the tertiary structure . Secondary structural elements identified in Tl Fd are a three-stranded antiparallel beta-strand involving the termini of the protein, a double beta-strand (also antiparallel), two alpha-helices and four turns . The existence of a disulfide bridge between the nonligated cysteines is also proposed . Dipolar contacts observed in the NOESY maps and by steady-state NOEs between the ligated cysteines and the 'diamagnetic' protein matrix indicate that the overall folding pattern of Tl Fd is very similar to that of the 3Fe ferredoxin from the mesophilic bacterium Desulfovibrio gigas {Kissinger et al . (1991) J . Mol . Biol., 219, 693-723} . The influence of the paramagnetism of the cluster on the relaxation properties of the proton signals of nonligated residues near the cluster, as well as on the ligated cysteines, correlates well with the proximity to the cluster iron(s), as predicted from the crystal structures for homologous protons of other single-cluster ferredoxins . Finally, the potential role of the various identified structural factors in contributing to the hyperthermostability of this protein is discussed. Ann Ital Chir, 1996 Jan-Feb, 67(1), 27 - 33; discussion 34 {B-cell lymphoma (MALToma) of the stomach and Helicobacter pylori infection}; Rodolico A et al.; The authors, after illustrating physiopathologic aspects of gastric MALTomas, examine the H.P . infections and the possible relations between this kind of bacterium and gastric MALTomas . They hypothesize that H.P . infection represents an important predisposition to gastric lymphoma, due to anatomopathological modifications over gastric mucosa . They conclude that a decreasing of gastric lymphoma could be correlatable an opportune eradication of H.P . despite of at moment it's impossible hypothesize a marked decreasing of lymphoma by an eradication of H.P. Lett Appl Microbiol, 1996 Jan, 22(1), 52 - 6 Genetic transfer of lactate-utilizing ability in the rumen bacterium Selenomonas ruminantium; Gilmour M et al.; Matings between the lactate-utilizing, tetracycline-sensitive Selenomonas ruminantium strains 5521C1 and 5934e and the lactate-non-utilizing, tetracycline-resistant strain FB322 resulted in putative recombinant strains capable of growth on lactate . Analysis of total protein by SDS-PAGE and chromosomal DNA by hybridization, indicated that the recombinants were derived from strain FB322 . DNA hybridization produced no evidence that plasmid transfer occurred, leaving chromosomal DNA transfer as the most likely mechanism for the altered phenotype . Analysis of strains 5934e, FB322 and the resulting recombinant TC3 indicated that all three strains contained D-nLDH and L-nLDH activities . In addition strains 5934e and TC3 possessed D-iLDH activity when grown on DL-lactate . The ability of strain FB322 to grow on pyruvate but not lactate suggested that the lactate-utilizing recombinant had acquired the ability to synthesize D-iLDH. Int J Syst Bacteriol, 1996 Jan, 46(1), 94 - 7 Phylogenetic relationships of the filamentous sulfur bacterium Thiothrix ramosa based on 16S rRNA sequence analysis; Polz MF et al.; The phylogeny of Thiothrix ramosa based on 16S rRNA sequences was determined . This species is the first species in this genus that has been shown to be capable of autotrophic growth with reduced sulfur compounds as sole energy sources . T . ramosa forms a monophyletic clade with Thiothrix nivea, as determined by distance, parsimony, and maximum-likelihood methods . Both of these species clearly belong to the gamma subdivision of the Proteobacteria, where they are loosely associated with other sulfur-oxidizing chemoautotrophic organisms. Appl Environ Microbiol, 1996 Jan, 62(1), 67 - 73 Description of a new polymer-secreting bacterium from a deep-sea hydrothermal vent, Alteromonas macleodii subsp . fijiensis, and preliminary characterization of the polymer; Raguenes G et al.; A deep-sea, aerobic, mesophilic, heterotrophic bacterium was isolated from fluid collected near an active hydrothermal vent . On the basis of phenotypic and phylogenetic analyses and DNA-DNA relatedness, strain ST716 could be assigned to the species Alteromonas macleodii as a new subspecies . This bacterium secreted an unusual high-molecular-weight polysaccharide in the presence of glucose in batch cultures . The viscosity of this exopolysaccharide is of the same order of magnitude as that of xanthan, another bacterial polysaccharide of industrial interest . This polysaccharide, produced during the stationary phase, contained glucose, mannose, pyruvated mannose, and galactose along with galacturonic acid and glucuronic acid. J Bacteriol, 1996 Jan, 178(2), 484 - 9 Thermostable chemotaxis proteins from the hyperthermophilic bacterium Thermotoga maritima; Swanson RV et al.; An expressed sequence tag homologous to cheA was previously isolated by random sequencing of Thermotoga maritima cDNA clones (C . W . Kim, P . Markiewicz, J . J . Lee, C . F . Schierle, and J . H . Miller, J . Mol . Biol . 231: 960-981, 1993) . Oligonucleotides complementary to this sequence tag were synthesized and used to identify a clone from a T . maritima lambda library by using PCR . Two partially overlapping restriction fragments were subcloned from the lambda clone and sequenced . The resulting 5,251-bp sequence contained five open reading frames, including cheA, cheW, and cheY . In addition to the chemotaxis genes, the fragment also encodes a putative protein isoaspartyl methyltransferase and an open reading frame of unknown function . Both the cheW and cheY genes were individually cloned into inducible Escherichia coli expression vectors . Upon induction, both proteins were synthesized at high levels . T . maritima CheW and CheY were both soluble and were easily purified from the bulk of the endogenous E . coli protein by heat treatment at 80 degrees C for 10 min . CheY prepared in this way was shown to be active by the demonstration of Mg(2+)-dependent autophosphorylation with {32P}acetyl phosphate . In E . coli, CheW mediates the physical coupling of the receptors to the kinase CheA . The availability of a thermostable homolog of CheW opens the possibility of structural characterization of this small coupling protein, which is among the least well characterized proteins in the bacterial chemotaxis signal transduction pathway. Gastroenterology, 1996 Jan, 110(1), 21 - 9 Extract of Helicobacter pylori induces neutrophils to injure endothelial cells and contains antielastase activity; Takemura T et al.; BACKGROUND & AIMS: Previous studies indicate that a water extract of Helicobacter pylori promotes leukocyte adhesion and emigration as well as endothelial barrier disruption (increased vascular protein leakage) in rat mesenteric venules . The aims of this study were to assess whether H . pylori extract-activated neutrophils disrupt endothelial cell monolayers and to identify the mechanisms involved in this process . METHODS: Human neutrophils were incubated with monolayers of human umbilical vein endothelial cells (HUVECs) in the presence or absence of H . pylori extract . RESULTS: H . pylori extract-activated human neutrophils produced endothelial cell detachment from HUVEC monolayers, the severity of which was dependent on the duration of exposure . Endothelial cell detachment was prevented by a monoclonal antibody directed against CD11/CD18 on neutrophils or a monoclonal antibody against intercellular adhesion molecule 1 on endothelial cells . HUVEC monolayer disruption was also prevented by superoxide dismutase, catalase, and a monoclonal antibody against elastase . Further studies indicated that H . pylori extract was capable of inhibiting human neutrophil elastase . The antielastase activity was not diminished by oxidants . CONCLUSIONS: These studies indicate that H . pylori extract-activated human neutrophils can disrupt HUVEC monolayers only when human neutrophils are allowed to adhere to HUVECs and may provide an explanation for the H . pylori extract-induced, neutrophil-dependent vascular protein leakage observed in vivo . The possibility that H . pylori releases antiproteases may explain, in part, why this bacterium is so virulent. Structure, 1995 Dec 15, 3(12), 1295 - 306 2.0 A structure of indole-3-glycerol phosphate synthase from the hyperthermophile Sulfolobus solfataricus: possible determinants of protein stability; Hennig M et al.; BACKGROUND: Recent efforts to understand the basis of protein stability have focused attention on comparative studies of proteins from hyperthermophilic and mesophilic organisms . Most work to date has been on either oligomeric enzymes or monomers comprising more than one domain . Such studies are hampered by the need to distinguish between stabilizing interactions acting between subunits or domains from those acting within domains . In order to simplify the search for determinants of protein stability we have chosen to study the monomeric enzyme indole-3-glycerol phosphate synthase from the hyperthermophilic archaeon Sulfolobus solfataricus (sIGPS), which grows optimally at 90 degrees C . RESULTS: The 2.0 A crystal structure of sIGPS was determined and compared with the known 2.0 A structure of the IGPS domain of the bifunctional enzyme from the mesophilic bacterium Escherichia coli (eIGPS) . sIGPS and eIGPS have only 30% sequence identity, but share high structural similarity . Both are single-domain (beta/alpha)8 barrel proteins, with one (eIGPS) or two (sIGPS) additional helices inserted before the first beta strand . The thermostable sIGPS has many more salt bridges than eIGPS . Several salt bridges crosslink adjacent alpha helices or participate in triple or quadruple salt-bridge clusters . The number of helix capping, dipole stabilizing and hydrophobic interactions is also increased in sIGPS . CONCLUSIONS: The higher stability of sIGPS compared with eIGPS seems to be the result of several improved interactions . These include a larger number of salt bridges, stabilization of alpha helices and strengthening of both polypeptide chain termini and solvent-exposed loops. Biochemistry, 1995 Dec 12, 34(49), 15997 - 6003 Ion pair formation between basic residues at 144 of the Cyt b polypeptide and the ubiquinones at the Qo site of the Cyt bc1 complex; Ding H et al.; Loci of spontaneous Qo site inhibitor resistant mutants in the cyt bc1 complex of the photosynthetic bacterium Rhodobacter capsulatus are M140, F144, G152, G158, and T163 of the cyt b polypeptide . In this report, we have studied the effects of arginine (R) substitution at these positions with a view to test for specific interactions with the {2Fe-2S} cluster, cyt bL with Qo site ubiquinone (Q), or hydroquinone (QH2) . All the arginine mutants displayed severely or completely impeded photosynthetic growth resulting from dysfunctional cyt bc1 complexes . The source of dysfunction in G158R and T163R was identified by a > 1000-fold decrease in the Qo site affinity for QH2 and Q, sufficient to empty the site in the presence of the 30 mM ubiquinone pool of the chromatophore membrane; they appear similar to the class of mutants described in the preceding paper {Ding, H., Moser, C . C., Robertson, D . E., Tokito, M., Daldal, F., & Dutton, P . L (1995) Biochemistry 34, 15979-15996} . The source(s) of dysfunction of M140R and G152R is not so apparent since they possess Qo sites with normal QH2/Q affinity; they appear to be members to the class of mutants identified and characterized in the following paper {Saribas, S., Ding, H., Dutton, P . L., & Daldal, F . (1995) Biochemistry 34, 16004-16012} . The present paper focuses on the unique affects of F144R . Redox potential and EPR spectral properties of the Qo site of F144R showed that arginine forms an ion pair with the head group of an anionic ubiquinone, tentatively suggested to be a ubihydroquinone anion (QH-) in the Qos domain.(ABSTRACT TRUNCATED AT 250 WORDS) Proc Natl Acad Sci U S A, 1995 Dec 5, 92(25), 11829 - 33 Characterization of repetitive DNA in the Mycoplasma genitalium genome: possible role in the generation of antigenic variation; Peterson SN et al.; We have characterized a family of repetitive DNA elements with homology to the MgPa cellular adhesion operon of Mycoplasma genitalium, a bacterium that has the smallest known genome of any free-living organism . One element, 2272 bp in length and flanked by DNA with no homology to MgPa, was completely sequenced . At least four others were partially sequenced . The complete element is a composite of six regions . Five of these regions show sequence similarity with nonadjacent segments of genes of the MgPa operon . The sixth region, located near the center of the element, is an A+T-rich sequence that has only been found in this repeat family . Open reading frames are present within the five individual regions showing sequence homology to MgPa and the adjacent open reading frame 3 (ORF3) gene . However, termination codons are found between adjacent regions of homology to the MgPa operon and in the A+T-rich sequence . Thus, these repetitive elements do not appear to be directly expressible protein coding sequences . The sequence of one region from five different repetitive elements was compared with the homologous region of the MgPa gene from the type strain G37 and four newly isolated M . genitalium strains . Recombination between repetitive elements of strain G37 and the MgPa operon can explain the majority of polymorphisms within our partial sequences of the MgPa genes of the new isolates . Therefore, we propose that the repetitive elements of M . genitalium provide a reservoir of sequence that contributes to antigenic variation in proteins of the MgPa cellular adhesion operon. FEMS Microbiol Rev, 1995 Dec, 17(4), 401 - 13 Molecular aspects of the electron transfer system which participates in the oxidation of ferrous ion by Thiobacillus ferrooxidans; Yamanaka T et al.; The enzymes and redox proteins, which participate in the oxidation of ferrous ion by the acidophilic iron-oxiding bacterium Thiobacillus ferrooxidans, have been isolated and characterized . They are Fe(II)-cytochrome c oxidoreductase, cytochromes c-552(s), c-552(m) and c-550(m), rusticyanin, and cytochrome c oxidase . On the basis of the interactions of these components, an electron transfer system has been proposed which seems to function in the oxidation of ferrous ion by the bacterium. Int J Biol Macromol, 1995 Dec, 17(6), 353 - 5 The cellulolytic system of Streptomyces reticuli; Schrempf H et al.; The bacterium Streptomyces reticuli produces an unusual mycelia-associated cellulase (Avicelase, Cel1) which is solely sufficient to degrade crystalline cellulose to cellobiose . The enzyme consists of a binding domain, one adjoining region with unknown function, and a catalytic domain belonging to the cellulase family E . During cultivation, the strain produces a specific protease which processes the Avicelase to a truncated enzyme lacking the binding domain . The cellulase synthesis is regulated by induction (Avicel) and repression (metabolizable sugars and glycerol). J Mol Evol, 1995 Dec, 41(6), 803 - 12 Arrangement and nucleotide sequence of the gene (fus) encoding elongation factor G (EF-G) from the hyperthermophilic bacterium Aquifex pyrophilus: phylogenetic depth of hyperthermophilic bacteria inferred from analysis of the EF-G/fus sequences; Bocchetta M et al.; The gene fus (for EF-G) of the hyperthermophilic bacterium Aquifex pyrophilus was cloned and sequenced . Unlike the other bacteria, which display the streptomycin-operon arrangement of EF genes (5'-rps12-rps7-fus-tuf-3'), the Aquifex fus gene (700 codons) is not preceded by the two small ribosomal subunit genes although it is still followed by a tuf gene (for EF-Tu) . The opposite strand upstream from the EF-G coding locus revealed an open reading frame (ORF) encoding a polypeptide having 52.5% identity with an E . coli protein (the pdxJ gene product) involved in pyridoxine condensation . The Aquifex EF-G was aligned with available homologs representative of Deinococci, high G+C Gram positives, Proteobacteria, cyanobacteria, and several Archaea . Outgroup-rooted phylogenies were constructed from both the amino acid and the DNA sequences using first and second codon positions in the alignments except sites containing synonymous changes . Both datasets and alternative tree-making methods gave a consistent topology, with Aquifex and Thermotoga maritima (a hyperthermophile) as the first and the second deepest offshoots, respectively . However, the robustness of the inferred phylogenies is not impressive . The branching of Aquifex more deeply than Thermotoga and the branching of Thermotoga more deeply than the other taxa examined are given at bootstrap values between 65 and 70% in the fus-based phylogenies, while the EF-G(2)-based phylogenies do not provide a statistically significant level of support (< or = 50% bootstrap confirmation) for the emergence of Thermotoga between Aquifex and the successive offshoot (Thermus genus) . At present, therefore, the placement of Aquifex at the root of the bacterial tree, albeit reproducible, can be asserted only with reservation, while the emergence of Thermotoga between the Aquificales and the Deinococci remains (statistically) indeterminate. Protein Sci, 1995 Dec, 4(12), 2619 - 20 Crystallization and preliminary X-ray analysis of L-2-haloacid dehalogenase from Xanthobacter autotrophicus GJ10; Ridder IS et al.; Haloacid dehalogenases are enzymes that cleave carbon-chlorine or carbon-bromine bonds of 2-haloalkanoates . X-ray-quality crystals of L-2-haloacid dehalogenase from the 1,2-dichloroethane-degrading bacterium Xanthobacter autotrophicus GJ10 have been grown at room temperature from 20% PEG 8000, 200 mM sodium formate at pH 6.8-7.0, using macroseeding techniques . The crystals, which diffract in the X-ray beam up to 2.0 A resolution, belong to the spacegroup C2221 . Cell parameters are a = 58.8 A, b = 93.1 A, c = 84.2 A . A native data set to 2.3 A has been collected, with a completeness of 97% and an Rsym of 6.0%. Microbiology, 1995 Dec, 141 ( Pt 12), 3113 - 8 Acetyl-CoA carboxylase activity in Helicobacter pylori and the requirement of increased CO2 for growth; Burns BP et al.; A biotinylated acetyl-CoA carboxylase from the microaerophilic bacterium Helicobacter pylori was partially purified and characterized . The approximate molecular mass of the native enzyme was estimated at 235 kDa by native PAGE . A single band corresponding to approximately 24 kDa was detected by SDS-PAGE, suggesting that the native enzyme is a multi-protein complex . The protein was isolated from the soluble fraction of the cell . Catalytic activity was acetyl-CoA-dependent and inhibited by avidin but unaffected by avidin pretreated with excess biotin . The end-product of the reaction was identified as malonyl-CoA and the reaction was shown to be reversible by NMR spectroscopy . The activity of the enzyme was 0.29 mumol min-1 (mg protein)-1 . The Vmax for bicarbonate was calculated at 0.73 mumol min-1 (mg protein)-1, and the affinity of the enzyme for this substrate was relatively low, with an apparent Km of 16.6 mM . These data provide the first evidence of a possible physiological role for the requirement of high levels of CO2 for growth in vitro of this bacterium. Plant Mol Biol, 1995 Dec, 29(5), 897 - 907 Transformation of Synechococcus with a gene for choline oxidase enhances tolerance to salt stress; Deshnium P et al.; Choline oxidase, isolated from the soil bacterium Arthrobacter globiformis, converts choline to glycinebetaine (N-trimethylglycine) without a requirement for any cofactors . The gene for this enzyme, designated codA, was cloned and introduced into the cyanobacterium Synechococcus sp . PCC 7942 . The codA gene was expressed under the control of a strong constitutive promoter, and the transformed cells accumulated glycinebetaine at intracellular levels of 60-80 mM . Consequently the cells acquired tolerance to salt stress, as evaluated in terms of growth, accumulation of chlorophyll and photosynthetic activity. Gaoxiong Yi Xue Ke Xue Za Zhi, 1995 Dec, 11(12), 650 - 3 Evaluation of the severity of Helicobacter pylori infection with urease test: its correlation with histopathology and bacterial density; Jan CM et al.; In 69 patients, the severity of Helicobactor pylori (H . pylori) infection was evaluated by bacterial density of tissue implants and inflammatory responses by histology . The specimens were taken from gastric angle and antrum (greater and lesser curvature sides) by gastroduodenal endoscopy . In urease test, the severity was measured in 3 grades according to color change of the agar: those change are within 30 minutes (grade 3), 30 minutes to 3 hours (grade 2), and 3 to 6 hours (grade 1), respectively; while the grade 0 indicated no color change occurring 6 hours after tissue inoculation . The severity of infection was assessed according to the bacterial density under high power microscopic fields (Gram's stain) . Grade 0 indicated no bacterium seen; grade 1, only 1 to 10 bacteria at all fields; grade 2, 1 to 3 bacteria in each high power field; and grade 3 was 4 bacteria or more on average in each high power field . The degree of inflammatory response was evaluated by inflammatory cell infiltration (H & E stain) and classified into grade 0, 1 and 2, which indicated the inflammatory cell infiltration below 50%, between 50% and 75%, and above 75%, respectively . There are no positive relationships among urease test reaction time, bacterial density grading and degrees of inflammatory cell infiltration . Clinically, the reaction time of urease test cannot reflect the severity of H . pylori infection semi-quantitatively, either in terms of bacterial density or cellular inflammatory response. Appl Environ Microbiol, 1995 Dec, 61(12), 4329 - 33 Identification of two pigments and a hydroxystilbene antibiotic from Photorhabdus luminescens; Li J et al.; Two yellow pigments were isolated for the first time from the entomopathogenic bacterium Photorhabdus luminescens in liquid culture and were identified as the anthraquinone derivatives 3,8-dimethoxy-1-hydroxy-9,10-anthraquinone (minor) and 1,3-dimethoxy-8-hydroxy-9,10-anthraquinone (major) . A known antibiotic, 3,5-dihydroxy-4-isopropylstilbene, was also detected and for the first time showed strong fungicidal activity against several fungi of medical and agricultural importance. Curr Microbiol, 1995 Dec, 31(6), 332 - 5 Legionella pneumophila has two 60-kilodalton heat-shock proteins; Lema MW et al.; Legionella pneumophila is a thermotolerant bacterium . To learn more about the thermal adaptation of this organism, we studied the properties of the Legionella 60-kDa heat-shock protein (MopA, GroEL-analog, HtpB, Lp-Hsp60) in L . pneumophila and in an Escherichia coli strain containing the cloned gene . Lp-Hsp60 was found in both cytosol and membrane fractions; however, Lp-Hsp60 in the membrane fraction of L . pneumophila was slightly larger than Lp-Hsp60 in the cytosol . In contrast, both membrane-associated and cytosolic Lp-Hsp60 in the E . coli clone were similar in size to the smaller cytosolic Lp-Hsp60 of L . pneumophila . While peptide mapping suggests there are differences between the two proteins, the larger membrane-associated Lp-Hsp60 and the smaller cytosolic LP-Hsp60 shared Legionella-specific and E . coli GroEL cross-reacting epitopes, and the sequence of their first 20 N-terminal amino acids was identical . Further, Southern blot analysis of EcoRI-digested chromosomal DNA from several strains of L . pneumophila showed two fragments reacting with an htpAB-operon probe . In summary, L . pneumophila contains two Hsp60 proteins, and possibly two hsp60 genes. Infect Immun, 1995 Dec, 63(12), 4877 - 82 Effect of free and vesicle-bound cysteine proteinases of Porphyromonas gingivalis on plasma clot formation: implications for bleeding tendency at periodontitis sites; Imamura T et al.; Infection by Porphyromonas gingivalis is strongly associated with adult periodontitis, with proteinases from this bacterium now considered to be important virulence factors . In order to investigate possible pathological functions of these enzymes, we examined the effect of both free and vesicle-bound forms of the two major cysteine proteinases (gingipains) of P . gingivalis on plasma clot formation by using thrombin time (TT) measurements . Both Lys-gingipain (gingipain-K) and Arg-gingipain (gingipain-R) prolonged plasma TT in a dose- and time-dependent manner, and this was also found with vesicles which are the biological carriers of P . gingivalis proteinases . The increase in plasma TT by vesicles could be completely reversed by treatment with nonspecific cysteine proteinase inhibitors but only partially by compounds selective for either gingipain-K or gingipain-R . Preincubation of vesicles with a gingipain-K-specific inhibitor (z-FK-ck) reduced plasma TT more than a gingipain-R-specific inhibitor (leupeptin), suggesting that under physiological conditions gingipain-K was more effective in fibrinogen destruction . Each purified enzyme also markedly increased fibrinogen TT, gingipain-R being fourfold more potent than gingipain-K . However, in plasma, gingipain-R was ineffective because of the inhibitory effect of albumin . These results imply that cysteine proteinases, especially gingipain-K, abrogate the clotting potential of fibrinogen and, therefore, may contribute to the bleeding tendency and to persistent inflammation in periodontitis sites infected with P . gingivalis. Infect Immun, 1995 Dec, 63(12), 4606 - 12 Escherichia coli-induced activation of neutrophil NADPH-oxidase: lipopolysaccharide and formylated peptides act synergistically to induce release of reactive oxygen metabolites; Karlsson A et al.; The prevailing view of neutrophil NADPH-oxidase activation during interaction with bacteria is that the production of toxic oxygen metabolites should be directed into the phagosome containing the engulfed prey . However, in this report we show that a common Escherichia coli strain, HB101, may induce a release of neutrophil oxygen metabolites to the extracellular milieu . This phenomenon is dependent on three factors: (i) the mobilization (upregulation) of neutrophil secretory vesicles prior to interaction with the bacteria, (ii) soluble bacterial factors binding to the formylmethionyl-leucyl-phenylalanine receptor and tentatively identified as formylated peptides, and (iii) a bacterium-associated priming factor identified as lipopolysaccharide. Biochemistry, 1995 Nov 21, 34(46), 15259 - 66 CP-MAS 13C-NMR dipolar correlation spectroscopy of 13C-enriched chlorosomes and isolated bacteriochlorophyll c aggregates of Chlorobium tepidum: the self-organization of pigments is the main structural feature of chlorosomes; Balaban TS et al.; Magic angle spinning (MAS) NMR dipolar correlation spectroscopy was applied for the first time to a biologically intact system, the light-harvesting chlorosomes of the green photosynthetic bacterium Chlorobium tepidum . The MAS spectra provide evidence that the self-organization of many thousands of bacteriochlorophyll c (BChl c) molecules is the predominant structural feature of the chlorosome . 13C-Enriched chlorosomes were prepared from nonuniformly labeled cultures grown with NaH13CO3 as the main carbon source and from a uniformly 13C-labeled culture grown with NaH13CO3 as the sole carbon source . For the nonuniformly labeled samples, the positions of the chlorin macrocycle originating from C-4 and C-5 of 5-aminolevulinic acid contained > 95% 13C while the remaining positions, which could have originated also from unlabeled acetate, were labeled to approximately 60% with 13C . The 1-D and 2-D MAS data of the labeled chlorosomes, when compared with data on the isolated labeled BChl c aggregated in n-hexane, show that the major component of the MAS signals in the chlorosomes is from BChl c, and only minor signal contributions arise from lipids and proteins . The 13C MAS signals of the BChl c aggregates were fully assigned by MAS 2-D dipolar correlation spectroscopy, using data on monomeric BChl c in CDCl3/CD3OD as reference . The 2(1)-, 3-, 3(2-), 5-, 12(1)-, 13-, and 13(1)-carbons are shifted by 2.5 ppm or more upfield with respect to the solution data.(ABSTRACT TRUNCATED AT 250 WORDS) Biochemistry, 1995 Nov 21, 34(46), 15235 - 47 Role of PufX protein in photosynthetic growth of Rhodobacter sphaeroides . 1 . PufX is required for efficient light-driven electron transfer and photophosphorylation under anaerobic conditions; Barz WP et al.; The pufX gene is essential for photoheterotrophic growth of the purple bacterium Rhodobacter sphaeroides . In order to analyze the molecular function of the PufX membrane protein, we constructed a chromosomal pufX deletion mutant and phenotypically compared it to a pufX+ control strain and to two suppressor mutants which are able to grow photosynthetically in the absence of pufX . Using this genetic background, we confirmed that PufX is required for photoheterotrophic growth under anaerobic conditions, although all components of the photosynthetic apparatus were present in similar amounts in all strains investigated . We show that the deletion of PufX is not lethal for illuminated pufX- cells, suggesting that PufX is required for photosynthetic cell division . Since chromatophores isolated from the pufX- mutant were found to be unsealed vesicles, the role of PufX in photosynthetic energy transduction was studied in vivo . We show that PufX is essential for light-induced ATP synthesis (photophosphorylation) in anaerobically incubated cells . Measurements of absorption changes induced by a single turnover flash demonstrated that PufX is not required for electron flow through the reaction center and the cytochrome bc1 complex under anaerobic conditions . During prolonged illumination, however, PufX is essential for the generation of a sufficiently large membrane potential to allow photosynthetic growth . These in vivo results demonstrate that under anaerobic conditions PufX plays an essential role in facilitating effective interaction of the components of the photosynthetic apparatus. Biochemistry, 1995 Nov 21, 34(46), 15230 - 4 The asymmetry of P+ in bacterial reaction centers revealed by circular dichroism spectroscopy; Olson JM et al.; The circular dichroism anisotropy, (AL-AR)/A, has been measured for the far-red absorption band of P+ in reaction centers of two purple bacteria (Rhodopseudomonas viridis and Rhodobacter sphaerides) and one green sulfur bacterium (Chlorobium tepidum) . The anisotropy values for P960+ (Rps . virdis) at 1310 nm was found to be +(13 +/- 2) x 10(-4) . The corresponding for P870+ (Rb . sphaeroides) at 1250 nm was +(11 +/- 1) x 10(-4), but for P840+ (C . tepdium) at 1160 nm the value was negative: -(27 +/- 2) x 10(-4) . These results show that the configuration of the special pair in P840 is significantly different from the configuration in P870 and P960. Antonie Van Leeuwenhoek, 1995 Nov, 68(4), 293 - 6 Sulfate reduction by a syntrophic propionate-oxidizing bacterium; Van Kuijk BL et al.; The syntrophic propionate-oxidizing bacterium MPOB was able to grow in the absence of methanogens by coupling the oxidation of propionate to the reduction of sulfate . Growth on propionate plus sulfate was very slow (mu = 0.024 day-1) . An average growth yield was found of 1.5 g (dry weight) per mol of propionate . MPOB grew even slower than other sulfate-reducing syntrophic propionate-oxidizing bacteria . The growth rates and yields of strict sulfate-reducing bacteria (Desulfobulbus sp.) grown on propionate plus sulfate are considerably higher. Mol Microbiol, 1995 Nov, 18(4), 779 - 89 Functional and regulatory analysis of the OmpF-like porin, OpnP, of the symbiotic bacterium Xenorhabdus nematophilus; Forst S et al.; The function and novel regulation of OpnP of the symbiotic/pathogenic bacterium, Xenorhabdus nematophilus was studied . In vitro pore-function analysis of purified OpnP indicated that the single-channel-conductance values were similar to that measured for the porin protein, OmpF, of Esherichia coli . Nucleotide sequence analysis revealed that the mature OpnP protein contained 348 amino acid residues and shared 55% amino acid sequence identity with OmpF . Similar to ompF, opnP mapped between asnS and aspC . The 16 transmembrane beta-sheet structures and the internal loop 3 were highly conserved, while the remaining external loop domains were more divergent . Primer extension analysis identified the start site of transcription of opnP . A sigma 70-type promoter, a perfect 20 bp OmpR-binding site, and a binding site for the antisense molecule, micF RNA, were found in the upstream region of opnP . While the overall sequence identity of the asn-opnP-aspC region was high, the intergenic region between asnS and opnP had diverged markedly . The asnS-opnP region was 313 bp shorter than the intergenic region between asnS and ompF and lacked the OmpR-binding site that is required for ompF repression by high osmolarity in E . coli . Results from osmolarity-shift experiments indicated that OpnP was not repressed by high osmolarity . It was also found that OpnP was thermally regulated. Fogorv Sz, 1995 Nov, 88(11), 355 - 64 {Current trends in antibiotic therapy in dentistry}; Gaspar L et al.; The place and role of surgical, dental physio- and pharmacotherapy in oral and head and neck diseases has been debated for decades . In addition the price and reimbursement system had been changed lately in our country that also underlines the relevance of this issue . The overconsumption (1.7 packages per inhabitant per year) of antibiotics is also proven in Hungary . Beside surgical and dental interventions the treatment of dental inflammations caused by pathogenics requires the administration of different kinds of antibiotics . The first choice antibiotic is determined on the base of clinical features and general resistance of oral flora in the given period . When the first choice antibiotic proves to be ineffective, treatment has to be followed by antibiotics determined on individual resistance . In stomatology antibiotics are administered for prevention or treatment of dental inflammations . The length of therapy has a great importance which is usually 4 days in prevention and 5 days in treatment of dental inflammations . The modern antibiotics have to comply with the following requirements: efficacy, safety and cost-effectiveness . The typical mistakes in the administration of antibiotics can be avoided by the application of therapeutical schedules . The macrolide and cephalosporin derivates have become more and more popular . The mixed bacterium flora has been changing in time and also influenced by geographical factors depending on the habit of prescriptions . Therefore the experiences obtained in other countries are not applicable. Gen Pharmacol, 1995 Nov, 26(7), 1553 - 8 Inhibition of gastric mucosal mucin receptor by H . pylori lipopolysaccharide: effect of ebrotidine; Slomiany BL et al.; 1 . H . pylori infection causes the loss of mucus coat continuity and its patchy appearance . Here, we present evidence that the bacterium, through its cell wall lipopolysaccharide, disrupts the interaction between mucin and its mucosal receptor, and that ebrotidine is capable of counteracting this process . 2 . The receptor for mucin, isolated from the solubilized gastric epithelial cell membrane by affinity chromatography on Sepharose-bound wheat germ agglutinin, displayed a molecular weight of 97 kDa and exhibited specific affinity towards mucin-coated surface . 3 . The mucin binding to the receptor was susceptible to the inhibitin by H . pylori lipopolysaccharide and reached a maximum of 91% . This effect of the lipopolysaccharide was counteracted by ebrotidine, which caused a dose-dependent relief of the lipopolysaccharide inhibitory effect with maximum restoration in mucin-receptor binding of 51% at 60 microliters/ml ebrotidine . 4 . The results show that H . pylori, through its lipopolysaccharide, is capable of disrupting the integrity of mucus perimeter of gastric mucosal defense and that antiulcer agent, ebrotidine, counteracts this untoward effect. Zentralbl Veterinarmed B, 1995 Nov, 42(9), 533 - 42 {Electron microscopic detection of spirochetes in dermatitis digitalis of cattle}; Grund S et al.; In typical Dermatitis digitalis (D.d.) lesions, spirochaete-like bacteria with variations in spiralization were revealed by electron microscopy . While, in the early stages of the disease, these are found to be associated with fibrillar material of keratocytes, they occur massively in vacuoles at more advanced stages . The spirochaetes carry one pair of endoflagella, originating with a hook from the poles of the bacteria . These flagellae are composed of coiled flagellating fibrils in the pole region, merging towards the centre of the bacterium . A coat of fibrils was found in association with the cytoplasmatic membrane . The winding of this coat follows and may influence the coiling of the protoplast, and is probably involved in the rapid motility of this spirochaetes, together with the flagella . Immuno-electronmicroscopy revealed an antigenic relationship with Borrelia burgdorferi, at least with regard to the regions of flagella and undulating membrane . The paper discusses: 1 . The possible classification of these spirochaetes with the genus Treponema; 2 . The layer of peptidoglycan occurring on the outer membrane; and 3 . The keratolytic activity of spirochaetes in D.d. Res Vet Sci, 1995 Nov, 59(3), 255 - 60 Entry of the bacterium ileal symbiont intracellularis into cultured enterocytes and its subsequent release; McOrist S et al.; Separate suspensions of two strains of ileal symbiont (IS) intracellularis, an obligate intracellular bacterium and the causative agent of porcine proliferative enteropathy, were added to 40 or 80 per cent confluent monolayers of established cultures of rat (IEC-18) or pig enterocytes (IPEC-J2) . Peak numbers of intracellular organisms were detected within the enterocytes six days later, but no cytopathic effects were evident . After an initial close association with the cell membrane of the enterocytes, single bacteria were internalised after three hours within membranes-bound vacuoles . The formation of an electron-dense projection between cell membranes and external bacteria was only evident if the bacterial suspensions were centrifuged on to the monolayers . The release of internalised bacteria into the cytoplasm, with the breakdown and loss of membrane-bound vacuoles, was also evident three hours after infection . Internalised bacteria were associated with, but not observed within, coated membrane pits . Mitochondria were closely associated with internalised vacuoles and with released bacteria . Two to six days after infection, multiplication of the bacteria free in the cytoplasm was frequently observed . In infected cells six days after the inoculation of monolayers, groups of bacteria were found within large, balloon-like, cytoplasmic protrusions, and the subsequent release of bacteria from the monolayer provided a means of bacterial exit from the cells . Many events in the in vitro culture model closely resembled events observed at the cellular level in animals infected with IS intracellularis and the model provides a useful basis for investigating the pathogenetic mechanisms of this bacterium. Arch Microbiol, 1995 Nov, 164(5), 337 - 45 Metabolism of cyclohexane carboxylic acid by the photosynthetic bacterium Rhodopseudomonas palustris; Kuver J et al.; Cyclohexane carboxylate supported relatively rapid growth (doubling times 7-8 h) of Rhodopseudomonas palustris under oxic or photosynthetic conditions, but did not serve as a substrate for either of the known aromatic CoA ligases . A CoA ligase that thioesterifies cyclohexane carboxylate was partially purified and did not cross react immunologically with the two CoA ligases purified previously from this bacterium . Crude extracts of R . palustris cells grown with a range of aromatic or alicyclic acids contained a dehydrogenase that reacted with cyclohexane carboxyl-CoA or cyclohex-1-ene carboxyl-CoA, using 2,6-dichlorophenolindophenol or ferricenium ion as electron carrier . This activity was not detected in extracts of adipate-, glutamate-, or succinate-grown cells . No oxidation or reduction of nonesterified cyclohexane carboxylate or cyclohexene carbocylate was detected in extracts of cells grown with aromatic or aliphatic substrates, neither aerobically nor anaerobically . A constitutively expressed thioesterase that hydrolyzed cyclohexane carboxyl-CoA and also some alicyclic and aliphatic CoA derivatives was purified and characterized . The enzyme had little or no activity on benzoyl-CoA or 4-hydroxybenzoyl-CoA . The presence of a thioesterase that effectively hydrolyzes cyclohexane carboxyl-CoA suggests that transient production of cyclohexane carboxylate is a physiological response to temporary excess of reductant during metabolism of aromatic compounds. Semin Pediatr Surg, 1995 Nov, 4(4), 221 - 7 The significance of Helicobacter pylori colonization of the stomach; Cilley RE et al.; Helicobacter pylori (Hp) was discovered in 1982 by the Australians Robin Warren and Barry Marshall . Initially rejected by a skeptical scientific community, it has since gained worldwide recognition as a clinically significant bacterium . The incidence of colonization with Hp increases with age, affecting approximately one third of the world's population . Hp is uniquely capable of surviving in the acid environment of the stomach, and has properties of adherence to epithelial cells that resist parastalsis . Strains of Hp associated with human disease produce specific cytotoxic proteins . After ingestion, there is a period of intense proliferation and ensuing gastric inflammation that may result in chronic gastritis . Hp infection in children may produce symptomatic antral gastritis or duodenal ulceration . The diagnosis of Hp infection is confirmed by gastric biopsy and culture, where the organism is recognized by its characteristic histological appearance . Treatment for Hp includes combinations of bismuth amoxicillin and metronidazole administered for several weeks . In adults, chronic infection with Hp is associated with chronic gastritis, achlorhydria, and gastric cancer . An organism that was unheard of 15 years ago is now recognized as a clinically significant pathological entity . The ultimate significance of Hp as an agent of disease remains to be seen. Appl Environ Microbiol, 1995 Nov, 61(11), 3884 - 8 Degradation of 1,4-dichlorobenzene by Xanthobacter flavus 14p1; Spiess E et al.; Xanthobacter flavus 14p1 was isolated from sludge of the river Mulde by selective enrichment with 1,4-dichlorobenzene as the sole source of carbon and energy . The bacterium did not use other aromatic or chloroaromatic compounds as growth substrates . During growth on 1,4-dichlorobenzene, stoichiometric amounts of chloride ions were released . Degradation products of 1,4-dichlorobenzene were identified by gas chromatography-mass spectrometry analysis . 3,6-Dichloro-cis-1,2-dihydroxycyclohexa-3,5-diene and 3,6-dichlorocatechol were isolated from culture fluid . 2,5-Dichloromuconic acid and 2-chloromaleylacetic acid as well as the decarboxylation product 2-chloroacetoacrylic acid were identified after enzymatic conversion of 3,6-dichlorocatechol by cell extract . 1,4-Dichlorobenzene dioxygenase, dihydrodiol dehydrogenase, and catechol 1,2-dioxygenase activity were induced in cells grown on 1,4-dichlorobenzene . The results demonstrate that 1,4-dichlorobenzene degradation is initiated by dioxygenation and that ring opening proceeds via ortho cleavage. Eur J Biochem, 1995 Nov 1, 233(3), 873 - 9 Molecular properties of the dissimilatory sulfite reductase from Desulfovibrio desulfuricans (Essex) and comparison with the enzyme from Desulfovibrio vulgaris (Hildenborough); Steuber J et al.; The dissimilatory sulfite reductase desulfoviridin was purified from the membrane (mSiR) and the soluble fraction (sSiR) of the sulfate-reducing bacterium Desulfovibrio desulfuricans (Essex) . Molecular and spectroscopic properties were determined and compared with the properties of the soluble desulfoviridin from Desulfovibrio vulgaris (Hildenborough) . The enzymes were isolated as alpha 2 beta 2 gamma n (n = 1-3) multimers with a relative molecular mass of 200 +/- 10 (gel filtration) . Both mSiR and sSiR from D . desulfuricans contained 24 +/- 3 Fe and 18 +/- 3 labile sulfide/200 kDa, respectively, and showed identical EPR spectra . Quantification of the high-spin Fe(III) heme resonances at g of approximately 6 indicated that close to 80% of the siroheme moiety in the enzyme from D . desulfuricans was demetallated . D . desulfuricans sulfite reductase showed S = 9/2 EPR signals with the highest apparent g value at g = 17 as reported for SiR from D . vulgaris . Antibodies raised against the alpha, beta and gamma subunit of the D . vulgaris enzyme exhibited cross-reactivity with the subunits of mSiR and sSiR from D . desulfuricans . N-terminal sequences of alpha, beta and gamma subunits of both mSiR and sSiR from D . desulfuricans were identical and showed a high degree of similarity with the sequences of the corresponding subunits obtained from the D . vulgaris enzyme . During gel filtration of sSiR from D . desulfuricans, under non-denaturing conditions, a small protein (molecular mass approximately 11 kDa) was separated . This 11-kDa protein exhibited cross-reactivity with the antibody raised against the gamma subunit of D . vulgaris sulfite reductase . In the case of D . desulfuricans sulfite reductase, the 11-kDa gamma subunit seems not to be an integral part of the protein and can be obtained from the soluble fraction and during purification of the soluble enzyme. J Bacteriol, 1995 Nov, 177(22), 6630 - 7 Flagellar structure and hyperthermophily: analysis of a single flagellin gene and its product in Aquifex pyrophilus; Behammer W et al.; The polytrichously inserted flagella of Aquifex pyrophilus, a marine hyperthermophilic bacterium growing at 85 degrees C, were isolated and purified . Electron micrographs of the 19-nm-diameter flagellar filaments show prominent helical arrays of subunits . The primary structure of these 54-kDa flagellin monomers determining the helical shape and heat stability of filaments was of particular interest . The genomic region encoding the flagellin subunit (flaA gene) and an upstream open reading frame (orf1) were cloned and sequenced . The 1,503-bp flaA and 696-bp orf1 are preceded by separate sigma 28-like promoters and ribosome-binding motifs and succeeded by palindromic transcription terminators . Both genes are actively transcribed, but the nature and function of the orf1-encoded 231-residue polypeptide remain unknown . The deduced primary structure of the 501-amino-acid flagellin encoded by flaA consists of conserved N- and C-terminal regions and a variable 246-residue central domain . In comparison to mesophilic flagellins, the thermostable A . pyrophilus flagellin is characterized by increases in aromatic residues and prolines as well as by a 7.9% +/- 3.2% increase in all hydrophobic residues that is balanced by a respective decrease in hydrophilic residues . This composition is thought to form more compact flagellin monomers and stable interface contacts between neighboring subunits in the polymer. J Bacteriol, 1995 Nov, 177(21), 6316 - 8 Extreme resistance to thermally induced DNA backbone breaks in the hyperthermophilic archaeon Pyrococcus furiosus; Peak MJ et al.; Pyrococcus furiosus is a hyperthermophilic archaeon that grows optimally at 100 degrees C . It is not conceivable that these organisms could survive with genomic DNA that was subject to thermal destruction, yet the mechanisms protecting the genomes of this and other hyperthermophiles against such destruction are obscure . We have determined the effect of elevated temperatures up to 110 degrees C on the molecular weight of DNA in intact P . furiosus cells, compared with the effect of elevated temperatures on DNA in the mesothermophilic bacterium Escherichia coli . At 100 degrees C, DNA in P . furiosus cells is about 20 times more resistant to thermal breakage than that in E . coli cells, and six times fewer breaks were found in P . furiosus DNA after exposure to 110 degrees C for 30 min than in E . coli DNA at 95 degrees C . Our hypothesis for this remarkable stability of DNA in a hyperthermophile is that this hyperthermophile possesses DNA-binding proteins that protect against hydrolytic damage, as well as other endogenous protective mechanisms and DNA repair enzyme systems. J Bacteriol, 1995 Nov, 177(21), 6170 - 5 Carbon dioxide fixation in the metabolism of propylene and propylene oxide by Xanthobacter strain Py2; Small FJ et al.; Evidence for a requirement for CO2 in the productive metabolism of aliphatic alkenes and epoxides by the propylene-oxidizing bacterium Xanthobacter strain Py2 is presented . In the absence of CO2, whole-cell suspensions of propylene-grown cells catalyzed the isomerization of propylene oxide (epoxypropane) to acetone . In the presence of CO2, no acetone was produced . Acetone was not metabolized by suspensions of propylene-grown cells, in either the absence or presence of CO2 . The degradation of propylene and propylene oxide by propylene-grown cells supported the fixation of 14CO2 into cell material, and the time course of 14C fixation correlated with the time course of propylene and propylene oxide degradation . The degradation of glucose and propionaldehyde by propylene-grown or glucose-grown cells did not support significant 14CO2 fixation . With propylene oxide as the substrate, the concentration dependence of 14CO2 fixation exhibited saturation kinetics, and at saturation, 0.9 mol of CO2 was fixed per mol of propylene oxide consumed . Cultures grown with propylene in a nitrogen-deficient medium supplemented with NaH13CO3 specifically incorporated 13C label into the C-1 (major labeled position) and C-3 (minor labeled position) carbon atoms of the endogenous storage compound poly-beta-hydroxybutyrate . No specific label incorporation was observed when cells were cultured with glucose or n-propanol as a carbon source . The depletion of CO2 from cultures grown with propylene, but not glucose or n-propanol, inhibited bacterial growth . We propose that propylene oxide metabolism in Xanthobacter strain Py2 proceeds by terminal carboxylation of an isomerization intermediate, which, in the absence of CO2, is released as acetone. Infect Immun, 1995 Nov, 63(11), 4345 - 9 Cloning and characterization of hemolytic genes from Helicobacter pylori; Drazek ES et al.; Strains of Helicobacter pylori, the bacterium associated with gastritis, peptic ulcer disease, and gastric cancer in humans, express different degrees of hemolysis on agar containing erythrocytes (RBC) . Here we report the isolation and characterization of six recombinant clones from a genomic library of H . pylori ATCC 49503 that confer on Escherichia coli the ability to lyse sheep RBC . DNA hybridizations indicated no sequence homology among these hemolytic clones . Hybridization mapping of them to an ordered H . pylori cosmid library identified their separate chromosomal locations . One clone hybridized to two regions separated by approximately 200 kb . The specificities of the hemolytic activities of these clones were tested with RBC from humans, monkeys, cattle, horses, guinea pigs, rabbits, and chickens as well as with RBC from sheep . One clone conferred the ability to lyse RBC from five species, a second clone allowed the lysis of RBC from four of these species, three other clones allowed the lysis of RBC from three of these species, and the sixth clone allowed the lysis of RBC from just two species . We propose that some or all of the genes that confer these various hemolytic activities contribute to pathogen-host tissue interactions and that the different specificities seen here are important for H . pylori infections of humans of different genotypes or disease states. J Biol Chem, 1995 Oct 27, 270(43), 25792 - 7 Accumulation of UDP-sulfoquinovose in a sulfolipid-deficient mutant of Rhodobacter sphaeroides; Rossak M et al.; The sulfolipid 6-sulfo-alpha-D-quinovosyl diacylglycerol is found in the photosynthetic membranes of all plants and most photosynthetic bacteria . Progress toward the elucidation of the pathway for sulfolipid biosynthesis has been slow in the past . However, the recent isolation of three genes of the photosynthetic bacterium Rhodobacter sphaeroides known to be involved in sulfolipid biosynthesis provides promising new opportunities . Two of the genes flank an open reading Rhodobacter sphaeroides known to be involved in sulfolipid biosynthesis provides promising new opportunities . Two of the genes flank an open reading frame predicted to encode a protein with amino acid sequence similarity to sugar nucleotide-dependent glycosyltransferases . The UDP-sulfoquinovose:diacylglcerol sulfoquinovosyltransferase thought to catalyze the last step of sulfolipid biosynthesis belongs to this group of glycosyltransferases . To test whether this open reading frame encodes the sulfoquinovosyltransferase of R . sphaeroides, it was inactivated by gene replacement avoiding polar mutagenesis . The resulting sulfolipid-deficient mutant defines a new gene, designated sqdD . Mutant cells grown in the presence of {35S}sulfate accumulate a water-soluble 35S-labeled compound . The purified compound was tentatively identified by co-chromatography with standards and enzymatic conversion as UDP-sulfoquinovose, the final precursor of sulfolipid biosynthesis . This result strongly suggests that the inactivation of sqdD causes a metabolic block in the last step of sulfolipid biosynthesis. Biochem Biophys Res Commun, 1995 Oct 24, 215(3), 855 - 60 Evidence of histidine coordination to the catalytic ferrous ion in the ring-cleaving 2,2',3-trihydroxybiphenyl dioxygenase from the dibenzofuran-degrading bacterium Sphingomonas sp . strain RW1; Bertini I et al.; The 1H NMR spectra of an aromatic ring-cleaving extradiol dioxygenase, 2,2',3-trihydroxybiphenyl dioxygenase of the dibenzofuran-degrading bacterium Sphingomonas sp . strain RW1, are reported . In the catalytically active reduced form of the monomeric enzyme (MW = 32 kDa), three broad strongly downfield shifted signals were observed, two of which disappeared in D2O solution . Their shifts and linewidths are consistent with ring NH and meta-like protons of coordinated histidines . These signals show strong sensitivity to the presence of the substrate . The oxidized form of the enzyme shows no hyperfine shifted signals . It is suggested that the high spin Fe(II) ion present in the active form of the enzyme is coordinated by at least two histidines . This is the first report of hyperfine shifted NMR signals being detected for an extradiol dioxygenase. FEBS Lett, 1995 Oct 23, 374(1), 130 - 4 A new mutation in the pufL gene responsible for the terbutryn resistance phenotype in Rubrivivax gelatinosus; Ouchane S et al.; Rubrivivax gelatinosus is a facultative phototrophic non-sulfur bacterium belonging to the beta subclass of the purple bacteria . A terbutryn-resistant mutant of R . gelatinosus has been isolated and characterized . Increased resistance levels to terbutryn (300-fold), atrazine (6-fold) and o-phenanthroline (3-fold) were observed for the mutant compared with wild type . Sequence analysis of the mutant revealed a new mutation in the pufL gene coding for the L subunit of the reaction centre (RC) at codon 192 leading to an amino-acid substitution from Gly in the wild type to Asp in the mutant . This substitution is located in the D helix of the L subunit, suggesting an interaction between terbutryn and this part of the polypeptide in the RC of R . gelatinosus . This is the first report of a mutation leading to herbicide resistance and affecting the D helix in purple bacteria . Furthermore R . gelatinosus wild type is highly sensitive to o-phenanthroline compared with other purple bacteria (Rhodobacter capsulatus and Rhodobacter sphaeroides) . Sequence comparison of the L subunit from six purple bacteria in which o-phenanthroline sensitivity was measured suggests that SerL226 might be responsible for this phenotype. Biochim Biophys Acta, 1995 Oct 10, 1231(3), 220 - 2 Molecular cloning and sequencing of cytochrome c' from the phototrophic purple sulfur bacterium Chromatium vinosum; Even MT et al.; The gene for cytochrome c' from Chromatium vinosum was cloned from a HindIII-SalI digest of genomic DNA . A 1.4 kbp fragment containing the gene was sequenced in both directions using the Sanger dideoxy method . The cytochrome c' gene codes for a 154-residue peptide, of which the last 131 amino acids match the previously determined sequence of the protein . The remaining 23 residues represent a signal sequence that is cleaved from the polypeptide upon translocation to the periplasmic space . An additional open reading frame on the other strand of the fragment codes for a peptide that contains four regions that are homologous to corresponding regions of the cytochrome b-type subunit of several Ni-Fe hydrogenases. Biochemistry, 1995 Oct 10, 34(40), 13091 - 7 Highly purified photosynthetic reaction center (PscA/cytochrome c551)2 complex of the green sulfur bacterium Chlorobium limicola; Oh-oka H et al.; The photosynthetic reaction center (RC) complex that forms a homodimer of core and cytochrome c subunits was isolated from Chlorobium limicola f . thiosulfatophilum, strain Larsen . The complex showed only two subunit bands at 68 (PscA core) and 21 kDa (cytochrome c551) on SDS-PAGE analysis, indicating the complete deletion of the light-harvesting bacteriochlorophyll a (BChl a) protein as well as the iron-sulfur protein . It contained 27 +/- 3 molecules of BChl a, 7 +/- 1 Chl-670, 3 +/- 1 carotenoids, and 1.6 +/- 0.1 c-type hemes per the primary electron donor P840 . The complex showed a light-induced charge separation and recombination between P840 and the acceptor Chl-670 at 77 K as follows: P840*Chl-670-->P840+Chl-670(-)-->P840TChl-670-->P84 0 Chl-670 . Pigment compositions and their function in the (PscA/cytochrome c551)2 complex were studied by absorption, circular dichroism, and fluorescence spectroscopy. J Theor Biol, 1995 Oct 7, 176(3), 411 - 30 A Monte Carlo simulation of the Escherichia coli cell cycle; Keasling JD et al.; A Monte-Carlo simulation of the division cycle of an individual bacterium has been developed to test theories concerning the control of cell cycle events and for the analysis of cell cycle data . The model is based on the work of Cooper and Helmstetter and other theories concerning the control of DNA replication initiation, chromosome segregation and cell division . Variability in the molecular events that initiate a particular cell cycle event is incorporated using a Monte Carlo approach . The model results are compared with experimental data from a number of different sources and collected using a number of different analytical techniques . This model is able to accurately represent the cell size distributions of an exponentially growing population as determined by a Coulter Counter and the DNA distributions as determined by flow cytometry . The model is also able to accurately simulate the cell age distribution and chromosome replication and segregation patterns as determined by the membrane-elution technique . Results from parameter sensitivity analysis indicate that variability in the symmetry of cell division and in the cell size at initiation of chromosome replication have the most significant impact on the cell size, age and DNA distributions . Results from the membrane-elution simulation support the hypothesis that total cell protein is synthesized exponentially during the division cycle and that cell size control is a plausible explanation for control of DNA replication . The simulation results for chromosome segregation agree with experimental data and support chromosome strand segregation models . In the future, this simulation should be useful in testing complex theories about molecular control of cell cycle events against experimental data. J Biol Chem, 1995 Oct 6, 270(40), 23875 - 82 Heterologous expression of genes encoding bacterial light-harvesting complexes in Rhodobacter sphaeroides; Fowler GJ et al.; One of the major problems in structural work on membrane-spanning proteins is the identification of an expression system which will allow the production of enough pure protein for structural studies; an inadequate expression system can lead, for example, to the formation of unwanted protein inclusion bodies . In the present work we report the expression of genes encoding the light-harvesting 2 (LH2) membrane-spanning proteins from a number of species of purple bacteria in mutants of Rhodobacter sphaeroides that lack the native LH2 antenna . The LH2 structural genes (pucBA) from the photosynthetic bacteria Rhodopseudomonas acidophila and Rubrivivax gelatinosus were amplified and tailed by polymerase chain reaction, and cloned into an LH2 expression vector, which was then introduced into three LH2-minus Rb . sphaeroides mutants; DBC omega/G5 and DD13 (DD13/G1); the resulting transconjugant strains synthesized LH2 complexes that were examined using absorption and fluorescence spectroscopy, and Western blotting . Thus, we have created a heterologous expression system which supports the assembly of a functional "foreign" light-harvesting complex . This work opens up the possibility of creating site-directed LH2 mutants from bacteria for which no genetic system is available; this is particularly significant in the case of Rps . acidophila, since this bacterium has been the source of the LH2 complex that has recently been structurally resolved to atomic resolution. Biochemistry, 1995 Oct 3, 34(39), 12830 - 41 Structure of the tetraheme cytochrome from Desulfovibrio desulfuricans ATCC 27774: X-ray diffraction and electron paramagnetic resonance studies; Morais J et al.; The three-dimensional X-ray structure of cytochrome c3 from a sulfate reducing bacterium, Desulfovibrio desulfuricans ATCC 27774 (107 residues, 4 heme groups), has been determined by the method of molecular replacement {Frazao et al . (1994) Acta Crystallogr . D50, 233-236} and refined at 1.75 A to an R-factor of 17.8% . When compared with the homologous proteins isolated from Desulfovibrio gigas, Desulfovibrio vulgaris Hildenborough, Desulfovibrio vulgaris Miyazaki F, and Desulfomicrobium baculatus, the general outlines of the structure are essentialy kept {heme-heme distances, heme-heme angles, His-His (axial heme ligands) dihedral angles, and the geometry of the conserved aromatic residues} . The three-dimensional structure of D . desulfuricans ATCC 27774 cytochrome c3Dd was modeled on the basis of the crystal structures available and amino acid sequence comparisons within this homologous family of multiheme cytochromes {Palma et al . (1994) Biochemistry 33, 6394-6407} . This model is compared with the refined crystal structure now reported, in order to discuss the validity of structure prediction methods and critically evaluate the steps used to predict protein structures by homology modeling . The four heme midpoint redox potentials were determined by using deconvoluted electron paramagnetic resonance (EPR) redox titrations . Structural criteria (electrostatic potentials, heme ligand orientation, EPR g values, heme exposure, data from protein-protein interaction studies) are invoked to assign the redox potentials corresponding to each specific heme in the three-dimensional structure. Mol Microbiol, 1995 Oct, 18(2), 225 - 36 Induction of complex intracytoplasmic membranes related to nitrogen fixation in Azoarcus sp . BH72; Hurek T et al.; We report the discovery of novel subcellular structures related to bacterial nitrogen fixation in the strictly respiratory diazotrophic bacterium Azoarcus sp . BH72, which was isolated as an endophyte from Kallar grass . Nitrogenase is derepressed under microaerobic conditions at O2 concentrations in the micromolar range . With increasing O2 deprivation, bacteria can develop into a hyperinduced state, which is characterized by high specific rates of respiration and efficient nitrogen fixation at approximately 30 nM O2 . Ultrastructural analysis of cells in the course of hyperinduction revealed that complex intracytoplasmic membrane systems are formed, which consist of stacks of membranes and which are absent under standard nitrogen-fixing conditions . The iron protein of nitrogenase was highly enriched on these membranes, as evidenced by immunohistochemical studies . Membrane deficiency in NifH/K- mutants, a deletion mutant in the nifK gene and the character of NH+4-grown cells suggested, in concert with the membrane localization of nitrogenase, that these structures are specialized membranes related to nitrogen fixation . We propose the term 'diazosomes' for them . Development of intracytoplasmic membranes coincides with the appearance of a high-molecular-mass form of the iron protein of nitrogenase, which was detectable in membrane fractions . Mutational analysis, and determination of the N-terminal amino acid sequence indicate that the nifH gene product is covalently modified by a mechanism probably different from adenosine diphosphoribosylation . Development of diazosomes in nitrogen-fixing cells can be induced in pure cultures and in co-culture with a fungus isolated from the rhizosphere of Kallar grass. New Microbiol, 1995 Oct, 18(4), 441 - 4 Gastrospirillum hominis and human chronic gastritis; Monno R et al.; Gastrospirillum hominis, a new spiral bacterium, was found in the gastric mucosa of two patients with antral chronic gastritis . These 2 cases originated from a series of 2781 consecutive gastric biopsies observed over a period of five years, with a prevalence of 0.072% . Dogs and cats may be responsible for transmission to humans but in our experience no contact with pets was documented . Detection of these organisms might provide new insight into the pathogenesis of human gastritis. J Bacteriol, 1995 Oct, 177(20), 5865 - 71 Characterization of a 2,3-dihydroxybiphenyl dioxygenase from the naphthalenesulfonate-degrading bacterium strain BN6; Heiss G et al.; An extradiol dioxygenase was cloned from the naphthalenesulfonate-degrading bacterial strain BN6 by screening a gene bank for colonies with 2,3-dihydroxybiphenyl dioxygenase activity . DNA sequence analysis of a 1,358-bp fragment revealed an open reading frame of only 486 bp . This is the smallest gene encoding an extradiol dioxygenase found until now . Expression of the gene in a T7 expression vector enabled purification of the enzyme . Gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed that the protein was a dimer with a subunit size of 21.7 kDa . The enzyme oxidized 2,3-dihydroxybiphenyl, 3-isopropylcatechol, 3- and 4-chlorocatechol, and 3- and 4-methylcatechol . Since the ability to convert 3-chlorocatechol is an unusual characteristic for an extradiol-cleaving dioxygenase, this reaction was analyzed in more detail . The deduced amino-terminal amino acid sequence differed from the corresponding sequence of the 1,2-dihydroxynaphthalene dioxygenase, which had been determined earlier from the enzyme purified from this strain . This indicates that strain BN6 carries at least two different extradiol dioxygenases. Eur J Biochem, 1995 Oct 1, 233(1), 238 - 48 A cluster of structural and regulatory genes for light-induced carotenogenesis in Myxococcus xanthus; Botella JA et al.; In the bacterium Myxococcus xanthus, several genes for carotenoid synthesis lie together at the carA-carB chromosomal locus and are co-ordinately activated by blue light . A 12-kb DNA stretch from wild-type M . xanthus has been sequenced that includes the entire carA-carB gene cluster . According to sequence analysis, the cluster contains 11 different genes . Intergenic distances are very short or nil (implying translational coupling), giving further support to previous evidence indicating that most (or all) of the genes in the cluster form a single operon . At the promoter region, a potential -35 site for the binding of sigma factors is found . However, the -10 region shows little similarity with analogous sites in other bacterial promoters . Five (possibly six) genes in the carA-carB operon code for enzymes acting on early or late steps of the pathway for carotenoid synthesis . Other genes in the operon show no overall similarity with previously known genes . However, peptide stretches in the predicted products of two genes exhibit strong similarity with the DNA binding domain of the MerR family of transcriptional regulators . At least one of the predicted DNA-binding domains is altered in a mutant strain affected in light-regulation of the car genes. Microbiology, 1995 Oct, 141 ( Pt 10), 2619 - 28 Acetyl-CoA-dependent pyruvate carboxylase from the photosynthetic bacterium Rhodobacter capsulatus: rapid and efficient purification using dye-ligand affinity chromatography; Modak HV et al.; Pyruvate carboxylase (PC) was purified to homogeneity from an overexpressing strain of the purple photosynthetic bacterium Rhodobacter capsulatus using a rapid dye-ligand affinity chromatography procedure, in which dye-bound enzyme was specifically eluted with a low concentration of acetyl-CoA, an allosteric activator of the enzyme . The enzyme purified by this method was obtained in 75% yield with a specific activity of 40 U (mg protein)-1 . In contrast, affinity chromatography on a monomeric avidin column, commonly used in the purification of biotin-containing carboxylases, resulted in a yield of < 40%, with a specific activity of 10 U (mg protein)-1 . The enzyme purified by the dye-linked procedure had a subunit molecular mass of 140,000 Da and was absolutely dependent on acetyl-CoA for activity . Acetyl-CoA was also effective in protecting the enzyme from thermal denaturation . The enzyme was inhibited by 2-oxoglutarate and, to a lesser extent, L-aspartate, with sigmoidal kinetics with respect to acetyl-CoA concentration . The amino acid composition, pH optimum and kinetic constants for pyruvate, ATP and bicarbonate were determined . An N-terminal sequence of 26 residues was obtained, which was homologous to the N-terminal regions of several eukaryotic PCs, propionyl-CoA carboxylases and acetyl-CoA carboxylase. Curr Opin Biotechnol, 1995 Oct, 6(5), 501 - 6 Gene fusion expression systems in Escherichia coli; LaVallie ER et al.; In recent years, Escherichia coli gene fusion expression systems have circumvented many of the problems inherent in the use of this bacterium for the production of recombinant proteins . These systems also provide a powerful means for identifying peptides or proteins with desired binding specificities . Gene fusion technology continues to expand with the introduction of new fusion partners, purification and detection tags, cleavage reagents and ways to display peptides on the surface of bacteria. J Bacteriol, 1995 Oct, 177(19), 5644 - 52 Purification, characterization, and genetic analysis of Mycobacterium tuberculosis urease, a potentially critical determinant of host-pathogen interaction; Clemens DL et al.; Mycobacterium tuberculosis urease (urea amidohydrolase {EC 3.5.1.5}) was purified and shown to contain three subunits: two small subunits, each approximately 11,000 Da, and a large subunit of 62,000 Da . The N-terminal sequences of the three subunits were homologous to those of the A, B, and C subunits, respectively, of other bacterial ureases . M . tuberculosis urease was specific for urea, with a Km of 0.3 mM, and did not hydrolyze thiourea, hydroxyurea, arginine, or asparagine . The enzyme was active over a broad pH range (optimal activity at pH 7.2) and was remarkably stable against heating to 60 degrees C and resistant to denaturation with urea . The enzyme was not inhibited by 1 mM EDTA but was inhibited by N-ethylmaleimide, hydroxyurea, acetohydroxamate, and phenylphosphorodiamidate . Urease activity was readily detectable in M . tuberculosis growing in nitrogen-rich broth, but expression increased 10-fold upon nitrogen deprivation, which is consistent with a role for the enzyme in nitrogen acquisition by the bacterium . The gene cluster encoding urease was shown to have organizational similarities to urease gene clusters of other bacteria . The nucleotide sequence of the M . tuberculosis urease gene cluster revealed open reading frames corresponding to the urease A, B, and C subunits, as well as to the urease accessory molecules F and G. J Bacteriol, 1995 Oct, 177(19), 5495 - 505 Interchromosomal recombination in the extremely radioresistant bacterium Deinococcus radiodurans; Daly MJ et al.; Deinococcus radiodurans and other members of the genus Deinococcus are remarkable for their extreme resistance to ionizing radiation and many other agents that damage DNA . We have recently shown that recombinational processes participate in interplasmidic repair following in vivo irradiation . We now present direct studies on interchromosomal recombination among chromosomes irradiated in vivo during stationary phase (four chromosomes per cell) . Following an exposure to 1.75 Mrad (the dose required to achieve a survival of 37%, which degrades the cells' four chromosomes into about 500 fragments), we determined that there may be as many as 175 crossovers per chromosome (700 crossovers per nucleoid) undergoing repair . In addition, these studies suggest that many of the crossovers occurring during repair are nonreciprocal. J Bacteriol, 1995 Oct, 177(19), 5480 - 4 Physical map of the genome of the green phototrophic bacterium Chlorobium tepidum; Naterstad K et al.; A physical restriction map of the chromosome of the green sulfur bacterium Chlorobium tepidum was generated by determining the order of the fragments obtained after digestion with the restriction endonucleases XbaI and PacI and subsequent separation of the fragments by pulsed-field gel electrophoresis . The size of the chromosome is estimated to be 2.1 Mb . Fifteen genes and operons, mainly encoding proteins involved in photosynthesis, have been placed on this map by hybridization to fragments obtained after single- and double-restriction digestions. Int J Syst Bacteriol, 1995 Oct, 45(4), 820 - 5 Characterization of Lawsonia intracellularis gen . nov., sp . nov., the obligately intracellular bacterium of porcine proliferative enteropathy; McOrist S et al.; A novel obligately intracellular bacterium, ileal symbiont intracellularis, which was obtained from the intestines of pigs with proliferative enteropathy disease, was grown in pure cocultures with tissue cultures of rat cells . An examination of the 16S ribosomal DNA gene sequence revealed that the isolates which we obtained are members of the delta subdivision of the Proteobacteria and that the sequences of these organisms exhibit a level of similarly of 91% with the sequence of Desulfovibrio desulfuricans ATCC 27774 . These isolates were homogeneous and differed in cellular morphology, acid fastness, phenotype, electrophoretic protein profile, and habitat from Desulfovibrio species . On the basis of the results of an integrated study of the phenotype and genotype of a consistent morphological entity found in particular porcine cells and associated with a well-defined clinical condition, we concluded that these bacteria belong to a previously undescribed genus and species, for which we propose the name Lawsonia intracellularis gen . nov., sp . nov . A species-specific recombinant DNA probe was cloned previously, and this probe was used to identify the bacterium in tissue culture cells and in the ileal epithelia of pigs with proliferative enteropathy disease . Coculture of the organism with a rat enterocyte cell line allowed us to designate strain NCTC 12656 the type strain and to describe the new genus and species . The organism which we cultured is pathogenic for pigs and causes proliferative enteropathy lesions in their ilea and colons, and Koch's postulates were fulfilled for this organism. Trends Biotechnol, 1995 Oct, 13(10), 418 - 21 Engineering gut flora of ruminant livestock to reduce forage toxicity: progress and problems; Gregg K; The rumen bacterium Butyrivibrio fibrosolvens has been genetically modified to detoxify fluoroacetate (a poisonous component of trees and shrubs in Australia, Africa and Central America) and has been shown to persist when it is returned to the rumen . Such bacteria may save animals from poisoning and, therefore, reduce economic losses for livestock industries in those countries . The ability to make genetic changes to rumen bacteria raises important questions about their practicality, and about the environmental factors that must be considered before releasing modified strains . The fluoroacetate-detoxifying bacterium provides an important model by which these issues can be examined. Recenti Prog Med, 1995 Oct, 86(10), 382 - 5 {Influence of Helicobacter pylori on gastric secretion . Study on variously associated gastric body, fundus and antrum chronic gastritis}; Testino G et al.; Among the various themes related to Helicobacter pylori (HP) which is still a subject of discussion, there is the possible influence of this bacterium on gastric secretory physiology . In the present study, an evaluation has been carried out of stimulated gastrinemia, stimulated acid secretion and total peptic activity in gastric juice in the course of a paradigmatic condition, as autonomous chronic gastritis, in order to reveal possible modifications induced by the HP infection . In cases of HP positive chronic superficial antral gastritis associated either with normal body-fundic mucosa or with superficial gastritis, there is a significant increase of stimulated gastrinemia in comparison to HP negative groups and controls . In the course of body-fundic atrophic and preatrophic chronic gastritis associated either with antral superficial chronic gastritis or with antral atrophic gastritis, there are no statistically significant differences between HP positive and HP negative subjects . As regards acid and pepsin secretion no significant differences emerge in any group between HP positive and HP negative subjects . In the HP positive subjects with antral superficial gastritis and higher gastrin values the study of acid and pepsin secretion has yielded no significant variations . From the results of this study it emerges how gastric secretory parameters vary exclusively according to the histologic state of gastric mucosa . Therefore, the lesion action of HP may mainly be attributed to a direct action, rather than to substantial gastric secretory changes. J Biol Chem, 1995 Sep 29, 270(39), 22801 - 6 Codon pair utilization biases influence translational elongation step times; Irwin B et al.; Two independent assays capable of measuring the relative in vivo translational step times across a selected codon pair in a growing polypeptide in the bacterium Escherichia coli have been employed to demonstrate that codon pairs observed in protein coding sequences more frequently than predicted (over-represented codon pairs) are translated slower than pairs observed less frequently than expected (under-represented codon pairs) . These results are consistent with the findings that translational step times are influenced by codon context and that these context effects are related to the compatabilities of adjacent tRNA isoacceptor molecules on the surface of a translating ribosome . These results also support our previous suggestion that the frequency of one codon next to another has co-evolved with the structure and abundance of tRNA isoacceptors in order to control the rates of translational step times without imposing additional constraints on amino acid sequences or protein structures. Gene, 1995 Sep 22, 163(1), 115 - 9 The citrate synthase-encoding gene of Rickettsia prowazekii is controlled by two promoters; Cai J et al.; The transcripts of the citrate synthase-encoding gene (gltA) in Rickettsia prowazekii (Rp), an obligate intracellular parasitic bacterium, were analyzed by RNase protection (RP), primer extension (PE) and in vitro transcription assays . Analysis of the 5' end of the gltA mRNA by RP and PE assays revealed that there were two gltA mRNAs with the 5' ends located at 16 bp and 307 bp upstream from the gltA coding region . Since these two mRNAs might represent two species of mRNA transcribed from two different promoters or a single transcript that was processed to give two mRNAs, an in vitro transcription analysis with purified Rp RNA polymerase (RNAP) was performed to distinguish these two possibilities . Purified Rp RNAP catalyzed the formation of two transcripts initiated from the same nucleotides indicated by RP and PE . Sequence analysis identified Escherichia coli (Ec) promoter-like sequences immediately upstream from both transcription start points (tsp) . The first promoter (promoter P1) had the core sequence TTCTAA-N17-TATACT, was 6 bp upstream from the tsp (base A) and was centered at 37 bp upstream from the coding region . The second promoter (promoter P2) had the core sequence ATGAAA-N17-TAAAGT, was 7 bp upstream from the tsp (base T) and was centered at 329 bp upstream from the coding region . This is the first demonstration of multiple promoters in this obligate intracellular parasite which has implications concerning transcriptional regulation. J Mol Biol, 1995 Sep 15, 252(2), 235 - 47 Refined crystal structure of ferrocytochrome c2 from Rhodopseudomonas viridis at 1.6 A resolution; Sogabe S et al.; The three-dimensional structure of ferrocytochrome c2 from the purple photosynthetic bacterium Rhodopseudomonas viridis has been refined to a final R-factor of 18.2% for 15,014 unique reflections collected by synchrotron radiation between 6.0 and 1.6 A resolution . The refined model includes 107 amino acid residues, one heme prosthetic group and 125 water molecules . The root-mean-square deviations from the ideal bond lengths and angles were 0.014 A and 3.0 degrees, respectively . The atomic coordinate error was estimated to be less than 0.3 A . A structure comparison of this cytochrome c2 with those of the other c-type cytochromes demonstrated that these cytochromes exhibit a high degree of structural similarity with the exception of the surface loop and the terminal region of the polypeptide chain . The deletion of an intrahelical amino residue distorted the conformation of the alpha-helix and it divided into two pieces . The C-terminal extension of the polypeptide chain caused significant conformational changes of the contact residues compared with the other c-type cytochromes . Of the water molecules conserved in various c-type cytochromes, two are located internally in the vicinity of the heme group . One of these water molecules found in this cytochrome c2 is evolutionarily conserved among eukaryotic cytochromes c . This water molecule is located in the heme proximate environment in a position similar to that of eukaryotic cytochromes c . The position of this water molecule is associated with the oxidation state of the heme iron in electron transfer. FEMS Microbiol Lett, 1995 Sep 15, 131(3), 307 - 12 The hyperthermophilic bacterium Thermotoga neapolitana possesses two isozymes of the 3-phosphoglycerate kinase/triosephosphate isomerase fusion protein; Yu JS et al.; The phosphoglycerate kinase (pgk), triosephosphate isomerase (tpi), and enolase (eno) genes from Thermotoga neapolitana have been cloned and expressed in Escherichia coli . In high copy number, the pgk gene complemented an E . coli pgk- strain . In T . neapolitana, the pgk and tpi genes appear to be fused and eno is near those genes . Like T . maritima, T . neapolitana produces phosphoglycerate kinase as both an individual enzyme and a fusion protein with triosephosphate isomerase, and triosephosphate isomerase activity is not found without associated phosphoglycerate kinase activity . Unlike T . maritima, which forms only a 70-kDa fusion protein, T . neapolitana expresses both 73-kDa and 81-kDa isozymes of this fusion protein . These isozymes are present in both T . neapolitana cells and in E . coli cells expressing T . neapolitana genes. EMBO J, 1995 Sep 15, 14(18), 4395 - 402 (Beta alpha)8-barrel proteins of tryptophan biosynthesis in the hyperthermophile Thermotoga maritima; Sterner R et al.; To better understand the evolution of a key metabolic pathway, we have sequenced the trpCFBA gene cluster of the hyperthermophilic bacterium Thermotoga maritima . The genes were cloned by complementation in vivo of trp deletion strains of Escherichia coli . The new sequences, together with earlier findings, establish that the trp operon of T.maritima has the order trpE(G.D)CFBA, which might represent the ancestral organization of the tryptophan operon . Heterologous expression of the trp(G.D) and trpC genes in E.coli and N-terminal sequencing of their polypeptide products showed that their translation is initiated at the rate start codons TTG and ATC, respectively . Consequently, the N-terminus of the trp(G.D) fusion protein is 43 residues shorter than previously postulated . Amino acid composition and sequence analyses of the protein products of T.maritima trpC (indoleglycerol phosphate synthase), trpF (phosphoribosyl anthranilate isomerase) and trpA (alpha-subunit of tryptophan synthase) suggest that these thermostable (beta alpha)8-barrel proteins may be stabilized by additional salt bridges, compared with the mesostable forms . Another notable feature is the predicted lack of the N-terminal helix alpha 0 in the alpha-subunit of tryptophan synthase. Biol Pharm Bull, 1995 Sep, 18(9), 1184 - 8 Purification and characterization of beta-glucuronidase from Escherichia coli HGU-3, a human intestinal bacterium; Kim DH et al.; beta-Glucuronidase was purified 360-fold from Escherichia coli HGU-3, an human intestinal bacterium . The specific activity of the purified enzyme was 17.78 units/mg protein . The enzyme (M.W . 290000) is composed of four subunits (M.W . 72000) with a pI and optimal pH of 4.8 and 6-7, respectively . The apparent Km for p-nitrophenyl-beta-D-glucuronide was found to be 0.22 mM . The enzyme was inhibited by saccharic acid 1,4-lactone, glycyrrhizin, N-ethylmaleimide (NEM) and p-chloromercuriphenylsulfonic acid (PCMS) . Using the bile containing bilirubin diglucuronide as a substrate, the purified beta-glucuronidase was able to hydrolyze it to bilirubin . This hydrolyzed bilirubin formed calcium bilirubinate with a reaction mixture containing CaCl2. Mol Microbiol, 1995 Sep, 17(5), 961 - 9 Analysis of the motA flagellar motor gene from Rhodobacter sphaeroides, a bacterium with a unidirectional, stop-start flagellum; Shah DS et al.; Rhodobacter sphaeroides swims by unidirectional rotation of a single medial flagellum, re-orienting randomly by Brownian motion when flagellar rotation stops and restarts . Previously we identified a mutant with a paralysed flagellum, which was complemented by a Rhodobacter gene that had homology to motB of Escherichia coli, a bacterium with bidirectional flagella . In the current work, interposon mutagenesis upstream of the Rhodobacter motB gene gave rise to another paralysed mutant, RED5 . DNA sequence analysis of this upstream region showed one open reading frame, the predicted polypeptide sequence of which shows homology to the MotA protein of E . coli . MotA is thought to be a proton 'pore' involved in converting proton-motive force into flagellar rotation . Several potential proton-binding amino acids were conserved between putative membrane-spanning regions of R . sphaeroides and E . coli MotA sequences, along with a highly charged cytoplasmic linker region . Complementation studies with mutant RED5 showed the presence of an active promoter upstream from motA which was found to be necessary for expression of both motA and motB . Examination of the upstream DNA sequence showed only one putative promoter-like sequence which resembled a sigma 54-type promoter, including a potential enhancer binding site . The overall similarities between the R . sphaeroides MotA protein and those from other bacteria suggest that, despite the novel unidirectional rotation of the R . sphaeroides flagellum, the function of the MotA protein is similar to that in bacteria with bidirectional flagella. Mol Microbiol, 1995 Sep, 17(5), 843 - 53 Gene-regulatory modules in Escherichia coli: nucleoprotein complexes formed by cAMP-CRP and CytR at the nupG promoter; Pedersen H et al.; Repression by CytR depends on the formation of nucleoprotein complexes in which the CytR repressor and the cAMP-CRP activator complex bind co-operatively to the DNA . Transcription initiation from CytR-regulated promoters requires cAMP-CRP; therefore, the cAMP-CRP complex functions both as an activator and as a co-repressor in these promoters . Another interesting aspect of the CytR regulon is that each promoter appears to have individual features . Therefore, structural and functional rules governing the formation of repression and activation complexes in one promoter may not be valid for other promoters of the CytR regulon . Here we show that the Escherichia coli nupG gene contains one CytR- and four CRP-binding sites in the control region . Notably, the architecture of the CytR binding site is different from previously described targets . In addition, the CytR repressor triggers a DNA repositioning of a cAMP-CRP complex in the -35 region upon binding to its operator . Thus, formation of the repression and activation complexes at the nupG promoter involves different subsets of CRP-binding sites . These findings show that the bacterium uses positive and negative regulatory modules to differentially control the expression of CytR- and cAMP-CRP-regulated genes. Baillieres Clin Gastroenterol, 1995 Sep, 9(3), 563 - 82 Helicobacter pylori as a risk factor for cancer; Webb PM et al.; In 1985, gastric cancer was the second most common cause of cancer death in the world . The rapid decline in gastric cancer rates over the last few decades has been attributed to a decline in the prevalence of environmental risk factors for gastric cancer and/or an increase in the prevalence of protective factors . One such risk factor could be the bacterium Helicobacter pylori . Epidemiological studies have shown that areas with high gastric cancer rates often have a correspondingly high prevalence of H . pylori and prospective studies have shown that subjects with serological evidence of H . pylori infection were significantly more likely to go on to develop gastric cancer than those who did not . Helicobacter pylori itself does not appear to be either genotoxic or mutagenic . Infection is, however, associated with increased cell turnover, a chronic immune response accompanied by increased levels of reactive oxygen metabolites and a reduction in gastric levels of ascorbic acid, all conditions that could favour the development of cancer . Nonetheless, the majority of those who are infected with H . pylori do not go on to develop gastric cancer and other factors, such as the strain of the infecting organism or consumption of dietary antioxidants including vitamin C, could also affect the risk of cancer . Finally, it has been estimated that more than one third, and possibly as many as 90% of gastric cancers might be attributable to infection with H . pylori . Prevention and treatment of infection are, therefore, possible approaches to reducing gastric cancer rates . It is, however, unclear what, if any, effect eradication of the infection would have on an individual's risk of gastric cancer and, to date, anti-Helicobacter therapy has only been shown to be of potential benefit in the treatment of low grade gastric MALT lymphomas. Baillieres Clin Gastroenterol, 1995 Sep, 9(3), 549 - 62 Nature of non-ulcer dyspepsia and related conditions; Porro GB et al.; To date, the precise role of Helicobacter pylori in the pathogenesis of NUD remains uncertain . There is some evidence to suggest that the organism is implicated in specific subgroups (mostly the ulcer-like form), but it is not enough for any firm conclusions to be drawn as to the importance of the bacterium as a cause of dyspeptic symptoms or as to the efficacy of anti-infective regimens in the treatment of NUD . Large, well-designed prospective studies with a long-term follow-up are needed to establish which subgroups of dyspeptic patients may benefit most from eradication of H . pylori. Biokhimiia, 1995 Sep, 60(9), 1429 - 34 {Analysis of amino acid sequences of Rhodobacter sphaeroides glutamine synthetase}; Zinchenko VV et al.; A comparative analysis of the amino acid sequence of glutamine synthetase (GS) of the photosynthetic purple bacterium Rhodobacter sphaeroides revealed that the enzyme is typical for first type procaryotic GSs and structurally resembles GSs of enteric bacteria . The data obtained indicate that the complex phenotype of purple bacterial mutants at the glnA gene coding for GS may be conditioned by specific regulation of nitrogen metabolism in bacterial cells rather than by structural-and-functional peculiarities of GS. Indian J Med Res, 1995 Sep, 102, 104 - 13 Propagation of Mycobacterium lepraemurium on supplemented minimal medium and its experimental pathogenesis; Banerjee P et al.; The splenic tissue of a mouse experimentally infected with M . lepraemurium (Hawaiian strain, M-65) and developing 'rat leprosy', yielded a pure culture of an acid - fast bacterium having all the characteristics of M . lepraemurium on mineral salt minimal medium supplemented with simple sources of C and N, e.g., NH4 -salts, liquid paraffin, urea, gelatin etc . This could be maintained, by serial passages in vitro with good growth . Its indefinite propagation with tissue - free washed, small inoculum on complex media including Ogawa medium was difficult, and its serial sub-culture was practically impossible . The in vitro isolate from supplemented minimal medium could produce pathological lesions in mice typical of rat leprosy. Biosci Biotechnol Biochem, 1995 Sep, 59(9), 1666 - 9 A hyperthermophilic sulfur-reducing archaebacterium, Thermococcus sp . DT1331, isolated from a deep-sea hydrothermal vent; Kwak YS et al.; A hyperthermophilic archaebacterium was isolated from a deep-sea black smoker chimney (depth, 760 m) at the Minami-ensei Knoll (28 degrees 23'N, 127 degrees 38'E) . The strain, designated DT1331, was a coccoid shaped bacterium about 0.5 to 1.0 microns in diameter . The cells were surrounded by a cell envelope . The temperature for growth was between 55 degrees C and 93 degrees C with an optimum 80 degrees C . The growth occurred from pH 4.5 to 8.5 and the optimum pH was 6.0 . DT1331 required 1% to 5% NaCl for growth and cell lysis was observed below 1% NaCl concentration . The strain was an anaerobic chemoorganotroph requiring elemental sulfur obligately . Organic substrates used included tryptone, peptone, soytone, casein, gelatin, and yeast extract . Under the optimal conditions, DT1331 had a generation time of 50 min and could reach densities of about 1.5 x 10(8) cells/ml . DT1331 was resistant to ampicillin, chloramphenicol, erythromycin, kanamycin, streptomycin, and tetracycline, which was one of the common characteristics of archaebacteria . The G+C content of DT1331 was 52.3 mol% . Analysis of the 16S rRNA gene by restriction enzymes coincided with those of Thermococcus celer, indicating that this strain belonged to the genus Thermococcus. Biophys J, 1995 Sep, 69(3), 1117 - 29 Nonlinear annihilation of excitations in photosynthetic systems; Valkunas L et al.; The theory of the singlet-singlet annihilation in quasi-homogeneous photosynthetic antenna systems is developed further . In the new model, the following important contributions are taken into account: 1) the finite excitation pulse duration, 2) the occupation of higher excited states during the annihilation, 3) excitation correlation effects, and 4) the effect of local heating . The main emphasis is concentrated on the analysis of pump-probe kinetic measurements demonstrating the first two above possible contributions . The difference with the results obtained from low-intensity fluorescence kinetic measurements is highlighted . The experimental data with picosecond time resolution obtained for the photosynthetic bacterium Rhodospirillum rubrum at room temperature are discussed on the basis of this theory. Am J Gastroenterol, 1995 Sep, 90(9), 1424 - 7 Triple therapy with sucralfate, tetracycline, and metronidazole for Helicobacter pylori-associated duodenal ulcers; Sung JJ et al.; Triple therapy with bismuth, metronidazole, and tetracycline or amoxicillin is effective for the treatment of Helicobacter pylori, but side effects are common . Sucralfate inhibits H . pylori hemagglutinin, protease, and lipase and thus might affect colonization of the bacterium in the stomach . OBJECTIVE: We compared the efficacy and side effects of triple therapy with sucralfate versus triple therapy with bismuth plus omeprazole in the treatment of H . pylori-associated duodenal ulcer (DU) . METHODS: One hundred and fifty DU patients were recruited in this study; 71 cases were randomized to receive bismuth 120 mg q.i.d., metronidazole 400 mg q.i.d., and tetracycline 500 mg q.i.d . (BMT) for 1 wk, and 79 cases were randomized to receive sucralfate 1 g q.i.d., metronidazole 400 mg q.i.d., and tetracycline 500 mg q.i.d . (SMT) for 1 wk . For the ulcer treatment, BMT patients were also given omeprazole 20 mg daily for 4 wk, and SMT patients received sucralfate for 4 wk from day of randomization . RESULTS: Fifty-three patients in the BMT group and 60 in the SMT group finished the treatment and follow-up at 8 wk . H . pylori was eradicated in 49 out of 53 (92%) patients in the BMT group and in 45 out of 60 (75%) patients in the SMT group (p = 0.0057) . Forty-nine (92%) patients who received omeprazole and BMT and 53 (88%) patients who received SMT had healed DU at 8 wk (p = 0.34) . Side effects related to medication were reported in 38 (71.7%) patients in the BMT group and in 42 (70%) patients in the SMT group . On an intention-to-treat basis, there was no difference in ulcer healing between the BMT group (93.1%) and the SMT group (89.7%) . H . pylori eradication was achieved in 84.4 and 66.2% in the BMT and SMT groups, respectively (p = 0.018) . CONCLUSION: Therapy of sucralfate, tetracycline, and metronidazole for 1 wk has a satisfactory but lower success rate in eradication of H . pylori when compared with the conventional triple therapy plus omeprazole . Side effects of this therapy are no fewer than the conventional triple therapy. J Biol Chem, 1995 Sep 1, 270(35), 20621 - 8 The leucyl/phenylalanyl-tRNA-protein transferase . Overexpression and characterization of substrate recognition, domain structure, and secondary structure; Abramochkin G et al.; Previous work has shown that, in the bacterium Escherichia coli, the aat gene is essential for the degradation of proteins bearing amino-terminal Arg and Lys residues via the N-end rule pathway of protein degradation . We now show that the aat gene encodes directly the leucyl/phenylalanyl-tRNA-protein transferase (L/F-transferase) . This enzyme catalyzes the transfer of Leu, Phe, and, less efficiently, Met and Trp, from aminoacyl-tRNAs, to the amino terminus of acceptor proteins . We have used the cloned aat gene to overexpress and purify an affinity tagged L/F-transferase . The recombinant L/F-transferase is as active as the previously purified wild type enzyme and contains no detectable RNA component . We have used the recombinant enzyme to demonstrate that both the solubility and substrate specificity, for aminoacyl-tRNA substrates, of the L/F-transferase are dependent on ionic strength conditions and that the modified nucleotides found in natural tRNAs are not essential for recognition by the enzyme . Limited digestion of the L/F-transferase with trypsin removes the proline rich NH2 terminus of the enzyme identifying a globular core, and circular dichroism demonstrates that the L/F-transferase is predominantly alpha-helical . Finally, a region of sequence conservation between the L/F-transferase and the NH2-terminal protein acetylases has been identified. Infect Immun, 1995 Sep, 63(9), 3739 - 44 Enterohemorrhagic Escherichia coli O157:H7 requires intimin to colonize the gnotobiotic pig intestine and to adhere to HEp-2 cells; McKee ML et al.; In a previous study, enterohemorrhagic Escherichia coli (EHEC) O157:H7 with a deletion and insertion in the eaeA gene encoding intimin was used to establish that intimin is required for the organism to attach to and efface microvilli in the piglet intestine (M . S . Donnenberg, S . Tzipori, M . L . McKee, A . D . O'Brien, J . Alroy, and J . B . Kaper, J . Clin . Invest . 92:1418-1424, 1993) . However, in the same investigation, a role for intimin in EHEC adherence to HEp-2 cells could not be definitively demonstrated . To analyze the basis for this discrepancy, we constructed an in-frame deletion of eaeA and compared the adherence capacity of this mutant with that of the wild-type strain in vitro and in vivo . We observed a direct correlation between the requisite for intimin in EHEC O157:H7 colonization of the gnotobiotic piglet intestine and adherence of the bacterium to HEp-2 cells . The in vitro-in vivo correlation lends credence to the use of the HEp-2 cell adherence model for further study of the intimin protein. Infect Immun, 1995 Sep, 63(9), 3527 - 30 Murine cytotoxic T lymphocytes induced following