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Infections with Nontyphoidal Salmonella Species Producing TEM-63 or a Novel TEM Enzyme, TEM-131, in South Africa. Tersia Kruger, 2004.Salmonella spp . producing extended-spectrum beta-lactamases (ESBLs) have been reported in many countries, but there is no information on their prevalence in Africa . ESBL-producing Salmonella enterica serotype Isangi and S . enterica serotype Typhimurium strains have been noted in South Africa since 2001 . A total of 160 consecutive isolates of Salmonella spp . were collected from 13 hospitals located in different cities in South Africa over a 5-month period from December 2002 to April 2003 . All strains were screened for production of ESBLs by the double disk diffusion test and for AmpC production by assessing resistance to cefoxitin . blaSHV, blaTEM, blaCTX-M, and blaCMY-2 were sought from all ESBL-positive and cefoxitin-resistant isolates . A total of 15.6% (25 of 160) isolates produced SHV or TEM ESBLs, and 1.9% (3 of 160) produced CMY-2 . Nine S . enterica serotype Typhimurium, eight S . enterica serotype Isangi, and three S . enterica serotype Muenchen strains produced either TEM-63 or a derivative of TEM-63 designated TEM-131 . Both TEM-63 and TEM-131 have an isoelectric point of 5.6, and their sequences have the following amino acid substitutions compared to the TEM-1 sequence: Leu21Phe, Glu104Lys, Arg164Ser, and Met182Thr . Additionally, TEM-131 has an Ala237Thr substitution . ESBL-producing Salmonella spp . have become a significant public health problem in South Africa with particular implications for the treatment of serious nontyphoidal Salmonella infections in children, for whom extended-spectrum cephalosporins were the preferred treatment . Evidence for Direct Protein-Protein Interaction between Members of the Enterobacterial Hha/YmoA and H-NS Families of Proteins. J. M. Nieto, 2002.Escherichia coli nucleoid-associated H-NS protein interacts with the Hha protein, a member of a new family of global modulators that also includes the YmoA protein from Yersinia enterocolitica . This interaction has been found to be involved in the regulation of the expression of the toxin  -hemolysin . In this study, we further characterize the interaction between H-NS and Hha . We show that the presence of DNA in preparations of copurified His-Hha and H-NS is not directly implicated in the interaction between the proteins . The precise molecular mass of the H-NS protein retained by Hha, obtained by mass spectrometry analysis, does not show any posttranslational modification other than removal of the N-terminal Met residue . We constructed an H-NS-His recombinant protein and found that, as expected, it interacts with Hha . We used a Ni2+-nitrilotriacetic acid agarose method for affinity chromatography copurification of proteins to identify the H-NS protein of Y . enterocolitica . We constructed a six-His-YmoA recombinant protein derived from YmoA, the homologue of Hha in Y . enterocolitica, and found that it interacts with Y . enterocolitica H-NS . We also cloned and sequenced the hns gene of this microorganism . In the course of these experiments we found that His-YmoA can also retain H-NS from E . coli . We also found that the hns gene of Y . enterocolitica can complement an hns mutation of E . coli . Finally, we describe for the first time systematic characterization of missense mutant alleles of hha and truncated Hha' proteins, and we report a striking and previously unnoticed similarity of the Hha family of proteins to the oligomerization domain of the H-NS proteins .
1,8-Dihydroxynaphthalene (DHN)-Melanin Biosynthesis Inhibitors Increase Erythritol Production in Torula corallina, and DHN-Melanin Inhibits Erythrose Reductase. Jung-Kul Lee, 2003.The yeast Torula corallina is a strong erythritol producer that is used in the industrial production of erythritol . However, melanin accumulation during culture represents a serious problem for the purification of erythritol from the fermentation broth . Melanin biosynthesis inhibitors such as 3,4-dihydroxyphenylalanine and 1,8-dihydroxynaphthalene (DHN)-melanin inhibitors were added to the T . corallina cultures . Only the DHN-melanin inhibitors showed an effect on melanin production, which suggests that the melanin formed during the culturing of T . corallina is derived from DHN . This finding was confirmed by the detection of a shunt product of the pentaketide pathway, flaviolin, and elemental analysis . Among the DHN-melanin inhibitors, tricyclazole was the most effective . Supplementation with tricyclazole enhanced the production of erythritol while significantly inhibiting the production of DHN-melanin and DHN-melanin biosynthetic enzymes, such as trihydroxynaphthalene reductase . The erythrose reductase from T . corallina was purified to homogeneity by ion-exchange and affinity chromatography . Purified erythrose reductase was significantly inhibited in vitro in a noncompetitive manner by elevated levels of DHN-melanin . In contrast, the level of erythrose reductase activity was unaffected by increasing concentrations of tricyclazole . These results suggest that supplemental tricyclazole reduces the production of DHN-melanin, which may lead to a reduction in the inhibition of erythrose reductase and a higher yield of erythritol . This is the first report to demonstrate that melanin biosynthesis inhibitors increase the production of a sugar alcohol in T . corallina . Species-Specific Peptide Ligands for the Detection of Bacillus anthracis Spores. David D. Williams, 2003.Currently available detectors for spores of Bacillus anthracis, the causative agent of anthrax, are inadequate for frontline use and general monitoring . There is a critical need for simple, rugged, and inexpensive detectors capable of accurate and direct identification of B . anthracis spores . Necessary components in such detectors are stable ligands that bind tightly and specifically to target spores . By screening a phage display peptide library, we identified a family of peptides, with the consensus sequence TYPXPXR, that bind selectively to B . anthracis spores . We extended this work by identifying a peptide variant, ATYPLPIR, with enhanced ability to bind to B . anthracis spores and an additional peptide, SLLPGLP, that preferentially binds to spores of species phylogenetically similar to, but distinct from, B . anthracis . These two peptides were used in tandem in simple assays to rapidly and unambiguously identify B . anthracis spores . We envision that these peptides can be used as sensors in economical and portable B . anthracis spore detectors that are essentially free of false-positive signals due to other environmental Bacillus spores .
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