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Synthesis of the Heteropolysaccharide O Antigen of Escherichia coli O52 Requires an ABC Transporter: Structural and Genetic Evidence. Lu Feng, 2004.The structural and genetic organization of the Escherichia coli O52 O antigen was studied . As identified by sugar and methylation analysis and nuclear magnetic resonance spectroscopy, the O antigen of E . coli O52 has a partially O-acetylated disaccharide repeating unit (O unit) containing D-fucofuranose and 6-deoxy-D-manno-heptopyranose, as well as a minor 6-deoxy-3-O-methylhexose (most likely, 3-O-methylfucose) . The O-antigen gene cluster of E . coli O52, which is located between the galF and gnd genes, was found to contain putative genes for the synthesis of the O-antigen constituents, sugar transferase genes, and ABC-2 transporter genes . Further analysis confirmed that O52 employs an ATP-binding cassette (ABC) transporter-dependent pathway for translocation and polymerization of the O unit . This is the first report of an ABC transporter being involved in translocation of a heteropolysaccharide O antigen in E . coli . Genes specific for E . coli O52 were also identified . In Vitro Activities of ME1036 (CP5609), a Novel Parenteral Carbapenem, against Methicillin-Resistant Staphylococci. Mizuyo Kurazono, 2004.ME1036, formerly CP5609, is a novel parenteral carbapenem with a 7-acylated imidazo[5,1-b]thiazole-2-yl group directly attached to the carbapenem moiety of the C-2 position . The present study evaluated the in vitro activities of ME1036 against clinical isolates of gram-positive and gram-negative bacteria . ME1036 displayed broad activity against aerobic gram-positive and gram-negative bacteria . Unlike other marketed ß-lactam antibiotics, ME1036 maintained excellent activity against multiple-drug-resistant gram-positive bacteria, such as methicillin-resistant staphylococci and penicillin-resistant Streptococcus pneumoniae (PRSP) . The MICs of this compound at which 90% of isolates were inhibited were 2 µg/ml for methicillin-resistant Staphylococcus aureus (MRSA), 2 µg/ml for methicillin-resistant coagulase-negative staphylococci, and 0.031 µg/ml for PRSP . In time-kill studies with six strains of MRSA, ME1036 at four times the MIC caused a time-dependent decrease in the numbers of viable MRSA cells . The activity of ME1036 against MRSA is related to its high affinity for penicillin-binding protein 2a, for which the 50% inhibitory concentration of ME1036 was approximately 300-fold lower than that of imipenem . In conclusion, ME1036 demonstrated a broad antibacterial spectrum and high levels of activity in vitro against staphylococci, including ß-lactam-resistant strains . Methods for Enhanced Culture Recovery of Francisella tularensis. Jeannine M. Petersen, 2004.Francisella tularensis is found in a wide variety of hosts and extrahost environments, making culture recovery a diagnostic challenge . Here we demonstrate improved recovery times and good sensitivity (90%) when cultures were inoculated on the site of an investigation using fresh tissues . For contaminated specimens, antibiotic supplementation of enriched cysteine heart agar blood culture medium improved recovery of F . tularensis by 81.1% . For transport of tissues, immediate freezing yielded culture recovery rates as high as 94% . L-Malyl-Coenzyme A Lyase/ß-Methylmalyl-Coenzyme A Lyase from Chloroflexus aurantiacus, a Bifunctional Enzyme Involved in Autotrophic CO2 Fixation. Sylvia Herter, 2002. Transcriptome Analysis of Neisseria meningitidis during Infection. Guido Dietrich, 2003.Neisseria meningitidis is the cause of septicemia and meningococcal meningitis . During the course of infection, N . meningitidis encounters multiple environments within its host, which makes rapid adaptation to environmental changes a crucial factor for neisserial pathogenicity . Employing oligonucleotide-based DNA microarrays, we analyzed the transcriptome of N . meningitidis during two key steps of meningococcal infection, i.e., the interaction with epithelial cells (HeLa cells) and endothelial cells (human brain microvascular endothelial cells) . Seventy-two genes were differentially regulated after contact with epithelial cells, and 48 genes were differentially regulated after contact with endothelial cells, including a considerable proportion of well-known virulence genes . While a considerable number of genes were in concordance between bacteria adherent to both cell types, we identified several open reading frames that were differentially regulated in only one system . The data obtained with this novel approach may provide insight into the pathogenicity mechanisms of N . meningitidis and could demonstrate the importance of gene regulation on the transcriptional level during different stages of meningococcal infection . Isolation and Characterization of Mutants of the Bacillus subtilis Oligopeptide Permease with Altered Specificity of Oligopeptide Transport. Jonathan Solomon, 2003.Bacterial oligopeptide permeases are members of the large family of ATP binding cassette transporters and typically import peptides of 3 to 5 amino acids, apparently independently of sequence . Oligopeptide permeases are needed for bacteria to utilize peptides as nutrient sources and are sometimes involved in signal transduction pathways . The Bacillus subtilis oligopeptide permease stimulates competence development and the initiation of sporulation, at least in part, by importing specific signaling peptides . We isolated rare, partly functional mutations in B . subtilis opp . The mutants were resistant to a toxic tripeptide but still retained the ability to sporulate and/or become competent . The mutations, mostly in the oligopeptide binding protein located on the cell surface, affected residues whose alteration appears to change the specificity of oligopeptide transport . Drastic Differences in Crh and HPr Synthesis Levels Reflect Their Different Impacts on Catabolite Repression in Bacillus subtilis. Boris Görke, 2004.In Bacillus subtilis, carbon catabolite repression (CCR) of catabolic genes is mediated by ATP-dependent phosphorylation of HPr and Crh . Here we show that the different efficiencies with which these two proteins contribute to CCR may be due to the drastic differences in their synthesis rates under conditions that cause CCR . Cytolytic Toxin Cyt1A and Its Mechanism of Membrane Damage: Data and Hypotheses. Peter Butko, 2003.
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