Journal of bacteriology
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Journal of bacteriology · Apr 2011
Genome of a European fresh-vegetable food safety outbreak strain of Salmonella enterica subsp. enterica serovar weltevreden.
The genome of Salmonella enterica subsp. enterica serovar Weltevreden strain 2007-60-3289-1 was sequenced. The genome sequence of this fresh-vegetable isolate from Scandinavia will be useful for the elucidation of plant host factors in comparison to other serovars of S. enterica subsp. enterica.
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Journal of bacteriology · Feb 2008
Structure of [NiFe] hydrogenase maturation protein HypE from Escherichia coli and its interaction with HypF.
Hydrogenases are enzymes involved in hydrogen metabolism, utilizing H2 as an electron source. [NiFe] hydrogenases are heterodimeric Fe-S proteins, with a large subunit containing the reaction center involving Fe and Ni metal ions and a small subunit containing one or more Fe-S clusters. Maturation of the [NiFe] hydrogenase involves assembly of nonproteinaceous ligands on the large subunit by accessory proteins encoded by the hyp operon. HypE is an essential accessory protein and participates in the synthesis of two cyano groups found in the large subunit. ⋯ The stoichiometry and molecular weights of the complex were verified by size exclusion chromatography and gel scanning densitometry. These experiments reveal that HypE and HypF associate to form a stoichiometric, hetero-oligomeric complex predominantly consisting of a [EF]2 heterotetramer which exists in a dynamic equilibrium with the EF heterodimer. The surface plasmon resonance results indicate that a conformational change occurs upon heterodimerization which facilitates formation of a productive complex as part of the carbamate transfer reaction.
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Journal of bacteriology · Nov 2006
Transcription modulation of Salmonella enterica serovar Typhimurium promoters by sub-MIC levels of rifampin.
Promoter-lux fusions that showed rifampin-modulated transcription were identified from a Salmonella enterica serovar Typhimurium 14028 reporter library. The transformation of a subset of fusions into mutants that lacked one of six global regulatory proteins or were rifampin resistant showed that transcription modulation was independent of the global regulators, promoter specific, and dependent on the interaction of rifampin with RNA polymerase.
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Journal of bacteriology · Feb 2006
Serotype differences and lack of biofilm formation characterize Yersinia pseudotuberculosis infection of the Xenopsylla cheopis flea vector of Yersinia pestis.
Yersinia pestis, the agent of plague, is usually transmitted by fleas. To produce a transmissible infection, Y. pestis colonizes the flea midgut and forms a biofilm in the proventricular valve, which blocks normal blood feeding. The enteropathogen Yersinia pseudotuberculosis, from which Y. pestis recently evolved, is not transmitted by fleas. ⋯ The other strains persisted in the flea midgut for 4 weeks but did not increase in numbers, and none of the 18 strains colonized the proventriculus or produced a biofilm in the flea. Y. pseudotuberculosis strains also varied greatly in their ability to produce biofilms in vitro, but there was no correlation between biofilm phenotype in vitro or on the surface of C. elegans and the ability to colonize or block fleas. Our results support a model in which a genetic change in the Y. pseudotuberculosis progenitor of Y. pestis extended its pre-existing ex vivo biofilm-forming ability to the flea gut environment, thus enabling proventricular blockage and efficient flea-borne transmission.
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Journal of bacteriology · Apr 2005
SarA is an essential positive regulator of Staphylococcus epidermidis biofilm development.
Staphylococcus epidermidis biofilm formation is associated with the production of the polysaccharide intercellular adhesin (PIA)--poly-N-acetylglucosamine polysaccharide (PNAG) by the products of the icaADBC operon. Recent evidence indicates that SarA, a central regulatory element that controls the production of Staphylococcus aureus virulence factors, is essential for the synthesis of PIA/PNAG and the ensuing biofilm development in this species. Based on the presence of a sarA homolog, we hypothesized that SarA could also be involved in the regulation of the biofilm formation process in S. epidermidis. ⋯ Furthermore, heterologous complementation of S. aureus sarA mutants with the sarA gene of S. epidermidis completely restored biofilm formation. In summary, SarA appeared to be a positive regulator of transcription of the ica locus, and in its absence, PIA/PNAG production and biofilm formation were diminished. Additionally, we present experimental evidence showing that SarA may be an important regulatory element that controls S. epidermidis virulence factors other than biofilm formation.