The H-NS-like protein StpA represses the RpoS (sigma 38) regulon during exponential growth of Salmonella Typhimurium.
Mol Microbiol
; 74(5): 1169-86, 2009 Dec.
Article
em En
| MEDLINE
| ID: mdl-19843227
ABSTRACT
StpA is a paralogue of the nucleoid-associated protein H-NS that is conserved in a range of enteric bacteria and had no known function in Salmonella Typhimurium. We show that 5% of the Salmonella genome is regulated by StpA, which contrasts with the situation in Escherichia coli where deletion of stpA only had minor effects on gene expression. The StpA-dependent genes of S. Typhimurium are a specific subset of the H-NS regulon that are predominantly under the positive control of sigma(38) (RpoS), CRP-cAMP and PhoP. Regulation by StpA varied with growth phase; StpA controlled sigma(38) levels at mid-exponential phase by preventing inappropriate activation of sigma(38) during rapid bacterial growth. In contrast, StpA only activated the CRP-cAMP regulon during late exponential phase. ChIP-chip analysis revealed that StpA binds to PhoP-dependent genes but not to most genes of the CRP-cAMP and sigma(38) regulons. In fact, StpA indirectly regulates sigma(38)-dependent genes by enhancing sigma(38) turnover by repressing the anti-adaptor protein rssC. We discovered that StpA is essential for the dynamic regulation of sigma(38) in response to increased glucose levels. Our findings identify StpA as a novel growth phase-specific regulator that plays an important physiological role by linking sigma(38) levels to nutrient availability.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Salmonella typhimurium
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Fator sigma
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Proteínas de Bactérias
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Regulação Bacteriana da Expressão Gênica
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Regulon
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Chaperonas Moleculares
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Proteínas de Ligação a DNA
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2009
Tipo de documento:
Article