Abstract
The LysR-type transcription factor LeuO is involved in regulation of pathogenicity determinants and stress responses in Enterobacteriaceae, and acts as antagonist of the global repressor H-NS. Expression of the leuO gene is repressed by H-NS, and it is upregulated in stationary phase and under amino acid starvation conditions. Here, we show that the heterodimer of the FixJ/NarL-type transcription regulators RcsB and BglJ strongly activates expression of leuO and that RcsB-BglJ regulates additional loci. Activation of leuO by RcsB-BglJ is independent of the Rcs phosphorelay system. RcsB-BglJ binds to the leuO promoter region and activates one of two leuO promoters mapped in vivo. Moreover, LeuO antagonizes activation of leuO by RcsB-BglJ and acts as negative autoregulator in vivo and in vitro. Further, the H-NS paralogue StpA causes repression of leuO in addition to H-NS. Together, our data suggest a complex arrangement of regulatory elements and they indicate a feedback control mechanism of leuO expression.
© 2012 Blackwell Publishing Ltd.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Base Sequence
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism
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Escherichia coli / genetics
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Escherichia coli / metabolism*
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Escherichia coli Proteins / antagonists & inhibitors
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Escherichia coli Proteins / genetics*
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Escherichia coli Proteins / metabolism*
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Fimbriae Proteins / antagonists & inhibitors
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Fimbriae Proteins / genetics
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Fimbriae Proteins / metabolism*
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Gene Expression Regulation, Bacterial*
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Molecular Chaperones / genetics
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Molecular Chaperones / metabolism
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Molecular Sequence Data
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Operon
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Promoter Regions, Genetic
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Protein Binding
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Trans-Activators / genetics
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Trans-Activators / metabolism*
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Transcription Factors / genetics*
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Transcription Factors / metabolism*
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Transcriptional Activation
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Virulence Factors / genetics
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Virulence Factors / metabolism*
Substances
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BglJ protein, E coli
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DNA-Binding Proteins
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Escherichia coli Proteins
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FimG protein, E coli
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LeuO protein, E coli
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Molecular Chaperones
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RcsB protein, E coli
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StpA protein, E coli
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Trans-Activators
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Transcription Factors
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Virulence Factors
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Fimbriae Proteins