PMID:15773988

Citation	Williams, CL, Boucher, PE, Stibitz, S and Cotter, PA (2005) BvgA functions as both an activator and a repressor to control Bvg phase expression of bipA in Bordetella pertussis. Mol. Microbiol. 56:175-88
Abstract	The Bordetella bipA gene is expressed maximally when the BvgAS phosphorelay is semi-active, i.e. in the Bvg-intermediate (Bvg(i)) phase. We used a BvgA-FeBABE cleavage approach together with site-directed mutagenesis and bipA-lacZ fusion analyses to determine precisely where BvgA-phosphate (BvgA approximately P) binds at the bipA promoter and how that binding contributes to the complex transcription pattern displayed by bipA. BvgA approximately P bound with high affinity and cooperatively with RNAP to sequences at the bipA promoter immediately 5' to and overlapping those bound by RNAP to activate transcription under Bvg(i) phase conditions. bipA therefore, like fhaB, appears to be similar to classical class-II promoters with regard to the mechanism by which its transcription is activated. BvgA approximately P bound with relatively low affinity to sequences immediately 3' of those bound by RNAP at the bipA promoter and this binding mediated repression of bipA transcription under Bvg+ phase conditions. BvgA approximately P binding to these sequences occurred simultaneously, if not cooperatively, with RNAP, indicating that BvgA approximately P represses bipA expression by inhibiting transcription initiation and/or elongation, rather than by competing with RNAP for binding. As bipA is the first Bvg(i) phase gene to be characterized, and the first gene shown to be repressed by BvgA approximately P directly, our results will provide a basis for comparison as additional Bvg-regulated genes are identified and characterized.
Links	PubMed Online version:10.1111/j.1365-2958.2004.04526.x
Keywords	Bacterial Outer Membrane Proteins/chemistry; Bacterial Outer Membrane Proteins/genetics; Bacterial Outer Membrane Proteins/metabolism; Bacterial Proteins/metabolism; Base Sequence; Bordetella pertussis/chemistry; Bordetella pertussis/genetics; Bordetella pertussis/metabolism; Gene Expression Regulation, Bacterial; Molecular Sequence Data; Mutagenesis, Site-Directed; Promoter Regions, Genetic; Signal Transduction; Trans-Activators/metabolism; Transcription Factors/metabolism; Transcription, Genetic
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
BORPE:BVGA		GO:0006355: regulation of transcription, DNA-templated	ECO:0000314:		P		Fig 5 shows in vitro transcription from wild type bipA promoter with increasing concentrations of Phosphorylated BvgA. Low concentrations are sufficient to activate bipA transcription, while higher concentrations inhibit transcription.	complete CACAO 11130
BORPT:A0A0E8BMW2		GO:0006355: regulation of transcription, DNA-templated	ECO:0000314:		P		Fig 5 shows in vitro transcription from wild type bipA promoter with increasing concentrations of Phosphorylated BvgA. Low concentrations are sufficient to activate bipA transcription, while higher concentrations inhibit transcription.	complete CACAO 11026

References

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