BvgAregulated

BvgAregulated refers to genes whose transcription is controlled by the BvgA response regulator in Bordetella species, including Bordetella pertussis, B. parapertussis, and B. bronchiseptica. BvgA is part of the BvgAS two-component regulatory system. When phosphorylated by the sensor kinase BvgS, BvgA~P binds to promoter regions to activate or, less commonly, repress transcription. The BvgA regulon comprises virulence-associated operons and genes involved in adherence, toxin production, and other aspects of host interaction.

Mechanism: Environmental cues such as temperature, nicotinic acid, sulfate, and divalent cations influence BvgS activity, shifting bacteria between Bvg+ (high BvgA~P, virulent) and Bvg- (low BvgA~P) states. BvgA~P activates transcription by binding to promoters with BvgA-binding motifs. Some genes may be repressed by BvgA~P under certain conditions, contributing to phase variation in virulence gene expression.

Examples of BvgA-regulated factors typically include virulence determinants such as pertussis toxin (ptx), adenylate cyclase toxin (cyaA), pertactin (prn), filamentous hemagglutinin (fhaB), and various fimbrial components. The regulon also encompasses regulatory and accessory genes that support host interaction and adaptation. The exact composition of the BvgAregulated set varies among Bordetella species and environmental conditions.

Significance: The BvgA regulon is central to Bordetella pathogenesis and environmental adaptation, governing virulence expression during infection and informing vaccine design, attenuation strategies in research models, and broader studies of two-component regulatory networks in Gram-negative bacteria.