CflP couples magnesium availability to CovS signaling in Group B Streptococcus
Opportunistic pathogens must coordinate virulence-factor production with changing conditions encountered during colonization and infection. Group B Streptococcus (GBS), a common human opportunistic pathogen, uses the CovRS two-component system to regulate virulence, but how the CovS sensor kinase is tuned to environmental conditions remains unclear. Here, we identify CflP, a noncatalytic membrane…
Group B Streptococcus, a frequent human opportunistic pathogen, utilizes the CovRS two-component system to manage virulence, but the regulation of the CovS sensor kinase in response to environmental factors remains unknown. Researchers have now discovered that CflP, a noncatalytic membrane protein from the CPBP family, functions as an accessory regulator of CovS.
CflP binds to CovS and enhances CovS-induced phosphorylation of the response regulator CovR, which in turn suppresses virulence-related genes, including the {beta}-hemolysin/cytolysin operon. When CflP is absent, the cytotoxicity towards human immune cells is increased. Importantly, CflP's abundance is controlled post-transcriptionally by magnesium ion availability, establishing a link between an environmental cue and CovRS signaling.
Genome analysis showed that cflP is typically maintained as an intact gene, although particular amino acid changes can reduce CflP levels, while abx1 is often damaged by recurring frameshifts. These findings reveal an additional control layer that adjusts CovS activity based on environmental conditions and may contribute to strain-specific differences in CovRS regulation.
The results also demonstrate how noncatalytic membrane proteins can modify bacterial signaling to strike a balance between virulence-factor production and adaptation to shifting host environments.
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