Genetic analysis of the role of the conserved inner membrane protein CvpA in EHEC resistance to deoxycholate.

The function of , a bacterial gene predicted to encode an inner membrane protein, is largely unknown. Early studies in linked to Colicin V secretion and recent work revealed that it is required for robust intestinal colonization by diverse enteric pathogens. In enterohemorrhagic (EHEC), is required for resistance to the bile salt deoxycholate (DOC). Here, we carried out genome-scale transposon-insertion mutagenesis and spontaneous suppressor analysis to uncover genetic interactions and identify common pathways that rescue the sensitivity of a Δ EHEC mutant to DOC. These screens demonstrated that mutations predicted to activate the σ-mediated extracytoplasmic stress response bypass the Δ mutant's susceptibility to DOC. Consistent with this idea, we found that deletions in and and direct overexpression of restored DOC resistance to the Δ mutant. Analysis of the distribution of CvpA homologs revealed that this inner membrane protein is conserved across diverse bacterial phyla, in both enteric and non-enteric bacteria that are not exposed to bile. Together, our findings suggest that CvpA plays a role in cell envelope homeostasis in response to DOC and similar stress stimuli in diverse bacterial species. Several enteric pathogens, including Enterohemorrhagic (EHEC), require CvpA to robustly colonize the intestine. This inner membrane protein is also important for secretion of a colicin and EHEC resistance to the bile salt deoxycholate (DOC), but its function is unknown. Genetic analyses carried out here showed that activation of the σ-mediated extracytoplasmic stress response restored the resistance of a mutant to DOC, suggesting that CvpA plays a role in cell envelope homeostasis. The conservation of CvpA across diverse bacterial phyla suggests that this membrane protein facilitates cell envelope homeostasis in response to varied cell envelope perturbations.