Small RNAcoaRcontributes to intestinal colonization inVibrio choleraevia the two-component system EnvZ/OmpR

Vibrio choleraeis a waterborne bacterium responsible for worldwide outbreaks of acute and fatal cholera. Recently, small regulatory RNAs (sRNAs) have become increasingly recognized as important regulators of virulence gene expression in response to environmental signals. In this study, we determined that two-component system EnvZ/OmpR was required for intestinal colonization inV. choleraeO1 EI Tor strain E12382. Analysis of the characteristics of OmpR revealed a potential binding site in the intergenic region betweenvc1470andvc1471, and qRT-PCR showed that expression of the intergenic region increased 5.3-fold in the small intestine compared to LB medium. Race and northern blot assays were performed and demonstrated a new sRNA,coaR(cholerae osmolarity and acidity related regulatory RNA). A Delta coaRmutant showed a deficient colonization ability in small intestine with CI of 0.15. We identified a target ofcoaR,tcpI, a negative regulator of the major pilin subunit of TcpA. The Delta tcpImutant has an increased colonization with CI of 3.16. The expression ofcoaRincreased 2.8-fold and 3.3-fold under relative acidic and hypertonic condition. In summary,coaRwas induced under the condition of high osmolarity and acid stress via EnvZ/OmpR and explained thattcpIrelieves pH-mediated repression of toxin co-regulated pilus synthesis.