A new Vibrio cholerae sRNA modulates colonization and affects release of outer membrane vesicles

Abstract

SummaryWe discovered a new small non-coding RNA (sRNA) gene, vrrA of Vibrio cholerae O1 strain A1552. A vrrA mutant overproduces OmpA porin, and we demonstrate that the 140 nt VrrA RNA represses ompA translation by base-pairing with the 5Ј region of the mRNA. The RNA chaperone Hfq is not stringently required for VrrA action, but expression of the vrrA gene requires the membrane stress sigma factor, s E , suggesting that VrrA acts on ompA in response to periplasmic protein folding stress. We also observed that OmpA levels inversely correlated with the number of outer membrane vesicles (OMVs), and that VrrA increased OMV production comparable to loss of OmpA. VrrA is the first sRNA known to control OMV formation. Moreover, a vrrA mutant showed a fivefold increased ability to colonize the intestines of infant mice as compared with the wild type. There was increased expression of the main colonization factor of V. cholerae, the toxin co-regulated pili, in the vrrA mutant as monitored by immunoblot detection of the TcpA protein. VrrA overproduction caused a distinct reduction in the TcpA protein level. Our findings suggest that VrrA contributes to bacterial fitness in certain stressful environments, and modulates infection of the host intestinal tract.

Legionella pneumophila 6S RNA optimizes intracellular multiplication

“…an sRNA involved in the regulation of ompA translation in Vibrio cholerae (22). The sixth sRNA we detected by northern analysis is encoded between pntAa and lpg0877 (Fig.…”

Differential RNA-seq of Vibrio cholerae identifies the VqmR small RNA as a regulator of biofilm formation

“…Our finding that vpsT is under the control of the unrelated VqmR sRNA in V. cholerae could indicate evolution of parallel regulatory pathways. Other examples like this exist: the V. cholerae VrrA sRNA and the E. coli MicA sRNA are not related to one another but both are controlled by the alternative sigma factor σ E and both base pair with the ompA mRNA (49,50). Likewise, in numerous bacterial species, sRNAs that are not related to one another are nonetheless required for responses to iron limitation, and all function by repressing mRNAs encoding iron-binding proteins (51).…”

Transcriptomic profiling of the oyster pathogen Vibrio splendidus opens a window on the evolutionary dynamics of the small RNA repertoire in the Vibrio genus

“…Only seven of these (including Qrr and one copy of CsrB) were encoded on chromosome II. These putative Vibrio core sRNAs include the previously characterized MicX (Davis and Waldor 2007), VrrA (Song et al 2008(Song et al , 2010Song and Wai 2009), and Tfor (Yamamoto et al 2011). Thirty-seven to 38 sRNAs are in common between V. splendidus and V. cholerae, depending on the strain (Supplemental Tables S1, S5A).…”

“…MicX regulates the expression of VC0972, which encodes an outer membrane protein of uncharacterized function (Davis and Waldor 2007). VrrA regulates expression of the outer membrane proteins OmpA and OmpT, modulates colonization, and affects release of outer membrane vesicles (Song et al 2008(Song et al , 2010. TarA is regulated by ToxT, a transcriptional activator of the cholera toxin gene, and targets the ptsG transcript, thus influencing glucose uptake (Richard et al 2010).…”