A new Vibrio cholerae sRNA modulates colonization and affects release of outer membrane vesicles.
We 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 5' 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, sigma(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.
Song
Tianyan
T
Department of Molecular Biology, Umeå University, SE-901 87 Umeå, Sweden.
Mika
Franziska
F
Lindmark
Barbro
B
Liu
Zhi
Z
Schild
Stefan
S
Bishop
Anne
A
Zhu
Jun
J
Camilli
Andrew
A
Johansson
Jörgen
J
Vogel
Jörg
J
Wai
Sun Nyunt
SN
D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D001483:Base Sequence; D002462:Cell Membrane / Q000378:metabolism*; D002771:Cholera / Q000382:microbiology; D004269:DNA, Bacterial / Q000235:genetics; D036781:Fimbriae Proteins / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D007422:Intestines / Q000382:microbiology; D051379:Mice; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000235:genetics*; D022661:RNA, Untranslated / Q000235:genetics*; D017384:Sequence Deletion; D012808:Sigma Factor / Q000235:genetics; D024363:Transcription Initiation Site; D041241:Vibrio cholerae O1 / Q000235:genetics* / Q000378:metabolism
D001425:Bacterial Outer Membrane Proteins; D004269:DNA, Bacterial; D012329:RNA, Bacterial; D022661:RNA, Untranslated; D012808:Sigma Factor; C085807:TcpA protein, Vibrio cholerae; C063202:sporulation-specific sigma factors; D036781:Fimbriae Proteins; C078167:OMPA outer membrane proteins