De. Higgins et Vj. Dirita, TRANSCRIPTIONAL CONTROL OF TOXT, A REGULATORY GENE IN THE TOXR REGULON OF VIBRIO-CHOLERAE, Molecular microbiology, 14(1), 1994, pp. 17-29
Co-ordinate expression of many virulence genes in Vibrio cholerae is u
nder the control of the ToxR and ToxT proteins. These proteins functio
n in a regulatory cascade in which ToxR is required to activate toxT,
and ToxT activates virulence genes. The precise mechanism for ToxR act
ivation of toxT is unknown, but data presented in this report suggest
a direct involvement of ToxR. Primer extension and gene fusion analyse
s identified a ToxR-regulated promoter directly upstream of toxT, imme
diately following a region of inverted repeats capable of terminating
transcription. Gel mobility shift studies indicate that ToxR binds DNA
within the inverted repeat region, yet preliminary evidence suggests
that ToxR binding alone is not sufficient for activation of toxT. Poss
ible mechanisms of ToxR-dependent toxT expression are discussed.