TRANSCRIPTIONAL CONTROL OF THE MTR EFFLUX SYSTEM OF NEISSERIA-GONORRHOEAE

The capacity of Neisseria gonorrhoeae to resist structurally diverse h ydrophobic agents (HAs) because of the mtr (multiple transferrable res istance) efflux system was found to be regulated at the level of trans cription by two distinct mechanisms. This was surmised because a delet ion that removed >90% of the coding sequence of the mtrR (multiple tra nsferrable resistance regulator) gene or a single-base-pair deletion w ithin a 13-bp inverted repeat sequence located in its promoter resulte d in altered expression of the mtrC gene; mtrC encodes a 44-kDa membra ne lipoprotein essential for the efflux of HAs, However, the single-ba se-pair deletion had the more significant impact on gene expression si nce it resulted in the loss of expression of mtrR and a threefold incr ease in the expression of mtrC. Hence, the mtr efflux system in gonoco cci is subject to both MtrR-dependent and MtrR-independent regulation, and the levels of mtrC mRNA correlate well with HA resistance levels in gonococci.