Open AccessMolecular mechanism of MexR‐mediated regulation of MexAB–OprM efflux pump expression in Pseudomonas aeruginosa
Author(s) -
Saito Kohjiro,
Eda Shima,
Maseda Hideaki,
Nakae Taiji
Publication year - 2001
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2001.tb10492.x
Subject(s) - efflux , biology , repressor , reporter gene , pseudomonas aeruginosa , transcription factor , gene , biochemistry , genetics , microbiology and biotechnology , gene expression , bacteria
To elucidate the molecular mechanism by which the MexR repressor regulates expression of the MexAB–OprM efflux pump, we investigated MexR and the mexR – mexA intergenic DNA ( mexOP ) interaction, and transcription of the mexA–lacZ reporter gene containing different lengths of mexOP . Homogeneously purified MexR bound specifically to mexOP proximal to mexR . The mexOP – lacZ fusion gene lacking the region immediately proximal to mexR showed minimum enzyme activity, thereby suggesting that a promoter element is located between mexR and the MexR‐binding sites. These observations explain the mechanism of self‐regulation of mexR expression as well as low and elevated expression of MexAB–OprM in the wild‐type strain and nalB ‐type mutant, respectively, of Pseudomonas aeruginosa .