Open AccessMetJ‐mediated regulation of the Salmonella typhimurium metE and metR genes occurs through a common operator region
Author(s) -
Wu WhiFin,
Urbanowski Mark L.,
Stauffer George V.
Publication year - 1993
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.1574-6968.1993.tb06090.x
Subject(s) - biology , repressor , genetics , psychological repression , gene , galactokinase , mutant , promoter , lac operon , microbiology and biotechnology , escherichia coli , mutation , gene expression
In Salmonella typhimurium the metE and metR promoters overlap and are divergently transcribed. Three tandem repeats of an 8 bp sequence defined previously as the metE operator site for MetJ‐mediated repression also overlap the −35 region of the metR promoter. Starting with a metE‐lacZ · metR‐galK double gene fusion, site‐directed mutagenesis was used to change nucleotides in each of the repeat units from the consensus sequence. Each mutation, along with the wild‐type metE‐lacZ · metR‐galK gene fusion, was cloned into phage λgt2. Regulation of the metE and metR genes was examined by measuring β‐galactosidase and galactokinase levels in Escherichia coli strains lysogenized with phage carrying the wild‐type and mutant fusions. Mutations in each of the 8 bp repeat units disrupt MetJ‐mediated repression for both the metE‐lacZ and metR‐galK gene fusions, suggesting that the metE and metR genes share a common operator site for the MetJ repressor.