MetJ-mediated regulation of the Salmonella typhimurium metE and metR genes occurs through a common operator region
Journal
FEMS Microbiology Letters
Journal Volume
108
Journal Volume
108
Journal Issue
2
Journal Issue
2
Pages
145-150
Start Page
145
End Page
150
ISSN
03781097
Date Issued
1993-04-01
Author(s)
Abstract
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 lambda gt2. Regulation of the metE and metR genes was examined by measuring beta-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.
Subjects
metE-metR operator region
MetJ-mediated regulation
Salmonella typhimurium
Site-directed mutagenesis
SDGs
Type
journal article