title: Salmonella typhimurium metE operator-constitutive mutations.
abstract: We used a metE-lacZ fusion phage (lambda Elac) to select for mutants with operator-constitutive mutations in the Salmonella typhimurium metE control region. All of the mutations identified were found to lie within a region containing tandemly-repeating 8-bp palindromes with the consensus sequence 5'-AGACGTCT-3', previously proposed to be the binding region for the metJ-encoded repressor. Lysogens carrying mutant lambda Elac phage exhibit high beta-galactosidase levels that are only partially repressible by methionine. Although repression of metE expression by vitamin B12 is not disrupted in metJ+ lysogens, vitamin B12 repression is disrupted in lysogens lacking an active MetJ repressor. These results suggest that there is an interaction between the metJ-encoded repressor and the vitamin B12 repression system mediated by the metH gene product.
authors.affiliation: Department of Microbiology, University of Iowa, Iowa City 52242.
authors.forename: L S
authors.initials: LS
authors.lastname: Plamann
authors.forename: M L
authors.initials: ML
authors.lastname: Urbanowski
authors.forename: G V
authors.initials: GV
authors.lastname: Stauffer
mesh_terms: D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D005796:Genes; D005798:Genes, Bacterial; D008780:Methyltransferases / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D009876:Operon; D010957:Plasmids; D012486:Salmonella typhimurium / Q000201:enzymology / Q000235:genetics*; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: D008780:Methyltransferases; D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase; D001616:beta-Galactosidase