Open AccessOxyR, a positive regulator of hydrogen peroxide-inducible genes in Escherichia coli and Salmonella typhimurium, is homologous to a family of bacterial regulatory proteins.
Author(s) -
Michael F. Christman,
Gisela Storz,
Bruce N. Ames
Publication year - 1989
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.86.10.3484
Subject(s) - biology , escherichia coli , regulon , gene , rpos , mutant , regulator gene , microbiology and biotechnology , open reading frame , genetics , peptide sequence , biochemistry , regulation of gene expression , promoter , gene expression
The oxyR gene is required for the induction of a regulon of hydrogen peroxide-inducible genes in Escherichia coli and Salmonella typhimurium. The E. coli oxyR gene has been cloned and sequenced, revealing an open reading frame (305 amino acids) that encodes a 34.4-kDa protein, which is produced in maxicells carrying the oxyR clone. The OxyR protein shows homology to a family of positive regulatory proteins including LysR in E. coli and NodD in Rhizobium. Like them, oxyR appears to be negatively autoregulated: an oxyR::lacZ gene fusion produced 5-fold higher levels of beta-galactosidase activity in oxyR null mutants compared to oxyR+ controls, and extracts from an OxyR-overproducing strain were able to protect regions (-27 to +21) of the oxyR promoter from DNase I digestion. DNA sequence analysis of the oxyR2 mutation, which causes overexpression of oxyR-regulated proteins in the absence of oxidative stress, showed that the oxyR2 phenotype is due to a missense mutation (C.G to T.A transition) that changes alanine to valine at amino acid position 234 of OxyR.