抄録
Treatment of Escherichia coli and Salmonella typhimurium cells with a low dose of hydrogen peroxide induces expression of a large number of genes, and confers the cells resistance to oxidative stresses. The oxyR gene encodes a positive regulatory protein for a subset of these genes involved in the defense against the oxidative damage. We cloned a DNA fragment that contains the E. coli oxyR region on a plasmid vector, and analyzed the nucleotide sequence of the gene. The amino acid sequence of OxyR protein shows an high degree of homology to the sequence of a number of bacterial protein including LysR, IlvY, MetR and NodD. OxyR protein specifically bound to the upstream regulatory regions of the oxyR and katG genes as demonstrated by the gel-retardation assay and the DNase I footprinting experiment. Experiments with gene fusion indicate that OxyR protein functions as a repressor for oxyR, in addition to its known function as a transcriptional activator for the genes in the oxyR regulon.
