[Activation of enzymes of soxRS-regulon by hydrogen peroxide in Escherichia coli].

A mutant strain (delta soxR), a derivative of strain of Escherichia coli AB 57, was obtained by general transduction. The authors have investigated the effect of oxidative stress on activity of enzymes of regulons oxyR (catalase, peroxidase, glutathione reductase) and soxRS(superoxide dismutase (SOD) and glucose-6-phosphate dehydrogenase (G6PDH) in the donor strain DJ901, recipient strain AB1157 and transductant. Oxidative stress induced by phenasine metasulfate had no effect on activity of the studied enzymes of regulon oxyR in either used strain, and on enzymes of regulon soxRS in DJ901 transductant, but caused an 1.6- and 1.3-fold increase in activity of SOD and G6PDH in AB 1157, respectively. The stress induced by 20 microM hydrogen peroxide in the last strain increased the enzyme activity of both regulons, and SOD activity increased by 28 % and that of G6PDH--by 42%. Under the same kind of stress only SOD activity increased by 20% in the transductant. Possible ways of regulation of activity in enzymes being the components of regulon soxRS are discussed.