Influence of the Escherichia coli oxyR gene function on lambda prophage maintenance

Abstract

In Escherichia coli hosts, hydrogen peroxide is one of the factors that may cause induction of lambda prophage. Here, we demonstrate that H2O2-mediated lambda prophage induction is signiWcantly enhanced in the oxyR mutant host. The mRNA levels for cI gene expression were increased in a lambda lysogen in the presence of H2O2. On the other hand, stimulation of the pM promoter by cI857 overproduced from a multicopy plasmid was decreased in the lambda oxyR mutant in the presence of H2O2 but not under normal growth conditions. The puriWed OxyR protein did bind speciWcally to the pM promoter region. This binding impaired eYciency of interaction of the cI protein with the OR3 site, while stimulating such a binding to OR2 and OR1 sites, in the regulatory region of the pM promoter. We propose that changes in cI gene expression, perhaps in combination with moderately induced SOS response, may be responsible for enhanced lambda prophage induction by hydrogen peroxide in the oxyR mutant. Therefore, OxyR seems to be a factor stimulating lambda prophage maintenance under conditions of oxidative stress. This proposal is discussed in the light of eYciency of induction of lambdoid prophages bearing genes coding for Shiga toxins.

Available Versions of this Item

• Influence of the Escherichia coli oxyR gene function on lambda prophage maintenance. (deposited 27 Apr 2011 14:58) [Currently Displayed]
  • Infuence of the Escherichia coli oxyR gene function on lambda prophage maintenance. (deposited 11 Apr 2014 11:25)