期刊
ARCHIVES OF MICROBIOLOGY
卷 192, 期 8, 页码 673-683出版社
SPRINGER
DOI: 10.1007/s00203-010-0596-2
关键词
lambda Prophage induction; Shiga toxin-encoding lambdoid phages; OxyR protein; Hydrogen peroxide
类别
资金
- Ministry of Science and Higher Education (Poland) [N301 122 31/3747, N303 291234]
- European Union [POIG.01.01.02-00-008/08]
In Escherichia coli hosts, hydrogen peroxide is one of the factors that may cause induction of lambda prophage. Here, we demonstrate that H(2)O(2)-mediated lambda prophage induction is significantly enhanced in the oxyR mutant host. The mRNA levels for cI gene expression were increased in a lambda lysogen in the presence of H(2)O(2). On the other hand, stimulation of the p (M) promoter by cI857 overproduced from a multicopy plasmid was decreased in the Delta oxyR mutant in the presence of H(2)O(2) but not under normal growth conditions. The purified OxyR protein did bind specifically to the p (M) promoter region. This binding impaired efficiency 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 p (M) 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 efficiency of induction of lambdoid prophages bearing genes coding for Shiga toxins.
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