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Following Cell-fate in E. coli After Infection by Phage Lambda
Published on: October 14, 2011
Influence of the Escherichia coli oxyR gene function on lambda prophage maintenance
Monika Glinkowska1, Joanna M Loś, Anna Szambowska
1Department of Molecular Biology, University of Gdańsk, Kładki 24, 80-822 Gdańsk, Poland.
Archives of Microbiology
|June 19, 2010
Summary
Hydrogen peroxide (H2O2) more strongly induces lambda prophage in oxyR mutant Escherichia coli. The OxyR protein normally helps maintain the prophage, but its absence enhances H2O2-induced prophage.
Area of Science:
- Microbiology
- Molecular Biology
- Bacteriology
Background:
- Hydrogen peroxide (H2O2) is a known inducer of lambda prophage in Escherichia coli.
- The oxyR gene product (OxyR) is a transcriptional regulator involved in the oxidative stress response.
Purpose of the Study:
- To investigate the role of the oxyR gene in H2O2-mediated lambda prophage induction.
- To elucidate the mechanism by which OxyR influences prophage stability under oxidative stress.
Main Methods:
- Construction and characterization of an oxyR deletion mutant (DeltaoxyR) in an E. coli lambda lysogen.
- Measurement of cI gene mRNA levels in the presence and absence of H2O2.
- Analysis of p(M) promoter activity using a multicopy plasmid expressing cI857.
- Electrophoretic mobility shift assays (EMSAs) to study OxyR binding to the p(M) promoter region.
Main Results:
- H2O2-induced lambda prophage induction was significantly enhanced in the DeltaoxyR mutant compared to the wild-type host.
- cI gene expression increased in the presence of H2O2 in lambda lysogens.
- OxyR protein binding to the p(M) promoter region was demonstrated, affecting cI protein interaction with specific operator sites (OR1, OR2, OR3).
- OxyR binding impaired cI interaction with OR3 but enhanced binding to OR1 and OR2.
Conclusions:
- OxyR acts as a factor that promotes lambda prophage maintenance under oxidative stress conditions.
- Enhanced lambda prophage induction in the oxyR mutant is likely due to altered cI gene expression and potentially a moderate SOS response.
- The findings have implications for understanding the induction of lambdoid prophages carrying virulence genes, such as Shiga toxins.
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