Suppression of the E. coli SOS response by dNTP pool changes

The Escherichia coli SOS system is a well-established model for the cellular response to DNA damage. Control of SOS depends largely on the RecA protein. When RecA is activated by single-stranded DNA in the presence of a nucleotide triphosphate cofactor, it mediates cleavage of the LexA repressor, le...

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Bibliographic Details
Published in:Nucleic acids research 2015-04, Vol.43 (8), p.4109-4120
Main Authors: Maslowska, Katarzyna H, Makiela-Dzbenska, Karolina, Fijalkowska, Iwona J, Schaaper, Roel M
Format: Article
Language:English
Subjects:
Bacterial Proteins - genetics
Deoxyribonucleotides - metabolism
DNA-Directed DNA Polymerase - metabolism
Drug Resistance, Bacterial - genetics
Escherichia coli
Escherichia coli - drug effects
Escherichia coli - genetics
Escherichia coli - metabolism
Escherichia coli Proteins - metabolism
Molecular Biology
Mutagenesis
Mutation
Nucleoside-Diphosphate Kinase - genetics
Nucleotide Deaminases - genetics
Rec A Recombinases - genetics
Regulon
Rifampin - pharmacology
Serine Endopeptidases - genetics
SOS Response (Genetics)
Suppression, Genetic
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Summary:The Escherichia coli SOS system is a well-established model for the cellular response to DNA damage. Control of SOS depends largely on the RecA protein. When RecA is activated by single-stranded DNA in the presence of a nucleotide triphosphate cofactor, it mediates cleavage of the LexA repressor, leading to expression of the 30(+)-member SOS regulon. RecA activation generally requires the introduction of DNA damage. However, certain recA mutants, like recA730, bypass this requirement and display constitutive SOS expression as well as a spontaneous (SOS) mutator effect. Presently, we investigated the possible interaction between SOS and the cellular deoxynucleoside triphosphate (dNTP) pools. We found that dNTP pool changes caused by deficiencies in the ndk or dcd genes, encoding nucleoside diphosphate kinase and dCTP deaminase, respectively, had a strongly suppressive effect on constitutive SOS expression in recA730 strains. The suppression of the recA730 mutator effect was alleviated in a lexA-deficient background. Overall, the findings suggest a model in which the dNTP alterations in the ndk and dcd strains interfere with the activation of RecA, thereby preventing LexA cleavage and SOS induction.
ISSN:0305-1048
1362-4962
DOI:10.1093/nar/gkv217