Premium
SOS mutator effect in E. coli mutants deficient in mismatch correction.
Author(s) -
CailletFauquet P.,
MaenhautMichel G.,
Radman M.
Publication year - 1984
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1984.tb01873.x
Subject(s) - mutagenesis , biology , reversion , escherichia coli , mutant , bacteriophage , genetics , dna , sos response , mutation , microbiology and biotechnology , gene , phenotype
We have used bacteriophage lambda to characterize the mutator effect of the SOS response induced by u.v. irradiation of Escherichia coli. Mutagenesis of unirradiated phages grown in irradiated or unirradiated bacteria was detected by measuring forward mutagenesis in the immunity genes or reversion mutagenesis of an amber codon in the R gene. Relative to the wild‐type, the SOS mutator effect was higher in E. coli mismatch correction‐deficient mutants (mutH, mutL and mutS) and lower in an adenine methylation‐deficient mutant (dam3). We conclude that a large proportion of SOS‐induced ‘untargeted’ mutations are removed by the methyl‐directed mismatch correction system, which acts on newly synthesized DNA strands. The lower SOS mutator effect observed in E. coli dam mutants may be due to a selective killing of mismatch‐bearing chromosomes resulting from undirected mismatch repair. The SOS mutator effect on undamaged lambda DNA, induced by u.v. irradiation of the host, appears to result from decreased fidelity of DNA synthesis.