Viability of Escherichia coli K-12 DNA adenine methylase (dam) mutants requires increased expression of specific genes in the SOS regulon

UMMS Affiliation

Department of Biochemistry and Molecular Pharmacology



Document Type


Medical Subject Headings

*DNA Repair; DNA, Bacterial; Escherichia coli; *Genes; *Genes, Bacterial; Genotype; Methyltransferases; *Mutation; Rec A Recombinases; Site-Specific DNA-Methyltransferase (Adenine-Specific); Species Specificity; Transduction, Genetic; beta-Galactosidase


We have examined the level of expression of the SOS regulon in cells lacking DNA adenine methylase activity (dam-). Mud (Ap, lac) fusions to several SOS operons (recA, lexA, uvrA, uvrB, uvrD, sulA, dinD and dinF) were found to express higher levels of beta-galactosidase in dam- strains than in isogenic dam+ strains. The attempted construction of dam- strains that were also mutant in one of several SOS genes indicated that the viability of methylase-deficient strains correlates with the inactivation of the SOS repressor (LexA protein). Consistent with this, the wild-type functions of two LexA-repressed genes (recA and ruv) appear to be required for dam- strain viability.

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Citation: Mol Gen Genet. 1985;201(1):14-9.

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