title: Viability of Escherichia coli K-12 DNA adenine methylase (dam) mutants requires increased expression of specific genes in the SOS regulon.
abstract: 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.
mesh_terms: D004260:DNA Repair; D004269:DNA, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D005796:Genes; D005798:Genes, Bacterial; D005838:Genotype; D008780:Methyltransferases / Q000235:genetics*; D009154:Mutation; D011938:Rec A Recombinases / Q000235:genetics; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific); D013045:Species Specificity; D014161:Transduction, Genetic; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: D004269:DNA, Bacterial; D008780:Methyltransferases; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific); D011938:Rec A Recombinases; D001616:beta-Galactosidase