title: Isolation and characterization of Dam+ revertants and suppressor mutations that modify secondary phenotypes of dam-3 strains of Escherichia coli K-12.
abstract: Bacteria mutant in the dam (DNA adenine methylation) gene and in either recA or recB or recC genes are inviable (Virm- phenotype). From crosses between dam-3 bacteria and recA1 or recB21 recC22 strains, Vrm+ recombinants were recovered. Among these recombinants, Dam+ revertants were present which did not show the phenotypes normally associated with dam-3 bacteria. Three classes of indirectly suppressed strains (dam-3 genotype) were also recovered which showed alterations in the secondary phenotypes normally associated with dam-3 bacteria. These strains contained a second unlinked mutation in either mutL or mutS or sin. In addition, mutation in either sbcA or sbcB supresses the Vrm- phenotype of dam-3 recB21 recC22 strains.
mesh_terms: D000225:Adenine; D003433:Crosses, Genetic; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D005796:Genes; D008780:Methyltransferases / Q000235:genetics*; D009154:Mutation; D010641:Phenotype; D011995:Recombination, Genetic; D013489:Suppression, Genetic
chemical_list: D008780:Methyltransferases; D004248:DNA (Cytosine-5-)-Methyltransferases; D000225:Adenine