title: The isolation and characterization of ngm2, a mutation that affects nitrosoguanidine mutagenesis in yeast.
abstract: We have isolated and characterized a new mutant of Saccharomyces cerevisiae, carrying a single mutant allele that we designate ngm2-1, which is defective with respect to induced mutagenesis. This mutant was isolated by screening mutagenized clones for reduced frequencies of reversion of the his1-7 allele, induced by N-methyl-N-nitro-N-nitrosoguanidine. As judged by the reversion of his1-7 and ilv1-92, ngm2-1 mutant strains are also deficient with respect to mutability induced by methyl methane sulfonate, ethyl methane sulfonate and, at least partially, by UV. UV-induced reversion of the ochre mutation arg4-17 and the frameshift mutation his4-38 was not much affected by ngm2-1, however. Like rev3 and rev7 mutations, ngm2-1 also has little influence on the reversion of the proline missense allele, cyc1-115. Ngm2-1 mutants are only at best very slightly more sensitive to the toxicity of the four mutagens used, and homozygous diploids sporulate normally.
mesh_terms: D000483:Alleles; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology*; D009153:Mutagens; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D009153:Mutagens; D008769:Methylnitronitrosoguanidine