title: Mutagenic specificity of N-methyl-N'-nitro-N-nitrosoguanidine in the tonB gene on the chromosome of Escherichia coli recA+ and recA- cells.
abstract: DNA base sequence changes induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) mutagenesis has been determined for the endogenous tonB gene of Escherichia coli recA+ strain and its isogenic recA56 strain. In the recA+ strain, base substitutions accounted for 48 mutations among 54 MNNG-induced independent mutations analyzed and consisted of 45 G:C to A:T transitions, two A:T to G:C transitions and one A:T to C:G transversion. In the recA56 strain, 67% (34/51) were base substitutions among which G:C to A:T transition (28/51) predominated, followed by three A:T to T:A transversions, two G:C to T:A transversions, and one A:T to G:C transition. These mutagenic specificities were consistent with the mispairing predicted by the methylation of the O6 position of guanine. In both strains the G:C to A:T mutations were found at guanine residues preceded by either guanine or thymine on the non-transcribed strand of the target gene.
authors.affiliation: Biological Institute, Graduate School of Science, Tohoku University, Sendai, Japan.
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: K
authors.initials: K
authors.lastname: Kitamura
authors.forename: K
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D001692:Biological Transport; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D029968:Escherichia coli Proteins; D016368:Frameshift Mutation; D005798:Genes, Bacterial / Q000187:drug effects*; D008565:Membrane Proteins / Q000235:genetics*; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology*; D016296:Mutagenesis; D009153:Mutagens / Q000494:pharmacology*; D017354:Point Mutation; D011938:Rec A Recombinases / Q000235:genetics* / Q000378:metabolism; D017384:Sequence Deletion
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D009153:Mutagens; C057616:tonB protein, Bacteria; C489181:tonB protein, E coli; D008769:Methylnitronitrosoguanidine; D011938:Rec A Recombinases