Characterization of mutations induced by N-methyl-N'-nitro-N-nitrosoguanidine in an industrial Corynebacterium glutamicum strain.
Mutations induced by classical whole-cell mutagenesis using N-methyl-N'-nitro-N-nitrosoguanidine (NTG) were determined for all genes of pathways from glucose to L-lysine in an industrial L-lysine producer of Corynebacterium glutamicum. A total of 50 mutations with a genome-wide distribution were identified and characterized for mutational types and mutagenic specificities. Those mutations were all point mutations with single-base substitutions and no deletions, frame shifts, and insertions were found. Among six possible types of base substitutions, the mutations consisted of only two types: 47 G.C-->A.T transitions and three A.T-->G.C transitions with no transversion. The findings indicate a limited repertoire of amino acid substitutions by classical NTG mutagenesis and thus raise a new possibility of further improving industrial strains by optimizing key mutations through PCR-mediated site-directed mutagenesis.
Bio-Frontier Laboratories, Kyowa Hakko Kogyo Co Ltd, Machida, Tokyo, Japan.
Junko
J
Ohnishi
Hiroshi
H
Mizoguchi
Seiki
S
Takeno
Masato
M
Ikeda
D048230:Corynebacterium glutamicum / Q000187:drug effects* / Q000235:genetics*; D004252:DNA Mutational Analysis; D016680:Genome, Bacterial; D008769:Methylnitronitrosoguanidine / Q000633:toxicity*; D009152:Mutagenicity Tests; D017354:Point Mutation / Q000187:drug effects*
D008769:Methylnitronitrosoguanidine