Promotion of mutagenesis by rumAB genes in Salmonella typhimurium strains TA1535 and TA2659

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The rumAB operon, which was recently identified as Escherichia coli umuDC-complementing genes, strongly enhances spontaneous mutagenesis. We investigated the mutation-enhancing effects of the rumAB operon on a low copy number plasmid. Its effect was tested at the hisG46 locus in strain TA1535 and the hisG428(ochre)locus in strain TA2659 of Salmonella typhimurium. Mutability of strains carrying rumAB on plasmid pRW290 was compared with the mutability of those carrying mucAB on plasmid pRW144. In both Salmonella strains, rumAB promoted approximately twice as many spontaneous mutations as mucAB. Both operons were equally effective, however, in enhancing sensitivity to mutagenesis induced by various kind of mutagens, such as UV light, 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide, 4-nitroquinoline 1-oxide, hydrogen peroxide, formaldehyde, cumene hydroperoxide, 2-nitrofluorene, 5-azacytidine, and N-ethyl-N'-nitro-N-nitrosoguanidine. When both strains carried either rumAB or mucAB, formaldehyde was strongly mutagenic to TA2659 but not to TA1535, whereas sodium azide was strongly mutagenic to TA1535 but not to TA2659. Neither rumAB nor mucAB genes seemed to enhance the mutagenicity of sodium azide or N^4-aminocytidine.
日本環境変異原学会の論文
1998-04-10