An in vivo approach to identifying sequence context of 8-oxoguanine mutagenesis.
Base substitution mutations are not distributed randomly in that most are located at a few specific hotspots sites. We have been studying 7,8-dihydro-8-oxoguanine mutagenesis in Escherichia coli in the supF gene carried in a plasmid. Among hotspots, guanine within the 5'-AGA-3' located in the anticodon site was susceptible to the induction of G:C-->T:A transversion. In this study, we constructed variants of the supF gene in which the hotspot 5'-AGA-3' was modified to 5'-AGT-3', 5'-AGG-3' and 5'-AGC-3' to determine the influence of 3' neighboring base on G:C-->T:A mutational activity. Using these variant supF genes propagated in a 7,8-dihydro-8-oxoguanine repair-deficient host, we found that guanine within 5'-AGA-3' and 5'-AGG-3' produce G:C-->T:A, but guanine within 5'-AGT-3' and 5'-AGC-3' reduce the formation of G:C-->T:A. These changes were thus due to the effect of sequence context on the efficiency of mutation formation at the sites of 7,8-dihydro-8-oxoguanine. We also observed a longer range base-pair effect on hotspot formation.
Watanabe
T
T
Institute of Molecular Life Science, Graduate School of Life Science, Tohoku University, Sendai, 980-8578, Japan.
Nunoshiba
T
T
Kawata
M
M
Yamamoto
K
K
D001483:Base Sequence; D004252:DNA Mutational Analysis; D004269:DNA, Bacterial / Q000187:drug effects / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics*; D016153:Genes, Suppressor; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016297:Mutagenesis, Site-Directed; D009153:Mutagens / Q000494:pharmacology; D017354:Point Mutation / Q000187:drug effects / Q000235:genetics; D012343:RNA, Transfer / Q000235:genetics*; D012680:Sensitivity and Specificity
D004269:DNA, Bacterial; D009153:Mutagens; C096275:supF tRNA; C024829:8-hydroxyguanine; D006147:Guanine; D012343:RNA, Transfer