Specificity of mutations induced by riboflavin mediated photosensitization in the supF gene of Escherichia coli.
Riboflavin-mediated photosensitization has been shown to produce 8-hydroxyguanine (oh8Gua) in DNA. We investigated the specificity of mutation of photosensitized supF gene induced in Escherichia coli. The oh8Gua repair deficient E. coli mutant mutM and mutY were transformed with plasmid pUB3 carrying the supF gene irradiated with white light in the presence of riboflavin. Under these conditions, riboflavin photosensitization increased the amounts of oh8Gua in pUB3 DNA. Three types of a single base substitution occurring at G:C pairs were detected in both wild-type and mutM mutant strains. Almost all base substitutions were transversions to T:A or C:G pairs occurring at a similar extent in both wild-type and mutM strains. Mutations derived from mutY strain transformed with photosensitized DNA were only G:C to T:A transversions. These G:C to T:A transversions observed in the mutY strain were suggested to be the result of mispairing of oh8Gua with adenine. Riboflavin-mediated photosensitization may also produce lesions on DNA causing G:C to C:G changes by unknown mechanisms.
Tano
K
K
Research Reactor Institute, Kyoto University, Kumatori, Osaka 590-0494, Japan.tano@rri.kyoto-u.ac.jp
Akasaka
S
S
Hashimoto
M
M
Asano
M
M
Yamamoto
K
K
Utsumi
H
H
Takimoto
K
K
D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D045647:DNA Glycosylases; D004269:DNA, Bacterial / Q000737:chemistry / Q000187:drug effects / Q000528:radiation effects; D043382:DNA-Formamidopyrimidine Glycosylase; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics* / Q000528:radiation effects; D029968:Escherichia coli Proteins; D016153:Genes, Suppressor; D006147:Guanine / Q000031:analogs & derivatives / Q000032:analysis / Q000096:biosynthesis; D008027:Light; D008969:Molecular Sequence Data; D009154:Mutation; D009699:N-Glycosyl Hydrolases / Q000737:chemistry / Q000235:genetics; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D010957:Plasmids / Q000187:drug effects / Q000528:radiation effects; D012343:RNA, Transfer / Q000737:chemistry / Q000235:genetics* / Q000528:radiation effects; D012256:Riboflavin / Q000737:chemistry / Q000494:pharmacology*; D017422:Sequence Analysis, DNA
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D017319:Photosensitizing Agents; C096275:supF tRNA; C024829:8-hydroxyguanine; D006147:Guanine; D012343:RNA, Transfer; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; C061738:mutY adenine glycosylase; D043382:DNA-Formamidopyrimidine Glycosylase; C468610:DNA-formamidopyrimidine glycosylase, E coli; D012256:Riboflavin