Mutational specificity of the ferrous ion in a supF gene of endonuclease III/VIII deficient Escherichia coli.
When 125 microM Fe2+/EDTA treated plasmid pUB3 was used to transfect an Escherichia coli NKJ2004 (nth nei) host, which is totally defective in glycosylases for thymine glycol and 5-hydroxycytosine, a 3.7 fold increase in mutation frequency was observed. Among 46 supF mutants sequenced, 28 had base substitutions, with G:C-->C:G transversion predominant (14 cases), followed by G:C-->T:A transversion (6 cases) and G:C-->A:T transition (6 cases). The results are consistent with our previous Fe2+ mutagenesis results where, in the wild type host, 78% were base substitutions, with G:C-->C:G transversion (59%) predominant, followed by G:C-->T:A transversion (28%) and G:C-->A:T transition (11%). Treatment of pUB3 DNA with Fe2+/EDTA did not yield formation of Endonuclease III sensitive sites. The possibility of 5-hydroxycytosine as the causative lesion for Fe2+ induced G:C-->C:G transversion is discussed.
Shimamura
H
H
Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, Osaka, Japan.
Akasaka
S
S
Kubo
K
K
Saito
Y
Y
Nakajima
S
S
Tano
K
K
Utsumi
H
H
Yamamoto
K
K
D004260:DNA Repair; D043224:Deoxyribonuclease (Pyrimidine Dimer); D004706:Endodeoxyribonucleases / Q000172:deficiency*; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D016153:Genes, Suppressor; D007501:Iron / Q000494:pharmacology*; D016296:Mutagenesis; D010957:Plasmids; D012343:RNA, Transfer / Q000235:genetics*; D014162:Transfection
D029968:Escherichia coli Proteins; C096275:supF tRNA; D012343:RNA, Transfer; D007501:Iron; D004706:Endodeoxyribonucleases; D043224:Deoxyribonuclease (Pyrimidine Dimer); C106403:NTH protein, E coli