DNA damage caused by ascorbate in the presence of Cu2+ induces mutations.
The DNA damage induced by ascorbate in the presence of Cu2+ was analyzed by sequencing, and the mutagenic consequences of damages to plasmid pUC18 lacZ' were assayed in a forward repairing system in E. coli JM109 in vivo. Ascorbate induced two classes of DNA damage in the presence of Cu2+, one being non-base-specific direct strand cleavage, and the other being sequence-specific base modification labile to alkali treatment. Radicals generated from ascorbate hydroperoxide were involved in DNA damaging reactions. Ascorbate and Cu2+ caused mutations in pUC18 lacZ' gene. The mutation frequency by this method was about 10(-4) at 18% survivors when measured as a loss of alpha-complementation. All the mutations found were single-base substitutions that occurred in the structural part of the lacZ' gene. They were predominantly G:C----A:T transitions.
Kobayashi
S
S
Department of Agricultural Chemistry, Kyoto University, Japan.
Yoshida
K
K
Ueda
K
K
Sakai
H
H
Komano
T
T
D001205:Ascorbic Acid / Q000494:pharmacology*; D001483:Base Sequence; D003300:Copper / Q000494:pharmacology*; D004249:DNA Damage; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial / Q000187:drug effects; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids / Q000187:drug effects*
D003300:Copper; D001205:Ascorbic Acid