N. Muratakamiya et al., MUTATIONAL SPECIFICITY OF GLYOXAL, A PRODUCT OF DNA OXIDATION, IN THELACI GENE OF WILD-TYPE ESCHERICHIA-COLI W3110, Mutation research, 377(2), 1997, pp. 255-262
To determine the mutation spectrum of glyoxal, which is produced from
DNA by oxygen free-radicals, we analyzed the chromosomal lad gene of m
utants induced by treatment of a wild-type Escherichia coli strain wit
h glyoxal. The cell death and the mutation frequency increased accordi
ng to the concentration of glyoxal added to the culture medium. The ma
jority of the spontaneous mutations (82%) and that of the glyoxal-indu
ced mutations (50%) were the addition or deletion of a 5'-TGGC-3' sequ
ence at positions 623-634, which was reported to be a mutational hot s
pot in the lacI gene. In the glyoxal-induced mutants, however, the rat
io of base-pair substitutions was increased (35%). Although all types
of base-pair substitutions were detected, 78% of the base-pair substit
utions occurred at G:C sites. Among them, G:C --> A:T transitions were
predominant, followed by G:C --> T:A transversions, These mutations a
ppeared to be distributed randomly within the lad gene. These results
suggest that glyoxal-induced mutations may correlate to mutations indu
ced by oxygen free-radicals.