INDUCTION OF CHROMOSOMAL GENE-MUTATIONS IN ESCHERICHIA-COLI BY DIRECTINCORPORATION OF OXIDATIVELY DAMAGED NUCLEOTIDES - NEW EVALUATION METHOD FOR MUTAGENESIS BY DAMAGED DNA PRECURSORS IN-VIVO
M. Inoue et al., INDUCTION OF CHROMOSOMAL GENE-MUTATIONS IN ESCHERICHIA-COLI BY DIRECTINCORPORATION OF OXIDATIVELY DAMAGED NUCLEOTIDES - NEW EVALUATION METHOD FOR MUTAGENESIS BY DAMAGED DNA PRECURSORS IN-VIVO, The Journal of biological chemistry, 273(18), 1998, pp. 11069-11074
We have developed a new strategy for the evaluation of the mutagenicit
y of a damaged DNA precursor (deoxyribonucleoside 5'-triphosphate) in
Escherichia coil, 8-Hydroxydeoxyguanosine triphosphate (8-OH-dGTP) and
2-hydroxydeoxyadenosine triphosphate (2-OH-dATP) were chosen for this
study because they appear to be formed abundantly by reactive oxygen
species in cells, We introduced the oxidatively damaged nucleotides in
to competent E. coli and selected mutants of the chromosomal loci gene
, Both damaged nucleotides induced loci gene mutations in a dose-depen
dent manner, whereas unmodified dATP and dGTP did not appear to elicit
the mutations, The addition of 50 nmol of 8-OH-dGTP and 2-OH-dATP int
o an E. coli suspension induced 12- and 9-fold more substitution mutat
ions than the spontaneous event, respectively. The 8-OH-dGTP induced A
.T --> C.G transversions, and the 2-OH-dATP elicited G.C --> T.A trans
versions. These results indicate that the two oxidatively damaged nucl
eotides are mutagenic in vivo and suggest that 8-OH-dGTP and 2-OH-dATP
were incorporated opposite A and G residues, respectively, in the E.
coil DNA, This new method enables the evaluation and comparison of the
mutagenic potentials of damaged DNA precursors in vivo.