B. Clerch et al., EFFICIENCY OF MUCAB AND ESCHERICHIA-COLI UMUDC PROTEINS IN QUINOLONE AND UV MUTAGENESIS IN SALMONELLA-TYPHIMURIUM - EFFECT OF MUCA AND UMUDPROCESSING, Mutation research, 349(2), 1996, pp. 201-208
The role of MucAB and Escherichia coli UmuDC proteins in mutagenesis b
y 4-quinolone (4-Q) compared to that in UV mutagenesis has been studie
d in hisG428 Salmonella typhimurium strains. A low-copy plasmid carryi
ng mucAB genes, but not umuDC, promotes reversion of the hisG428 mutat
ion by the 4-Q ciprofloxacin. In contrast, a umuDC plasmid mediates th
e reversion of hisG428 by UV, although less efficiently than a mucAB o
ne. In addition, a unique copy of mucAB genes is enough to promote UV
mutagenesis, whereas, several copies of them are required to detect ci
profloxacin mutagenesis. Therefore, the mutagenic repair of quinolone
damage by MucAB proteins is not a very efficient process. The presence
of an umuD'C plasmid but not a mucA'B one, slightly increases the rev
ersion of the hisG428 mutation by ciprofloxacin and this finding is fu
rther discussed. In contrast, MucA'B are still more active than UmuD'C
proteins in UV mutagenesis. These results suggest that the enhanced p
rocessing of MucA compared to UmuD would not explain all functional di
fferences between MucAB and UmuDC proteins in the error-prone DNA repa
ir.