Escherichia coli mutT mutator effect during in vitro DNA synthesis. Enhanced A.G replicational errors.
The mechanism of the Escherichia coli mutT mutator effect was investigated using single-stranded phage as a mutational target. In vivo experiments showed that two M13mp2 lacZ alpha nonsense mutants reverted at a higher rate on a mutT1 host than on the wild-type host. The specificity of this mutator effect was identical to that observed for E. coli genes: A.T----C.G transversions. The mutT effect was subsequently demonstrated in vitro during DNA replication of M13mp2 DNA in cell-free extracts of E. coli. Replication (the single-stranded----replicative form conversion) in mutT1 extracts proceeded with a higher error rate than in wild-type extracts, and DNA sequence analysis of the in vitro revertants revealed the specific induction of A.T----C.G transversions. On the basis of the template specificity of the mutT effect in vitro, we conclude that the mutT effect involves the aberrant processing of A.G rather than T.C mispairs.
Schaaper
R M
RM
Laboratory of Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709.
Dunn
R L
RL
D001426:Bacterial Proteins / Q000378:metabolism; D001435:Bacteriophages / Q000235:genetics; D004261:DNA Replication; D004269:DNA, Bacterial / Q000096:biosynthesis; D004926:Escherichia coli / Q000235:genetics*; D009154:Mutation; D011061:Poly A; D011066:Poly C; D011068:Poly G; D011071:Poly T
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D011061:Poly A; D011071:Poly T; D011068:Poly G; C008961:poly G-poly C; C008950:poly A-T; D011066:Poly C