PMID:11292335
| Citation |
Yoshiyama, K, Higuchi, K, Matsumura, H and Maki, H (2001) Directionality of DNA replication fork movement strongly affects the generation of spontaneous mutations in Escherichia coli. J. Mol. Biol. 307:1195-206 |
|---|---|
| Abstract |
Using a pair of plasmids carrying the rpsL target sequence in different orientations to the replication origin, we analyzed a large number of forward mutations generated in wild-type and mismatch-repair deficient (MMR(-)) Escherichia coli cells to assess the effects of directionality of replication-fork movement on spontaneous mutagenesis and the generation of replication error. All classes of the mutations found in wild-type cells but not MMR(-) cells were strongly affected by the directionality of replication fork movement. It also appeared that the directionality of replication-fork movement governs the directionality of sequence substitution mutagenesis, which occurred in wild-type cells at a frequency comparable to base substitutions and single-base frameshift mutations. A very strong orientation-dependent hot-spot site for single-base frameshift mutations was discovered and demonstrated to be caused by the same process involved in sequence substitution mutagenesis. It is surprising that dnaE173, a potent mutator mutation specific for sequence substitution as well as single-base frameshift, did not enhance the frequency of the hot-spot frameshift mutation. Furthermore, the frequency of the hot-spot frameshift mutation was unchanged in the MMR(-) strain, whereas the mutHLS-dependent mismatch repair system efficiently suppressed the generation of single-base frameshift mutations. These results suggested that the hot-spot frameshift mutagenesis might be initiated at a particular location containing a DNA lesion, and thereby produce a premutagenic replication intermediate resistant to MMR. Significant numbers of spontaneous single-base frameshift mutations are probably caused by similar mechanisms. |
| Links |
PubMed Online version:10.1006/jmbi.2001.4557 |
| Keywords |
Adenosine Triphosphatases; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Base Pair Mismatch/genetics; Base Sequence; DNA Mutational Analysis; DNA Polymerase III/genetics; DNA Polymerase III/metabolism; DNA Replication/genetics; DNA-Binding Proteins; Escherichia coli/enzymology; Escherichia coli/genetics; Escherichia coli Proteins; Frameshift Mutation/genetics; Genes, Bacterial/genetics; Models, Genetic; Molecular Sequence Data; MutS DNA Mismatch-Binding Protein; Mutagenesis/genetics; Plasmids/genetics; Point Mutation/genetics; Polymerase Chain Reaction |
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