Mutator strains of Escherichia coli, mutD and dnaQ, with defective exonucleolytic editing by DNA polymerase III holoenzyme.
- 1 April 1983
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 80 (8), 2189-2192
- https://doi.org/10.1073/pnas.80.8.2189
Abstract
The closely linked mutD and dnaQ mutations confer a vastly increased mutation rate on E. coli and thus might define a gene with a central role in the fidelity of DNA replication. To look for the biochemical function of the mutD gene product, one measured the 3'' .fwdarw. 5'' exonucleolytic editing activity of polymerase III holoenzyme from mutD5 and dnaQ49 mutants. The editing activities of the mutant enzymes are defective compared to wild type, as judged by 2 assays: decreased excision of a terminal mispaired base from a copolymer substrate and turnover of dTTP to dTMP during replication with a phage G4 DNA template. The mutD (dnaQ) gene product is likely to control the editing (proofreading) capacity of polymerase III holoenzyme.Keywords
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