Open AccessMutator strains of Escherichia coli, mutD and dnaQ, with defective exonucleolytic editing by DNA polymerase III holoenzyme.
Author(s) -
Harrison Echols,
Chi Zen Lu,
Peter M. Burgers
Publication year - 1983
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.80.8.2189
Subject(s) - dna polymerase , biology , polymerase , dna polymerase ii , dna polymerase i , proofreading , dna replication , dna clamp , escherichia coli , mutant , genetics , microbiology and biotechnology , dna , gene , polymerase chain reaction , reverse transcriptase
The closely linked mutD and dnaQ mutations confer a vastly increased mutation rate on Escherichia 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, we have measured the 3' leads to 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 two assays: (i) decreased excision of a terminal mispaired base from a copolymer substrate and (ii) turnover of dTTP to dTMP during replication with a phage G4 DNA template. Thus, the mutD (dnaQ) gene product is likely to control the editing (proofreading) capacity of polymerase III holoenzyme.