Role of the 5́ → 3́ exonuclease and Klenow fragment of Escherichia coli DNA polymerase I in base mismatch repair

Masaru Imai, Yu Ichiro Tago, Makoto Ihara, Masakado Kawata, Kazuo Yamamoto

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

We have previously demonstrated that the Escherichia coli strain mutS ΔpolA had a higher rate of transition and minus frameshift mutations than mutS or ΔpolA strains. We argued that DNA polymerase I (PolI) corrects transition mismatches. PolI, encoded by the polA gene, possesses Klenow and 5́ → 3́ exonuclease domains. In the present study, rates of mutation were found to be higher in Klenow-defective mutS strains and 5́ → 3́ exonuclease-defective mutS strains than mutS or polA strains. The Klenow-defective or 5́ → 3́ exonuclease-defective mutS strains showed a marked increase in transition mutations. Sites of transition mutations in mutS, Klenow-defective mutS and 5́ → 3́ exonuclease-defective mutS strains are different. Thus, it is suggested that, in addition to mutS function, both the Klenow and 5́ → 3́ exonuclease domains are involved in the decrease of transition mutations. Transition hot and warm spots in mutS + polA + strains were found to differ from those in mutS and mutS ΔpolA strains. We thus argue that all the spontaneous transition mutations in the wild-type strain do not arise from transition mismatches left unrepaired by the MutS system or MutS PolI system.

Original languageEnglish
Pages (from-to)211-220
Number of pages10
JournalMolecular Genetics and Genomics
Volume278
Issue number2
DOIs
Publication statusPublished - 2007 Aug

Keywords

  • 5́ → 3́ exonuclease
  • DNA polymerase I
  • Klenow domain
  • Spontaneous mutation
  • Transition mismatch repair

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics

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