PMID:17457612

Citation	Imai, M, Tago, Y, Ihara, M, Kawata, M and Yamamoto, K (2007) Role of the 5' --> 3' exonuclease and Klenow fragment of Escherichia coli DNA polymerase I in base mismatch repair. Mol. Genet. Genomics 278:211-20
Abstract	We have previously demonstrated that the Escherichia coli strain mutS DeltapolA had a higher rate of transition and minus frameshift mutations than mutS or DeltapolA strains. We argued that DNA polymerase I (PolI) corrects transition mismatches. PolI, encoded by the polA gene, possesses Klenow and 5' --> 3' exonuclease domains. In the present study, rates of mutation were found to be higher in Klenow-defective mutS strains and 5' --> 3' exonuclease-defective mutS strains than mutS or polA strains. The Klenow-defective or 5' --> 3' exonuclease-defective mutS strains showed a marked increase in transition mutations. Sites of transition mutations in mutS, Klenow-defective mutS and 5' --> 3' exonuclease-defective mutS strains are different. Thus, it is suggested that, in addition to mutS function, both the Klenow and 5' --> 3' 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 DeltapolA 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.
Links	PubMed Online version:10.1007/s00438-007-0239-8
Keywords	DNA Mismatch Repair; DNA Polymerase I/chemistry; DNA Polymerase I/metabolism; Escherichia coli/enzymology; Escherichia coli/genetics; Exonucleases/chemistry; Exonucleases/metabolism; MutS DNA Mismatch-Binding Protein/chemistry; MutS DNA Mismatch-Binding Protein/metabolism; Mutation/genetics
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
9CAUD:S5YPK3	Contributes to	GO:0008409: 5'-3' exonuclease activity	ECO:0000315:		F		HHpred search on protein sequence of Gene 149 of Troll led to the first result being Klenow fragment of DNA polymerase I with an e-value of 1e-128 and 100% probability. The other 100% probability results show that this gene is most likely a part of DNA polymerase I. A search for the function of the Klenow fragment led to the PubMed article with ID number listed as a Reference. The function of Klenow in E.coli, according to the Reference article, is to decrease transition mutations.	complete CACAO 10950

References

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