The Roles of Klenow Processing and Flap Processing Activities of DNA Polymerase I in Chromosome Instability in Escherichia coli K12 Strains

Corresponding author: Kazuo Yamamoto, Graduate School of Life Sciences, Tohoku University, Sendai 9808578, Japan., yamamot{at}mail.cc.tohoku.ac.jp (E-mail)

Communicating editor: R. MAURER

The sequences of spontaneous mutations occurring in the endogenous tonB gene of Escherichia coli in the polA and polA107 mutant strains were compared. Five categories of mutations were found: (1) deletions, (2) minus frameshifts, (3) plus frameshifts, (4) duplications, and (5) other mutations. The polA strain, which is deficient in both Klenow domain and 5' 3' exonuclease domain of DNA polymerase I, shows a marked increase in categories 1–4. The polA107 strain, which is deficient in the 5' 3' exonuclease domain but proficient in the Klenow domain, shows marked increases in categories 3 and 4 but not in 1 or 2. Previously, we reported that the polA1 strain, which is known to be deficient in the Klenow domain but proficient in the 5' 3' exonuclease domain, shows increases in categories 1 and 2 but not in 3 or 4. The 5' 3' exonuclease domain of DNA polymerase I is a homolog of the mammalian FEN1 and the yeast RAD27 flap nucleases. We therefore proposed the model that the Klenow domain can process deletion and minus frameshift mismatch in the nascent DNA and that flap nuclease can process plus frameshift and duplication mismatch in the nascent DNA.

This article has been cited by other articles:

				S. Fukushima, M. Itaya, H. Kato, N. Ogasawara, and H. Yoshikawa Reassessment of the In Vivo Functions of DNA Polymerase I and RNase H in Bacterial Cell Growth J. Bacteriol., December 1, 2007; 189(23): 8575 - 8583. [Abstract] [Full Text] [PDF]

				T. Shibata, T. Hishida, Y. Kubota, Y.-W. Han, H. Iwasaki, and H. Shinagawa Functional overlap between RecA and MgsA (RarA) in the rescue of stalled replication forks in Escherichia coli Genes Cells, March 1, 2005; 10(3): 181 - 191. [Abstract] [Full Text] [PDF]

				C. D. Bayliss, W. A. Sweetman, and E. R. Moxon Destabilization of tetranucleotide repeats in Haemophilus influenzae mutants lacking RnaseHI or the Klenow domain of PolI Nucleic Acids Res., January 14, 2005; 33(1): 400 - 408. [Abstract] [Full Text] [PDF]

				K. Mashimo, M. Kawata, and K. Yamamoto Roles of the RecJ and RecQ proteins in spontaneous formation of deletion mutations in the Escherichia coli K12 endogenous tonB gene Mutagenesis, July 1, 2003; 18(4): 355 - 363. [Abstract] [Full Text] [PDF]

				Y. Liu and R. A. Bambara Analysis of Human Flap Endonuclease 1 Mutants Reveals a Mechanism to Prevent Triplet Repeat Expansion J. Biol. Chem., April 11, 2003; 278(16): 13728 - 13739. [Abstract] [Full Text] [PDF]