DNA Polymerase ε Catalytic Domains Are Dispensable for DNA Replication, DNA Repair, and Cell Viability

Kesti, Tapio; Flick, Karin; Keränen, Sirkka; Syväoja, Juhani E.; Wittenberg, Curt

doi:10.1016/s1097-2765(00)80361-5

Cited by 256 publications

(273 citation statements)

References 30 publications

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“…Recently, we have shown that the DNA polymerase and exonuclease domains of Pol ⑀ are dispensable for cell viability in fission yeast (Feng and D'Urso, 2001). Similar observations have been made for the evolutionarily distant yeast, Saccharomyces cerevisiae (Kesti et al, 1999;Dua et al, 2000). These findings have raised important questions regarding the essential role of this replicative enzyme in DNA synthesis.…”

Section: Introductionsupporting

confidence: 66%

Schizosacchromyces pombeDpb2 Binds to Origin DNA Early in S Phase and Is Required for Chromosomal DNA Replication

Feng

Rodriguez-Menocal

Tolun

et al. 2003

MBoC

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Genetic evidence suggests that DNA polymerase epsilon (Pol ⑀) has a noncatalytic essential role during the early stages of DNA replication initiation. Herein, we report the cloning and characterization of the second largest subunit of Pol ⑀ in fission yeast, called Dpb2. We demonstrate that Dpb2 is essential for cell viability and that a temperature-sensitive mutant of dpb2 arrests with a 1C DNA content, suggesting that Dpb2 is required for initiation of DNA replication. Using a chromatin immunoprecipitation assay, we show that Dpb2, binds preferentially to origin DNA at the beginning of S phase. We also show that the C terminus of Pol ⑀ associates with origin DNA at the same time as Dpb2. We conclude that Dpb2 is an essential protein required for an early step in DNA replication. We propose that the primary function of Dpb2 is to facilitate assembly of the replicative complex at the start of S phase. These conclusions are based on the novel cell cycle arrest phenotype of the dpb2 mutant, on the previously uncharacterized binding of Dpb2 to replication origins, and on the observation that the essential function of Pol ⑀ is not dependent on its DNA synthesis activity. INTRODUCTIONChromosomal DNA replication in eukaryotic cells requires the activity of at least three DNA polymerases: ␣, ␦, and ⑀ (Waga and Stillman, 1998;Hubscher et al., 2000;Bell and Dutta, 2002). Pol ␣ is tightly associated with a primase activity capable of de novo DNA synthesis, suggesting that this enzyme is responsible for initiation of both leading and lagging strands (Waga and Stillman, 1998). Pol ␣/primase can only synthesize short primers that must then be extended by the activity of a processive DNA polymerase(s). Biochemical analysis of simian virus 40 (SV40) DNA replication, which has been extensively used as a model system for eukaryotic DNA replication, has shown that primers synthesized by Pol ␣ can be extended by Pol ␦ and that these two polymerases are sufficient for SV40 replication in vitro (Weinberg et al., 1990;Waga et al., 1994).A second processive DNA polymerase, Pol ⑀, is required for cell viability and chromosomal DNA replication in both fission (D'Urso and Nurse, 1997) and budding yeast (Morrison et al., 1990;Araki et al., 1992;Budd and Campbell, 1993). Pol ⑀ has also been implicated in both DNA repair (Jessberger et al., 1993;Wang et al., 1993;Shivji et al., 1995;Holmes, 1999) and cell cycle checkpoint control in eukaryotic cells (Navas et al., 1995). Recently, we have shown that the DNA polymerase and exonuclease domains of Pol ⑀ are dispensable for cell viability in fission yeast (Feng and D'Urso, 2001). Similar observations have been made for the evolutionarily distant yeast, Saccharomyces cerevisiae (Kesti et al., 1999;Dua et al., 2000). These findings have raised important questions regarding the essential role of this replicative enzyme in DNA synthesis. Although the N-terminal catalytic domains are dispensable, the C-terminal half of the enzyme is essential for cell viability and chromosomal replication in fission...

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Section: Introductionsupporting

confidence: 66%

Schizosacchromyces pombeDpb2 Binds to Origin DNA Early in S Phase and Is Required for Chromosomal DNA Replication

Feng

Rodriguez-Menocal

Tolun

et al. 2003

MBoC

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“…The polymerase activity of E. coli DNA polymerase I is not essential, but the unique 5Ј-3Ј exonuclease activity is essential, being required to remove the RNA from the ends of Okazaki fragments (63). Eukaryotic Pol ⑀ is essential, but one report on this subject indicates that the region encoding the polymerase activity is dispensable (64). Despite these arguments, DnaE could still be the lagging strand polymerase and thus reflect major differences and requirements between Gram-positive and Gram-negative cells.…”

Section: Does Dnae Function At the Replicationmentioning

confidence: 99%

The Essential C Family DnaE Polymerase Is Error-prone and Efficient at Lesion Bypass

Bruck

Goodman

O'Donnell

2003

Journal of Biological Chemistry

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DnaE-type DNA polymerases belong to the C family of DNA polymerases and are responsible for chromosomal replication in prokaryotes. Like most closely related Gram-positive cells, Streptococcus pyogenes has two DnaE homologs Pol C and DnaE; both are essential to cell viability. Pol C is an established replicative polymerase, and DnaE has been proposed to serve a replicative role. In this report, we characterize S. pyogenes DnaE polymerase and find that it is highly error-prone. DnaE can bypass coding and noncoding lesions with high efficiency. Error-prone extension is accomplished by either of two pathways, template-primer misalignment or direct primer extension. The bypass of abasic sites is accomplished mainly through "dNTP-stabilized" misalignment of template, thereby generating (؊1) deletions in the newly synthesized strand. This mechanism may be similar to the dNTP-stabilized misalignment mechanism used by the Y family of DNA polymerases and is the first example of lesion bypass and error-prone synthesis catalyzed by a C family polymerase. Thus, DnaE may function in an error-prone capacity that may be essential in Gram-positive cells but not Gram-negative cells, suggesting a fundamental difference in DNA metabolism between these two classes of bacteria.

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“…As pol epsilon possesses a relatively high processivity, it is now widely accepted that in eukaryotic cells pol delta and epsilon are responsible for the lagging-and leading-strand synthesis, respectively, 19 although pol epsilon has been demonstrated not to be essential in yeast. 20 The catalytic subunits of pol delta and epsilon, for example, p125 [21][22][23] and p261 24,25 in mammals, include the 3¢ exonuclease, that is, proofreading, domains. Indeed, in the yeast mutants in which pol delta or epsilon proofreading is selectively inactivated, the mutations rates are 10-100 times higher than the wild-type strains.…”

Section: Introductionmentioning

confidence: 99%

Concurrent genetic alterations in DNA polymerase proofreading and mismatch repair in human colorectal cancer

et al. 2010

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Genomic sequences encoding the 3¢ exonuclease (proofreading) domains of both replicative DNA polymerases, pol delta and pol epsilon, were explored simultaneously in human colorectal carcinomas including six established cell lines. Three unequivocal sequence alterations, including one previously reported, were found, and all these were considered as dysfunctional mutations in light of the local amino-acid sequences. In particular, the F367S mutation found in the POLE gene encoding the pol epsilon catalytic subunit, which includes the proofreading domain, is the first found in human diseases. Surprisingly, the tumours carrying these proofreading domain mutations were all defective in DNA mismatch repair (MMR). In addition to the two cell lines with acknowledged MMR gene mutations, the third tumour was also demonstrated to harbour a distinct mutation in MLH1, and indeed exhibited a microsatellite-unstable phenotype. These findings suggest that, in concert with MMR deficiency, defective polymerase proofreading may also contribute to the mutator phenotype observed in human colorectal cancer. Our observations may suggest previously unrecognised complexities in the molecular abnormalities underlying the mutator phenotype in human neoplasms. Keywords: polymerase delta; polymerase epsilon; proofreading domain; colorectal cancer INTRODUCTION Mutation rates on the genome are invariably regulated and typically suppressed to an extremely low level, such as 10 À10 per base replicated, in the organisms. 1 The high fidelity of DNA replication is achieved by several molecular mechanisms. The frequency of erroneous nucleotide incorporation is indeed extremely low compared with that expected from base-pairing energetics, and the vast reduction of the misincorporation frequency involves three steps of molecular events: (a) correct incorporation of complementary nucleotides by DNA polymerases, (b) removal of the newly added nucleotides, particularly incorrectly paired nucleotides, by the 3¢ exonuclease activities associated with the DNA polymerases (proofreading) and (c) postreplicative scanning of mispaired bases by DNA mismatch repair (MMR). 2,3 Various Escherichia coli (E. coli) mutator strains have been used to study these molecular mechanisms by which organisms maintain their mutation rates at very low levels. The dnaQ + (mutD + ) gene of E. coli encodes the epsilon subunit of the DNA polymerase III holoenzyme that is involved in 3¢ exonuclease proofreading activity, 4 and, therefore, the mutation frequencies in the dnaQ mutators are sometimes 1000-10 000 times higher than the wild-type levels. 4,5 In E. coli, MMR is chiefly directed by the proteins encoded by the three genes: mutS + , mutL + and mutH + . 6 The mutS or mutL mutators exhibit an approximately 100 times increase in the mutation frequency. 7 Thus, polymerase proofreading and MMR are the two major

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DNA Polymerase ε Catalytic Domains Are Dispensable for DNA Replication, DNA Repair, and Cell Viability

Cited by 256 publications

References 30 publications

Schizosacchromyces pombeDpb2 Binds to Origin DNA Early in S Phase and Is Required for Chromosomal DNA Replication

Schizosacchromyces pombeDpb2 Binds to Origin DNA Early in S Phase and Is Required for Chromosomal DNA Replication

The Essential C Family DnaE Polymerase Is Error-prone and Efficient at Lesion Bypass

Concurrent genetic alterations in DNA polymerase proofreading and mismatch repair in human colorectal cancer

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