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Feltes BC, Menck CFM. Current state of knowledge of human DNA polymerase eta protein structure and disease-causing mutations. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2022; 790:108436. [PMID: 35952573 DOI: 10.1016/j.mrrev.2022.108436] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 06/29/2022] [Accepted: 07/31/2022] [Indexed: 01/01/2023]
Abstract
POLη, encoded by the POLH gene, is a crucial protein for replicating damaged DNA and the most studied specialized translesion synthesis polymerases. Mutations in POLη are associated with cancer and the human syndrome xeroderma pigmentosum variant, which is characterized by extreme photosensitivity and an increased likelihood of developing skin cancers. The myriad of structural information about POLη is vast, covering dozens of different mutants, numerous crucial residues, domains, and posttranslational modifications that are essential for protein function within cells. Since POLη is key vital enzyme for cell survival, and mutations in this protein are related to aggressive diseases, understanding its structure is crucial for biomedical sciences, primarily due to its similarities with other Y-family polymerases and its potential as a targeted therapy-drug for tumors. This work provides an up-to-date review on structural aspects of the human POLη: from basic knowledge about critical residues and protein domains to its mutant variants, posttranslational modifications, and our current understanding of therapeutic molecules that target POLη. Thus, this review provides lessons about POLη's structure and gathers critical discussions and hypotheses that may contribute to understanding this protein's vital roles within the cells.
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Affiliation(s)
- Bruno César Feltes
- Department of Theoretical Informatics, Institute of Informatics, Department of Theoretical Informatics, Federal University of Rio Grande do Sul, Porto Alegre, RS Brazil; Department of Genetics, Institute of Bioscience, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil; Department of Biophysics, Institute of Bioscience, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
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2
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Comparative molecular dynamics studies of heterozygous open reading frames of DNA polymerase eta (η) in pathogenic yeast Candida albicans. Sci Rep 2017; 7:41087. [PMID: 28120914 PMCID: PMC5264235 DOI: 10.1038/srep41087] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 12/15/2016] [Indexed: 01/20/2023] Open
Abstract
Genomic instability in Candida albicans is believed to play a crucial role in fungal pathogenesis. DNA polymerases contribute significantly to stability of any genome. Although Candida Genome database predicts presence of S. cerevisiae DNA polymerase orthologs; functional and structural characterizations of Candida DNA polymerases are still unexplored. DNA polymerase eta (Polη) is unique as it promotes efficient bypass of cyclobutane pyrimidine dimers. Interestingly, C. albicans is heterozygous in carrying two Polη genes and the nucleotide substitutions were found only in the ORFs. As allelic differences often result in functional differences of the encoded proteins, comparative analyses of structural models and molecular dynamic simulations were performed to characterize these orthologs of DNA Polη. Overall structures of both the ORFs remain conserved except subtle differences in the palm and PAD domains. The complementation analysis showed that both the ORFs equally suppressed UV sensitivity of yeast rad30 deletion strain. Our study has predicted two novel molecular interactions, a highly conserved molecular tetrad of salt bridges and a series of π-π interactions spanning from thumb to PAD. This study suggests these ORFs as the homologues of yeast Polη, and due to its heterogeneity in C. albicans they may play a significant role in pathogenicity.
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3
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Ucisik MN, Hammes-Schiffer S. Comparative Molecular Dynamics Studies of Human DNA Polymerase η. J Chem Inf Model 2015; 55:2672-81. [PMID: 26562587 PMCID: PMC4696480 DOI: 10.1021/acs.jcim.5b00606] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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High-energy
ultraviolet radiation damages DNA through the formation
of cyclobutane pyrimidine dimers, which stall replication. When the
lesion is a thymine–thymine dimer (TTD), human DNA polymerase
η (Pol η) assists in resuming the replication process
by inserting nucleotides opposite the damaged site. We performed extensive
molecular dynamics (MD) simulations to investigate the structural
and dynamical effects of four different Pol η complexes with
or without a TTD and with either dATP or dGTP as the incoming base.
No major differences in the overall structures and equilibrium dynamics
were detected among the four systems, suggesting that the specificity
of this enzyme is due predominantly to differences in local interactions
in the binding regions. Analysis of the hydrogen-bonding interactions
between the enzyme and the DNA and dNTP provided molecular-level insights.
Specifically, the TTD was observed to engage in more hydrogen-bonding
interactions with the enzyme than its undamaged counterpart of two
normal thymines. The resulting greater rigidity and specific orientation
of the TTD are consistent with the experimental observation of higher
processivity and overall efficiency at TTD sites than at analogous
sites with two normal thymines. The similarities between the systems
containing dATP and dGTP are consistent with the experimental observation
of relatively low fidelity with respect to the incoming base. Moreover,
Q38 and R61, two strictly conserved amino acids across the Pol η
family, were found to exhibit persistent hydrogen-bonding interactions
with the TTD and cation-π interactions with the free base, respectively.
Thus, these simulations provide molecular level insights into the
basis for the selectivity and efficiency of this enzyme, as well as
the roles of the two most strictly conserved residues.
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Affiliation(s)
- Melek N Ucisik
- Department of Chemistry, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801-3364, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801-3364, United States
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4
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Site-directed Mutagenesis (Y52E) of POLH Affects Its Ability to Bypass Ultraviolet-induced DNA Lesions in HaCaT Cells. W INDIAN MED J 2014; 63:307-11. [PMID: 25429473 DOI: 10.7727/wimj.2014.063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 03/27/2014] [Indexed: 11/18/2022]
Abstract
DNA polymerase eta (Pol η) is one of several Y family trans-lesion synthesis (TLS) polymerases in humans and plays an important role in maintaining genome stability after ultraviolet (UV) irradiation, as it carries out error-free TLS at sites of UV-induced lesions. We performed site-directed mutagenesis of human polymerase η gene (Y52E), confirmed by sequencing, then cloned wild-type mutant and POLH genes into the eukaryotic vector pEGFP-N1. After transfecting wild-type and mutant plasmids into HaCaT keratinocytes, we tested for UV induced cis-syn cyclobutane pyrimidine dimer (CPDs) DNA lesions, and analysed cellular viability by MTT cell proliferation assay. The results showed that CPD levels decreased both with empty vector control (EVC), wild-type POLH, and Y52E-POLH over 48 hours post UV irradiation with 0.1 mW/cm2 UVB for 15 minutes (p = 0.025). The rate in CPD reduction of mutant POLH was less than in wild-type POLH. Cell viabilities of all three groups increased over 48 hours after UV irradiation, with the increased rate in the wild-type being higher than for mutant protein (p = 0.046). We conclude that Y52E POLH has reduced capacity to bypass UV induced DNA lesions in HaCaT cells.
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5
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Suarez SC, Beardslee RA, Toffton SM, McCulloch SD. Biochemical analysis of active site mutations of human polymerase η. Mutat Res 2013; 745-746:46-54. [PMID: 23499771 DOI: 10.1016/j.mrfmmm.2013.03.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 03/04/2013] [Accepted: 03/06/2013] [Indexed: 10/27/2022]
Abstract
DNA polymerase η (pol η) plays a critical role in suppressing mutations caused by the bypass of cis-syn cyclobutane pyrimidine dimers (CPD) that escape repair. There is evidence this is also the case for the oxidative lesion 7,8-dihydro-8-oxo-guanine (8-oxoG). Both of these lesions cause moderate to severe blockage of synthesis when encountered by replicative polymerases, while pol η displays little no to pausing during translesion synthesis. However, since lesion bypass does not remove damaged DNA from the genome and can possibly be accompanied by errors in synthesis during bypass, the process is often called 'damage tolerance' to delineate it from classical DNA repair pathways. The fidelity of lesion bypass is therefore of importance when determining how pol η suppresses mutations after DNA damage. As pol η has been implicated in numerous in vivo pathways other than lesion bypass, we wanted to better understand the molecular mechanisms involved in the relatively low-fidelity synthesis displayed by pol η. To that end, we have created a set of mutant pol η proteins each containing a single amino acid substitution in the active site and closely surrounding regions. We determined overall DNA synthesis ability as well as the efficiency and fidelity of bypass of thymine-thymine CPD (T-T CPD) and 8-oxoG containing DNA templates. Our results show that several amino acids are critical for normal polymerase function, with changes in overall activity and fidelity being observed. Of the mutants that retain polymerase activity, we demonstrate that amino acids Q38, Y52, and R61 play key roles in determining polymerase fidelity, with substation of alanine causing both increases and decreases in fidelity. Remarkably, the Q38A mutant displays increased fidelity during synthesis opposite 8-oxoG but decreased fidelity during synthesis opposite a T-T CPD.
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Affiliation(s)
- Samuel C Suarez
- Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, NC 27695, USA
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6
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Sherrer SM, Fiala KA, Fowler JD, Newmister SA, Pryor JM, Suo Z. Quantitative analysis of the efficiency and mutagenic spectra of abasic lesion bypass catalyzed by human Y-family DNA polymerases. Nucleic Acids Res 2010; 39:609-22. [PMID: 20846959 PMCID: PMC3025555 DOI: 10.1093/nar/gkq719] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Higher eukaryotes encode various Y-family DNA polymerases to perform global DNA lesion bypass. To provide complete mutation spectra for abasic lesion bypass, we employed short oligonucleotide sequencing assays to determine the sequences of abasic lesion bypass products synthesized by human Y-family DNA polymerases eta (hPolη), iota (hPolι) and kappa (hPolκ). The fourth human Y-family DNA polymerase, Rev1, failed to generate full-length lesion bypass products after 3 h. The results indicate that hPolι generates mutations with a frequency from 10 to 80% during each nucleotide incorporation event. In contrast, hPolη is the least error prone, generating the fewest mutations in the vicinity of the abasic lesion and inserting dAMP with a frequency of 67% opposite the abasic site. While the error frequency of hPolκ is intermediate to those of hPolη and hPolι, hPolκ has the highest potential to create frameshift mutations opposite the abasic site. Moreover, the time (t50bypass) required to bypass 50% of the abasic lesions encountered by hPolη, hPolι and hPolκ was 4.6, 112 and 1 823 s, respectively. These t50bypass values indicate that, among the enzymes, hPolη has the highest abasic lesion bypass efficiency. Together, our data suggest that hPolη is best suited to perform abasic lesion bypass in vivo.
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Affiliation(s)
- Shanen M Sherrer
- Department of Biochemistry, The Ohio State University, Columbus, OH 43210, USA
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7
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Cruet-Hennequart S, Gallagher K, Sokòl AM, Villalan S, Prendergast AM, Carty MP. DNA polymerase eta, a key protein in translesion synthesis in human cells. Subcell Biochem 2010; 50:189-209. [PMID: 20012583 DOI: 10.1007/978-90-481-3471-7_10] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Genomic DNA is constantly damaged by exposure to exogenous and endogenous agents. Bulky adducts such as UV-induced cyclobutane pyrimidine dimers (CPDs) in the template DNA present a barrier to DNA synthesis by the major eukaryotic replicative polymerases including DNA polymerase delta. Translesion synthesis (TLS) carried out by specialized DNA polymerases is an evolutionarily conserved mechanism of DNA damage tolerance. The Y family of DNA polymerases, including DNA polymerase eta (Pol eta), the subject of this chapter, play a key role in TLS. Mutations in the human POLH gene encoding Pol eta underlie the genetic disease xeroderma pigmentosum variant (XPV), characterized by sun sensitivity, elevated incidence of skin cancer, and at the cellular level, by delayed replication and hypermutability after UV-irradiation. Pol eta is a low fidelity enzyme when copying undamaged DNA, but can carry out error-free TLS at sites of UV-induced dithymine CPDs. The active site of Pol eta has an open conformation that can accommodate CPDs, as well as cisplatin-induced intrastrand DNA crosslinks. Pol eta is recruited to sites of replication arrest in a tightly regulated process through interaction with PCNA. Pol eta-deficient cells show strong activation of downstream DNA damage responses including ATR signaling, and accumulate strand breaks as a result of replication fork collapse. Thus, Pol eta plays an important role in preventing genome instability after UV- and cisplatin-induced DNA damage. Inhibition of DNA damage tolerance pathways in tumors might also represent an approach to potentiate the effects of DNA damaging agents such as cisplatin.
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Affiliation(s)
- Séverine Cruet-Hennequart
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland, Galway, Galway, Galway, Ireland
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A DinB variant reveals diverse physiological consequences of incomplete TLS extension by a Y-family DNA polymerase. Proc Natl Acad Sci U S A 2009; 106:21137-42. [PMID: 19948952 DOI: 10.1073/pnas.0907257106] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The only Y-family DNA polymerase conserved among all domains of life, DinB and its mammalian ortholog pol kappa, catalyzes proficient bypass of damaged DNA in translesion synthesis (TLS). Y-family DNA polymerases, including DinB, have been implicated in diverse biological phenomena ranging from adaptive mutagenesis in bacteria to several human cancers. Complete TLS requires dNTP insertion opposite a replication blocking lesion and subsequent extension with several dNTP additions. Here we report remarkably proficient TLS extension by DinB from Escherichia coli. We also describe a TLS DNA polymerase variant generated by mutation of an evolutionarily conserved tyrosine (Y79). This mutant DinB protein is capable of catalyzing dNTP insertion opposite a replication-blocking lesion, but cannot complete TLS, stalling three nucleotides after an N(2)-dG adduct. Strikingly, expression of this variant transforms a bacteriostatic DNA damaging agent into a bactericidal drug, resulting in profound toxicity even in a dinB(+) background. We find that this phenomenon is not exclusively due to a futile cycle of abortive TLS followed by exonucleolytic reversal. Rather, gene products with roles in cell death and metal homeostasis modulate the toxicity of DinB(Y79L) expression. Together, these results indicate that DinB is specialized to perform remarkably proficient insertion and extension on damaged DNA, and also expose unexpected connections between TLS and cell fate.
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Anderson HJ, Vonarx EJ, Pastushok L, Nakagawa M, Katafuchi A, Gruz P, Di Rubbo A, Grice DM, Osmond MJ, Sakamoto AN, Nohmi T, Xiao W, Kunz BA. Arabidopsis thaliana Y-family DNA polymerase eta catalyses translesion synthesis and interacts functionally with PCNA2. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 55:895-908. [PMID: 18494853 DOI: 10.1111/j.1365-313x.2008.03562.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Upon blockage of chromosomal replication by DNA lesions, Y-family polymerases interact with monoubiquitylated proliferating cell nuclear antigen (PCNA) to catalyse translesion synthesis (TLS) and restore replication fork progression. Here, we assessed the roles of Arabidopsis thaliana POLH, which encodes a homologue of Y-family polymerase eta (Poleta), PCNA1 and PCNA2 in TLS-mediated UV resistance. A T-DNA insertion in POLH sensitized the growth of roots and whole plants to UV radiation, indicating that AtPoleta contributes to UV resistance. POLH alone did not complement the UV sensitivity conferred by deletion of yeast RAD30, which encodes Poleta, although AtPoleta exhibited cyclobutane dimer bypass activity in vitro, and interacted with yeast PCNA, as well as with Arabidopsis PCNA1 and PCNA2. Co-expression of POLH and PCNA2, but not PCNA1, restored normal UV resistance and mutation kinetics in the rad30 mutant. A single residue difference at site 201, which lies adjacent to the residue (lysine 164) ubiquitylated in PCNA, appeared responsible for the inability of PCNA1 to function with AtPoleta in UV-treated yeast. PCNA-interacting protein boxes and an ubiquitin-binding motif in AtPoleta were found to be required for the restoration of UV resistance in the rad30 mutant by POLH and PCNA2. These observations indicate that AtPoleta can catalyse TLS past UV-induced DNA damage, and links the biological activity of AtPoleta in UV-irradiated cells to PCNA2 and PCNA- and ubiquitin-binding motifs in AtPoleta.
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Affiliation(s)
- Heather J Anderson
- School of Life and Environmental Sciences, Deakin University, Geelong, Vic. 3217, Australia
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10
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Howell CA, Kondratick CM, Washington MT. Substitution of a residue contacting the triphosphate moiety of the incoming nucleotide increases the fidelity of yeast DNA polymerase zeta. Nucleic Acids Res 2008; 36:1731-40. [PMID: 18263611 PMCID: PMC2275142 DOI: 10.1093/nar/gkn023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
DNA polymerase zeta (pol zeta), which is required for DNA damage-induced mutagenesis, functions in the error-prone replication of a wide range of DNA lesions. During this process, pol zeta extends from nucleotides incorporated opposite template lesions by other polymerases. Unlike classical polymerases, pol zeta efficiently extends from primer-terminal base pairs containing mismatches or lesions, and it synthesizes DNA with moderate fidelity. Here we describe genetic and biochemical studies of three yeast pol zeta mutant proteins containing substitutions of highly conserved amino acid residues that contact the triphosphate moiety of the incoming nucleotide. The R1057A and K1086A proteins do not complement the rev3Delta mutation, and these proteins have significantly reduced polymerase activity relative to the wild-type protein. In contrast, the K1061A protein partially complements the rev3Delta mutation and has nearly normal polymerase activity. Interestingly, the K1061A protein has increased fidelity relative to wild-type pol zeta and is somewhat less efficient at extending from mismatched primer-terminal base pairs. These findings have important implications both for the evolutionary divergence of pol zeta from classical polymerases and for the mechanism by which this enzyme accommodates distortions in the DNA caused by mismatches and lesions.
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Affiliation(s)
- Craig A Howell
- Department of Biochemistry, University of Iowa College of Medicine, Iowa City, IA 52242-1109, USA
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11
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Jarosz DF, Beuning PJ, Cohen SE, Walker GC. Y-family DNA polymerases in Escherichia coli. Trends Microbiol 2007; 15:70-7. [PMID: 17207624 DOI: 10.1016/j.tim.2006.12.004] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2006] [Revised: 11/13/2006] [Accepted: 12/14/2006] [Indexed: 10/23/2022]
Abstract
The observation that mutations in the Escherichia coli genes umuC+ and umuD+ abolish mutagenesis induced by UV light strongly supported the counterintuitive notion that such mutagenesis is an active rather than passive process. Genetic and biochemical studies have revealed that umuC+ and its homolog dinB+ encode novel DNA polymerases with the ability to catalyze synthesis past DNA lesions that otherwise stall replication--a process termed translesion synthesis (TLS). Similar polymerases have been identified in nearly all organisms, constituting a new enzyme superfamily. Although typically viewed as unfaithful copiers of DNA, recent studies suggest that certain TLS polymerases can perform proficient and moderately accurate bypass of particular types of DNA damage. Moreover, various cellular factors can modulate their activity and mutagenic potential.
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Affiliation(s)
- Daniel F Jarosz
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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12
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Showalter AK, Lamarche BJ, Bakhtina M, Su MI, Tang KH, Tsai MD. Mechanistic comparison of high-fidelity and error-prone DNA polymerases and ligases involved in DNA repair. Chem Rev 2006; 106:340-60. [PMID: 16464009 DOI: 10.1021/cr040487k] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Vaisman A, Ling H, Woodgate R, Yang W. Fidelity of Dpo4: effect of metal ions, nucleotide selection and pyrophosphorolysis. EMBO J 2005; 24:2957-67. [PMID: 16107880 PMCID: PMC1201362 DOI: 10.1038/sj.emboj.7600786] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2005] [Accepted: 07/22/2005] [Indexed: 11/09/2022] Open
Abstract
We report the crystal structures of a translesion DNA polymerase, Dpo4, complexed with a matched or mismatched incoming nucleotide and with a pyrophosphate product after misincorporation. These structures suggest two mechanisms by which Dpo4 may reject a wrong incoming nucleotide with its preformed and open active site. First, a mismatched replicating base pair leads to poor base stacking and alignment of the metal ions and as a consequence, inhibits incorporation. By replacing Mg2+ with Mn2+, which has a relaxed coordination requirement and tolerates misalignment, the catalytic efficiency of misincorporation increases dramatically. Mn2+ also enhances translesion synthesis by Dpo4. Subtle conformational changes that lead to the proper metal ion coordination may, therefore, be a key step in catalysis. Second, the slow release of pyrophosphate may increase the fidelity of Dpo4 by stalling mispaired primer extension and promoting pyrophosphorolysis that reverses the polymerization reaction. Indeed, Dpo4 has robust pyrophosphorolysis activity and degrades the primer strand in the presence of pyrophosphate. The correct incoming nucleotide allows DNA synthesis to overcome pyrophosphorolysis, but an incorrect incoming nucleotide does not.
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Affiliation(s)
- Alexandra Vaisman
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Hong Ling
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Roger Woodgate
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Wei Yang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA. Tel.: +1 301 402 4645; Fax: +1 301 496 0201; E-mail:
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Niimi A, Limsirichaikul S, Yoshida S, Iwai S, Masutani C, Hanaoka F, Kool ET, Nishiyama Y, Suzuki M. Palm mutants in DNA polymerases alpha and eta alter DNA replication fidelity and translesion activity. Mol Cell Biol 2004; 24:2734-46. [PMID: 15024063 PMCID: PMC371111 DOI: 10.1128/mcb.24.7.2734-2746.2004] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We isolated active mutants in Saccharomyces cerevisiae DNA polymerase alpha that were associated with a defect in error discrimination. Among them, L868F DNA polymerase alpha has a spontaneous error frequency of 3 in 100 nucleotides and 570-fold lower replication fidelity than wild-type (WT) polymerase alpha. In vivo, mutant DNA polymerases confer a mutator phenotype and are synergistic with msh2 or msh6, suggesting that DNA polymerase alpha-dependent replication errors are recognized and repaired by mismatch repair. In vitro, L868F DNA polymerase alpha catalyzes efficient bypass of a cis-syn cyclobutane pyrimidine dimer, extending the 3' T 26000-fold more efficiently than the WT. Phe34 is equivalent to residue Leu868 in translesion DNA polymerase eta, and the F34L mutant of S. cerevisiae DNA polymerase eta has reduced translesion DNA synthesis activity in vitro. These data suggest that high-fidelity DNA synthesis by DNA polymerase alpha is required for genomic stability in yeast. The data also suggest that the phenylalanine and leucine residues in translesion and replicative DNA polymerases, respectively, might have played a role in the functional evolution of these enzyme classes.
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Affiliation(s)
- Atsuko Niimi
- Division of Molecular Carcinogenesis, Center for Neural Disease and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
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Collins CH, Yokobayashi Y, Umeno D, Arnold FH. Engineering proteins that bind, move, make and break DNA. Curr Opin Biotechnol 2003; 14:371-8. [PMID: 12943845 DOI: 10.1016/s0958-1669(03)00091-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Recent protein engineering efforts have generated artificial transcription factors that bind new target DNA sequences and enzymes that modify DNA at new target sites. Zinc-finger-based transcription factors are favored targets for design; important technological advances in their construction and numerous biotechnological applications have been reported. Other notable advances include the generation of endonucleases and recombinases with altered specificities, made by innovative combinatorial and evolutionary protein engineering strategies. An unexpectedly high tolerance to mutation in the active sites of DNA polymerases is being exploited to engineer polymerases to incorporate artificial nucleotides or to display other, nonnatural activities.
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Affiliation(s)
- Cynthia H Collins
- Biochemistry and Molecular Biophysics, California Institute of Technology, mail code 210-41, Pasadena, California 91125, USA
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