1
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Yuan Z, Georgescu R, Yao NY, Yurieva O, O'Donnell ME, Li H. Mechanism of PCNA loading by Ctf18-RFC for leading-strand DNA synthesis. Science 2024; 385:eadk5901. [PMID: 39088616 DOI: 10.1126/science.adk5901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 02/10/2024] [Accepted: 05/31/2024] [Indexed: 08/03/2024]
Abstract
The proliferating cell nuclear antigen (PCNA) clamp encircles DNA to hold DNA polymerases (Pols) to DNA for processivity. The Ctf18-RFC PCNA loader, a replication factor C (RFC) variant, is specific to the leading-strand Pol (Polε). We reveal here the underlying mechanism of Ctf18-RFC specificity to Polε using cryo-electron microscopy and biochemical studies. We found that both Ctf18-RFC and Polε contain specific structural features that direct PCNA loading onto DNA. Unlike other clamp loaders, Ctf18-RFC has a disordered ATPase associated with a diverse cellular activities (AAA+) motor that requires Polε to bind and stabilize it for efficient PCNA loading. In addition, Ctf18-RFC can pry prebound Polε off of DNA, then load PCNA onto DNA and transfer the PCNA-DNA back to Polε. These elements in both Ctf18-RFC and Polε provide specificity in loading PCNA onto DNA for Polε.
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Affiliation(s)
- Zuanning Yuan
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA
| | - Roxana Georgescu
- DNA Replication Laboratory, The Rockefeller University, New York, NY, USA
- Howard Hughes Medical Institute, New York, NY, USA
| | - Nina Y Yao
- DNA Replication Laboratory, The Rockefeller University, New York, NY, USA
| | - Olga Yurieva
- DNA Replication Laboratory, The Rockefeller University, New York, NY, USA
- Howard Hughes Medical Institute, New York, NY, USA
| | - Michael E O'Donnell
- DNA Replication Laboratory, The Rockefeller University, New York, NY, USA
- Howard Hughes Medical Institute, New York, NY, USA
| | - Huilin Li
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA
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2
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Mullins EA, Salay LE, Durie CL, Bradley NP, Jackman JE, Ohi MD, Chazin WJ, Eichman BF. A mechanistic model of primer synthesis from catalytic structures of DNA polymerase α-primase. Nat Struct Mol Biol 2024; 31:777-790. [PMID: 38491139 PMCID: PMC11102853 DOI: 10.1038/s41594-024-01227-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Accepted: 01/12/2024] [Indexed: 03/18/2024]
Abstract
The mechanism by which polymerase α-primase (polα-primase) synthesizes chimeric RNA-DNA primers of defined length and composition, necessary for replication fidelity and genome stability, is unknown. Here, we report cryo-EM structures of Xenopus laevis polα-primase in complex with primed templates representing various stages of DNA synthesis. Our data show how interaction of the primase regulatory subunit with the primer 5' end facilitates handoff of the primer to polα and increases polα processivity, thereby regulating both RNA and DNA composition. The structures detail how flexibility within the heterotetramer enables synthesis across two active sites and provide evidence that termination of DNA synthesis is facilitated by reduction of polα and primase affinities for the varied conformations along the chimeric primer-template duplex. Together, these findings elucidate a critical catalytic step in replication initiation and provide a comprehensive model for primer synthesis by polα-primase.
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Affiliation(s)
- Elwood A Mullins
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Lauren E Salay
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Clarissa L Durie
- Department of Cell and Developmental Biology, University of Michigan School of Medicine, Ann Arbor, MI, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Biochemistry, University of Missouri, Columbia, MO, USA
| | - Noah P Bradley
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Jane E Jackman
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA
- Center for RNA Biology, The Ohio State University, Columbus, OH, USA
| | - Melanie D Ohi
- Department of Cell and Developmental Biology, University of Michigan School of Medicine, Ann Arbor, MI, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Walter J Chazin
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA.
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA.
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA.
| | - Brandt F Eichman
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA.
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA.
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3
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Shaw AE, Whitted JE, Mihelich MN, Reitman HJ, Timmerman AJ, Schauer GD. Revised Mechanism of Hydroxyurea Induced Cell Cycle Arrest and an Improved Alternative. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.02.583010. [PMID: 38496404 PMCID: PMC10942336 DOI: 10.1101/2024.03.02.583010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Replication stress describes various types of endogenous and exogenous challenges to DNA replication in S-phase. Stress during this critical process results in helicase-polymerase decoupling at replication forks, triggering the S-phase checkpoint, which orchestrates global replication fork stalling and delayed entry into G2. The replication stressor most often used to induce the checkpoint response is hydroxyurea (HU), a chemotherapeutic agent. The primary mechanism of S-phase checkpoint activation by HU has thus far been considered to be a reduction of dNTP synthesis by inhibition of ribonucleotide reductase (RNR), leading to helicase-polymerase decoupling and subsequent activation of the checkpoint, mediated by the replisome associated effector kinase Mrc1. In contrast, we observe that HU causes cell cycle arrest in budding yeast independent of both the Mrc1-mediated replication checkpoint response and the Psk1-Mrc1 oxidative signaling pathway. We demonstrate a direct relationship between HU incubation and reactive oxygen species (ROS) production in yeast nuclei. We further observe that ROS strongly inhibits the in vitro polymerase activity of replicative polymerases (Pols), Pol α, Pol δ, and Pol ε, causing polymerase complex dissociation and subsequent loss of DNA substrate binding, likely through oxidation of their integral iron sulfur Fe-S clusters. Finally, we present "RNR-deg," a genetically engineered alternative to HU in yeast with greatly increased specificity of RNR inhibition, allowing researchers to achieve fast, nontoxic, and more readily reversible checkpoint activation compared to HU, avoiding harmful ROS generation and associated downstream cellular effects that may confound interpretation of results.
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Affiliation(s)
- Alisa E Shaw
- Department of Biochemistry and Molecular Biology, Colorado State University, CO, USA
| | - Jackson E Whitted
- Department of Biochemistry and Molecular Biology, Colorado State University, CO, USA
| | - Mattias N Mihelich
- Department of Biochemistry and Molecular Biology, Colorado State University, CO, USA
| | - Hannah J Reitman
- Department of Biochemistry and Molecular Biology, Colorado State University, CO, USA
| | - Adam J Timmerman
- Department of Biochemistry and Molecular Biology, Colorado State University, CO, USA
| | - Grant D Schauer
- Department of Biochemistry and Molecular Biology, Colorado State University, CO, USA
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4
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Shah SM, Demidova EV, Ringenbach S, Faezov B, Andrake M, Gandhi A, Mur P, Viana-Errasti J, Xiu J, Swensen J, Valle L, Dunbrack RL, Hall MJ, Arora S. Exploring Co-occurring POLE Exonuclease and Non-exonuclease Domain Mutations and Their Impact on Tumor Mutagenicity. CANCER RESEARCH COMMUNICATIONS 2024; 4:213-225. [PMID: 38282550 PMCID: PMC10812383 DOI: 10.1158/2767-9764.crc-23-0312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 10/05/2023] [Accepted: 01/02/2024] [Indexed: 01/13/2024]
Abstract
POLE driver mutations in the exonuclease domain (ExoD driver) are prevalent in several cancers, including colorectal cancer and endometrial cancer, leading to dramatically ultra-high tumor mutation burden (TMB). To understand whether POLE mutations that are not classified as drivers (POLE Variant) contribute to mutagenesis, we assessed TMB in 447 POLE-mutated colorectal cancers, endometrial cancers, and ovarian cancers classified as TMB-high ≥10 mutations/Mb (mut/Mb) or TMB-low <10 mut/Mb. TMB was significantly highest in tumors with "POLE ExoD driver plus POLE Variant" (colorectal cancer and endometrial cancer, P < 0.001; ovarian cancer, P < 0.05). TMB increased with additional POLE variants (P < 0.001), but plateaued at 2, suggesting an association between the presence of these variants and TMB. Integrated analysis of AlphaFold2 POLE models and quantitative stability estimates predicted the impact of multiple POLE variants on POLE functionality. The prevalence of immunogenic neoepitopes was notably higher in the "POLE ExoD driver plus POLE Variant" tumors. Overall, this study reveals a novel correlation between POLE variants in POLE ExoD-driven tumors, and ultra-high TMB. Currently, only select pathogenic ExoD mutations with a reliable association with ultra-high TMB inform clinical practice. Thus, these findings are hypothesis-generating, require functional validation, and could potentially inform tumor classification, treatment responses, and clinical outcomes. SIGNIFICANCE Somatic POLE ExoD driver mutations cause proofreading deficiency that induces high TMB. This study suggests a novel modifier role for POLE variants in POLE ExoD-driven tumors, associated with ultra-high TMB. These data, in addition to future functional studies, may inform tumor classification, therapeutic response, and patient outcomes.
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Affiliation(s)
- Shreya M. Shah
- Cancer Prevention and Control Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
- Science Scholars Program, Temple University, Philadelphia, Pennsylvania
| | - Elena V. Demidova
- Cancer Prevention and Control Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation
| | - Salena Ringenbach
- Cancer Prevention and Control Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
- Lewis Katz School of Medicine, Temple University, Bethlehem, Pennsylvania
| | - Bulat Faezov
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation
- Program in Cancer Signaling and Microenvironment, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Mark Andrake
- Program in Cancer Signaling and Microenvironment, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Arjun Gandhi
- Cancer Prevention and Control Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
- University College Dublin School of Medicine and Medical Science, Dublin, Ireland
| | - Pilar Mur
- Hereditary Cancer Program, Catalan Institute of Oncology, IDIBELL, Hospitalet de Llobregat, Barcelona, Spain
| | - Julen Viana-Errasti
- Hereditary Cancer Program, Catalan Institute of Oncology, IDIBELL, Hospitalet de Llobregat, Barcelona, Spain
| | | | | | - Laura Valle
- Hereditary Cancer Program, Catalan Institute of Oncology, IDIBELL, Hospitalet de Llobregat, Barcelona, Spain
| | - Roland L. Dunbrack
- Program in Cancer Signaling and Microenvironment, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Michael J. Hall
- Cancer Prevention and Control Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
- Department of Clinical Genetics, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Sanjeevani Arora
- Cancer Prevention and Control Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
- Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania
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5
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Ostroverkhova D, Tyryshkin K, Beach AK, Moore EA, Masoudi-Sobhanzadeh Y, Barbari SR, Rogozin IB, Shaitan KV, Panchenko AR, Shcherbakova PV. DNA polymerase ε and δ variants drive mutagenesis in polypurine tracts in human tumors. Cell Rep 2024; 43:113655. [PMID: 38219146 PMCID: PMC10830898 DOI: 10.1016/j.celrep.2023.113655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 11/07/2023] [Accepted: 12/19/2023] [Indexed: 01/16/2024] Open
Abstract
Alterations in the exonuclease domain of DNA polymerase ε cause ultramutated cancers. These cancers accumulate AGA>ATA transversions; however, their genomic features beyond the trinucleotide motifs are obscure. We analyze the extended DNA context of ultramutation using whole-exome sequencing data from 524 endometrial and 395 colorectal tumors. We find that G>T transversions in POLE-mutant tumors predominantly affect sequences containing at least six consecutive purines, with a striking preference for certain positions within polypurine tracts. Using this signature, we develop a machine-learning classifier to identify tumors with hitherto unknown POLE drivers and validate two drivers, POLE-E978G and POLE-S461L, by functional assays in yeast. Unlike other pathogenic variants, the E978G substitution affects the polymerase domain of Pol ε. We further show that tumors with POLD1 drivers share the extended signature of POLE ultramutation. These findings expand the understanding of ultramutation mechanisms and highlight peculiar mutagenic properties of polypurine tracts in the human genome.
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Affiliation(s)
- Daria Ostroverkhova
- Department of Pathology and Molecular Medicine, School of Medicine, Queen's University, Kingston, ON, Canada
| | - Kathrin Tyryshkin
- Department of Pathology and Molecular Medicine, School of Medicine, Queen's University, Kingston, ON, Canada
| | - Annette K Beach
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA
| | - Elizabeth A Moore
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA
| | - Yosef Masoudi-Sobhanzadeh
- Department of Pathology and Molecular Medicine, School of Medicine, Queen's University, Kingston, ON, Canada
| | - Stephanie R Barbari
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA
| | - Igor B Rogozin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | | | - Anna R Panchenko
- Department of Pathology and Molecular Medicine, School of Medicine, Queen's University, Kingston, ON, Canada.
| | - Polina V Shcherbakova
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA.
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6
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Selves J, de Castro E Gloria H, Brunac AC, Saffi J, Guimbaud R, Brousset P, Hoffmann JS. Exploring the basis of heterogeneity of cancer aggressiveness among the mutated POLE variants. Life Sci Alliance 2024; 7:e202302290. [PMID: 37891003 PMCID: PMC10610022 DOI: 10.26508/lsa.202302290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 10/04/2023] [Accepted: 10/18/2023] [Indexed: 10/29/2023] Open
Abstract
Germline pathogenic variants in the exonuclease domain of the replicative DNA polymerase Pol ε encoded by the POLE gene, predispose essentially to colorectal and endometrial tumors by inducing an ultramutator phenotype. It is still unclear whether all the POLE alterations influence similar strength tumorigenesis, immune microenvironment, and treatment response. In this review, we summarize the current understanding of the mechanisms and consequences of POLE mutations in human malignancies; we highlight the heterogeneity of mutation rate and cancer aggressiveness among POLE variants, propose some mechanistic basis underlining such heterogeneity, and discuss novel considerations for the choice and efficacy of therapies of POLE tumors.
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Affiliation(s)
- Janick Selves
- Department of Pathology, Institut Universitaire du Cancer-Oncopole de Toulouse; Centre Hospitalier Universitaire (CHU), Toulouse, France
- Université Fédérale Toulouse Midi-Pyrénées, Université Toulouse III Paul Sabatier, INSERM, CRCT, Toulouse, France
| | - Helena de Castro E Gloria
- Laboratory of Genetic Toxicology, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil
| | - Anne-Cécile Brunac
- Department of Pathology, Institut Universitaire du Cancer-Oncopole de Toulouse; Centre Hospitalier Universitaire (CHU), Toulouse, France
| | - Jenifer Saffi
- Laboratory of Genetic Toxicology, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil
| | - Rosine Guimbaud
- Université Fédérale Toulouse Midi-Pyrénées, Université Toulouse III Paul Sabatier, INSERM, CRCT, Toulouse, France
- Department of Digestive Oncology, Centre Hospitalier Universitaire (CHU), Toulouse, France
- Department of Digestive Surgery, Centre Hospitalier Universitaire (CHU), Toulouse, France
| | - Pierre Brousset
- Department of Pathology, Institut Universitaire du Cancer-Oncopole de Toulouse; Centre Hospitalier Universitaire (CHU), Toulouse, France
- Université Fédérale Toulouse Midi-Pyrénées, Université Toulouse III Paul Sabatier, INSERM, CRCT, Toulouse, France
- Laboratoire d'Excellence Toulouse Cancer (TOUCAN), Toulouse, France
| | - Jean-Sébastien Hoffmann
- Department of Pathology, Institut Universitaire du Cancer-Oncopole de Toulouse; Centre Hospitalier Universitaire (CHU), Toulouse, France
- Laboratoire d'Excellence Toulouse Cancer (TOUCAN), Toulouse, France
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7
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Li Q, Zhou J, Li S, Zhang W, Du Y, Li K, Wang Y, Sun Q. DNA polymerase ε harmonizes topological states and R-loops formation to maintain genome integrity in Arabidopsis. Nat Commun 2023; 14:7763. [PMID: 38012183 PMCID: PMC10682485 DOI: 10.1038/s41467-023-43680-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 11/16/2023] [Indexed: 11/29/2023] Open
Abstract
Genome topology is tied to R-loop formation and genome stability. However, the regulatory mechanism remains to be elucidated. By establishing a system to sense the connections between R-loops and genome topology states, we show that inhibiting DNA topoisomerase 1 (TOP1i) triggers the global increase of R-loops (called topoR-loops) and DNA damages, which are exacerbated in the DNA damage repair-compromised mutant atm. A suppressor screen identifies a mutation in POL2A, the catalytic subunit of DNA polymerase ε, rescuing the TOP1i-induced topoR-loop accumulation and genome instability in atm. Importantly we find that a highly conserved junction domain between the exonuclease and polymerase domains in POL2A is required for modulating topoR-loops near DNA replication origins and facilitating faithful DNA replication. Our results suggest that DNA replication acts in concert with genome topological states to fine-tune R-loops and thereby maintain genome integrity, revealing a likely conserved regulatory mechanism of TOP1i resistance in chemotherapy for ATM-deficient cancers.
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Affiliation(s)
- Qin Li
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Jincong Zhou
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Tsinghua-Peking Center for Life Sciences, Beijing, 100084, China
| | - Shuai Li
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Tsinghua-Peking Center for Life Sciences, Beijing, 100084, China
| | - Weifeng Zhang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Tsinghua-Peking Center for Life Sciences, Beijing, 100084, China
| | - Yingxue Du
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Tsinghua-Peking Center for Life Sciences, Beijing, 100084, China
| | - Kuan Li
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Tsinghua-Peking Center for Life Sciences, Beijing, 100084, China
- Chinese Institute for Brain Research, Beijing, 102206, China
| | - Yingxiang Wang
- College of Life Science, South China Agricultural University, Guangdong Laboratory for Lingnan Morden Agriculture, Guangzhou, 510642, China
- State Key Laboratory of Genetic Engineering, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Qianwen Sun
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
- Tsinghua-Peking Center for Life Sciences, Beijing, 100084, China.
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8
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Parkash V, Kulkarni Y, Bylund GO, Osterman P, Kamerlin S, Johansson E. A sensor complements the steric gate when DNA polymerase ϵ discriminates ribonucleotides. Nucleic Acids Res 2023; 51:11225-11238. [PMID: 37819038 PMCID: PMC10639073 DOI: 10.1093/nar/gkad817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 09/01/2023] [Accepted: 09/20/2023] [Indexed: 10/13/2023] Open
Abstract
The cellular imbalance between high concentrations of ribonucleotides (NTPs) and low concentrations of deoxyribonucleotides (dNTPs), is challenging for DNA polymerases when building DNA from dNTPs. It is currently believed that DNA polymerases discriminate against NTPs through a steric gate model involving a clash between a tyrosine and the 2'-hydroxyl of the ribonucleotide in the polymerase active site in B-family DNA polymerases. With the help of crystal structures of a B-family polymerase with a UTP or CTP in the active site, molecular dynamics simulations, biochemical assays and yeast genetics, we have identified a mechanism by which the finger domain of the polymerase sense NTPs in the polymerase active site. In contrast to the previously proposed polar filter, our experiments suggest that the amino acid residue in the finger domain senses ribonucleotides by steric hindrance. Furthermore, our results demonstrate that the steric gate in the palm domain and the sensor in the finger domain are both important when discriminating NTPs. Structural comparisons reveal that the sensor residue is conserved among B-family polymerases and we hypothesize that a sensor in the finger domain should be considered in all types of DNA polymerases.
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Affiliation(s)
- Vimal Parkash
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå 90187, Sweden
| | - Yashraj Kulkarni
- Department of Chemistry - BMC, Uppsala University, Box 576, Uppsala S-751 23, Sweden
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Göran O Bylund
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå 90187, Sweden
| | - Pia Osterman
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå 90187, Sweden
| | - Shina Caroline Lynn Kamerlin
- Department of Chemistry - BMC, Uppsala University, Box 576, Uppsala S-751 23, Sweden
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, GA 30332-0400, USA
| | - Erik Johansson
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå 90187, Sweden
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9
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Mullins EA, Salay LE, Durie CL, Bradley NP, Jackman JE, Ohi MD, Chazin WJ, Eichman BF. A mechanistic model of primer synthesis from catalytic structures of DNA polymerase α-primase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.16.533013. [PMID: 36993335 PMCID: PMC10055150 DOI: 10.1101/2023.03.16.533013] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The mechanism by which polymerase α-primase (polα-primase) synthesizes chimeric RNA-DNA primers of defined length and composition, necessary for replication fidelity and genome stability, is unknown. Here, we report cryo-EM structures of polα-primase in complex with primed templates representing various stages of DNA synthesis. Our data show how interaction of the primase regulatory subunit with the primer 5'-end facilitates handoff of the primer to polα and increases polα processivity, thereby regulating both RNA and DNA composition. The structures detail how flexibility within the heterotetramer enables synthesis across two active sites and provide evidence that termination of DNA synthesis is facilitated by reduction of polα and primase affinities for the varied conformations along the chimeric primer/template duplex. Together, these findings elucidate a critical catalytic step in replication initiation and provide a comprehensive model for primer synthesis by polα-primase.
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10
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Dmowski M, Makiela-Dzbenska K, Sharma S, Chabes A, Fijalkowska IJ. Impairment of the non-catalytic subunit Dpb2 of DNA Pol ɛ results in increased involvement of Pol δ on the leading strand. DNA Repair (Amst) 2023; 129:103541. [PMID: 37481989 DOI: 10.1016/j.dnarep.2023.103541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/29/2023] [Accepted: 07/05/2023] [Indexed: 07/25/2023]
Abstract
The generally accepted model assumes that leading strand synthesis is performed by Pol ε, while lagging-strand synthesis is catalyzed by Pol δ. Pol ε has been shown to target the leading strand by interacting with the CMG helicase [Cdc45 Mcm2-7 GINS(Psf1-3, Sld5)]. Proper functioning of the CMG-Pol ɛ, the helicase-polymerase complex is essential for its progression and the fidelity of DNA replication. Dpb2p, the essential non-catalytic subunit of Pol ε plays a key role in maintaining the correct architecture of the replisome by acting as a link between Pol ε and the CMG complex. Using a temperature-sensitive dpb2-100 mutant previously isolated in our laboratory, and a genetic system which takes advantage of a distinct mutational signature of the Pol δ-L612M variant which allows detection of the involvement of Pol δ in the replication of particular DNA strands we show that in yeast cells with an impaired Dpb2 subunit, the contribution of Pol δ to the replication of the leading strand is significantly increased.
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Affiliation(s)
- Michal Dmowski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland.
| | - Karolina Makiela-Dzbenska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland
| | - Sushma Sharma
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå, Sweden
| | - Andrei Chabes
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå, Sweden
| | - Iwona J Fijalkowska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland.
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11
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Strauss JD, Pursell ZF. Replication DNA polymerases, genome instability and cancer therapies. NAR Cancer 2023; 5:zcad033. [PMID: 37388540 PMCID: PMC10304742 DOI: 10.1093/narcan/zcad033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 05/24/2023] [Accepted: 06/25/2023] [Indexed: 07/01/2023] Open
Abstract
It has been over a decade since the initial identification of exonuclease domain mutations in the genes encoding the catalytic subunits of replication DNA polymerases ϵ and δ (POLE and POLD1) in tumors from highly mutated endometrial and colorectal cancers. Interest in studying POLE and POLD1 has increased significantly since then. Prior to those landmark cancer genome sequencing studies, it was well documented that mutations in replication DNA polymerases that reduced their DNA synthesis accuracy, their exonuclease activity or their interactions with other factors could lead to increased mutagenesis, DNA damage and even tumorigenesis in mice. There are several recent, well-written reviews of replication DNA polymerases. The aim of this review is to gather and review in some detail recent studies of DNA polymerases ϵ and δ as they pertain to genome instability, cancer and potential therapeutic treatments. The focus here is primarily on recent informative studies on the significance of mutations in genes encoding their catalytic subunits (POLE and POLD1), mutational signatures, mutations in associated genes, model organisms, and the utility of chemotherapy and immune checkpoint inhibition in polymerase mutant tumors.
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Affiliation(s)
- Juliet D Strauss
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, 70118 LA, USA
| | - Zachary F Pursell
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, 70118 LA, USA
- Tulane Cancer Center, Tulane University School of Medicine, New Orleans, 70118 LA, USA
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12
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Gallitto M, Zhang Z. The evolving tale of Pol2 function. Genes Dev 2023; 37:72-73. [PMID: 36813532 PMCID: PMC10069447 DOI: 10.1101/gad.350527.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
DNA replication is complex and highly regulated, and DNA replication errors can lead to human diseases such as cancer. DNA polymerase ε (polε) is a key player in DNA replication and contains a large subunit called POLE, which possesses both a DNA polymerase domain and a 3'-5' exonuclease domain (EXO). Mutations at the EXO domain and other missense mutations on POLE with unknown significance have been detected in a variety of human cancers. Based on cancer genome databases, Meng and colleagues (pp. 74-79) previously identified several missense mutations in POPS (pol2 family-specific catalytic core peripheral subdomain), and mutations at the conserved residues of yeast Pol2 (pol2-REL) showed reduced DNA synthesis and growth. In this issue of Genes & Development, Meng and colleagues (pp. 74-79) found unexpectedly that mutations at the EXO domain rescue the growth defects of pol2-REL. They further discovered that EXO-mediated polymerase backtracking impedes forward movement of the enzyme when POPS is defective, revealing a novel interplay between the EXO domain and POPS of Pol2 for efficient DNA synthesis. Additional molecular insight into this interplay will likely inform the impact of cancer-associated mutations found in both the EXO domain and POPS on tumorigenesis and uncover future novel therapeutic strategies.
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Affiliation(s)
- Matthew Gallitto
- Institute for Cancer Genetics, Department of Pediatrics, Department of Genetics and Development, Irving Cancer Research Center, Columbia University, New York, New York 10032, USA
| | - Zhiguo Zhang
- Institute for Cancer Genetics, Department of Pediatrics, Department of Genetics and Development, Irving Cancer Research Center, Columbia University, New York, New York 10032, USA
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13
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Meng X, Claussin C, Regan-Mochrie G, Whitehouse I, Zhao X. Balancing act of a leading strand DNA polymerase-specific domain and its exonuclease domain promotes genome-wide sister replication fork symmetry. Genes Dev 2023; 37:74-79. [PMID: 36702483 PMCID: PMC10069448 DOI: 10.1101/gad.350054.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 12/19/2022] [Indexed: 01/28/2023]
Abstract
Pol2 is the leading-strand DNA polymerase in budding yeast. Here we describe an antagonism between its conserved POPS (Pol2 family-specific catalytic core peripheral subdomain) and exonuclease domain and the importance of this antagonism in genome replication. We show that multiple defects caused by POPS mutations, including impaired growth and DNA synthesis, genome instability, and reliance on other genome maintenance factors, were rescued by exonuclease inactivation. Single-molecule data revealed that the rescue stemmed from allowing sister replication forks to progress at equal rates. Our data suggest that balanced activity of Pol2's POPS and exonuclease domains is vital for genome replication and stability.
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Affiliation(s)
- Xiangzhou Meng
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Clémence Claussin
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Gemma Regan-Mochrie
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
- Gerstner Sloan Kettering Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Iestyn Whitehouse
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA;
| | - Xiaolan Zhao
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA;
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14
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Byareddy SN, Sharma K, Sachdev S, Reddy AS, Acharya A, Klaustermeier KM, Lorson CL, Singh K. Potential therapeutic targets for Mpox: the evidence to date. Expert Opin Ther Targets 2023; 27:419-431. [PMID: 37368464 PMCID: PMC10722886 DOI: 10.1080/14728222.2023.2230361] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 06/07/2023] [Accepted: 06/23/2023] [Indexed: 06/28/2023]
Abstract
INTRODUCTION The global Mpox (MPX) disease outbreak caused by the Mpox virus (MPXV) in 2022 alarmed the World Health Organization (WHO) and health regulation agencies of individual countries leading to the declaration of MPX as a Public Health Emergency. Owing to the genetic similarities between smallpox-causing poxvirus and MPXV, vaccine JYNNEOS, and anti-smallpox drugs Brincidofovir and Tecovirimat were granted emergency use authorization by the United States Food and Drug Administration. The WHO also included cidofovir, NIOCH-14, and other vaccines as treatment options. AREAS COVERED This article covers the historical development of EUA-granted antivirals, resistance to these antivirals, and the projected impact of signature mutations on the potency of antivirals against currently circulating MPXV. Since a high prevalence of MPXV infections in individuals coinfected with HIV and MPXV, the treatment results among these individuals have been included. EXPERT OPINION All EUA-granted drugs have been approved for smallpox treatment. These antivirals show good potency against Mpox. However, conserved resistance mutation positions in MPXV and related poxviruses, and the signature mutations in the 2022 MPXV can potentially compromise the efficacy of the EUA-granted treatments. Therefore, MPXV-specific medications are required not only for the current but also for possible future outbreaks.
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Affiliation(s)
- Siddappa N Byareddy
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | | | - Shrikesh Sachdev
- Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Athreya S. Reddy
- Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Arpan Acharya
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | | | - Christian L Lorson
- Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO 65211, USA
| | - Kamal Singh
- Department of Pharmaceutical Chemistry, DPSRU, New Delhi-110017
- Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO 65211, USA
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15
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Lisova AE, Baranovskiy AG, Morstadt LM, Babayeva ND, Tahirov T. Human DNA polymerase α has a strong mutagenic potential at the initial steps of DNA synthesis. Nucleic Acids Res 2022; 50:12266-12273. [PMID: 36454017 PMCID: PMC9757036 DOI: 10.1093/nar/gkac1101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 09/16/2022] [Accepted: 11/10/2022] [Indexed: 12/05/2022] Open
Abstract
DNA polymerase α (Polα) is essential for DNA replication initiation and makes a notable contribution to genome mutagenesis. The activity and fidelity of Polα during the early steps of DNA replication have not been well studied. Here we show that at the beginning of DNA synthesis, when extending the RNA primer received from primase, Polα is more mutagenic than during the later DNA elongation steps. Kinetic and binding studies revealed substantially higher activity and affinity to the template:primer when Polα interacts with ribonucleotides of a chimeric RNA-DNA primer. Polα activity greatly varies during first six steps of DNA synthesis, and the bias in the rates of correct and incorrect dNTP incorporation leads to impaired fidelity, especially upon the second step of RNA primer extension. Furthermore, increased activity and stability of Polα/template:primer complexes containing RNA-DNA primers result in higher efficiency of mismatch extension.
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Affiliation(s)
| | | | - Lucia M Morstadt
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Nigar D Babayeva
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Tahir H Tahirov
- To whom correspondence should be addressed. Tel: +1 402 559 7608; Fax: +1 402 559 3739;
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16
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Chen L, Pranantyo D, Xia F. Nano-confined superfluid-based highly efficient chemical reaction and signal transmission. Sci Bull (Beijing) 2022; 67:1509-1512. [PMID: 36546271 DOI: 10.1016/j.scib.2022.06.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Linfeng Chen
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Dicky Pranantyo
- Antimicrobial Resistance Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, Singapore 138602, Singapore
| | - Fan Xia
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China.
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17
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Barbari SR, Beach AK, Markgren JG, Parkash V, Moore EA, Johansson E, Shcherbakova PV. Enhanced polymerase activity permits efficient synthesis by cancer-associated DNA polymerase ϵ variants at low dNTP levels. Nucleic Acids Res 2022; 50:8023-8040. [PMID: 35822874 PMCID: PMC9371911 DOI: 10.1093/nar/gkac602] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 06/13/2022] [Accepted: 06/29/2022] [Indexed: 11/28/2022] Open
Abstract
Amino acid substitutions in the exonuclease domain of DNA polymerase ϵ (Polϵ) cause ultramutated tumors. Studies in model organisms suggested pathogenic mechanisms distinct from a simple loss of exonuclease. These mechanisms remain unclear for most recurrent Polϵ mutations. Particularly, the highly prevalent V411L variant remained a long-standing puzzle with no detectable mutator effect in yeast despite the unequivocal association with ultramutation in cancers. Using purified four-subunit yeast Polϵ, we assessed the consequences of substitutions mimicking human V411L, S459F, F367S, L424V and D275V. While the effects on exonuclease activity vary widely, all common cancer-associated variants have increased DNA polymerase activity. Notably, the analog of Polϵ-V411L is among the strongest polymerases, and structural analysis suggests defective polymerase-to-exonuclease site switching. We further show that the V411L analog produces a robust mutator phenotype in strains that lack mismatch repair, indicating a high rate of replication errors. Lastly, unlike wild-type and exonuclease-dead Polϵ, hyperactive variants efficiently synthesize DNA at low dNTP concentrations. We propose that this characteristic could promote cancer cell survival and preferential participation of mutator polymerases in replication during metabolic stress. Our results support the notion that polymerase fitness, rather than low fidelity alone, is an important determinant of variant pathogenicity.
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Affiliation(s)
- Stephanie R Barbari
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Annette K Beach
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Joel G Markgren
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-90187 Umeå, Sweden
| | - Vimal Parkash
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-90187 Umeå, Sweden
| | - Elizabeth A Moore
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Erik Johansson
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-90187 Umeå, Sweden
| | - Polina V Shcherbakova
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
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18
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He R, Zhang Z. Rad53 arrests leading and lagging strand DNA synthesis via distinct mechanisms in response to DNA replication stress. Bioessays 2022; 44:e2200061. [PMID: 35778827 DOI: 10.1002/bies.202200061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Revised: 06/19/2022] [Accepted: 06/22/2022] [Indexed: 12/18/2022]
Abstract
DNA replication stress threatens ordinary DNA synthesis. The evolutionarily conserved DNA replication stress response pathway involves sensor kinase Mec1/ATR, adaptor protein Mrc1/Claspin, and effector kinase Rad53/Chk1, which spurs a host of changes to stabilize replication forks and maintain genome integrity. DNA replication forks consist of largely distinct sets of proteins at leading and lagging strands that function autonomously in DNA synthesis in vitro. In this article, we discuss eSPAN and BrdU-IP-ssSeq, strand-specific sequencing technologies that permit analysis of protein localization and DNA synthesis at individual strands in budding yeast. Using these approaches, we show that under replication stress Rad53 stalls DNA synthesis on both leading and lagging strands. On lagging strands, it stimulates PCNA unloading, and on leading strands, it attenuates the replication function of Mrc1-Tof1. We propose that in doing so, Rad53 couples leading and lagging strand DNA synthesis during replication stress, thereby preventing the emergence of harmful ssDNA.
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Affiliation(s)
- Richard He
- Institute for Cancer Genetics, Columbia University Irving Medical Center, New York, New York, USA.,Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, New York, USA.,Department of Pediatrics, Columbia University Medical Center, New York, New York, USA.,Department of Genetics and Development, Columbia University Medical Center, New York, New York, USA
| | - Zhiguo Zhang
- Institute for Cancer Genetics, Columbia University Irving Medical Center, New York, New York, USA.,Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, New York, USA.,Department of Pediatrics, Columbia University Medical Center, New York, New York, USA.,Department of Genetics and Development, Columbia University Medical Center, New York, New York, USA
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19
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Efficient discrimination against RNA-containing primers by human DNA polymerase ε. Sci Rep 2022; 12:10163. [PMID: 35715491 PMCID: PMC9205888 DOI: 10.1038/s41598-022-14602-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 06/09/2022] [Indexed: 01/13/2023] Open
Abstract
DNA polymerase ε (Polε) performs bulk synthesis of DNA on the leading strand during genome replication. Polε binds two substrates, a template:primer and dNTP, and catalyzes a covalent attachment of dNMP to the 3' end of the primer. Previous studies have shown that Polε easily inserts and extends ribonucleotides, which may promote mutagenesis and genome instability. In this work, we analyzed the mechanisms of discrimination against RNA-containing primers by human Polε (hPolε), performing binding and kinetic studies at near-physiological salt concentration. Pre-steady-state kinetic studies revealed that hPolεCD extends RNA primers with approximately 3300-fold lower efficiency in comparison to DNA, and addition of one dNMP to the 3' end of an RNA primer increases activity 36-fold. Likewise, addition of one rNMP to the 3' end of a DNA primer reduces activity 38-fold. The binding studies conducted in the presence of 0.15 M NaCl revealed that human hPolεCD has low affinity to DNA (KD of 1.5 µM). Strikingly, a change of salt concentration from 0.1 M to 0.15 M reduces the stability of the hPolεCD/DNA complex by 25-fold. Upon template:primer binding, the incoming dNTP and magnesium ions make hPolε discriminative against RNA and chimeric RNA-DNA primers. In summary, our studies revealed that hPolε discrimination against RNA-containing primers is based on the following factors: incoming dNTP, magnesium ions, a steric gate for the primer 2'OH, and the rigid template:primer binding pocket near the catalytic site. In addition, we showed the importance of conducting functional studies at near-physiological salt concentration.
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20
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Zhang X, Song B, Jiang L. From Dynamic Superwettability to Ionic/Molecular Superfluidity. Acc Chem Res 2022; 55:1195-1204. [PMID: 35445598 DOI: 10.1021/acs.accounts.2c00053] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Life systems present ultralow energy consumption in high-efficiency energy conversion, information transmission, and biosynthesis. The total energy intake of the human body is about 2000 kcal/day to maintain all of our activities, which is comparable to a power of ∼100 W. The energy required for the brain to work is equivalent to ∼20 W, and the rest of the energy (∼80 W) is used for other activities. All in vivo biosyntheses take place only at body temperature, which is much lower than that of in vitro reactions. To achieve these ultralow energy-consumption processes, there should be a kind of ultralow-resistivity matter transport in nanochannels (e.g., ionic and molecular channels), in which the directional collective motion of ions or molecules is a necessary condition rather than traditional Newton diffusion. The directional collective motion of ions and molecules is considered to be ionic/molecular superfluidity. The driving force of ionic/molecular superfluidity formation requires two necessary conditions: (1) Ions or molecules are confined at a certain distance (e.g., approximately twice Debye length (2λD) for ions or twice the van der Waals equilibrium distance (2d0) for molecules). (2) When the attractive potential energy (E0) is stronger than the thermal noise (kBTc), ionic/molecular superfluidity can be formed. The concept of ionic/molecular superfluidity will promote the understanding of energy conversion with ultralow energy consumption in biological systems. The swing of an eel's body generating electricity and cardiac resuscitation denote the conversion from mechanical energy to electrical energy, and mechanical modulation might result in a coherent resonance of ionic motion. The coherent resonance of Ca2+ in myocardium cells can induce a heartbeat, realizing the conversion from the electrical energy to the mechanical energy of a biological system. The macroscopic quantum state of ion channels is considered to be a carrier of neural information, and the environment field might play a significant role in regulating the macroscopic quantum states of various ion channels. In the biological ion channels system, the coupling of ion channels and their released photons might induce an environment wave which in turn regulates the ion oscillations in the channels to a coherent state. The states of decoherence and coherence might correspond to the states of sleep and action. We also demonstrated the decomposition of ATP to ADP released photons with a frequency of ∼34 THz, which could further drive DNA polymerization in the nanocavity of DNA polymerase. The photochemical (mid- and far-IR) reaction might be the driving force in high-efficiency biosynthesis. Quantized syntheses resonantly driven by multiple mid- and far-IR photons could be further designed in a tubular reactor with membranes of different microporous structures to achieve a high-efficiency synthesis with a low energy consumption. Finally, we point out that the Bose-Einstein condensate potentially widely exists. We expect that this Account will provide new ideas for the key problem in life science: how can life systems present ultralow energy consumption in high-efficiency energy conversion, information transmission, and biosynthesis?
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Affiliation(s)
- Xiqi Zhang
- Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Bo Song
- School of Optical-Electrical Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, P. R. China
| | - Lei Jiang
- Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing 101407, P. R. China
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21
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Shen Y, Wang X, Lei J, Wang S, Hou Y, Hou X. Catalytic confinement effects in nanochannels: from biological synthesis to chemical engineering. NANOSCALE ADVANCES 2022; 4:1517-1526. [PMID: 36134369 PMCID: PMC9418946 DOI: 10.1039/d2na00021k] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 02/14/2022] [Indexed: 06/16/2023]
Abstract
Catalytic reactions within nanochannels are of significant importance in disclosing the mechanisms of catalytic confinement effects and developing novel reaction systems for scientific and industrial demands. Interestingly, catalytic confinement effects exist in both biological and artificial nanochannels, which enhance the reaction performance of various chemical reactions. In this minireview, we investigate the recent advances on catalytic confinement effects in terms of the reactants, reaction processes, catalysts, and products in nanochannels. A systematic discussion of catalytic confinement effects associated with biological synthesis in bio-nanochannels and catalytic reactions in artificial nanochannels in chemical engineering is presented. Furthermore, we summarize the properties of reactions both in nature and chemical engineering and provide a brief overlook of this research field.
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Affiliation(s)
- Yigang Shen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
| | - Xin Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
| | - Jinmei Lei
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
| | - Shuli Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
| | - Yaqi Hou
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
| | - Xu Hou
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, College of Physical Science and Technology, Xiamen University Xiamen Fujian 361005 China
- Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM) Xiamen 361102 Fujian China
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22
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Abstract
DNA replication in eukaryotic cells initiates from large numbers of sites called replication origins. Initiation of replication from these origins must be tightly controlled to ensure the entire genome is precisely duplicated in each cell cycle. This is accomplished through the regulation of the first two steps in replication: loading and activation of the replicative DNA helicase. Here we describe what is known about the mechanism and regulation of these two reactions from a genetic, biochemical, and structural perspective, focusing on recent progress using proteins from budding yeast. Expected final online publication date for the Annual Review of Biochemistry, Volume 91 is June 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Alessandro Costa
- Macromolecular Machines Laboratory, The Francis Crick Institute, London, UK;
| | - John F X Diffley
- Chromosome Replication Laboratory, The Francis Crick Institute, London, UK;
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23
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Multiple roles of Pol epsilon in eukaryotic chromosome replication. Biochem Soc Trans 2022; 50:309-320. [PMID: 35129614 PMCID: PMC9022971 DOI: 10.1042/bst20210082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 12/23/2021] [Accepted: 01/06/2022] [Indexed: 11/17/2022]
Abstract
Pol epsilon is a tetrameric assembly that plays distinct roles during eukaryotic chromosome replication. It catalyses leading strand DNA synthesis; yet this function is dispensable for viability. Its non-catalytic domains instead play an essential role in the assembly of the active replicative helicase and origin activation, while non-essential histone-fold subunits serve a critical function in parental histone redeposition onto newly synthesised DNA. Furthermore, Pol epsilon plays a structural role in linking the RFC–Ctf18 clamp loader to the replisome, supporting processive DNA synthesis, DNA damage response signalling as well as sister chromatid cohesion. In this minireview, we discuss recent biochemical and structural work that begins to explain various aspects of eukaryotic chromosome replication, with a focus on the multiple roles of Pol epsilon in this process.
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24
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Garmezy B, Gheeya J, Lin HY, Huang Y, Kim T, Jiang X, Thein KZ, Pilié PG, Zeineddine F, Wang W, Shaw KR, Rodon J, Shen JP, Yuan Y, Meric-Bernstam F, Chen K, Yap TA. Clinical and Molecular Characterization of POLE Mutations as Predictive Biomarkers of Response to Immune Checkpoint Inhibitors in Advanced Cancers. JCO Precis Oncol 2022; 6:e2100267. [PMID: 35108036 PMCID: PMC8820927 DOI: 10.1200/po.21.00267] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 11/16/2021] [Accepted: 12/28/2021] [Indexed: 12/12/2022] Open
Abstract
PURPOSE DNA polymerase epsilon is critical to DNA proofreading and replication. Mutations in POLE have been associated with hypermutated tumors and antitumor response to immune checkpoint inhibitor (ICI) therapy. We present a clinicopathologic analysis of patients with advanced cancers harboring POLE mutations, the pattern of co-occurring mutations, and their response to ICI therapy within the context of mutation pathogenicity. METHODS We conducted a retrospective analysis of next-generation sequencing data at MD Anderson Cancer Center to identify patient tumors with POLE mutations and their co-occurring mutations. The pathogenicity of each mutation was annotated using InterVar and ClinVar. Differences in therapeutic response to ICI, survival, and co-occurring mutations were reported by POLE pathogenicity status. RESULTS Four hundred fifty-eight patient tumors with POLE mutations were identified from 14,229 next-generation sequencing reports; 15.0% of POLE mutations were pathogenic, 15.9% benign, and 69.1% variant of unknown significance. Eighty-two patients received either programmed death 1 or programmed death ligand-1 inhibitors as monotherapy or in combination with cytotoxic T-cell lymphocyte-4 inhibitors. Patients with pathogenic POLE mutations had improved clinical benefit rate (82.4% v 30.0%; P = .013), median progression-free survival (15.1 v 2.2 months; P < .001), overall survival (29.5 v 6.8 months; P < .001), and longer treatment duration (median 15.5 v 2.5 months; P < .001) compared to those with benign variants. Progression-free survival and overall survival remained superior when adjusting for number of co-occurring mutations (≥ 10 v < 10) and/or microsatellite instability status (proficient mismatch repair v deficient mismatch repair). The number of comutations was not associated with response to ICI (clinical benefit v progressive disease: median 13 v 11 comutations; P = .18). CONCLUSION Pathogenic POLE mutations were associated with clinical benefit to ICI therapy. Further studies are warranted to validate POLE mutation as a predictive biomarker of ICI therapy.
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Affiliation(s)
- Benjamin Garmezy
- Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Jinesh Gheeya
- The University of Texas Health Science Center at Houston, Houston, TX
| | - Heather Y. Lin
- Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Yuefan Huang
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Taebeom Kim
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Xianli Jiang
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Kyaw Z. Thein
- Department of Investigational Cancer Therapeutics (Phase I Clinical Trials Program), The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Patrick G. Pilié
- Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Fadl Zeineddine
- Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Wanlin Wang
- Department of Investigational Cancer Therapeutics (Phase I Clinical Trials Program), The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Kenna R. Shaw
- Khalifa Institute for Personalized Cancer Therapy, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Jordi Rodon
- Department of Investigational Cancer Therapeutics (Phase I Clinical Trials Program), The University of Texas MD Anderson Cancer Center, Houston, TX
| | - John Paul Shen
- Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Ying Yuan
- Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Funda Meric-Bernstam
- Department of Investigational Cancer Therapeutics (Phase I Clinical Trials Program), The University of Texas MD Anderson Cancer Center, Houston, TX
- Khalifa Institute for Personalized Cancer Therapy, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Ken Chen
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Timothy A. Yap
- Department of Investigational Cancer Therapeutics (Phase I Clinical Trials Program), The University of Texas MD Anderson Cancer Center, Houston, TX
- Khalifa Institute for Personalized Cancer Therapy, The University of Texas MD Anderson Cancer Center, Houston, TX
- The Institute for Applied Cancer Science, The University of Texas MD Anderson Cancer Center, Houston, TX
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25
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Dahl JM, Thomas N, Tracy MA, Hearn BL, Perera L, Kennedy SR, Herr AJ, Kunkel TA. Probing the mechanisms of two exonuclease domain mutators of DNA polymerase ϵ. Nucleic Acids Res 2022; 50:962-974. [PMID: 35037018 DOI: 10.1093/nar/gkab1255] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 11/21/2021] [Accepted: 12/08/2021] [Indexed: 11/15/2022] Open
Abstract
We report the properties of two mutations in the exonuclease domain of the Saccharomyces cerevisiae DNA polymerase ϵ. One, pol2-Y473F, increases the mutation rate by about 20-fold, similar to the catalytically dead pol2-D290A/E290A mutant. The other, pol2-N378K, is a stronger mutator. Both retain the ability to excise a nucleotide from double-stranded DNA, but with impaired activity. pol2-Y473F degrades DNA poorly, while pol2-N378K degrades single-stranded DNA at an elevated rate relative to double-stranded DNA. These data suggest that pol2-Y473F reduces the capacity of the enzyme to perform catalysis in the exonuclease active site, while pol2-N378K impairs partitioning to the exonuclease active site. Relative to wild-type Pol ϵ, both variants decrease the dNTP concentration required to elicit a switch between proofreading and polymerization by more than an order of magnitude. While neither mutation appears to alter the sequence specificity of polymerization, the N378K mutation stimulates polymerase activity, increasing the probability of incorporation and extension of a mismatch. Considered together, these data indicate that impairing the primer strand transfer pathway required for proofreading increases the probability of common mutations by Pol ϵ, elucidating the association of homologous mutations in human DNA polymerase ϵ with cancer.
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Affiliation(s)
- Joseph M Dahl
- Genome Integrity Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, DHHS, Research Triangle Park, NC 27709, USA
| | - Natalie Thomas
- Genome Integrity Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, DHHS, Research Triangle Park, NC 27709, USA
| | - Maxwell A Tracy
- Department of Laboratory Medicine and Pathology, UW Medicine, Seattle, WA 98195, USA
| | - Brady L Hearn
- Department of Laboratory Medicine and Pathology, UW Medicine, Seattle, WA 98195, USA
| | - Lalith Perera
- Genome Integrity Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, DHHS, Research Triangle Park, NC 27709, USA
| | - Scott R Kennedy
- Department of Laboratory Medicine and Pathology, UW Medicine, Seattle, WA 98195, USA
| | - Alan J Herr
- Department of Laboratory Medicine and Pathology, UW Medicine, Seattle, WA 98195, USA
| | - Thomas A Kunkel
- Genome Integrity Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, DHHS, Research Triangle Park, NC 27709, USA
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26
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Jenkyn-Bedford M, Jones ML, Baris Y, Labib KPM, Cannone G, Yeeles JTP, Deegan TD. A conserved mechanism for regulating replisome disassembly in eukaryotes. Nature 2021; 600:743-747. [PMID: 34700328 PMCID: PMC8695382 DOI: 10.1038/s41586-021-04145-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 10/14/2021] [Indexed: 11/28/2022]
Abstract
Replisome disassembly is the final step of eukaryotic DNA replication and is triggered by ubiquitylation of the CDC45-MCM-GINS (CMG) replicative helicase1-3. Despite being driven by evolutionarily diverse E3 ubiquitin ligases in different eukaryotes (SCFDia2 in budding yeast1, CUL2LRR1 in metazoa4-7), replisome disassembly is governed by a common regulatory principle, in which ubiquitylation of CMG is suppressed before replication termination, to prevent replication fork collapse. Recent evidence suggests that this suppression is mediated by replication fork DNA8-10. However, it is unknown how SCFDia2 and CUL2LRR1 discriminate terminated from elongating replisomes, to selectively ubiquitylate CMG only after termination. Here we used cryo-electron microscopy to solve high-resolution structures of budding yeast and human replisome-E3 ligase assemblies. Our structures show that the leucine-rich repeat domains of Dia2 and LRR1 are structurally distinct, but bind to a common site on CMG, including the MCM3 and MCM5 zinc-finger domains. The LRR-MCM interaction is essential for replisome disassembly and, crucially, is occluded by the excluded DNA strand at replication forks, establishing the structural basis for the suppression of CMG ubiquitylation before termination. Our results elucidate a conserved mechanism for the regulation of replisome disassembly in eukaryotes, and reveal a previously unanticipated role for DNA in preserving replisome integrity.
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Affiliation(s)
| | | | | | - Karim P M Labib
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, UK
| | | | | | - Tom D Deegan
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, UK.
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, UK.
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27
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Zhou ZX, Lujan SA, Burkholder AB, St. Charles J, Dahl J, Farrell CE, Williams JS, Kunkel TA. How asymmetric DNA replication achieves symmetrical fidelity. Nat Struct Mol Biol 2021; 28:1020-1028. [PMID: 34887558 PMCID: PMC8815454 DOI: 10.1038/s41594-021-00691-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 10/22/2021] [Indexed: 11/09/2022]
Abstract
Accurate DNA replication of an undamaged template depends on polymerase selectivity for matched nucleotides, exonucleolytic proofreading of mismatches, and removal of remaining mismatches via DNA mismatch repair (MMR). DNA polymerases (Pols) δ and ε have 3'-5' exonucleases into which mismatches are partitioned for excision in cis (intrinsic proofreading). Here we provide strong evidence that Pol δ can extrinsically proofread mismatches made by itself and those made by Pol ε, independently of both Pol δ's polymerization activity and MMR. Extrinsic proofreading across the genome is remarkably efficient. We report, with unprecedented accuracy, in vivo contributions of nucleotide selectivity, proofreading, and MMR to the fidelity of DNA replication in Saccharomyces cerevisiae. We show that extrinsic proofreading by Pol δ improves and balances the fidelity of the two DNA strands. Together, we depict a comprehensive picture of how nucleotide selectivity, proofreading, and MMR cooperate to achieve high and symmetrical fidelity on the two strands.
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Affiliation(s)
- Zhi-Xiong Zhou
- Genome Integrity & Structural Biology Laboratory, NIH/NIEHS, DHHS, Research Triangle Park, North Carolina, USA
| | - Scott A. Lujan
- Genome Integrity & Structural Biology Laboratory, NIH/NIEHS, DHHS, Research Triangle Park, North Carolina, USA
| | - Adam B. Burkholder
- Integrative Bioinformatics Support Group, NIH/NIEHS, DHHS, Research Triangle Park, North Carolina, USA
| | - Jordan St. Charles
- Genome Integrity & Structural Biology Laboratory, NIH/NIEHS, DHHS, Research Triangle Park, North Carolina, USA
| | - Joseph Dahl
- Genome Integrity & Structural Biology Laboratory, NIH/NIEHS, DHHS, Research Triangle Park, North Carolina, USA
| | - Corinne E. Farrell
- Genome Integrity & Structural Biology Laboratory, NIH/NIEHS, DHHS, Research Triangle Park, North Carolina, USA
| | - Jessica S. Williams
- Genome Integrity & Structural Biology Laboratory, NIH/NIEHS, DHHS, Research Triangle Park, North Carolina, USA
| | - Thomas A. Kunkel
- Genome Integrity & Structural Biology Laboratory, NIH/NIEHS, DHHS, Research Triangle Park, North Carolina, USA
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28
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Pinto MN, Ter Beek J, Ekanger LA, Johansson E, Barton JK. The [4Fe4S] Cluster of Yeast DNA Polymerase ε Is Redox Active and Can Undergo DNA-Mediated Signaling. J Am Chem Soc 2021; 143:16147-16153. [PMID: 34559527 PMCID: PMC8499023 DOI: 10.1021/jacs.1c07150] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Many DNA replication and DNA repair enzymes have been found to carry [4Fe4S] clusters. The major leading strand polymerase, DNA polymerase ε (Pol ε) from Saccharomyces cerevisiae, was recently reported to have a [4Fe4S] cluster located within the catalytic domain of the largest subunit, Pol2. Here the redox characteristics of the [4Fe4S] cluster in the context of that domain, Pol2CORE, are explored using DNA electrochemistry, and the effects of oxidation and rereduction on polymerase activity are examined. The exonuclease deficient variant D290A/E292A, Pol2COREexo-, was used to limit DNA degradation. While no redox signal is apparent for Pol2COREexo- on DNA-modified electrodes, a large cathodic signal centered at -140 mV vs NHE is observed after bulk oxidation. A double cysteine to serine mutant (C665S/C668S) of Pol2COREexo-, which lacks the [4Fe4S] cluster, shows no similar redox signal upon oxidation. Significantly, protein oxidation yields a sharp decrease in polymerization, while rereduction restores activity almost to the level of untreated enzyme. Moreover, the addition of reduced EndoIII, a bacterial DNA repair enzyme containing [4Fe4S]2+, to oxidized Pol2COREexo- bound to its DNA substrate also significantly restores polymerase activity. In contrast, parallel experiments with EndoIIIY82A, a variant of EndoIII, defective in DNA charge transport (CT), does not show restoration of activity of Pol2COREexo-. We propose a model in which EndoIII bound to the DNA duplex may shuttle electrons through DNA to the DNA-bound oxidized Pol2COREexo- via DNA CT and that this DNA CT signaling offers a means to modulate the redox state and replication by Pol ε.
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Affiliation(s)
- Miguel N Pinto
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Josy Ter Beek
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-910 87 Umeå, Sweden
| | - Levi A Ekanger
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.,Department of Chemistry, The College of New Jersey, Ewing, New Jersey 08628, United States
| | - Erik Johansson
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-910 87 Umeå, Sweden
| | - Jacqueline K Barton
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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29
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'PIPs' in DNA polymerase: PCNA interaction affairs. Biochem Soc Trans 2021; 48:2811-2822. [PMID: 33196097 DOI: 10.1042/bst20200678] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/19/2020] [Accepted: 10/21/2020] [Indexed: 01/15/2023]
Abstract
Interaction of PCNA with DNA polymerase is vital to efficient and processive DNA synthesis. PCNA being a homotrimeric ring possesses three hydrophobic pockets mostly involved in an interaction with its binding partners. PCNA interacting proteins contain a short sequence of eight amino acids, popularly coined as PIP motif, which snuggly fits into the hydrophobic pocket of PCNA to stabilize the interaction. In the last two decades, several PIP motifs have been mapped or predicted in eukaryotic DNA polymerases. In this review, we summarize our understandings of DNA polymerase-PCNA interaction, the function of such interaction during DNA synthesis, and emphasize the lacunae that persist. Because of the presence of multiple ligands in the replisome complex and due to many interaction sites in DNA polymerases, we also propose two modes of DNA polymerase positioning on PCNA required for DNA synthesis to rationalize the tool-belt model of DNA replication.
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30
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Soriano I, Vazquez E, De Leon N, Bertrand S, Heitzer E, Toumazou S, Bo Z, Palles C, Pai CC, Humphrey TC, Tomlinson I, Cotterill S, Kearsey SE. Expression of the cancer-associated DNA polymerase ε P286R in fission yeast leads to translesion synthesis polymerase dependent hypermutation and defective DNA replication. PLoS Genet 2021; 17:e1009526. [PMID: 34228709 PMCID: PMC8284607 DOI: 10.1371/journal.pgen.1009526] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 07/16/2021] [Accepted: 06/11/2021] [Indexed: 12/15/2022] Open
Abstract
Somatic and germline mutations in the proofreading domain of the replicative DNA polymerase ε (POLE-exonuclease domain mutations, POLE-EDMs) are frequently found in colorectal and endometrial cancers and, occasionally, in other tumours. POLE-associated cancers typically display hypermutation, and a unique mutational signature, with a predominance of C > A transversions in the context TCT and C > T transitions in the context TCG. To understand better the contribution of hypermutagenesis to tumour development, we have modelled the most recurrent POLE-EDM (POLE-P286R) in Schizosaccharomyces pombe. Whole-genome sequencing analysis revealed that the corresponding pol2-P287R allele also has a strong mutator effect in vivo, with a high frequency of base substitutions and relatively few indel mutations. The mutations are equally distributed across different genomic regions, but in the immediate vicinity there is an asymmetry in AT frequency. The most abundant base-pair changes are TCT > TAT transversions and, in contrast to human mutations, TCG > TTG transitions are not elevated, likely due to the absence of cytosine methylation in fission yeast. The pol2-P287R variant has an increased sensitivity to elevated dNTP levels and DNA damaging agents, and shows reduced viability on depletion of the Pfh1 helicase. In addition, S phase is aberrant and RPA foci are elevated, suggestive of ssDNA or DNA damage, and the pol2-P287R mutation is synthetically lethal with rad3 inactivation, indicative of checkpoint activation. Significantly, deletion of genes encoding some translesion synthesis polymerases, most notably Pol κ, partially suppresses pol2-P287R hypermutation, indicating that polymerase switching contributes to this phenotype.
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Affiliation(s)
- Ignacio Soriano
- ZRAB, University of Oxford, Oxford, United Kingdom
- Edinburgh Cancer Research Centre, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
| | - Enrique Vazquez
- Genomics Unit, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Nagore De Leon
- ZRAB, University of Oxford, Oxford, United Kingdom
- Edinburgh Cancer Research Centre, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
| | | | - Ellen Heitzer
- Institute of Human Genetics, Diagnostic & Research Center for Molecular BioMedicine, Medical University of Graz, Graz, Austria
| | - Sophia Toumazou
- ZRAB, University of Oxford, Oxford, United Kingdom
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom
| | - Zhihan Bo
- ZRAB, University of Oxford, Oxford, United Kingdom
| | - Claire Palles
- Gastrointestinal Cancer Genetics Laboratory, Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Chen-Chun Pai
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom
| | - Timothy C. Humphrey
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom
| | - Ian Tomlinson
- Edinburgh Cancer Research Centre, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
| | - Sue Cotterill
- St. George’s, University of London, Cranmer Terrace, Tooting, London, United Kingdom
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31
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Checkpoint-mediated DNA polymerase ε exonuclease activity curbing counteracts resection-driven fork collapse. Mol Cell 2021; 81:2778-2792.e4. [PMID: 33932350 PMCID: PMC7612761 DOI: 10.1016/j.molcel.2021.04.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 04/06/2021] [Accepted: 04/08/2021] [Indexed: 02/01/2023]
Abstract
DNA polymerase ε (Polε) carries out high-fidelity leading strand synthesis owing to its exonuclease activity. Polε polymerase and exonuclease activities are balanced, because of partitioning of nascent DNA strands between catalytic sites, so that net resection occurs when synthesis is impaired. In vivo, DNA synthesis stalling activates replication checkpoint kinases, which act to preserve the functional integrity of replication forks. We show that stalled Polε drives nascent strand resection causing fork functional collapse, averted via checkpoint-dependent phosphorylation. Polε catalytic subunit Pol2 is phosphorylated on serine 430, influencing partitioning between polymerase and exonuclease active sites. A phosphormimetic S430D change reduces exonucleolysis in vitro and counteracts fork collapse. Conversely, non-phosphorylatable pol2-S430A expression causes resection-driven stressed fork defects. Our findings reveal that checkpoint kinases switch Polε to an exonuclease-safe mode preventing nascent strand resection and stabilizing stalled replication forks. Elective partitioning suppression has implications for the diverse Polε roles in genome integrity maintenance.
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32
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Raina A, Sahu PK, Laskar RA, Rajora N, Sao R, Khan S, Ganai RA. Mechanisms of Genome Maintenance in Plants: Playing It Safe With Breaks and Bumps. Front Genet 2021; 12:675686. [PMID: 34239541 PMCID: PMC8258418 DOI: 10.3389/fgene.2021.675686] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 05/04/2021] [Indexed: 01/14/2023] Open
Abstract
Maintenance of genomic integrity is critical for the perpetuation of all forms of life including humans. Living organisms are constantly exposed to stress from internal metabolic processes and external environmental sources causing damage to the DNA, thereby promoting genomic instability. To counter the deleterious effects of genomic instability, organisms have evolved general and specific DNA damage repair (DDR) pathways that act either independently or mutually to repair the DNA damage. The mechanisms by which various DNA repair pathways are activated have been fairly investigated in model organisms including bacteria, fungi, and mammals; however, very little is known regarding how plants sense and repair DNA damage. Plants being sessile are innately exposed to a wide range of DNA-damaging agents both from biotic and abiotic sources such as ultraviolet rays or metabolic by-products. To escape their harmful effects, plants also harbor highly conserved DDR pathways that share several components with the DDR machinery of other organisms. Maintenance of genomic integrity is key for plant survival due to lack of reserve germline as the derivation of the new plant occurs from the meristem. Untowardly, the accumulation of mutations in the meristem will result in a wide range of genetic abnormalities in new plants affecting plant growth development and crop yield. In this review, we will discuss various DNA repair pathways in plants and describe how the deficiency of each repair pathway affects plant growth and development.
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Affiliation(s)
- Aamir Raina
- Mutation Breeding Laboratory, Department of Botany, Aligarh Muslim University, Aligarh, India
- Botany Section, Women’s College, Aligarh Muslim University, Aligarh, India
| | - Parmeshwar K. Sahu
- Department of Genetics and Plant Breeding, Indira Gandhi Agriculture University, Raipur, India
| | | | - Nitika Rajora
- National Agri-Food Biotechnology Institute, Mohali, India
| | - Richa Sao
- Department of Genetics and Plant Breeding, Indira Gandhi Agriculture University, Raipur, India
| | - Samiullah Khan
- Mutation Breeding Laboratory, Department of Botany, Aligarh Muslim University, Aligarh, India
| | - Rais A. Ganai
- Watson-Crick Centre for Molecular Medicine, Islamic University of Science and Technology, Awantipora, India
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33
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Hayes RP, Heo MR, Mason M, Reid J, Burlein C, Armacost KA, Tellers DM, Raheem I, Shaw AW, Murray E, McKenna PM, Abeywickrema P, Sharma S, Soisson SM, Klein D. Structural understanding of non-nucleoside inhibition in an elongating herpesvirus polymerase. Nat Commun 2021; 12:3040. [PMID: 34031403 PMCID: PMC8144222 DOI: 10.1038/s41467-021-23312-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 04/21/2021] [Indexed: 12/03/2022] Open
Abstract
All herpesviruses encode a conserved DNA polymerase that is required for viral genome replication and serves as an important therapeutic target. Currently available herpesvirus therapies include nucleoside and non-nucleoside inhibitors (NNI) that target the DNA-bound state of herpesvirus polymerase and block replication. Here we report the ternary complex crystal structure of Herpes Simplex Virus 1 DNA polymerase bound to DNA and a 4-oxo-dihydroquinoline NNI, PNU-183792 (PNU), at 3.5 Å resolution. PNU bound at the polymerase active site, displacing the template strand and inducing a conformational shift of the fingers domain into an open state. These results demonstrate that PNU inhibits replication by blocking association of dNTP and stalling the enzyme in a catalytically incompetent conformation, ultimately acting as a nucleotide competing inhibitor (NCI). Sequence conservation of the NCI binding pocket further explains broad-spectrum activity while a direct interaction between PNU and residue V823 rationalizes why mutations at this position result in loss of inhibition.
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Affiliation(s)
- Robert P Hayes
- Computational and Structural Chemistry, Merck & Co., Inc., West Point, PA, USA.
| | - Mee Ra Heo
- Computational and Structural Chemistry, Merck & Co., Inc., West Point, PA, USA
| | - Mark Mason
- Computational and Structural Chemistry, Merck & Co., Inc., West Point, PA, USA
| | - John Reid
- Computational and Structural Chemistry, Merck & Co., Inc., West Point, PA, USA
| | | | - Kira A Armacost
- Computational and Structural Chemistry, Merck & Co., Inc., West Point, PA, USA
| | | | - Izzat Raheem
- Discovery Chemistry, Merck & Co., Inc., West Point, PA, USA
| | - Anthony W Shaw
- Discovery Chemistry, Merck & Co., Inc., West Point, PA, USA
| | - Edward Murray
- Infectious Diseases and Vaccines, Merck & Co., Inc., West Point, PA, USA
| | - Philip M McKenna
- Infectious Diseases and Vaccines, Merck & Co., Inc., West Point, PA, USA
| | | | - Sujata Sharma
- Computational and Structural Chemistry, Merck & Co., Inc., West Point, PA, USA
| | - Stephen M Soisson
- Computational and Structural Chemistry, Merck & Co., Inc., West Point, PA, USA
| | - Daniel Klein
- Computational and Structural Chemistry, Merck & Co., Inc., West Point, PA, USA
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34
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Bersch B, Tarbouriech N, Burmeister WP, Iseni F. Solution Structure of the C-terminal Domain of A20, the Missing Brick for the Characterization of the Interface between Vaccinia Virus DNA Polymerase and its Processivity Factor. J Mol Biol 2021; 433:167009. [PMID: 33901538 DOI: 10.1016/j.jmb.2021.167009] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/16/2021] [Accepted: 04/17/2021] [Indexed: 11/26/2022]
Abstract
Poxviruses are enveloped viruses with a linear, double-stranded DNA genome. Viral DNA synthesis is achieved by a functional DNA polymerase holoenzyme composed of three essential proteins. For vaccinia virus (VACV) these are E9, the catalytic subunit, a family B DNA polymerase, and the heterodimeric processivity factor formed by D4 and A20. The A20 protein links D4 to the catalytic subunit. High-resolution structures have been obtained for the VACV D4 protein in complex with an N-terminal fragment of A20 as well as for E9. In addition, biochemical studies provided evidence that a poxvirus-specific insertion (insert 3) in E9 interacts with the C-terminal residues of A20. Here, we provide solution structures of two different VACV A20 C-terminal constructs containing residues 304-426, fused at their C-terminus to either a BAP (Biotin Acceptor Peptide)-tag or a short peptide containing the helix of E9 insert 3. Together with results from titration studies, these structures shed light on the molecular interface between the catalytic subunit and the processivity factor component A20. The interface comprises hydrophobic residues conserved within the Chordopoxvirinae subfamily. Finally, we constructed a HADDOCK model of the VACV A20304-426-E9 complex, which is in excellent accordance with previous experimental data.
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Affiliation(s)
- Beate Bersch
- Institut de Biologie Structurale, Univ. Grenoble Alpes, CNRS, CEA, IBS, F-38000 Grenoble, France.
| | - Nicolas Tarbouriech
- Institut de Biologie Structurale, Univ. Grenoble Alpes, CNRS, CEA, IBS, F-38000 Grenoble, France
| | - Wim P Burmeister
- Institut de Biologie Structurale, Univ. Grenoble Alpes, CNRS, CEA, IBS, F-38000 Grenoble, France
| | - Frédéric Iseni
- Unité de Virologie, Institut de Recherche Biomédicale des Armées, BP73, F-91223 Brétigny-sur-Orge Cedex, France
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35
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Herzog M, Alonso-Perez E, Salguero I, Warringer J, Adams D, Jackson SP, Puddu F. Mutagenic mechanisms of cancer-associated DNA polymerase ϵ alleles. Nucleic Acids Res 2021; 49:3919-3931. [PMID: 33764464 PMCID: PMC8053093 DOI: 10.1093/nar/gkab160] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 03/03/2021] [Indexed: 01/08/2023] Open
Abstract
A single amino acid residue change in the exonuclease domain of human DNA polymerase ϵ, P286R, is associated with the development of colorectal cancers, and has been shown to impart a mutator phenotype. The corresponding Pol ϵ allele in the yeast Saccharomyces cerevisiae (pol2-P301R), was found to drive greater mutagenesis than an entirely exonuclease-deficient Pol ϵ (pol2-4), an unexpected phenotype of ultra-mutagenesis. By studying the impact on mutation frequency, type, replication-strand bias, and sequence context, we show that ultra-mutagenesis is commonly observed in yeast cells carrying a range of cancer-associated Pol ϵ exonuclease domain alleles. Similarities between mutations generated by these alleles and those generated in pol2-4 cells indicate a shared mechanism of mutagenesis that yields a mutation pattern similar to cancer Signature 14. Comparison of POL2 ultra-mutator with pol2-M644G, a mutant in the polymerase domain decreasing Pol ϵ fidelity, revealed unexpected analogies in the sequence context and strand bias of mutations. Analysis of mutational patterns unique to exonuclease domain mutant cells suggests that backtracking of the polymerase, when the mismatched primer end cannot be accommodated in the proofreading domain, results in the observed insertions and T>A mutations in specific sequence contexts.
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Affiliation(s)
- Mareike Herzog
- The Wellcome/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
- The Wellcome Sanger Institute, Hinxton CB10 1HH, UK
| | - Elisa Alonso-Perez
- Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 9 C, 413 90, Göteborg, Sweden
| | - Israel Salguero
- The Wellcome/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Jonas Warringer
- Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 9 C, 413 90, Göteborg, Sweden
| | | | - Stephen P Jackson
- The Wellcome/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Fabio Puddu
- The Wellcome/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
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36
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Stepchenkova EI, Zhuk AS, Cui J, Tarakhovskaya ER, Barbari SR, Shcherbakova PV, Polev DE, Fedorov R, Poliakov E, Rogozin IB, Lada AG, Pavlov YI. Compensation for the absence of the catalytically active half of DNA polymerase ε in yeast by positively selected mutations in CDC28. Genetics 2021; 218:6222163. [PMID: 33844024 DOI: 10.1093/genetics/iyab060] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 04/02/2021] [Indexed: 11/14/2022] Open
Abstract
Current eukaryotic replication models postulate that leading and lagging DNA strands are replicated predominantly by dedicated DNA polymerases. The catalytic subunit of the leading strand DNA polymerase ε, Pol2, consists of two halves made of two different ancestral B-family DNA polymerases. Counterintuitively, the catalytically active N-terminal half is dispensable, while the inactive C-terminal part is required for viability. Despite extensive studies of yeast Saccharomyces cerevisiae strains lacking the active N-terminal half, it is still unclear how these strains survive and recover. We designed a robust method for constructing mutants with only the C-terminal part of Pol2. Strains without the active polymerase part show severe growth defects, sensitivity to replication inhibitors, chromosomal instability, and elevated spontaneous mutagenesis. Intriguingly, the slow-growing mutant strains rapidly accumulate fast-growing clones. Analysis of genomic DNA sequences of these clones revealed that the adaptation to the loss of the catalytic N-terminal part of Pol2 occurs by a positive selection of mutants with improved growth. Elevated mutation rates help generate sufficient numbers of these variants. Single nucleotide changes in the cell cycle-dependent kinase gene, CDC28, improve the growth of strains lacking the N-terminal part of Pol2, and rescue their sensitivity to replication inhibitors and, in parallel, lower mutation rates. Our study predicts that changes in mammalian homologs of cyclin-dependent kinases may contribute to cellular responses to the leading strand polymerase defects.
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Affiliation(s)
- Elena I Stepchenkova
- Laboratory of Mutagenesis and Genetic Toxicology, Vavilov Institute of General Genetics, Saint-Petersburg Branch, Russian Academy of Sciences, Saint-Petersburg 199034, Russia.,Department of Genetics and Biotechnology, Saint-Petersburg State University, Saint-Petersburg 199034, Russia.,Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Anna S Zhuk
- ITMO University, Saint-Petersburg 191002, Russia
| | - Jian Cui
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Elena R Tarakhovskaya
- Laboratory of Mutagenesis and Genetic Toxicology, Vavilov Institute of General Genetics, Saint-Petersburg Branch, Russian Academy of Sciences, Saint-Petersburg 199034, Russia.,Department of Plant Physiology and Biochemistry, Saint-Petersburg State University, Saint-Petersburg 199034, Russia
| | - Stephanie R Barbari
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Polina V Shcherbakova
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Dmitrii E Polev
- Research Resource Center "Biobank," Research Park, Saint-Petersburg State University, Saint-Petersburg 198504, Russia
| | - Roman Fedorov
- Department of Mathematics, University of Pittsburgh, PA 15213, USA
| | - Eugenia Poliakov
- Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Igor B Rogozin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Artem G Lada
- Department of Microbiology and Molecular Genetics, University of California Davis, Davis, CA 92697, USA
| | - Youri I Pavlov
- Department of Genetics and Biotechnology, Saint-Petersburg State University, Saint-Petersburg 199034, Russia.,Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Department of Microbiology and Pathology, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Department of Genetics Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
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37
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Abstract
The faithful and timely copying of DNA by molecular machines known as replisomes depends on a disparate suite of enzymes and scaffolding factors working together in a highly orchestrated manner. Large, dynamic protein-nucleic acid assemblies that selectively morph between distinct conformations and compositional states underpin this critical cellular process. In this article, we discuss recent progress outlining the physical basis of replisome construction and progression in eukaryotes.
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Affiliation(s)
- Ilan Attali
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, USA;
| | - Michael R Botchan
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
| | - James M Berger
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, USA;
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38
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Zimmermann MT, Mathison AJ, Stodola T, Evans DB, Abrudan JL, Demos W, Tschannen M, Aldakkak M, Geurts J, Lomberk G, Tsai S, Urrutia R. Interpreting Sequence Variation in PDAC-Predisposing Genes Using a Multi-Tier Annotation Approach Performed at the Gene, Patient, and Cohort Level. Front Oncol 2021; 11:606820. [PMID: 33747920 PMCID: PMC7973372 DOI: 10.3389/fonc.2021.606820] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 01/21/2021] [Indexed: 12/12/2022] Open
Abstract
We investigated germline variation in pancreatic ductal adenocarcinoma (PDAC) predisposition genes in 535 patients, using a custom-built panel and a new complementary bioinformatic approach. Our panel assessed genes belonging to DNA repair, cell cycle checkpoints, migration, and preneoplastic pancreatic conditions. Our bioinformatics approach integrated annotations of variants by using data derived from both germline and somatic references. This integrated approach with expanded evidence enabled us to consider patterns even among private mutations, supporting a functional role for certain alleles, which we believe enhances individualized medicine beyond classic gene-centric approaches. Concurrent evaluation of three levels of evidence, at the gene, sample, and cohort level, has not been previously done. Overall, we identified in PDAC patient germline samples, 12% with mutations previously observed in pancreatic cancers, 23% with mutations previously discovered by sequencing other human tumors, and 46% with mutations with germline associations to cancer. Non-polymorphic protein-coding pathogenic variants were found in 18.4% of patient samples. Moreover, among patients with metastatic PDAC, 16% carried at least one pathogenic variant, and this subgroup was found to have an improved overall survival (22.0 months versus 9.8; p=0.008) despite a higher pre-treatment CA19-9 level (p=0.02). Genetic alterations in DNA damage repair genes were associated with longer overall survival among patients who underwent resection surgery (92 months vs. 46; p=0.06). ATM alterations were associated with more frequent metastatic stage (p = 0.04) while patients with BRCA1 or BRCA2 alterations had improved overall survival (79 months vs. 39; p=0.05). We found that mutations in genes associated with chronic pancreatitis were more common in non-white patients (p<0.001) and associated with longer overall survival (52 months vs. 26; p=0.004), indicating the need for greater study of the relationship among these factors. More than 90% of patients were found to have variants of uncertain significance, which is higher than previously reported. Furthermore, we generated 3D models for selected mutant proteins, which suggested distinct mechanisms underlying their dysfunction, likely caused by genetic alterations. Notably, this type of information is not predictable from sequence alone, underscoring the value of structural bioinformatics to improve genomic interpretation. In conclusion, the variation in PDAC predisposition genes appears to be more extensive than anticipated. This information adds to the growing body of literature on the genomic landscape of PDAC and brings us closer to a more widespread use of precision medicine for this challenging disease.
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Affiliation(s)
- Michael T Zimmermann
- Bioinformatics Research and Development Laboratory, Genomic Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, WI, United States.,Clinical and Translational Sciences Institute, Medical College of Wisconsin, Milwaukee, WI, United States.,Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Angela J Mathison
- Division of Research, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, United States.,Genomic Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Tim Stodola
- Division of Research, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Douglas B Evans
- Division of Surgical Oncology, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, United States.,LaBahn Pancreatic Cancer Program, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Jenica L Abrudan
- Genomic Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Wendy Demos
- Genomic Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Michael Tschannen
- Genomic Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Mohammed Aldakkak
- Division of Surgical Oncology, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Jennifer Geurts
- Genomic Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, WI, United States.,Genetic Counseling Program, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Gwen Lomberk
- Division of Research, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, United States.,Genomic Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, WI, United States.,LaBahn Pancreatic Cancer Program, Medical College of Wisconsin, Milwaukee, WI, United States.,Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Susan Tsai
- Division of Research, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, United States.,Division of Surgical Oncology, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, United States.,LaBahn Pancreatic Cancer Program, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Raul Urrutia
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, United States.,Division of Research, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, United States.,Genomic Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, WI, United States.,LaBahn Pancreatic Cancer Program, Medical College of Wisconsin, Milwaukee, WI, United States
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39
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Vrtis KB, Dewar JM, Chistol G, Wu RA, Graham TGW, Walter JC. Single-strand DNA breaks cause replisome disassembly. Mol Cell 2021; 81:1309-1318.e6. [PMID: 33484638 DOI: 10.1016/j.molcel.2020.12.039] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 12/11/2020] [Accepted: 12/23/2020] [Indexed: 11/16/2022]
Abstract
DNA damage impedes replication fork progression and threatens genome stability. Upon encounter with most DNA adducts, the replicative CMG helicase (CDC45-MCM2-7-GINS) stalls or uncouples from the point of synthesis, yet eventually resumes replication. However, little is known about the effect on replication of single-strand breaks or "nicks," which are abundant in mammalian cells. Using Xenopus egg extracts, we reveal that CMG collision with a nick in the leading strand template generates a blunt-ended double-strand break (DSB). Moreover, CMG, which encircles the leading strand template, "runs off" the end of the DSB. In contrast, CMG collision with a lagging strand nick generates a broken end with a single-stranded overhang. In this setting, CMG translocates along double-stranded DNA beyond the break and is then ubiquitylated and removed from chromatin by the same pathway used during replication termination. Our results show that nicks are uniquely dangerous DNA lesions that invariably cause replisome disassembly, and they suggest that CMG cannot be stored on dsDNA while cells resolve replication stress.
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Affiliation(s)
- Kyle B Vrtis
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA
| | - James M Dewar
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA
| | - Gheorghe Chistol
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA
| | - R Alex Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA
| | - Thomas G W Graham
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA
| | - Johannes C Walter
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA.
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40
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Abstract
In all cell types, a multi-protein machinery is required to accurately duplicate the large duplex DNA genome. This central life process requires five core replisome factors in all cellular life forms studied thus far. Unexpectedly, three of the five core replisome factors have no common ancestor between bacteria and eukaryotes. Accordingly, the replisome machines of bacteria and eukaryotes have important distinctions in the way that they are organized and function. This chapter outlines the major replication proteins that perform DNA duplication at replication forks, with particular attention to differences and similarities in the strategies used by eukaryotes and bacteria.
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Affiliation(s)
- Nina Y Yao
- DNA Replication Laboratory, The Rockefeller University, New York, USA, 10065
| | - Michael E O'Donnell
- DNA Replication Laboratory, The Rockefeller University, New York, USA, 10065. .,Howard Hughes Medical Institute, The Rockefeller University, New York, USA, 10065.
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41
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Chung J, Maruvka YE, Sudhaman S, Kelly J, Haradhvala NJ, Bianchi V, Edwards M, Forster VJ, Nunes NM, Galati MA, Komosa M, Deshmukh S, Cabric V, Davidson S, Zatzman M, Light N, Hayes R, Brunga L, Anderson ND, Ho B, Hodel KP, Siddaway R, Morrissy AS, Bowers DC, Larouche V, Bronsema A, Osborn M, Cole KA, Opocher E, Mason G, Thomas GA, George B, Ziegler DS, Lindhorst S, Vanan M, Yalon-Oren M, Reddy AT, Massimino M, Tomboc P, Van Damme A, Lossos A, Durno C, Aronson M, Morgenstern DA, Bouffet E, Huang A, Taylor MD, Villani A, Malkin D, Hawkins CE, Pursell ZF, Shlien A, Kunkel TA, Getz G, Tabori U. DNA Polymerase and Mismatch Repair Exert Distinct Microsatellite Instability Signatures in Normal and Malignant Human Cells. Cancer Discov 2020; 11:1176-1191. [PMID: 33355208 DOI: 10.1158/2159-8290.cd-20-0790] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 09/23/2020] [Accepted: 12/15/2020] [Indexed: 12/11/2022]
Abstract
Although replication repair deficiency, either by mismatch repair deficiency (MMRD) and/or loss of DNA polymerase proofreading, can cause hypermutation in cancer, microsatellite instability (MSI) is considered a hallmark of MMRD alone. By genome-wide analysis of tumors with germline and somatic deficiencies in replication repair, we reveal a novel association between loss of polymerase proofreading and MSI, especially when both components are lost. Analysis of indels in microsatellites (MS-indels) identified five distinct signatures (MS-sigs). MMRD MS-sigs are dominated by multibase losses, whereas mutant-polymerase MS-sigs contain primarily single-base gains. MS deletions in MMRD tumors depend on the original size of the MS and converge to a preferred length, providing mechanistic insight. Finally, we demonstrate that MS-sigs can be a powerful clinical tool for managing individuals with germline MMRD and replication repair-deficient cancers, as they can detect the replication repair deficiency in normal cells and predict their response to immunotherapy. SIGNIFICANCE: Exome- and genome-wide MSI analysis reveals novel signatures that are uniquely attributed to mismatch repair and DNA polymerase. This provides new mechanistic insight into MS maintenance and can be applied clinically for diagnosis of replication repair deficiency and immunotherapy response prediction.This article is highlighted in the In This Issue feature, p. 995.
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Affiliation(s)
- Jiil Chung
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada.,The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.,Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Yosef E Maruvka
- Massachusetts General Hospital Center for Cancer Research, Charlestown, Massachusetts.,Broad Institute of Harvard and MIT, Cambridge, Massachusetts
| | - Sumedha Sudhaman
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada.,The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Jacalyn Kelly
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada.,The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Nicholas J Haradhvala
- Massachusetts General Hospital Center for Cancer Research, Charlestown, Massachusetts.,Broad Institute of Harvard and MIT, Cambridge, Massachusetts.,Harvard Graduate Program in Biophysics, Harvard University, Cambridge, Massachusetts
| | - Vanessa Bianchi
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Melissa Edwards
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Victoria J Forster
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada.,The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Nuno M Nunes
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada.,The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Melissa A Galati
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada.,The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.,Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Martin Komosa
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Shriya Deshmukh
- Department of Experimental Medicine, McGill University, Montreal, Quebec, Canada.,The Research Institute of the McGill University Health Center, Montreal, Quebec, Canada
| | - Vanja Cabric
- Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada
| | - Scott Davidson
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Matthew Zatzman
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Nicholas Light
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada.,Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Reid Hayes
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Ledia Brunga
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Nathaniel D Anderson
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Ben Ho
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Karl P Hodel
- Department of Biochemistry and Molecular Biology, Tulane Cancer Center, Tulane University of Medicine, New Orleans, Louisiana
| | - Robert Siddaway
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - A Sorana Morrissy
- Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Charbonneau Cancer Institute and Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Daniel C Bowers
- Department of Pediatrics and Harold C. Simmons Comprehensive Cancer Center, The University of Texas Southwestern Medical Center, Dallas, Texas.,Pauline Allen Gill Center for Cancer and Blood Disorders, Children's Health, Dallas, Texas
| | - Valérie Larouche
- Department of Pediatrics, Centre Mere-enfant Soleil du CHU de Quebec, CRCHU de Quebec, Universite Laval, Quebec City, Quebec, Canada
| | - Annika Bronsema
- Department of Pediatric Hematology and Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Michael Osborn
- Department of Haematology and Oncology, Women's and Children's Hospital, North Adelaide, South Australia, Australia
| | - Kristina A Cole
- Division of Oncology and Center for Childhood Cancer Research, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.,Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Enrico Opocher
- Pediatric Oncology and Hematology, Azienda Ospedaliera-Universita' degli Studi di Padova, Padova, Italy
| | - Gary Mason
- Department of Pediatric Hematology-Oncology, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania
| | - Gregory A Thomas
- Division of Pediatric Hematology-Oncology, Oregon Health and Science University, Portland, Oregon
| | - Ben George
- Division of Hematology and Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - David S Ziegler
- Kids Cancer Centre, Sydney Children's Hospital, Randwick, New South Wales, Australia.,Children's Cancer Institute, Lowy Cancer Research Centre, University of New South Wales, Randwick, New South Wales, Australia
| | - Scott Lindhorst
- Neuro-Oncology, Department of Neurosurgery, and Department of Medicine, Division of Hematology/Medical Oncology, Medical University of South Carolina Charleston, South Carolina
| | - Magimairajan Vanan
- Department of Pediatric Hematology-Oncology, Cancer Care Manitoba; Research Institute in Oncology and Hematology (RIOH), University of Manitoba, Winnipeg, Manitoba, Canada
| | - Michal Yalon-Oren
- Pediatric Hemato-Oncology, Edmond and Lilly Safra Children's Hospital and Cancer Research Center, Sheba Medical Center, Tel Hashomer Affiliated to the Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel
| | - Alyssa T Reddy
- Division of Pediatric Hematology and Oncology, Department of Pediatrics, University of Alabama at Birmingham, Birmingham, Alabama
| | - Maura Massimino
- Pediatric Unit, Fondazione IRCCS Istituto Nazionale dei Tumori (INT), Milano, Italy
| | - Patrick Tomboc
- Department of Pediatrics Section of Hematology-Oncology, WVU Medicine Children's, Morgantown, West Virginia
| | - An Van Damme
- Division of Hematology and Oncology, Department of Pediatrics, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Alexander Lossos
- Department of Neurology, Agnes Ginges Center for Human Neurogenetics, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Carol Durno
- Zane Cohen Centre for Digestive Diseases, Mount Sinai Hospital, Toronto, Ontario, Canada.,Division of Gastroenterology, Hepatology and Nutrition, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Melyssa Aronson
- Zane Cohen Centre for Digestive Diseases, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Daniel A Morgenstern
- Department of Paediatrics, Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada
| | - Eric Bouffet
- Department of Hematology/Oncology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Annie Huang
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,Department of Hematology/Oncology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Michael D Taylor
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Neurosurgery, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Anita Villani
- Department of Hematology/Oncology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - David Malkin
- Department of Hematology/Oncology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Cynthia E Hawkins
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,Program in Cell Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Zachary F Pursell
- Department of Biochemistry and Molecular Biology, Tulane Cancer Center, Tulane University of Medicine, New Orleans, Louisiana
| | - Adam Shlien
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Thomas A Kunkel
- Genome Integrity Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Durham, North Carolina
| | - Gad Getz
- Massachusetts General Hospital Center for Cancer Research, Charlestown, Massachusetts. .,Broad Institute of Harvard and MIT, Cambridge, Massachusetts.,Harvard Medical School, Boston, Massachusetts.,Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts
| | - Uri Tabori
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada. .,The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Hematology/Oncology, The Hospital for Sick Children, Toronto, Ontario, Canada
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42
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Galati MA, Hodel KP, Gams MS, Sudhaman S, Bridge T, Zahurancik WJ, Ungerleider NA, Park VS, Ercan AB, Joksimovic L, Siddiqui I, Siddaway R, Edwards M, de Borja R, Elshaer D, Chung J, Forster VJ, Nunes NM, Aronson M, Wang X, Ramdas J, Seeley A, Sarosiek T, Dunn GP, Byrd JN, Mordechai O, Durno C, Martin A, Shlien A, Bouffet E, Suo Z, Jackson JG, Hawkins CE, Guidos CJ, Pursell ZF, Tabori U. Cancers from Novel Pole-Mutant Mouse Models Provide Insights into Polymerase-Mediated Hypermutagenesis and Immune Checkpoint Blockade. Cancer Res 2020; 80:5606-5618. [PMID: 32938641 PMCID: PMC8218238 DOI: 10.1158/0008-5472.can-20-0624] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 06/25/2020] [Accepted: 09/11/2020] [Indexed: 12/31/2022]
Abstract
POLE mutations are a major cause of hypermutant cancers, yet questions remain regarding mechanisms of tumorigenesis, genotype-phenotype correlation, and therapeutic considerations. In this study, we establish mouse models harboring cancer-associated POLE mutations P286R and S459F, which cause rapid albeit distinct time to cancer initiation in vivo, independent of their exonuclease activity. Mouse and human correlates enabled novel stratification of POLE mutations into three groups based on clinical phenotype and mutagenicity. Cancers driven by these mutations displayed striking resemblance to the human ultrahypermutation and specific signatures. Furthermore, Pole-driven cancers exhibited a continuous and stochastic mutagenesis mechanism, resulting in intertumoral and intratumoral heterogeneity. Checkpoint blockade did not prevent Pole lymphomas, but rather likely promoted lymphomagenesis as observed in humans. These observations provide insights into the carcinogenesis of POLE-driven tumors and valuable information for genetic counseling, surveillance, and immunotherapy for patients. SIGNIFICANCE: Two mouse models of polymerase exonuclease deficiency shed light on mechanisms of mutation accumulation and considerations for immunotherapy.See related commentary by Wisdom and Kirsch p. 5459.
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Affiliation(s)
- Melissa A Galati
- Program in Genetics and Genome Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Karl P Hodel
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, Louisiana
- Tulane Cancer Center, Tulane University School of Medicine, New Orleans, Louisiana
| | - Miki S Gams
- Program in Developmental and Stem Cell Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Immunology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Sumedha Sudhaman
- Program in Genetics and Genome Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Taylor Bridge
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
- Program in Cell Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Walter J Zahurancik
- The Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio
| | - Nathan A Ungerleider
- Tulane Cancer Center, Tulane University School of Medicine, New Orleans, Louisiana
| | - Vivian S Park
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, Louisiana
- Tulane Cancer Center, Tulane University School of Medicine, New Orleans, Louisiana
| | - Ayse B Ercan
- Program in Genetics and Genome Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Lazar Joksimovic
- Program in Genetics and Genome Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Iram Siddiqui
- Department of Pediatric Laboratory Medicine, Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Robert Siddaway
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
- Program in Cell Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Melissa Edwards
- Program in Genetics and Genome Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Richard de Borja
- Program in Genetics and Genome Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Dana Elshaer
- Program in Genetics and Genome Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Jiil Chung
- Program in Genetics and Genome Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Victoria J Forster
- Program in Genetics and Genome Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Nuno M Nunes
- Program in Genetics and Genome Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Melyssa Aronson
- The Familial Gastrointestinal Cancer Registry at the Zane Cohen Centre for Digestive Disease, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Xia Wang
- H Lee Moffitt Cancer Centre and Research Institute, Tampa, Florida
| | - Jagadeesh Ramdas
- Department of Pediatrics, Geisinger Medical Center, Danville, Pennsylvania
| | - Andrea Seeley
- Department of Pediatrics, Geisinger Medical Center, Danville, Pennsylvania
| | | | - Gavin P Dunn
- Department of Neurological Surgery, Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, St. Louis, Missouri
| | - Jonathan N Byrd
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri
| | - Oz Mordechai
- Department of Pediatric Hematology Oncology, Rambam Health Care Campus, Haifa, Israel
| | - Carol Durno
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Paediatrics, University of Toronto, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Alberto Martin
- Department of Immunology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Adam Shlien
- Program in Genetics and Genome Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Eric Bouffet
- Division of Haematology/Oncology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Zucai Suo
- The Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida
| | - James G Jackson
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, Louisiana
- Tulane Cancer Center, Tulane University School of Medicine, New Orleans, Louisiana
| | - Cynthia E Hawkins
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
- Program in Cell Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Pediatric Laboratory Medicine, Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Cynthia J Guidos
- Program in Developmental and Stem Cell Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Immunology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Zachary F Pursell
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, Louisiana
- Tulane Cancer Center, Tulane University School of Medicine, New Orleans, Louisiana
| | - Uri Tabori
- Program in Genetics and Genome Biology, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario, Canada.
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Division of Haematology/Oncology, The Hospital for Sick Children, Toronto, Ontario, Canada
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43
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Pavlov YI, Zhuk AS, Stepchenkova EI. DNA Polymerases at the Eukaryotic Replication Fork Thirty Years after: Connection to Cancer. Cancers (Basel) 2020; 12:E3489. [PMID: 33255191 PMCID: PMC7760166 DOI: 10.3390/cancers12123489] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/13/2020] [Accepted: 11/13/2020] [Indexed: 12/13/2022] Open
Abstract
Recent studies on tumor genomes revealed that mutations in genes of replicative DNA polymerases cause a predisposition for cancer by increasing genome instability. The past 10 years have uncovered exciting details about the structure and function of replicative DNA polymerases and the replication fork organization. The principal idea of participation of different polymerases in specific transactions at the fork proposed by Morrison and coauthors 30 years ago and later named "division of labor," remains standing, with an amendment of the broader role of polymerase δ in the replication of both the lagging and leading DNA strands. However, cancer-associated mutations predominantly affect the catalytic subunit of polymerase ε that participates in leading strand DNA synthesis. We analyze how new findings in the DNA replication field help elucidate the polymerase variants' effects on cancer.
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Affiliation(s)
- Youri I. Pavlov
- Eppley Institute for Research in Cancer and Allied Diseases and Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Genetics and Biotechnology, Saint-Petersburg State University, 199034 Saint Petersburg, Russia;
| | - Anna S. Zhuk
- International Laboratory of Computer Technologies, ITMO University, 197101 Saint Petersburg, Russia;
| | - Elena I. Stepchenkova
- Department of Genetics and Biotechnology, Saint-Petersburg State University, 199034 Saint Petersburg, Russia;
- Laboratory of Mutagenesis and Genetic Toxicology, Vavilov Institute of General Genetics, Saint-Petersburg Branch, Russian Academy of Sciences, 199034 Saint Petersburg, Russia
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44
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Stokes K, Winczura A, Song B, Piccoli GD, Grabarczyk DB. Ctf18-RFC and DNA Pol ϵ form a stable leading strand polymerase/clamp loader complex required for normal and perturbed DNA replication. Nucleic Acids Res 2020; 48:8128-8145. [PMID: 32585006 PMCID: PMC7641331 DOI: 10.1093/nar/gkaa541] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 06/05/2020] [Accepted: 06/16/2020] [Indexed: 12/28/2022] Open
Abstract
The eukaryotic replisome must faithfully replicate DNA and cope with replication fork blocks and stalling, while simultaneously promoting sister chromatid cohesion. Ctf18-RFC is an alternative PCNA loader that links all these processes together by an unknown mechanism. Here, we use integrative structural biology combined with yeast genetics and biochemistry to highlight the specific functions that Ctf18-RFC plays within the leading strand machinery via an interaction with the catalytic domain of DNA Pol ϵ. We show that a large and unusually flexible interface enables this interaction to occur constitutively throughout the cell cycle and regardless of whether forks are replicating or stalled. We reveal that, by being anchored to the leading strand polymerase, Ctf18-RFC can rapidly signal fork stalling to activate the S phase checkpoint. Moreover, we demonstrate that, independently of checkpoint signaling or chromosome cohesion, Ctf18-RFC functions in parallel to Chl1 and Mrc1 to protect replication forks and cell viability.
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Affiliation(s)
- Katy Stokes
- University of Warwick, Warwick Medical School, Coventry, UK
| | | | - Boyuan Song
- Rudolf Virchow Center for Integrative and Translational Bioimaging, Institute for Structural Biology, University of Würzburg, Josef-Schneider-Str. 2, Würzburg 97080, Germany.,Department of Biochemistry, Biocenter, University of Würzburg, Am Hubland, Würzburg 97074, Germany
| | | | - Daniel B Grabarczyk
- Rudolf Virchow Center for Integrative and Translational Bioimaging, Institute for Structural Biology, University of Würzburg, Josef-Schneider-Str. 2, Würzburg 97080, Germany
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45
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Kazlauskas D, Krupovic M, Guglielmini J, Forterre P, Venclovas Č. Diversity and evolution of B-family DNA polymerases. Nucleic Acids Res 2020; 48:10142-10156. [PMID: 32976577 PMCID: PMC7544198 DOI: 10.1093/nar/gkaa760] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/27/2020] [Accepted: 09/02/2020] [Indexed: 12/20/2022] Open
Abstract
B-family DNA polymerases (PolBs) represent the most common replicases. PolB enzymes that require RNA (or DNA) primed templates for DNA synthesis are found in all domains of life and many DNA viruses. Despite extensive research on PolBs, their origins and evolution remain enigmatic. Massive accumulation of new genomic and metagenomic data from diverse habitats as well as availability of new structural information prompted us to conduct a comprehensive analysis of the PolB sequences, structures, domain organizations, taxonomic distribution and co-occurrence in genomes. Based on phylogenetic analysis, we identified a new, widespread group of bacterial PolBs that are more closely related to the catalytically active N-terminal half of the eukaryotic PolEpsilon (PolEpsilonN) than to Escherichia coli Pol II. In Archaea, we characterized six new groups of PolBs. Two of them show close relationships with eukaryotic PolBs, the first one with PolEpsilonN, and the second one with PolAlpha, PolDelta and PolZeta. In addition, structure comparisons suggested common origin of the catalytically inactive C-terminal half of PolEpsilon (PolEpsilonC) and PolAlpha. Finally, in certain archaeal PolBs we discovered C-terminal Zn-binding domains closely related to those of PolAlpha and PolEpsilonC. Collectively, the obtained results allowed us to propose a scenario for the evolution of eukaryotic PolBs.
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Affiliation(s)
- Darius Kazlauskas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, Vilnius 10257, Lithuania
| | - Mart Krupovic
- Archaeal Virology Unit, Department of Microbiology, Institut Pasteur, 25 rue du Docteur Roux, Paris 75015, France
| | - Julien Guglielmini
- Hub de Bioinformatique et Biostatistique - Département Biologie Computationnelle, Institut Pasteur, USR 3756 CNRS, Paris, France
| | - Patrick Forterre
- Archaeal Virology Unit, Department of Microbiology, Institut Pasteur, 25 rue du Docteur Roux, Paris 75015, France
| | - Česlovas Venclovas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, Vilnius 10257, Lithuania
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46
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Yuan Z, Li H. Molecular mechanisms of eukaryotic origin initiation, replication fork progression, and chromatin maintenance. Biochem J 2020; 477:3499-3525. [PMID: 32970141 PMCID: PMC7574821 DOI: 10.1042/bcj20200065] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/29/2020] [Accepted: 09/04/2020] [Indexed: 12/13/2022]
Abstract
Eukaryotic DNA replication is a highly dynamic and tightly regulated process. Replication involves several dozens of replication proteins, including the initiators ORC and Cdc6, replicative CMG helicase, DNA polymerase α-primase, leading-strand DNA polymerase ε, and lagging-strand DNA polymerase δ. These proteins work together in a spatially and temporally controlled manner to synthesize new DNA from the parental DNA templates. During DNA replication, epigenetic information imprinted on DNA and histone proteins is also copied to the daughter DNA to maintain the chromatin status. DNA methyltransferase 1 is primarily responsible for copying the parental DNA methylation pattern into the nascent DNA. Epigenetic information encoded in histones is transferred via a more complex and less well-understood process termed replication-couple nucleosome assembly. Here, we summarize the most recent structural and biochemical insights into DNA replication initiation, replication fork elongation, chromatin assembly and maintenance, and related regulatory mechanisms.
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Affiliation(s)
- Zuanning Yuan
- Structural Biology Program, Van Andel Institute, Grand Rapids, Michigan, U.S.A
| | - Huilin Li
- Structural Biology Program, Van Andel Institute, Grand Rapids, Michigan, U.S.A
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47
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Guilliam TA, Yeeles JTP. An updated perspective on the polymerase division of labor during eukaryotic DNA replication. Crit Rev Biochem Mol Biol 2020; 55:469-481. [PMID: 32883112 DOI: 10.1080/10409238.2020.1811630] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In eukaryotes three DNA polymerases (Pols), α, δ, and ε, are tasked with bulk DNA synthesis of nascent strands during genome duplication. Most evidence supports a model where Pol α initiates DNA synthesis before Pol ε and Pol δ replicate the leading and lagging strands, respectively. However, a number of recent reports, enabled by advances in biochemical and genetic techniques, have highlighted emerging roles for Pol δ in all stages of leading-strand synthesis; initiation, elongation, and termination, as well as fork restart. By focusing on these studies, this review provides an updated perspective on the division of labor between the replicative polymerases during DNA replication.
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Affiliation(s)
- Thomas A Guilliam
- Division of Protein and Nucleic Acid Chemistry, Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Joseph T P Yeeles
- Division of Protein and Nucleic Acid Chemistry, Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
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48
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Abstract
A helium atom superfluid was originally discovered by Kapitsa and Allen. Biological channels in such a fluid allow ultrafast molecule and ion transport, defined as a quantum-confined superfluid (QSF). In the process of enzymatic biosynthesis, unique performances can be achieved with high flux, 100% selectivity and low reaction activation energy at room temperature, under atmospheric pressure in an aqueous environment. Such reactions are considered as QSF reactions. In this perspective, we introduce the concept of QSF reactions in artificial systems. Through designing the channel size at the van der Waals equilibrium distance (r0) for molecules or the Debye length (λD) for ions, and arranging the reactants orderly in the channel to satisfy symmetry-matching principles, QSF reactions in artificial systems can be realized with high flux, 100% selectivity and low reaction activation energy. Several types of QSF-like molecular reactions are summarized, including quantum-confined polymerizations, quasi-superfluid-based reactions and superfluid-based molecular reactions, followed by the discussion of QSF ion redox reactions. We envision in the future that chemical engineering, based on multi-step QSF reactions, and a tubular reactor with continuous nanochannel membranes taking advantage of high flux, high selectivity and low energy consumption, will replace the traditional tower reactor, and bring revolutionary technology to both chemistry and chemical engineering. The concept of quantum-confined superfluid reactions is introduced into artificial systems, which is expected to be useful in future chemical engineering.![]()
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Affiliation(s)
- Yuwei Hao
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University Beijing 100191 P. R. China
| | - Shuai Pang
- CAS Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences Beijing 100190 P. R. China
| | - Xiqi Zhang
- CAS Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences Beijing 100190 P. R. China
| | - Lei Jiang
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University Beijing 100191 P. R. China .,CAS Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences Beijing 100190 P. R. China .,School of Future Technology, University of Chinese Academy of Sciences Beijing 100049 P. R. China
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49
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Abstract
We report here crystal structures of a reverse transcriptase RTX, which was evolved in vitro from the B family polymerase KOD, in complex with either a DNA duplex or an RNA-DNA hybrid. Compared with the apo, binary, and ternary complex structures of the original KOD polymerase, the 16 substitutions that result in the function of copying RNA to DNA do not change the overall protein structure. Only six substitutions occur at the substrate-binding surface, and the others change domain-domain interfaces in the polymerase to enable RNA-DNA hybrid binding and reverse transcription. Most notably, F587L at the Palm and Thumb interface stabilizes the open and apo conformation of the Thumb. The intrinsically flexible Thumb domain seems to play a major role in accommodating the RNA-DNA hybrid product distal to the active site. This is reminiscent of naturally occurring RNA-dependent DNA polymerases, including telomerase, which have a dramatically augmented Thumb domain, and of reverse transcriptase, which extends its Thumb with the RNase H domain.
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50
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Structure of the polymerase ε holoenzyme and atomic model of the leading strand replisome. Nat Commun 2020; 11:3156. [PMID: 32572031 PMCID: PMC7308368 DOI: 10.1038/s41467-020-16910-5] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 06/02/2020] [Indexed: 01/01/2023] Open
Abstract
The eukaryotic leading strand DNA polymerase (Pol) ε contains 4 subunits, Pol2, Dpb2, Dpb3 and Dpb4. Pol2 is a fusion of two B-family Pols; the N-terminal Pol module is catalytic and the C-terminal Pol module is non-catalytic. Despite extensive efforts, there is no atomic structure for Pol ε holoenzyme, critical to understanding how DNA synthesis is coordinated with unwinding and the DNA path through the CMG helicase-Pol ε-PCNA clamp. We show here a 3.5-Å cryo-EM structure of yeast Pol ε revealing that the Dpb3–Dpb4 subunits bridge the two DNA Pol modules of Pol2, holding them rigid. This information enabled an atomic model of the leading strand replisome. Interestingly, the model suggests that an OB fold in Dbp2 directs leading ssDNA from CMG to the Pol ε active site. These results complete the DNA path from entry of parental DNA into CMG to exit of daughter DNA from PCNA. DNA polymerase epsilon (Pol ε) is responsible for leading strand synthesis during DNA replication. Here the authors use Cryo-EM to describe the architecture of the Pol ε holoenzyme and to provide an atomic model for the leading strand replisome.
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