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Norris J, Rogers L, Pytko K, Dannenberg R, Perreault S, Kaushik V, Kuppa S, Antony E, Hedglin M. Replication protein A dynamically re-organizes on primer/template junctions to permit DNA polymerase δ holoenzyme assembly and initiation of DNA synthesis. Nucleic Acids Res 2024; 52:7650-7664. [PMID: 38842913 PMCID: PMC11260492 DOI: 10.1093/nar/gkae475] [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: 08/28/2023] [Revised: 05/03/2024] [Accepted: 05/21/2024] [Indexed: 06/07/2024] Open
Abstract
DNA polymerase δ (pol δ) holoenzymes, comprised of pol δ and the processivity sliding clamp, PCNA, carry out DNA synthesis during lagging strand replication, initiation of leading strand replication, and the major DNA damage repair and tolerance pathways. Pol δ holoenzymes are assembled at primer/template (P/T) junctions and initiate DNA synthesis in a stepwise process involving the major single strand DNA (ssDNA)-binding protein complex, RPA, the processivity sliding clamp loader, RFC, PCNA and pol δ. During this process, the interactions of RPA, RFC and pol δ with a P/T junction all significantly overlap. A burning issue that has yet to be resolved is how these overlapping interactions are accommodated during this process. To address this, we design and utilize novel, ensemble FRET assays that continuously monitor the interactions of RPA, RFC, PCNA and pol δ with DNA as pol δ holoenzymes are assembled and initiate DNA synthesis. Results from the present study reveal that RPA remains engaged with P/T junctions throughout this process and the RPA•DNA complexes dynamically re-organize to allow successive binding of RFC and pol δ. These results have broad implications as they highlight and distinguish the functional consequences of dynamic RPA•DNA interactions in RPA-dependent DNA metabolic processes.
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Affiliation(s)
- Jessica L Norris
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Lindsey O Rogers
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Kara G Pytko
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Rachel L Dannenberg
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Samuel Perreault
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Vikas Kaushik
- The Saint Louis University School of Medicine, Department of Biochemistry and Molecular Biology, St. Louis, MO 63104, USA
| | - Sahiti Kuppa
- The Saint Louis University School of Medicine, Department of Biochemistry and Molecular Biology, St. Louis, MO 63104, USA
| | - Edwin Antony
- The Saint Louis University School of Medicine, Department of Biochemistry and Molecular Biology, St. Louis, MO 63104, USA
| | - Mark Hedglin
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
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2
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Kang S, Yoo J, Myung K. PCNA cycling dynamics during DNA replication and repair in mammals. Trends Genet 2024; 40:526-539. [PMID: 38485608 DOI: 10.1016/j.tig.2024.02.006] [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: 01/17/2024] [Revised: 02/18/2024] [Accepted: 02/20/2024] [Indexed: 06/06/2024]
Abstract
Proliferating cell nuclear antigen (PCNA) is a eukaryotic replicative DNA clamp. Furthermore, DNA-loaded PCNA functions as a molecular hub during DNA replication and repair. PCNA forms a closed homotrimeric ring that encircles the DNA, and association and dissociation of PCNA from DNA are mediated by clamp-loader complexes. PCNA must be actively released from DNA after completion of its function. If it is not released, abnormal accumulation of PCNA on chromatin will interfere with DNA metabolism. ATAD5 containing replication factor C-like complex (RLC) is a PCNA-unloading clamp-loader complex. ATAD5 deficiency causes various DNA replication and repair problems, leading to genome instability. Here, we review recent progress regarding the understanding of the action mechanisms of PCNA unloading complex in DNA replication/repair pathways.
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Affiliation(s)
- Sukhyun Kang
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Juyeong Yoo
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea; Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Kyungjae Myung
- Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea; Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea.
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3
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Pytko KG, Dannenberg RL, Eckert KA, Hedglin M. Replication of [AT/TA] 25 Microsatellite Sequences by Human DNA Polymerase δ Holoenzymes Is Dependent on dNTP and RPA Levels. Biochemistry 2024; 63:969-983. [PMID: 38623046 DOI: 10.1021/acs.biochem.4c00006] [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] [Indexed: 04/17/2024]
Abstract
Fragile sites are unstable genomic regions that are prone to breakage during stressed DNA replication. Several common fragile sites (CFS) contain A+T-rich regions including perfect [AT/TA] microsatellite repeats that may collapse into hairpins when in single-stranded DNA (ssDNA) form and coincide with chromosomal hotspots for breakage and rearrangements. While many factors contribute to CFS instability, evidence exists for replication stalling within [AT/TA] microsatellite repeats. Currently, it is unknown how stress causes replication stalling within [AT/TA] microsatellite repeats. To investigate this, we utilized FRET to characterize the structures of [AT/TA]25 sequences and also reconstituted lagging strand replication to characterize the progression of pol δ holoenzymes through A+T-rich sequences. The results indicate that [AT/TA]25 sequences adopt hairpins that are unwound by the major ssDNA-binding complex, RPA, and the progression of pol δ holoenzymes through A+T-rich sequences saturated with RPA is dependent on the template sequence and dNTP concentration. Importantly, the effects of RPA on the replication of [AT/TA]25 sequences are dependent on dNTP concentration, whereas the effects of RPA on the replication of A+T-rich, nonstructure-forming sequences are independent of dNTP concentration. Collectively, these results reveal complexities in lagging strand replication and provide novel insights into how [AT/TA] microsatellite repeats contribute to genome instability.
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Affiliation(s)
- Kara G Pytko
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, United States
| | - Rachel L Dannenberg
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, United States
| | - Kristin A Eckert
- Department of Pathology and Laboratory Medicine, The Jake Gittlen Laboratories for Cancer Research, Hershey, PA 17033, United States
| | - Mark Hedglin
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, United States
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4
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Muoio D, Laspata N, Dannenberg RL, Curry C, Darkoa-Larbi S, Hedglin M, Uttam S, Fouquerel E. PARP2 promotes Break Induced Replication-mediated telomere fragility in response to replication stress. Nat Commun 2024; 15:2857. [PMID: 38565848 PMCID: PMC10987537 DOI: 10.1038/s41467-024-47222-7] [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: 05/30/2023] [Accepted: 03/22/2024] [Indexed: 04/04/2024] Open
Abstract
PARP2 is a DNA-dependent ADP-ribosyl transferase (ARTs) enzyme with Poly(ADP-ribosyl)ation activity that is triggered by DNA breaks. It plays a role in the Base Excision Repair pathway, where it has overlapping functions with PARP1. However, additional roles for PARP2 have emerged in the response of cells to replication stress. In this study, we demonstrate that PARP2 promotes replication stress-induced telomere fragility and prevents telomere loss following chronic induction of oxidative DNA lesions and BLM helicase depletion. Telomere fragility results from the activity of the break-induced replication pathway (BIR). During this process, PARP2 promotes DNA end resection, strand invasion and BIR-dependent mitotic DNA synthesis by orchestrating POLD3 recruitment and activity. Our study has identified a role for PARP2 in the response to replication stress. This finding may lead to the development of therapeutic approaches that target DNA-dependent ART enzymes, particularly in cancer cells with high levels of replication stress.
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Affiliation(s)
- Daniela Muoio
- UPMC Hillman Cancer Center, University of Pittsburgh Cancer Institute, Department of Pharmacology and Chemical Biology, Pittsburgh, PA, 15213, USA
| | - Natalie Laspata
- UPMC Hillman Cancer Center, University of Pittsburgh Cancer Institute, Department of Pharmacology and Chemical Biology, Pittsburgh, PA, 15213, USA
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233S. 10th street, Philadelphia, PA, 19107, USA
| | - Rachel L Dannenberg
- Department of Chemistry, The Pennsylvania State University, University park, State College, PA, 16802, USA
| | - Caroline Curry
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233S. 10th street, Philadelphia, PA, 19107, USA
| | - Simone Darkoa-Larbi
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233S. 10th street, Philadelphia, PA, 19107, USA
| | - Mark Hedglin
- Department of Chemistry, The Pennsylvania State University, University park, State College, PA, 16802, USA
| | - Shikhar Uttam
- Department of Computational and Systems Biology, UPMC Hillman Cancer Center, University of Pittsburgh, 5117 Centre Avenue, Pittsburgh, PA, 15213, USA
| | - Elise Fouquerel
- UPMC Hillman Cancer Center, University of Pittsburgh Cancer Institute, Department of Pharmacology and Chemical Biology, Pittsburgh, PA, 15213, USA.
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5
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Pytko KG, Dannenberg RL, Eckert KA, Hedglin M. Replication of [AT/TA] 25 microsatellite sequences by human DNA polymerase δ holoenzymes is dependent on dNTP and RPA levels. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.07.566133. [PMID: 37986888 PMCID: PMC10659299 DOI: 10.1101/2023.11.07.566133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Difficult-to-Replicate Sequences (DiToRS) are natural impediments in the human genome that inhibit DNA replication under endogenous replication. Some of the most widely-studied DiToRS are A+T-rich, high "flexibility regions," including long stretches of perfect [AT/TA] microsatellite repeats that have the potential to collapse into hairpin structures when in single-stranded DNA (ssDNA) form and are sites of recurrent structural variation and double-stranded DNA (dsDNA) breaks. Currently, it is unclear how these flexibility regions impact DNA replication, greatly limiting our fundamental understanding of human genome stability. To investigate replication through flexibility regions, we utilized FRET to characterize the effects of the major ssDNA-binding complex, RPA, on the structure of perfect [AT/TA]25 microsatellite repeats and also re-constituted human lagging strand replication to quantitatively characterize initial encounters of pol δ holoenzymes with A+T-rich DNA template sequences. The results indicate that [AT/TA]25 sequences adopt hairpin structures that are unwound by RPA and pol δ holoenzymes support dNTP incorporation through the [AT/TA]25 sequences as well as an A+T-rich, non-structure forming sequence. Furthermore, the extent of dNTP incorporation is dependent on the sequence of the DNA template and the concentration of dNTPs. Importantly, the effects of RPA on the replication of [AT/TA]25 sequences are dependent on the concentration of dNTPs, whereas the effects of RPA on the replication of an A+T-rich, non-structure forming sequence are independent of dNTP concentration. Collectively, these results reveal complexities in lagging strand replication and provide novel insights into how flexibility regions contribute to genome instability.
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Affiliation(s)
- Kara G. Pytko
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
| | - Rachel L. Dannenberg
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
| | - Kristin A. Eckert
- Department of Pathology and Laboratory Medicine, The Jake Gittlen Laboratories for Cancer Research, Hershey, PA 17033
| | - Mark Hedglin
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
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6
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Jain A, Casanova D, Padilla AV, Paniagua Bojorges A, Kotla S, Ko KA, Samanthapudi VSK, Chau K, Nguyen MTH, Wen J, Hernandez Gonzalez SL, Rodgers SP, Olmsted-Davis EA, Hamilton DJ, Reyes-Gibby C, Yeung SCJ, Cooke JP, Herrmann J, Chini EN, Xu X, Yusuf SW, Yoshimoto M, Lorenzi PL, Hobbs B, Krishnan S, Koutroumpakis E, Palaskas NL, Wang G, Deswal A, Lin SH, Abe JI, Le NT. Premature senescence and cardiovascular disease following cancer treatments: mechanistic insights. Front Cardiovasc Med 2023; 10:1212174. [PMID: 37781317 PMCID: PMC10540075 DOI: 10.3389/fcvm.2023.1212174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 08/03/2023] [Indexed: 10/03/2023] Open
Abstract
Cardiovascular disease (CVD) is a leading cause of morbidity and mortality, especially among the aging population. The "response-to-injury" model proposed by Dr. Russell Ross in 1999 emphasizes inflammation as a critical factor in atherosclerosis development, with atherosclerotic plaques forming due to endothelial cell (EC) injury, followed by myeloid cell adhesion and invasion into the blood vessel walls. Recent evidence indicates that cancer and its treatments can lead to long-term complications, including CVD. Cellular senescence, a hallmark of aging, is implicated in CVD pathogenesis, particularly in cancer survivors. However, the precise mechanisms linking premature senescence to CVD in cancer survivors remain poorly understood. This article aims to provide mechanistic insights into this association and propose future directions to better comprehend this complex interplay.
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Affiliation(s)
- Ashita Jain
- Department of Cardiology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Diego Casanova
- Department of Cardiology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | | | | | - Sivareddy Kotla
- Department of Cardiology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Kyung Ae Ko
- Department of Cardiology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | | | - Khanh Chau
- Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX, United States
| | - Minh T. H. Nguyen
- Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX, United States
| | - Jake Wen
- Department of Cardiology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | | | - Shaefali P. Rodgers
- Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX, United States
| | | | - Dale J. Hamilton
- Department of Medicine, Center for Bioenergetics, Houston Methodist Research Institute, Houston, TX, United States
| | - Cielito Reyes-Gibby
- Department of Emergency Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Sai-Ching J. Yeung
- Department of Emergency Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - John P. Cooke
- Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX, United States
| | - Joerg Herrmann
- Cardio Oncology Clinic, Division of Preventive Cardiology, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, United States
| | - Eduardo N. Chini
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Jacksonville, FL, United States
| | - Xiaolei Xu
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, United States
| | - Syed Wamique Yusuf
- Department of Cardiology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Momoko Yoshimoto
- Center for Stem Cell & Regenerative Medicine, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Philip L. Lorenzi
- Department of Bioinformatics and Computational Biology, Division of VP Research, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Brain Hobbs
- Department of Population Health, The University of Texas at Austin, Austin, TX, United States
| | - Sunil Krishnan
- Department of Neurosurgery, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Efstratios Koutroumpakis
- Department of Cardiology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Nicolas L. Palaskas
- Department of Cardiology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Guangyu Wang
- Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX, United States
| | - Anita Deswal
- Department of Cardiology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Steven H. Lin
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Jun-ichi Abe
- Department of Cardiology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Nhat-Tu Le
- Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX, United States
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7
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Norris JL, Rogers LO, Pytko KG, Dannenberg RL, Perreault S, Kaushik V, Kuppa S, Antony E, Hedglin M. Interplay of macromolecular interactions during assembly of human DNA polymerase δ holoenzymes and initiation of DNA synthesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.09.539896. [PMID: 37215012 PMCID: PMC10197535 DOI: 10.1101/2023.05.09.539896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In humans, DNA polymerase δ (Pol δ) holoenzymes, comprised of Pol δ and the processivity sliding clamp, proliferating cell nuclear antigen (PCNA), carry out DNA synthesis during lagging strand DNA replication, initiation of leading strand DNA replication, and the major DNA damage repair and tolerance pathways. Pol δ holoenzymes are assembled at primer/template (P/T) junctions and initiate DNA synthesis in a coordinated process involving the major single strand DNA-binding protein complex, replication protein A (RPA), the processivity sliding clamp loader, replication factor C (RFC), PCNA, and Pol δ. Each of these factors interact uniquely with a P/T junction and most directly engage one another. Currently, the interplay between these macromolecular interactions is largely unknown. In the present study, novel Förster Resonance Energy Transfer (FRET) assays reveal that dynamic interactions of RPA with a P/T junction during assembly of a Pol δ holoenzyme and initiation of DNA synthesis maintain RPA at a P/T junction and accommodate RFC, PCNA, and Pol δ, maximizing the efficiency of each process. Collectively, these studies significantly advance our understanding of human DNA replication and DNA repair.
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Affiliation(s)
- Jessica L. Norris
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
| | - Lindsey O. Rogers
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
| | - Kara G. Pytko
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
| | - Rachel L. Dannenberg
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
| | - Samuel Perreault
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
| | - Vikas Kaushik
- The Saint Louis University School of Medicine, Department of Biochemistry and Molecular Biology, St. Louis MO, 63104
| | - Sahiti Kuppa
- The Saint Louis University School of Medicine, Department of Biochemistry and Molecular Biology, St. Louis MO, 63104
| | - Edwin Antony
- The Saint Louis University School of Medicine, Department of Biochemistry and Molecular Biology, St. Louis MO, 63104
| | - Mark Hedglin
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
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8
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Dannenberg RL, Cardina JA, Pytko KG, Hedglin M. Tracking of progressing human DNA polymerase δ holoenzymes reveals distributions of DNA lesion bypass activities. Nucleic Acids Res 2022; 50:9893-9908. [PMID: 36107777 PMCID: PMC9508823 DOI: 10.1093/nar/gkac745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 08/10/2022] [Accepted: 08/23/2022] [Indexed: 11/13/2022] Open
Abstract
During DNA replication, DNA lesions in lagging strand templates are initially encountered by DNA polymerase δ (pol δ) holoenzymes comprised of pol δ and the PCNA processivity sliding clamp. These encounters are thought to stall replication of an afflicted template before the lesion, activating DNA damage tolerance (DDT) pathways that replicate the lesion and adjacent DNA sequence, allowing pol δ to resume. However, qualitative studies observed that human pol δ can replicate various DNA lesions, albeit with unknown proficiencies, which raises issues regarding the role of DDT in replicating DNA lesions. To address these issues, we re-constituted human lagging strand replication to quantitatively characterize initial encounters of pol δ holoenzymes with DNA lesions. The results indicate pol δ holoenzymes support dNTP incorporation opposite and beyond multiple lesions and the extent of these activities depends on the lesion and pol δ proofreading. Furthermore, after encountering a given DNA lesion, subsequent dissociation of pol δ is distributed around the lesion and a portion does not dissociate. The distributions of these events are dependent on the lesion and pol δ proofreading. Collectively, these results reveal complexity and heterogeneity in the replication of lagging strand DNA lesions, significantly advancing our understanding of human DDT.
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Affiliation(s)
- Rachel L Dannenberg
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Joseph A Cardina
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Kara G Pytko
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Mark Hedglin
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
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9
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Post-Translational Modifications of PCNA: Guiding for the Best DNA Damage Tolerance Choice. J Fungi (Basel) 2022; 8:jof8060621. [PMID: 35736104 PMCID: PMC9225081 DOI: 10.3390/jof8060621] [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: 04/29/2022] [Revised: 06/01/2022] [Accepted: 06/07/2022] [Indexed: 02/01/2023] Open
Abstract
The sliding clamp PCNA is a multifunctional homotrimer mainly linked to DNA replication. During this process, cells must ensure an accurate and complete genome replication when constantly challenged by the presence of DNA lesions. Post-translational modifications of PCNA play a crucial role in channeling DNA damage tolerance (DDT) and repair mechanisms to bypass unrepaired lesions and promote optimal fork replication restart. PCNA ubiquitination processes trigger the following two main DDT sub-pathways: Rad6/Rad18-dependent PCNA monoubiquitination and Ubc13-Mms2/Rad5-mediated PCNA polyubiquitination, promoting error-prone translation synthesis (TLS) or error-free template switch (TS) pathways, respectively. However, the fork protection mechanism leading to TS during fork reversal is still poorly understood. In contrast, PCNA sumoylation impedes the homologous recombination (HR)-mediated salvage recombination (SR) repair pathway. Focusing on Saccharomyces cerevisiae budding yeast, we summarized PCNA related-DDT and repair mechanisms that coordinately sustain genome stability and cell survival. In addition, we compared PCNA sequences from various fungal pathogens, considering recent advances in structural features. Importantly, the identification of PCNA epitopes may lead to potential fungal targets for antifungal drug development.
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10
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PCNA Loaders and Unloaders-One Ring That Rules Them All. Genes (Basel) 2021; 12:genes12111812. [PMID: 34828416 PMCID: PMC8618651 DOI: 10.3390/genes12111812] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 11/15/2021] [Accepted: 11/17/2021] [Indexed: 12/23/2022] Open
Abstract
During each cell duplication, the entirety of the genomic DNA in every cell must be accurately and quickly copied. Given the short time available for the chore, the requirement of many proteins, and the daunting amount of DNA present, DNA replication poses a serious challenge to the cell. A high level of coordination between polymerases and other DNA and chromatin-interacting proteins is vital to complete this task. One of the most important proteins for maintaining such coordination is PCNA. PCNA is a multitasking protein that forms a homotrimeric ring that encircles the DNA. It serves as a processivity factor for DNA polymerases and acts as a landing platform for different proteins interacting with DNA and chromatin. Therefore, PCNA is a signaling hub that influences the rate and accuracy of DNA replication, regulates DNA damage repair, controls chromatin formation during the replication, and the proper segregation of the sister chromatids. With so many essential roles, PCNA recruitment and turnover on the chromatin is of utmost importance. Three different, conserved protein complexes are in charge of loading/unloading PCNA onto DNA. Replication factor C (RFC) is the canonical complex in charge of loading PCNA during the S-phase. The Ctf18 and Elg1 (ATAD5 in mammalian) proteins form complexes similar to RFC, with particular functions in the cell’s nucleus. Here we summarize our current knowledge about the roles of these important factors in yeast and mammals.
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11
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Benkovic SJ. From Bioorganic Models to Cells. Annu Rev Biochem 2021; 90:57-76. [PMID: 34153218 DOI: 10.1146/annurev-biochem-062320-062929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
I endeavor to share how various choices-some deliberate, some unconscious-and the unmistakable influence of many others shaped my scientific pursuits. I am fascinated by how two long-term, major streams of my research, DNA replication and purine biosynthesis, have merged with unexpected interconnections. If I have imparted to many of the talented individuals who have passed through my lab a degree of my passion for uncloaking the mysteries hidden in scientific research and an understanding of the honesty and rigor it demands and its impact on the world community, then my mentorship has been successful.
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Affiliation(s)
- Stephen J Benkovic
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA;
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12
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Lee KY, Park SH. Eukaryotic clamp loaders and unloaders in the maintenance of genome stability. Exp Mol Med 2020; 52:1948-1958. [PMID: 33339954 PMCID: PMC8080817 DOI: 10.1038/s12276-020-00533-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 10/08/2020] [Accepted: 10/12/2020] [Indexed: 12/22/2022] Open
Abstract
Eukaryotic sliding clamp proliferating cell nuclear antigen (PCNA) plays a critical role as a processivity factor for DNA polymerases and as a binding and acting platform for many proteins. The ring-shaped PCNA homotrimer and the DNA damage checkpoint clamp 9-1-1 are loaded onto DNA by clamp loaders. PCNA can be loaded by the pentameric replication factor C (RFC) complex and the CTF18-RFC-like complex (RLC) in vitro. In cells, each complex loads PCNA for different purposes; RFC-loaded PCNA is essential for DNA replication, while CTF18-RLC-loaded PCNA participates in cohesion establishment and checkpoint activation. After completing its tasks, PCNA is unloaded by ATAD5 (Elg1 in yeast)-RLC. The 9-1-1 clamp is loaded at DNA damage sites by RAD17 (Rad24 in yeast)-RLC. All five RFC complex components, but none of the three large subunits of RLC, CTF18, ATAD5, or RAD17, are essential for cell survival; however, deficiency of the three RLC proteins leads to genomic instability. In this review, we describe recent findings that contribute to the understanding of the basic roles of the RFC complex and RLCs and how genomic instability due to deficiency of the three RLCs is linked to the molecular and cellular activity of RLC, particularly focusing on ATAD5 (Elg1). The attachment and removal of clamp proteins that encircle DNA as it is copied and assist its replication and maintenance is mediated by DNA clamp loader and unloader proteins; defects in loading and unloading can increase the rate of damaging mutations. Kyoo-young Lee and Su Hyung Park at the Institute for Basic Science in Ulsan, South Korea, review current understanding of the activity of clamp loading and unloading proteins. They examine research on the proteins in eukaryotic cells, those containing a cell nucleus, making their discussion relevant to understanding the stability of the human genome. They focus particular attention on a protein called ATAD5, which is involved in unloading the clamp proteins. Deficiencies in ATAD5 function have been implicated in genetic instability that might lead to several different types of cancer.
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Affiliation(s)
- Kyoo-Young Lee
- Center for Genomic Integrity, Institute for Basic Science, Ulsan, Korea.
| | - Su Hyung Park
- Center for Genomic Integrity, Institute for Basic Science, Ulsan, Korea
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13
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Structure of the human clamp loader reveals an autoinhibited conformation of a substrate-bound AAA+ switch. Proc Natl Acad Sci U S A 2020; 117:23571-23580. [PMID: 32907938 DOI: 10.1073/pnas.2007437117] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
DNA replication requires the sliding clamp, a ring-shaped protein complex that encircles DNA, where it acts as an essential cofactor for DNA polymerases and other proteins. The sliding clamp needs to be opened and installed onto DNA by a clamp loader ATPase of the AAA+ family. The human clamp loader replication factor C (RFC) and sliding clamp proliferating cell nuclear antigen (PCNA) are both essential and play critical roles in several diseases. Despite decades of study, no structure of human RFC has been resolved. Here, we report the structure of human RFC bound to PCNA by cryogenic electron microscopy to an overall resolution of ∼3.4 Å. The active sites of RFC are fully bound to adenosine 5'-triphosphate (ATP) analogs, which is expected to induce opening of the sliding clamp. However, we observe the complex in a conformation before PCNA opening, with the clamp loader ATPase modules forming an overtwisted spiral that is incapable of binding DNA or hydrolyzing ATP. The autoinhibited conformation observed here has many similarities to a previous yeast RFC:PCNA crystal structure, suggesting that eukaryotic clamp loaders adopt a similar autoinhibited state early on in clamp loading. Our results point to a "limited change/induced fit" mechanism in which the clamp first opens, followed by DNA binding, inducing opening of the loader to release autoinhibition. The proposed change from an overtwisted to an active conformation reveals an additional regulatory mechanism for AAA+ ATPases. Finally, our structural analysis of disease mutations leads to a mechanistic explanation for the role of RFC in human health.
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14
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Drosopoulos WC, Vierra DA, Kenworthy CA, Coleman RA, Schildkraut CL. Dynamic Assembly and Disassembly of the Human DNA Polymerase δ Holoenzyme on the Genome In Vivo. Cell Rep 2020; 30:1329-1341.e5. [PMID: 32023453 PMCID: PMC7597369 DOI: 10.1016/j.celrep.2019.12.101] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 11/21/2019] [Accepted: 12/30/2019] [Indexed: 12/15/2022] Open
Abstract
Human DNA polymerase delta (Pol δ) forms a holoenzyme complex with the DNA sliding clamp proliferating cell nuclear antigen (PCNA) to perform its essential roles in genome replication. Here, we utilize live-cell single-molecule tracking to monitor Pol δ holoenzyme interaction with the genome in real time. We find holoenzyme assembly and disassembly in vivo are highly dynamic and ordered. PCNA generally loads onto the genome before Pol δ. Once assembled, the holoenzyme has a relatively short lifetime on the genome, implying multiple Pol δ binding events may be needed to synthesize an Okazaki fragment. During disassembly, Pol δ dissociation generally precedes PCNA unloading. We also find that Pol δ p125, the catalytic subunit of the holoenzyme, is maintained at a constant cellular level, indicating an active mechanism for control of Pol δ levels in vivo. Collectively, our studies reveal that Pol δ holoenzyme assembly and disassembly follow a predominant pathway in vivo; however, alternate pathways are observed.
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Affiliation(s)
- William C Drosopoulos
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461 USA.
| | - David A Vierra
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461 USA
| | - Charles A Kenworthy
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461 USA
| | - Robert A Coleman
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461 USA.
| | - Carl L Schildkraut
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461 USA.
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15
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Li M, Larsen L, Hedglin M. Rad6/Rad18 Competes with DNA Polymerases η and δ for PCNA Encircling DNA. Biochemistry 2020; 59:407-416. [PMID: 31887036 DOI: 10.1021/acs.biochem.9b00938] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Translesion DNA synthesis (TLS) bypasses DNA lesions encountered during S-phase and is critical for cell survival after exposure to DNA-damaging agents. In humans, Rad6/Rad18 attaches single ubiquitin moieties (i.e., monoubiquitination) to proliferating cell nuclear antigen (PCNA) sliding clamps encircling primer/template (P/T) junctions that are stalled at DNA lesions. TLS occurs via PCNA monoubiquitination-independent and -dependent pathways, and both contribute to cell survival. The interaction of Rad6/Rad18 with PCNA is paramount to PCNA monoubiquitination and remains poorly defined. In particular, the location of the Rad6/Rad18 binding site on PCNA is unknown. Many PCNA-binding proteins, particularly DNA polymerases (pols), converge on PCNA encircling stalled P/T junctions in human cells, and all interact in a similar manner with the universal binding sites on PCNA. We reasoned the following: if Rad6/Rad18 utilizes the universal binding sites (or nearby sites), then PCNA monoubiquitination may be suppressed by pols involved in TLS. Results from quantitative studies reveal that (1) a Y-family pol (pol η) and a B-family pol (pol δ) critical to TLS each inhibit the transfer of ubiquitin from Rad6/Rad18 to PCNA and that (2) the observed inhibitions are dependent on the interaction of these pols with PCNA encircling DNA. These studies suggest that Rad6/Rad18 utilizes the universal PCNA-binding sites or nearby sites and, hence, competes for PCNA encircling DNA with pols η and δ and possibly other PCNA-binding proteins involved in TLS. These findings provide valuable insight into the nature of the interaction between Rad6/Rad18 and PCNA and have important implications for the division of human TLS pathways.
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Affiliation(s)
- Mingjie Li
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Leah Larsen
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Mark Hedglin
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
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16
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Tehseen M, Raducanu VS, Rashid F, Shirbini A, Takahashi M, Hamdan SM. Proliferating cell nuclear antigen-agarose column: A tag-free and tag-dependent tool for protein purification affinity chromatography. J Chromatogr A 2019; 1602:341-349. [DOI: 10.1016/j.chroma.2019.06.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 06/01/2019] [Accepted: 06/03/2019] [Indexed: 10/26/2022]
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17
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Regulation of PCNA cycling on replicating DNA by RFC and RFC-like complexes. Nat Commun 2019; 10:2420. [PMID: 31160570 PMCID: PMC6546911 DOI: 10.1038/s41467-019-10376-w] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 05/07/2019] [Indexed: 02/03/2023] Open
Abstract
Replication-Factor-C (RFC) and RFC-like complexes (RLCs) mediate chromatin engagement of the proliferating cell nuclear antigen (PCNA). It remains controversial how RFC and RLCs cooperate to regulate PCNA loading and unloading. Here, we show the distinct PCNA loading or unloading activity of each clamp loader. ATAD5-RLC possesses the potent PCNA unloading activity. ATPase motif and collar domain of ATAD5 are crucial for the unloading activity. DNA structures did not affect PCNA unloading activity of ATAD5-RLC. ATAD5-RLC could unload ubiquitinated PCNA. Through single molecule measurements, we reveal that ATAD5-RLC unloaded PCNA through one intermediate state before ATP hydrolysis. RFC loaded PCNA through two intermediate states on DNA, separated by ATP hydrolysis. Replication proteins such as Fen1 could inhibit the PCNA unloading activity of Elg1-RLC, a yeast homolog of ATAD5-RLC in vitro. Our findings provide molecular insights into how PCNA is released from chromatin to finalize DNA replication/repair.
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18
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Perumal SK, Xu X, Yan C, Ivanov I, Benkovic SJ. Recognition of a Key Anchor Residue by a Conserved Hydrophobic Pocket Ensures Subunit Interface Integrity in DNA Clamps. J Mol Biol 2019; 431:2493-2510. [PMID: 31051173 DOI: 10.1016/j.jmb.2019.04.035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Revised: 04/22/2019] [Accepted: 04/22/2019] [Indexed: 10/26/2022]
Abstract
Sliding clamp proteins encircle duplex DNA and are involved in processive DNA replication and the DNA damage response. Clamp proteins are ring-shaped oligomers (dimers or trimers) and are loaded onto DNA by an ATP-dependent clamp loader complex that ruptures the interface between two adjacent subunits. Here we measured the solution dynamics of the human clamp protein, proliferating cell nuclear antigen, by monitoring the change in the fluorescence of a site-specifically labeled. To unravel the origins of clamp subunit interface stability, we carried out comprehensive comparative analysis of the interfaces of seven sliding clamps. We used computational modeling (molecular dynamic simulations and MM/GBSA binding energy decomposition analyses) to identify conserved networks of hydrophobic residues critical for clamp stability and ring-opening dynamics. The hydrophobic network is shared among clamp proteins and exhibits a "key in a keyhole" pattern where a bulky aromatic residue from one clamp subunit is anchored into a hydrophobic pocket of the opposing subunit. Bioinformatics and dynamic network analyses showed that this oligomeric latch is conserved across DNA sliding clamps from all domains of life and dictates the dynamics of clamp opening and closing.
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Affiliation(s)
- Senthil K Perumal
- Department of Chemistry, 414 Wartik Laboratory, The Pennsylvania State University, University Park, PA 16802, USA
| | - Xiaojun Xu
- Department of Chemistry and Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30302, USA
| | - Chunli Yan
- Department of Chemistry and Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30302, USA
| | - Ivaylo Ivanov
- Department of Chemistry and Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30302, USA.
| | - Stephen J Benkovic
- Department of Chemistry, 414 Wartik Laboratory, The Pennsylvania State University, University Park, PA 16802, USA.
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19
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De March M, De Biasio A. The dark side of the ring: role of the DNA sliding surface of PCNA. Crit Rev Biochem Mol Biol 2017; 52:663-673. [DOI: 10.1080/10409238.2017.1364218] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Matteo De March
- Structural Biology Laboratory, Elettra-Sincrotrone Trieste S.C.p.A, Trieste, Italy
| | - Alfredo De Biasio
- Structural Biology Laboratory, Elettra-Sincrotrone Trieste S.C.p.A, Trieste, Italy
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20
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Hedglin M, Benkovic SJ. Eukaryotic Translesion DNA Synthesis on the Leading and Lagging Strands: Unique Detours around the Same Obstacle. Chem Rev 2017; 117:7857-7877. [PMID: 28497687 PMCID: PMC5662946 DOI: 10.1021/acs.chemrev.7b00046] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
During S-phase, minor DNA damage may be overcome by DNA damage tolerance (DDT) pathways that bypass such obstacles, postponing repair of the offending damage to complete the cell cycle and maintain cell survival. In translesion DNA synthesis (TLS), specialized DNA polymerases replicate the damaged DNA, allowing stringent DNA synthesis by a replicative polymerase to resume beyond the offending damage. Dysregulation of this DDT pathway in human cells leads to increased mutation rates that may contribute to the onset of cancer. Furthermore, TLS affords human cancer cells the ability to counteract chemotherapeutic agents that elicit cell death by damaging DNA in actively replicating cells. Currently, it is unclear how this critical pathway unfolds, in particular, where and when TLS occurs on each template strand. Given the semidiscontinuous nature of DNA replication, it is likely that TLS on the leading and lagging strand templates is unique for each strand. Since the discovery of DDT in the late 1960s, most studies on TLS in eukaryotes have focused on DNA lesions resulting from ultraviolet (UV) radiation exposure. In this review, we revisit these and other related studies to dissect the step-by-step intricacies of this complex process, provide our current understanding of TLS on leading and lagging strand templates, and propose testable hypotheses to gain further insights.
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Affiliation(s)
- Mark Hedglin
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, U.S.A
| | - Stephen J. Benkovic
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, U.S.A
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21
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Hedglin M, Aitha M, Benkovic SJ. Monitoring the Retention of Human Proliferating Cell Nuclear Antigen at Primer/Template Junctions by Proteins That Bind Single-Stranded DNA. Biochemistry 2017; 56:3415-3421. [PMID: 28590137 DOI: 10.1021/acs.biochem.7b00386] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In humans, proliferating cell nuclear antigen (PCNA) sliding clamps encircling DNA coordinate various aspects of DNA metabolism throughout the cell cycle. A critical aspect of this is restricting PCNA to the vicinity of its DNA target site. For example, PCNA must be maintained at or near primer/template (P/T) junctions during DNA synthesis. With a diverse array of cellular factors implicated, many of which interact with PCNA, DNA, or both, it is unknown how this critical feat is achieved. Furthermore, current biochemical assays that examine the retention of PCNA near P/T junctions are inefficient, discontinuous, and qualitative and significantly deviate from physiologically relevant conditions. To overcome these challenges and limitations, we recently developed a novel and convenient Förster resonance energy transfer (FRET) assay that directly and continuously monitors the retention of human PCNA at a P/T junction. Here we describe in detail the design, methodology, interpretation, and limitations of this quantitative FRET assay using the single-stranded DNA-binding protein, SSB, from Escherichia coli as an example. This powerful tool is broadly applicable to any single-stranded DNA-binding protein and may be utilized and/or expanded upon to dissect DNA metabolic pathways that are dependent upon PCNA.
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Affiliation(s)
- Mark Hedglin
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Mahesh Aitha
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Stephen J Benkovic
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
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22
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Hedglin M, Benkovic SJ. Replication Protein A Prohibits Diffusion of the PCNA Sliding Clamp along Single-Stranded DNA. Biochemistry 2017; 56:1824-1835. [PMID: 28177605 PMCID: PMC5382571 DOI: 10.1021/acs.biochem.6b01213] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The replicative polymerases cannot accommodate distortions to the native DNA sequence such as modifications (lesions) to the native template bases from exposure to reactive metabolites and environmental mutagens. Consequently, DNA synthesis on an afflicted template abruptly stops upon encountering these lesions, but the replication fork progresses onward, exposing long stretches of the damaged template before eventually stalling. Such arrests may be overcome by translesion DNA synthesis (TLS) in which specialized TLS polymerases bind to the resident proliferating cell nuclear antigen (PCNA) and replicate the damaged DNA. Hence, a critical aspect of TLS is maintaining PCNA at or near a blocked primer/template (P/T) junction upon uncoupling of fork progression from DNA synthesis by the replicative polymerases. The single-stranded DNA (ssDNA) binding protein, replication protein A (RPA), coats the exposed template and might prohibit diffusion of PCNA along the single-stranded DNA adjacent to a blocked P/T junction. However, this idea had yet to be directly tested. We recently developed a unique Cy3-Cy5 Forster resonance energy transfer (FRET) pair that directly reports on the occupancy of DNA by PCNA. In this study, we utilized this FRET pair to directly and continuously monitor the retention of human PCNA at a blocked P/T junction. Results from extensive steady state and pre-steady state FRET assays indicate that RPA binds tightly to the ssDNA adjacent to a blocked P/T junction and restricts PCNA to the upstream duplex region by physically blocking diffusion of PCNA along ssDNA.
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Affiliation(s)
- Mark Hedglin
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Stephen J Benkovic
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
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23
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Kelch BA. Review: The lord of the rings: Structure and mechanism of the sliding clamp loader. Biopolymers 2017; 105:532-46. [PMID: 26918303 DOI: 10.1002/bip.22827] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 02/15/2016] [Accepted: 02/23/2016] [Indexed: 12/15/2022]
Abstract
Sliding clamps are ring-shaped polymerase processivity factors that act as master regulators of cellular replication by coordinating multiple functions on DNA to ensure faithful transmission of genetic and epigenetic information. Dedicated AAA+ ATPase machines called clamp loaders actively place clamps on DNA, thereby governing clamp function by controlling when and where clamps are used. Clamp loaders are also important model systems for understanding the basic principles of AAA+ mechanism and function. After nearly 30 years of study, the ATP-dependent mechanism of opening and loading of clamps is now becoming clear. Here I review the structural and mechanistic aspects of the clamp loading process, as well as comment on questions that will be addressed by future studies. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 532-546, 2016.
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Affiliation(s)
- Brian A Kelch
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605
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24
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De March M, Merino N, Barrera-Vilarmau S, Crehuet R, Onesti S, Blanco FJ, De Biasio A. Structural basis of human PCNA sliding on DNA. Nat Commun 2017; 8:13935. [PMID: 28071730 PMCID: PMC5234079 DOI: 10.1038/ncomms13935] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 11/14/2016] [Indexed: 02/06/2023] Open
Abstract
Sliding clamps encircle DNA and tether polymerases and other factors to the genomic template. However, the molecular mechanism of clamp sliding on DNA is unknown. Using crystallography, NMR and molecular dynamics simulations, here we show that the human clamp PCNA recognizes DNA through a double patch of basic residues within the ring channel, arranged in a right-hand spiral that matches the pitch of B-DNA. We propose that PCNA slides by tracking the DNA backbone via a ‘cogwheel' mechanism based on short-lived polar interactions, which keep the orientation of the clamp invariant relative to DNA. Mutation of residues at the PCNA–DNA interface has been shown to impair the initiation of DNA synthesis by polymerase δ (pol δ). Therefore, our findings suggest that a clamp correctly oriented on DNA is necessary for the assembly of a replication-competent PCNA-pol δ holoenzyme. DNA sliding clamps are ring-shaped proteins that encircle DNA and harbour polymerases and other factors that promote processive DNA replication. Here the authors use X-ray crystallography, NMR and MD simulations to propose a model for a PCNA sliding mechanism that relies on short-lived polar interactions.
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Affiliation(s)
- Matteo De March
- Structural Biology Laboratory, Elettra-Sincrotrone Trieste S.C.p.A., 34149 Trieste, Italy
| | - Nekane Merino
- CIC bioGUNE, Parque Tecnologico de Bizkaia Edificio 800, 48160 Derio, Spain
| | - Susana Barrera-Vilarmau
- Institute of Advanced Chemistry of Catalonia (IQAC), CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain
| | - Ramon Crehuet
- Institute of Advanced Chemistry of Catalonia (IQAC), CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain
| | - Silvia Onesti
- Structural Biology Laboratory, Elettra-Sincrotrone Trieste S.C.p.A., 34149 Trieste, Italy
| | - Francisco J Blanco
- CIC bioGUNE, Parque Tecnologico de Bizkaia Edificio 800, 48160 Derio, Spain.,IKERBASQUE, Basque Foundation for Science, Bilbao 48013, Spain
| | - Alfredo De Biasio
- Structural Biology Laboratory, Elettra-Sincrotrone Trieste S.C.p.A., 34149 Trieste, Italy
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25
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Hedglin M, Pandey B, Benkovic SJ. Characterization of human translesion DNA synthesis across a UV-induced DNA lesion. eLife 2016; 5. [PMID: 27770570 PMCID: PMC5123862 DOI: 10.7554/elife.19788] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 10/21/2016] [Indexed: 12/11/2022] Open
Abstract
Translesion DNA synthesis (TLS) during S-phase uses specialized TLS DNA polymerases to replicate a DNA lesion, allowing stringent DNA synthesis to resume beyond the offending damage. Human TLS involves the conjugation of ubiquitin to PCNA clamps encircling damaged DNA and the role of this post-translational modification is under scrutiny. A widely-accepted model purports that ubiquitinated PCNA recruits TLS polymerases such as pol η to sites of DNA damage where they may also displace a blocked replicative polymerase. We provide extensive quantitative evidence that the binding of pol η to PCNA and the ensuing TLS are both independent of PCNA ubiquitination. Rather, the unique properties of pols η and δ are attuned to promote an efficient and passive exchange of polymerases during TLS on the lagging strand. DOI:http://dx.doi.org/10.7554/eLife.19788.001
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Affiliation(s)
- Mark Hedglin
- Department of Chemistry, The Pennsylvania State University, University Park, United States
| | - Binod Pandey
- Department of Chemistry, The Pennsylvania State University, University Park, United States
| | - Stephen J Benkovic
- Department of Chemistry, The Pennsylvania State University, University Park, United States
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26
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Kawasoe Y, Tsurimoto T, Nakagawa T, Masukata H, Takahashi TS. MutSα maintains the mismatch repair capability by inhibiting PCNA unloading. eLife 2016; 5. [PMID: 27402201 PMCID: PMC4942255 DOI: 10.7554/elife.15155] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 05/26/2016] [Indexed: 12/03/2022] Open
Abstract
Eukaryotic mismatch repair (MMR) utilizes single-strand breaks as signals to target the strand to be repaired. DNA-bound PCNA is also presumed to direct MMR. The MMR capability must be limited to a post-replicative temporal window during which the signals are available. However, both identity of the signal(s) involved in the retention of this temporal window and the mechanism that maintains the MMR capability after DNA synthesis remain unclear. Using Xenopus egg extracts, we discovered a mechanism that ensures long-term retention of the MMR capability. We show that DNA-bound PCNA induces strand-specific MMR in the absence of strand discontinuities. Strikingly, MutSα inhibited PCNA unloading through its PCNA-interacting motif, thereby extending significantly the temporal window permissive to strand-specific MMR. Our data identify DNA-bound PCNA as the signal that enables strand discrimination after the disappearance of strand discontinuities, and uncover a novel role of MutSα in the retention of the post-replicative MMR capability. DOI:http://dx.doi.org/10.7554/eLife.15155.001 To pass on genetic information from one generation to the next, the DNA in a cell must be precisely copied. DNA is made of two strands and genetic information is encoded by sequences of molecules called bases in the strands. The bases from one strand form pairs with complementary bases on the other strand. However, errors in the copying process result in unmatched pairs of bases. Such errors are corrected by a repair system called mismatch repair. When DNA is copied, the two strands are separated and used as templates to make new complementary strands. This means that errors only arise on the new strands. Mismatch repair must therefore target the new strands to maintain the original information encoded by the template DNA. The repair needs to happen before the copying process is complete because the template strands and the new strands become indistinguishable afterwards. However, it is not clear how the two processes communicate with each other. Previous studies have identified a ring-shaped molecule called the replication clamp – which is essential for the copying process – as a prime candidate for the molecule responsible for this communication. This molecule binds to the DNA to promote the copying process, and afterwards it is removed from the DNA by other molecules. Furthermore, a group of proteins called the MutSα complex, which recognizes unmatched bases in DNA molecules, physically interacts with the replication clamp. Kawasoe et al. used eggs from African clawed frogs to study how the replication clamp connects the copying process and mismatch repair in more detail. The experiments show that when the replication clamp is bound to the DNA, it is able to direct mismatch repair to a specific DNA strand. When MutSα recognizes unmatched bases, it prevents the replication clamp from being removed from the DNA. By doing so, MutSα prevents the information about the new DNA strand from being lost until mismatch repair has taken place. These findings reveal new interactions between DNA copying and the correction of errors by mismatch repair. The next steps will be to understand how MutSα is able to keep the replication clamp on the DNA and to clarify its role in protecting DNA from gaining mutations. DOI:http://dx.doi.org/10.7554/eLife.15155.002
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Affiliation(s)
| | - Toshiki Tsurimoto
- Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan
| | - Takuro Nakagawa
- Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Hisao Masukata
- Graduate School of Science, Osaka University, Toyonaka, Japan
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27
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Stability of the human polymerase δ holoenzyme and its implications in lagging strand DNA synthesis. Proc Natl Acad Sci U S A 2016; 113:E1777-86. [PMID: 26976599 DOI: 10.1073/pnas.1523653113] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In eukaryotes, DNA polymerase δ (pol δ) is responsible for replicating the lagging strand template and anchors to the proliferating cell nuclear antigen (PCNA) sliding clamp to form a holoenzyme. The stability of this complex is integral to every aspect of lagging strand replication. Most of our understanding comes from Saccharomyces cerevisae where the extreme stability of the pol δ holoenzyme ensures that every nucleobase within an Okazaki fragment is faithfully duplicated before dissociation but also necessitates an active displacement mechanism for polymerase recycling and exchange. However, the stability of the human pol δ holoenzyme is unknown. We designed unique kinetic assays to analyze the processivity and stability of the pol δ holoenzyme. Surprisingly, the results indicate that human pol δ maintains a loose association with PCNA while replicating DNA. Such behavior has profound implications on Okazaki fragment synthesis in humans as it limits the processivity of pol δ on undamaged DNA and promotes the rapid dissociation of pol δ from PCNA on stalling at a DNA lesion.
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28
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Völker-Albert MC, Pusch MC, Fedisch A, Schilcher P, Schmidt A, Imhof A. A Quantitative Proteomic Analysis of In Vitro Assembled Chromatin. Mol Cell Proteomics 2016; 15:945-59. [PMID: 26811354 PMCID: PMC4813712 DOI: 10.1074/mcp.m115.053553] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 01/17/2016] [Indexed: 12/30/2022] Open
Abstract
The structure of chromatin is critical for many aspects of cellular physiology and is considered to be the primary medium to store epigenetic information. It is defined by the histone molecules that constitute the nucleosome, the positioning of the nucleosomes along the DNA and the non-histone proteins that associate with it. These factors help to establish and maintain a largely DNA sequence-independent but surprisingly stable structure. Chromatin is extensively disassembled and reassembled during DNA replication, repair, recombination or transcription in order to allow the necessary factors to gain access to their substrate. Despite such constant interference with chromatin structure, the epigenetic information is generally well maintained. Surprisingly, the mechanisms that coordinate chromatin assembly and ensure proper assembly are not particularly well understood. Here, we use label free quantitative mass spectrometry to describe the kinetics of in vitro assembled chromatin supported by an embryo extract prepared from preblastoderm Drosophila melanogaster embryos. The use of a data independent acquisition method for proteome wide quantitation allows a time resolved comparison of in vitro chromatin assembly. A comparison of our in vitro data with proteomic studies of replicative chromatin assembly in vivo reveals an extensive overlap showing that the in vitro system can be used for investigating the kinetics of chromatin assembly in a proteome-wide manner.
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Affiliation(s)
- Moritz Carl Völker-Albert
- From the ‡BioMedical Center and Center for Integrated Protein Sciences Munich, Ludwig-Maximilians-University of Munich, Groβhaderner Straβe 9, 82152 Planegg-Martinsried, Germany
| | - Miriam Caroline Pusch
- From the ‡BioMedical Center and Center for Integrated Protein Sciences Munich, Ludwig-Maximilians-University of Munich, Groβhaderner Straβe 9, 82152 Planegg-Martinsried, Germany
| | - Andreas Fedisch
- From the ‡BioMedical Center and Center for Integrated Protein Sciences Munich, Ludwig-Maximilians-University of Munich, Groβhaderner Straβe 9, 82152 Planegg-Martinsried, Germany
| | - Pierre Schilcher
- §Zentrallabor für Proteinanalytik (Protein Analyis Unit), Ludwig-Maximilians-University of Munich, Groβhaderner Straβe 9, 82152 Planegg-Martinsried, Germany
| | - Andreas Schmidt
- §Zentrallabor für Proteinanalytik (Protein Analyis Unit), Ludwig-Maximilians-University of Munich, Groβhaderner Straβe 9, 82152 Planegg-Martinsried, Germany
| | - Axel Imhof
- From the ‡BioMedical Center and Center for Integrated Protein Sciences Munich, Ludwig-Maximilians-University of Munich, Groβhaderner Straβe 9, 82152 Planegg-Martinsried, Germany; §Zentrallabor für Proteinanalytik (Protein Analyis Unit), Ludwig-Maximilians-University of Munich, Groβhaderner Straβe 9, 82152 Planegg-Martinsried, Germany
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Dillehay KL, Seibel WL, Zhao D, Lu S, Dong Z. Target validation and structure-activity analysis of a series of novel PCNA inhibitors. Pharmacol Res Perspect 2015; 3:e00115. [PMID: 25729582 PMCID: PMC4324689 DOI: 10.1002/prp2.115] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 10/14/2014] [Accepted: 10/30/2014] [Indexed: 01/17/2023] Open
Abstract
Proliferating cell nuclear antigen (PCNA) plays an essential role in DNA replication and repair. Tumor cells express high levels of PCNA, identifying it as a potentially ideal target for cancer therapy. Previously, we identified nine compounds termed PCNA inhibitors (PCNA-Is) that bind directly to PCNA, stabilize PCNA trimer structure, reduce chromatin-associated PCNA, and selectively inhibit tumor cell growth. Of these compounds, PCNA-I1 was most potent. The purpose of this study is to further establish targeting of PCNA by PCNA-I1 and to identify PCNA-I1 analogs with superior potencies. We found that PCNA-I1 does not affect the level of chromatin-associated PCNA harboring point mutations at the predicted binding site of PCNA-I1. Forty-six PCNA-I1 analogs with structures of 1-hydrazonomethyl-2-hydroxy (scaffold A), 2-hydrazonomethyl-1-hydroxy (scaffold B), 2-hydrazonomethyl-3-hydroxy (scaffold C), and 4-pyridyl hydrazine (scaffold D) were analyzed for their effects on cell growth in four tumor cell lines and PCNA trimer stabilization. Compounds in scaffold group A and group B showed the highest trimer stabilization and the most potent cell growth inhibitory activities with a significant potency advantage observed in the Z isomers of scaffold A. The absence of trimer stabilization and growth inhibitory effects in compounds of scaffold group D confirms the essentiality of the hydroxynaphthyl substructure. Compounds structure-activity relationship (SAR)-6 and SAR-24 were analyzed for their effects on and found to reduce chromatin-associated PCNA in tumor cells. This study led to the identification of SAR-24, a compound with superior potencies and potentially improved solubility, which will be used for future development of PCNA-targeting cancer therapies.
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Affiliation(s)
- Kelsey L Dillehay
- Department of Internal Medicine, University of Cincinnati College of Medicine Cincinnati, OH, 45267
| | - William L Seibel
- Department of Pediatrics, Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center Cincinnati, OH, 46119
| | - Daoli Zhao
- Department of Chemistry, University of Cincinnati College of Medicine Cincinnati, OH, 45219
| | - Shan Lu
- Department of Pathology and Laboratory Medicine, University of Cincinnati College of Medicine Cincinnati, OH, 45219
| | - Zhongyun Dong
- Department of Internal Medicine, University of Cincinnati College of Medicine Cincinnati, OH, 45267
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Bauer RJ, Wolff ID, Zuo X, Lin HK, Trakselis MA. Assembly and distributive action of an archaeal DNA polymerase holoenzyme. J Mol Biol 2013; 425:4820-36. [PMID: 24035812 DOI: 10.1016/j.jmb.2013.09.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 09/03/2013] [Accepted: 09/04/2013] [Indexed: 11/25/2022]
Abstract
The assembly and enzymatic ability of the replication DNA polymerase holoenzyme from Sulfolobus solfataricus (Sso) was investigated using presteady-state fluorescence resonance energy transfer assays coupled with functional and structural studies. Kinetic experiments reveal that ATP binding to replication factor C (RFC) is sufficient for loading the heterotrimeric PCNA123 [proliferating cell nuclear antigen (PCNA)] clamp onto DNA that includes a rate-limiting conformational rearrangement of the complex. ATP hydrolysis is required for favorable recruitment and interactions with the replication polymerase (PolB1) that most likely include clamp closing and RFC dissociation. Surprisingly, the assembled holoenzyme complex synthesizes DNA distributively and with low processivity, unlike most other well-characterized DNA polymerase holoenzyme complexes. We show that PolB1 repeatedly disengages from the DNA template, leaving PCNA123 behind. Interactions with a newly identified C-terminal PCNA-interacting peptide (PIP) motif on PolB1 specifically with PCNA2 are required for holoenzyme formation and continuous re-recruitment during synthesis. The extended tail-like structure of the C-terminal PIP motif in PolB1 is revealed alone and when bound to DNA using small-angle X-ray scattering allowing us to develop a model for the holoenzyme complex. This is the first detailed kinetic description of clamp loading and holoenzyme assembly in crenarchaea and has revealed a novel mode for dynamic processivity that occurs by a polymerase exchange mechanism. This work has important implications for processive DNA replication synthesis and also suggests a potential mechanism for polymerase switching to bypass lesions.
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Affiliation(s)
- Robert J Bauer
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
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