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Varon M, Dovrat D, Heuzé J, Tsirkas I, Singh SP, Pasero P, Galletto R, Aharoni A. Rrm3 and Pif1 division of labor during replication through leading and lagging strand G-quadruplex. Nucleic Acids Res 2024; 52:1753-1762. [PMID: 38117984 PMCID: PMC10899776 DOI: 10.1093/nar/gkad1205] [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: 01/17/2023] [Revised: 12/03/2023] [Accepted: 12/06/2023] [Indexed: 12/22/2023] Open
Abstract
Members of the conserved Pif1 family of 5'-3' DNA helicases can unwind G4s and mitigate their negative impact on genome stability. In Saccharomyces cerevisiae, two Pif1 family members, Pif1 and Rrm3, contribute to the suppression of genomic instability at diverse regions including telomeres, centromeres and tRNA genes. While Pif1 can resolve lagging strand G4s in vivo, little is known regarding Rrm3 function at G4s and its cooperation with Pif1 for G4 replication. Here, we monitored replication through G4 sequences in real time to show that Rrm3 is essential for efficient replisome progression through G4s located on the leading strand template, but not on the lagging strand. We found that Rrm3 importance for replication through G4s is dependent on its catalytic activity and its N-terminal unstructured region. Overall, we show that Rrm3 and Pif1 exhibit a division of labor that enables robust replication fork progression through leading and lagging strand G4s, respectively.
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Affiliation(s)
- Mor Varon
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Be'er Sheva 84105, Israel
| | - Daniel Dovrat
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Be'er Sheva 84105, Israel
| | - Jonathan Heuzé
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Equipe Labellisée Ligue Contre le Cancer, 34396 Montpellier, France
| | - Ioannis Tsirkas
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Be'er Sheva 84105, Israel
| | - Saurabh P Singh
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Philippe Pasero
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Equipe Labellisée Ligue Contre le Cancer, 34396 Montpellier, France
| | - Roberto Galletto
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Amir Aharoni
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Be'er Sheva 84105, Israel
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2
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Botto MM, Borsellini A, Lamers MH. A four-point molecular handover during Okazaki maturation. Nat Struct Mol Biol 2023; 30:1505-1515. [PMID: 37620586 DOI: 10.1038/s41594-023-01071-y] [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: 07/30/2022] [Accepted: 07/17/2023] [Indexed: 08/26/2023]
Abstract
DNA replication introduces thousands of RNA primers into the lagging strand that need to be removed for replication to be completed. In Escherichia coli when the replicative DNA polymerase Pol IIIα terminates at a previously synthesized RNA primer, DNA Pol I takes over and continues DNA synthesis while displacing the downstream RNA primer. The displaced primer is subsequently excised by an endonuclease, followed by the sealing of the nick by a DNA ligase. Yet how the sequential actions of Pol IIIα, Pol I polymerase, Pol I endonuclease and DNA ligase are coordinated is poorly defined. Here we show that each enzymatic activity prepares the DNA substrate for the next activity, creating an efficient four-point molecular handover. The cryogenic-electron microscopy structure of Pol I bound to a DNA substrate with both an upstream and downstream primer reveals how it displaces the primer in a manner analogous to the monomeric helicases. Moreover, we find that in addition to its flap-directed nuclease activity, the endonuclease domain of Pol I also specifically cuts at the RNA-DNA junction, thus marking the end of the RNA primer and creating a 5' end that is a suitable substrate for the ligase activity of LigA once all RNA has been removed.
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Affiliation(s)
- Margherita M Botto
- Department of Cell and Chemical Biology, Leiden University Medical Center (LUMC), Leiden, the Netherlands
- Department of Molecular and Cellular Biology, Geneva University, Geneva, Switzerland
| | - Alessandro Borsellini
- Department of Cell and Chemical Biology, Leiden University Medical Center (LUMC), Leiden, the Netherlands
- Department of Structural Biology, Human Technopole, Milan, Italy
| | - Meindert H Lamers
- Department of Cell and Chemical Biology, Leiden University Medical Center (LUMC), Leiden, the Netherlands.
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3
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Shao Z, Yang J, Gao Y, Zhang Y, Zhao X, Shao Q, Zhang W, Cao C, Liu H, Gan J. Structural and functional studies of PCNA from African swine fever virus. J Virol 2023; 97:e0074823. [PMID: 37534905 PMCID: PMC10506467 DOI: 10.1128/jvi.00748-23] [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: 05/19/2023] [Accepted: 06/16/2023] [Indexed: 08/04/2023] Open
Abstract
Proliferating cell nuclear antigen (PCNA) belongs to the DNA sliding clamp family. Via interacting with various partner proteins, PCNA plays critical roles in DNA replication, DNA repair, chromatin assembly, epigenetic inheritance, chromatin remodeling, and many other fundamental biological processes. Although PCNA and PCNA-interacting partner networks are conserved across species, PCNA of a given species is rarely functional in heterologous systems, emphasizing the importance of more representative PCNA studies. Here, we report two crystal structures of PCNA from African swine fever virus (ASFV), which is the only member of the Asfarviridae family. Compared to the eukaryotic and archaeal PCNAs and the sliding clamp structural homologs from other viruses, AsfvPCNA possesses unique sequences and/or conformations at several regions, such as the J-loop, interdomain-connecting loop (IDCL), P-loop, and C-tail, which are involved in partner recognition or modification of sliding clamps. In addition to double-stranded DNA binding, we also demonstrate that AsfvPCNA can modestly enhance the ligation activity of the AsfvLIG protein. The unique structural features of AsfvPCNA can serve as a potential target for the development of ASFV-specific inhibitors and help combat the deadly virus. IMPORTANCE Two high-resolution crystal structures of African swine fever virus proliferating cell nuclear antigen (AsfvPCNA) are presented here. Structural comparison revealed that AsfvPCNA is unique at several regions, such as the J-loop, the interdomain-connecting loop linker, and the P-loop, which may play important roles in ASFV-specific partner selection of AsfvPCNA. Unlike eukaryotic and archaeal PCNAs, AsfvPCNA possesses high double-stranded DNA-binding affinity. Besides DNA binding, AsfvPCNA can also modestly enhance the ligation activity of the AsfvLIG protein, which is essential for the replication and repair of ASFV genome. The unique structural features make AsfvPCNA a potential target for drug development, which will help combat the deadly virus.
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Affiliation(s)
- Zhiwei Shao
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, China
| | - Jie Yang
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, China
| | - Yanqing Gao
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, China
| | - Yixi Zhang
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, China
| | - Xin Zhao
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, China
| | - Qiyuan Shao
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, China
| | - Weizhen Zhang
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, China
| | - Chulei Cao
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, China
| | - Hehua Liu
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, China
| | - Jianhua Gan
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, China
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4
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Magrino J, Munford V, Martins DJ, Homma TK, Page B, Gaubitz C, Freire BL, Lerario AM, Vilar JB, Amorin A, Leão EKE, Kok F, Menck CF, Jorge AA, Kelch BA. A thermosensitive PCNA allele underlies an ataxia-telangiectasia-like disorder. J Biol Chem 2023; 299:104656. [PMID: 36990216 PMCID: PMC10165274 DOI: 10.1016/j.jbc.2023.104656] [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: 11/04/2022] [Revised: 02/25/2023] [Accepted: 03/10/2023] [Indexed: 03/29/2023] Open
Abstract
Proliferating cell nuclear antigen (PCNA) is a sliding clamp protein that coordinates DNA replication with various DNA maintenance events that are critical for human health. Recently, a hypomorphic homozygous serine to isoleucine (S228I) substitution in PCNA was described to underlie a rare DNA repair disorder known as PCNA-associated DNA repair disorder (PARD). PARD symptoms range from UV sensitivity, neurodegeneration, telangiectasia, and premature aging. We, and others, previously showed that the S228I variant changes the protein-binding pocket of PCNA to a conformation that impairs interactions with specific partners. Here, we report a second PCNA substitution (C148S) that also causes PARD. Unlike PCNA-S228I, PCNA-C148S has WT-like structure and affinity toward partners. In contrast, both disease-associated variants possess a thermostability defect. Furthermore, patient-derived cells homozygous for the C148S allele exhibit low levels of chromatin-bound PCNA and display temperature-dependent phenotypes. The stability defect of both PARD variants indicates that PCNA levels are likely an important driver of PARD disease. These results significantly advance our understanding of PARD and will likely stimulate additional work focused on clinical, diagnostic, and therapeutic aspects of this severe disease.
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Affiliation(s)
- Joseph Magrino
- Department of Biochemistry and Biotechnology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Veridiana Munford
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Davi Jardim Martins
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Thais K Homma
- Genetic Endocrinology Unit, Cellular and Molecular Endocrinology Laboratory LIM25, Endocrinology Discipline of the Faculty of Medicine of the University of São Paulo, São Paulo, Brazil; Developmental Endocrinology Unit, Laboratory of Hormones and Molecular Genetics LIM42, Faculty of Medicine of the University of São Paulo, São Paulo, Brazil
| | - Brendan Page
- Department of Biochemistry and Biotechnology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Christl Gaubitz
- Department of Biochemistry and Biotechnology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Bruna L Freire
- Genetic Endocrinology Unit, Cellular and Molecular Endocrinology Laboratory LIM25, Endocrinology Discipline of the Faculty of Medicine of the University of São Paulo, São Paulo, Brazil; Developmental Endocrinology Unit, Laboratory of Hormones and Molecular Genetics LIM42, Faculty of Medicine of the University of São Paulo, São Paulo, Brazil
| | - Antonio M Lerario
- Developmental Endocrinology Unit, Laboratory of Hormones and Molecular Genetics LIM42, Faculty of Medicine of the University of São Paulo, São Paulo, Brazil; Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, Michigan, USA
| | - Juliana Brandstetter Vilar
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Antonio Amorin
- Neurogenetics, Neurology Department, Faculty of Medicine of the University of São Paulo, São Paulo, Brazil
| | - Emília K E Leão
- Medical Genetics Service of the Professor Edgard Santos University Hospital - Federal University of Bahia, Salvador, Brazil
| | - Fernando Kok
- Neurogenetics, Neurology Department, Faculty of Medicine of the University of São Paulo, São Paulo, Brazil; Mendelics Genomic Analysis, São Paulo, São Paulo, Brazil
| | - Carlos Fm Menck
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Alexander Al Jorge
- Genetic Endocrinology Unit, Cellular and Molecular Endocrinology Laboratory LIM25, Endocrinology Discipline of the Faculty of Medicine of the University of São Paulo, São Paulo, Brazil
| | - Brian A Kelch
- Department of Biochemistry and Biotechnology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA.
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5
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Mechanistic investigation of human maturation of Okazaki fragments reveals slow kinetics. Nat Commun 2022; 13:6973. [PMID: 36379932 PMCID: PMC9666535 DOI: 10.1038/s41467-022-34751-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Accepted: 11/04/2022] [Indexed: 11/16/2022] Open
Abstract
The final steps of lagging strand synthesis induce maturation of Okazaki fragments via removal of the RNA primers and ligation. Iterative cycles between Polymerase δ (Polδ) and Flap endonuclease-1 (FEN1) remove the primer, with an intermediary nick structure generated for each cycle. Here, we show that human Polδ is inefficient in releasing the nick product from FEN1, resulting in non-processive and remarkably slow RNA removal. Ligase 1 (Lig1) can release the nick from FEN1 and actively drive the reaction toward ligation. These mechanisms are coordinated by PCNA, which encircles DNA, and dynamically recruits Polδ, FEN1, and Lig1 to compete for their substrates. Our findings call for investigating additional pathways that may accelerate RNA removal in human cells, such as RNA pre-removal by RNase Hs, which, as demonstrated herein, enhances the maturation rate ~10-fold. They also suggest that FEN1 may attenuate the various activities of Polδ during DNA repair and recombination.
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6
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Sobhy MA, Tehseen M, Takahashi M, Bralić A, De Biasio A, Hamdan SM. Implementing fluorescence enhancement, quenching, and FRET for investigating flap endonuclease 1 enzymatic reaction at the single-molecule level. Comput Struct Biotechnol J 2021; 19:4456-4471. [PMID: 34471492 PMCID: PMC8385120 DOI: 10.1016/j.csbj.2021.07.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 07/23/2021] [Accepted: 07/25/2021] [Indexed: 11/24/2022] Open
Abstract
Flap endonuclease 1 (FEN1) is an important component of the intricate molecular machinery for DNA replication and repair. FEN1 is a structure-specific 5' nuclease that cleaves nascent single-stranded 5' flaps during the maturation of Okazaki fragments. Here, we review our research primarily applying single-molecule fluorescence to resolve important mechanistic aspects of human FEN1 enzymatic reaction. The methodology presented in this review is aimed as a guide for tackling other biomolecular enzymatic reactions by fluorescence enhancement, quenching, and FRET and their combinations. Using these methods, we followed in real-time the structures of the substrate and product and 5' flap cleavage during catalysis. We illustrate that FEN1 actively bends the substrate to verify its features and continues to mold it to induce a protein disorder-to-order transitioning that controls active site assembly. This mechanism suppresses off-target cleavage of non-cognate substrates and promotes their dissociation with an accuracy that was underestimated from bulk assays. We determined that product release in FEN1 after the 5' flap release occurs in two steps; a brief binding to the bent nicked-product followed by longer binding to the unbent nicked-product before dissociation. Based on our cryo-electron microscopy structure of the human lagging strand replicase bound to FEN1, we propose how this two-step product release mechanism may regulate the final steps during the maturation of Okazaki fragments.
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Affiliation(s)
- Mohamed A Sobhy
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Muhammad Tehseen
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Masateru Takahashi
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Amer Bralić
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Alfredo De Biasio
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester LE1 7HB, UK
| | - Samir M Hamdan
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
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7
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Sundaram R, Manohar K, Patel SK, Acharya N, Vasudevan D. Structural analyses of PCNA from the fungal pathogen Candida albicans identify three regions with species-specific conformations. FEBS Lett 2021; 595:1328-1349. [PMID: 33544878 DOI: 10.1002/1873-3468.14055] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 01/11/2023]
Abstract
An assembly of multiprotein complexes achieves chromosomal DNA replication at the replication fork. In eukaryotes, proliferating cell nuclear antigen (PCNA) plays a vital role in the assembly of multiprotein complexes at the replication fork and is essential for cell viability. PCNA from several organisms, including Saccharomyces cerevisiae, has been structurally characterised. However, the structural analyses of PCNA from fungal pathogens are limited. Recently, we have reported that PCNA from the opportunistic fungal pathogen Candida albicans complements the essential functions of ScPCNA in S. cerevisiae. Still, it only partially rescues the loss of ScPCNA when the yeast cells are under genotoxic stress. To understand this further, herein, we have determined the crystal structure of CaPCNA and compared that with the existing structures of other fungal and human PCNA. Our comparative structural and in-solution small-angle X-ray scattering (SAXS) analyses reveal that CaPCNA forms a stable homotrimer, both in crystal and in solution. It displays noticeable structural alterations in the oligomerisation interface, P-loop and hydrophobic pocket regions, suggesting its differential function in a heterologous system and avenues for developing specific therapeutics. DATABASES: The PDB and SASBDB accession codes for CaPCNA are 7BUP and SASDHQ9, respectively.
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Affiliation(s)
- Rajivgandhi Sundaram
- Laboratory of Macromolecular Crystallography, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India.,Manipal Academy of Higher Education, India
| | - Kodavati Manohar
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Shraddheya Kumar Patel
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Narottam Acharya
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Dileep Vasudevan
- Laboratory of Macromolecular Crystallography, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
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8
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Comprehensive Mutational and Phenotypic Characterization of New Metastatic Cutaneous Squamous Cell Carcinoma Cell Lines Reveal Novel Drug Susceptibilities. Int J Mol Sci 2020; 21:ijms21249536. [PMID: 33333825 PMCID: PMC7765308 DOI: 10.3390/ijms21249536] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/01/2020] [Accepted: 12/03/2020] [Indexed: 12/12/2022] Open
Abstract
Cutaneous squamous cell carcinoma (cSCC) is a common skin cancer. Most patients who develop metastases (2–5%) present with advanced disease that requires a combination of radical surgery and adjuvant radiation therapy. There are few effective therapies for refractory disease. In this study, we describe novel patient-derived cell lines from cSCC metastases of the head and neck (designated UW-CSCC1 and UW-CSCC2). The cell lines genotypically and phenotypically resembled the original patient tumor and were tumorogenic in mice. Differences in cancer-related gene expression between the tumor and cell lines after various culturing conditions could be largely reversed by xenografting and reculturing. The novel drug susceptibilities of UW-CSCC1 and an irradiated subclone UW-CSCC1-R to drugs targeting cell cycle, PI3K/AKT/mTOR, and DNA damage pathways were observed using high-throughput anti-cancer and kinase-inhibitor compound libraries, which correlate with either copy number variations, targetable mutations and/or the upregulation of gene expression. A secondary screen of top hits in all three cell lines including PIK3CA-targeting drugs supports the utility of targeting the PI3K/AKT/mTOR pathway in this disease. UW-CSCC cell lines are thus useful preclinical models for determining targetable pathways and candidate therapeutics.
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9
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Matsumoto Y, Brooks RC, Sverzhinsky A, Pascal JM, Tomkinson AE. Dynamic DNA-bound PCNA complexes co-ordinate Okazaki fragment synthesis, processing and ligation. J Mol Biol 2020; 432:166698. [PMID: 33157085 DOI: 10.1016/j.jmb.2020.10.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 10/07/2020] [Accepted: 10/27/2020] [Indexed: 11/28/2022]
Abstract
More than a million Okazaki fragments are synthesized, processed and joined during replication of the human genome. After synthesis of an RNA-DNA oligonucleotide by DNA polymerase α holoenzyme, proliferating cell nuclear antigen (PCNA), a homotrimeric DNA sliding clamp and polymerase processivity factor, is loaded onto the primer-template junction by replication factor C (RFC). Although PCNA interacts with the enzymes DNA polymerase δ (Pol δ), flap endonuclease 1 (FEN1) and DNA ligase I (LigI) that complete Okazaki fragment processing and joining, it is not known how the activities of these enzymes are coordinated. Here we describe a novel interaction between Pol δ and LigI that is critical for Okazaki fragment joining in vitro. Both LigI and FEN1 associate with PCNA-Pol δ during gap-filling synthesis, suggesting that gap-filling synthesis is carried out by a complex of PCNA, Pol δ, FEN1 and LigI. Following ligation, PCNA and LigI remain on the DNA, indicating that Pol δ and FEN1 dissociate during 5' end processing and that LigI engages PCNA at the DNA nick generated by FEN1 and Pol δ. Thus, dynamic PCNA complexes coordinate Okazaki fragment synthesis and processing with PCNA and LigI forming a terminal structure of two linked protein rings encircling the ligated DNA.
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Affiliation(s)
- Yoshihiro Matsumoto
- Departments of Internal Medicine, Molecular Genetics and Microbiology and the University of New Mexico Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM 87131, United States
| | - Rhys C Brooks
- Departments of Internal Medicine, Molecular Genetics and Microbiology and the University of New Mexico Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM 87131, United States
| | - Aleksandr Sverzhinsky
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec, Canada
| | - John M Pascal
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec, Canada
| | - Alan E Tomkinson
- Departments of Internal Medicine, Molecular Genetics and Microbiology and the University of New Mexico Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM 87131, United States.
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10
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Verma P, Tandon R, Yadav G, Gaur V. Structural Aspects of DNA Repair and Recombination in Crop Improvement. Front Genet 2020; 11:574549. [PMID: 33024442 PMCID: PMC7516265 DOI: 10.3389/fgene.2020.574549] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 08/25/2020] [Indexed: 12/18/2022] Open
Abstract
The adverse effects of global climate change combined with an exponentially increasing human population have put substantial constraints on agriculture, accelerating efforts towards ensuring food security for a sustainable future. Conventional plant breeding and modern technologies have led to the creation of plants with better traits and higher productivity. Most crop improvement approaches (conventional breeding, genome modification, and gene editing) primarily rely on DNA repair and recombination (DRR). Studying plant DRR can provide insights into designing new strategies or improvising the present techniques for crop improvement. Even though plants have evolved specialized DRR mechanisms compared to other eukaryotes, most of our insights about plant-DRRs remain rooted in studies conducted in animals. DRR mechanisms in plants include direct repair, nucleotide excision repair (NER), base excision repair (BER), mismatch repair (MMR), non-homologous end joining (NHEJ) and homologous recombination (HR). Although each DRR pathway acts on specific DNA damage, there is crosstalk between these. Considering the importance of DRR pathways as a tool in crop improvement, this review focuses on a general description of each DRR pathway, emphasizing on the structural aspects of key DRR proteins. The review highlights the gaps in our understanding and the importance of studying plant DRR in the context of crop improvement.
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Affiliation(s)
- Prabha Verma
- National Institute of Plant Genome Research, New Delhi, India
| | - Reetika Tandon
- National Institute of Plant Genome Research, New Delhi, India
| | - Gitanjali Yadav
- National Institute of Plant Genome Research, New Delhi, India
| | - Vineet Gaur
- National Institute of Plant Genome Research, New Delhi, India
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11
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Sparks MA, Burgers PM, Galletto R. Pif1, RPA, and FEN1 modulate the ability of DNA polymerase δ to overcome protein barriers during DNA synthesis. J Biol Chem 2020; 295:15883-15891. [PMID: 32913126 DOI: 10.1074/jbc.ra120.015699] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 09/09/2020] [Indexed: 01/20/2023] Open
Abstract
Successful DNA replication requires carefully regulated mechanisms to overcome numerous obstacles that naturally occur throughout chromosomal DNA. Scattered across the genome are tightly bound proteins, such as transcription factors and nucleosomes, that are necessary for cell function, but that also have the potential to impede timely DNA replication. Using biochemically reconstituted systems, we show that two transcription factors, yeast Reb1 and Tbf1, and a tightly positioned nucleosome, are strong blocks to the strand displacement DNA synthesis activity of DNA polymerase δ. Although the block imparted by Tbf1 can be overcome by the DNA-binding activity of the single-stranded DNA-binding protein RPA, efficient DNA replication through either a Reb1 or a nucleosome block occurs only in the presence of the 5'-3' DNA helicase Pif1. The Pif1-dependent stimulation of DNA synthesis across strong protein barriers may be beneficial during break-induced replication where barriers are expected to pose a problem to efficient DNA bubble migration. However, in the context of lagging strand DNA synthesis, the efficient disruption of a nucleosome barrier by Pif1 could lead to the futile re-replication of newly synthetized DNA. In the presence of FEN1 endonuclease, the major driver of nick translation during lagging strand replication, Pif1-dependent stimulation of DNA synthesis through a nucleosome or Reb1 barrier is prevented. By cleaving the short 5' tails generated during strand displacement, FEN1 eliminates the entry point for Pif1. We propose that this activity would protect the cell from potential DNA re-replication caused by unwarranted Pif1 interference during lagging strand replication.
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Affiliation(s)
- Melanie A Sparks
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri USA
| | - Peter M Burgers
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri USA.
| | - Roberto Galletto
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri USA.
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12
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Rose E, Carvalho JL, Hecht M. Mechanisms of DNA repair in Trypanosoma cruzi: What do we know so far? DNA Repair (Amst) 2020; 91-92:102873. [PMID: 32505694 DOI: 10.1016/j.dnarep.2020.102873] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 03/27/2020] [Accepted: 05/22/2020] [Indexed: 12/13/2022]
Abstract
Trypanosoma cruzi is the etiological agent of Chagas Disease, which affects 6-7 million people worldwide. Since the early stages of infection and throughout its life cycle, the parasite is exposed to several genotoxic agents. Furthermore, DNA damage is also part of the mechanism of action of at least a few trypanocidal drugs, including Benznidazole. Thus, it is paramount for the parasite to count on an efficient DNA repair machinery to guarantee genome integrity and survival. The present work provides an up-to-date review of both the conserved and peculiar DNA repair mechanisms described in T. cruzi against oxidative stress, ultraviolet and ionizing radiation, DNA adduct-inducing agents, and Benznidazole. The comprehension of the DNA repair mechanisms of the parasite may shed light on the parasite evolution and possibly pave the way for the development of novel and more effective trypanocidal drugs.
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Affiliation(s)
- Ester Rose
- Interdisciplinary Laboratory of Biosciences, Faculty of Medicine, University of Brasília, Brasília, Brazil.
| | - Juliana Lott Carvalho
- Interdisciplinary Laboratory of Biosciences, Faculty of Medicine, University of Brasília, Brasília, Brazil; Genomic Sciences and Biotechnology Program, Catholic University of Brasília, Brasília, Brazil
| | - Mariana Hecht
- Interdisciplinary Laboratory of Biosciences, Faculty of Medicine, University of Brasília, Brasília, Brazil
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13
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Bender D, Da Silva EML, Chen J, Poss A, Gawey L, Rulon Z, Rankin S. Multivalent interaction of ESCO2 with the replication machinery is required for sister chromatid cohesion in vertebrates. Proc Natl Acad Sci U S A 2020; 117:1081-1089. [PMID: 31879348 PMCID: PMC6969535 DOI: 10.1073/pnas.1911936117] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The tethering together of sister chromatids by the cohesin complex ensures their accurate alignment and segregation during cell division. In vertebrates, sister chromatid cohesion requires the activity of the ESCO2 acetyltransferase, which modifies the Smc3 subunit of cohesin. It was shown recently that ESCO2 promotes cohesion through interaction with the MCM replicative helicase. However, ESCO2 does not significantly colocalize with the MCM complex, suggesting there are additional interactions important for ESCO2 function. Here we show that ESCO2 is recruited to replication factories, sites of DNA replication, through interaction with PCNA. We show that ESCO2 contains multiple PCNA-interaction motifs in its N terminus, each of which is essential to its ability to establish cohesion. We propose that multiple PCNA-interaction motifs embedded in a largely flexible and disordered region of the protein underlie the unique ability of ESCO2 to establish cohesion between sister chromatids precisely as they are born during DNA replication.
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Affiliation(s)
- Dawn Bender
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
- Department of Cell Biology, Oklahoma University Health Science Center, Oklahoma City, OK 73104
| | | | - Jingrong Chen
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Annelise Poss
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Lauren Gawey
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Zane Rulon
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Susannah Rankin
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104;
- Department of Cell Biology, Oklahoma University Health Science Center, Oklahoma City, OK 73104
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14
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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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15
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Khandagale P, Peroumal D, Manohar K, Acharya N. Human DNA polymerase delta is a pentameric holoenzyme with a dimeric p12 subunit. Life Sci Alliance 2019; 2:2/2/e201900323. [PMID: 30885984 PMCID: PMC6424025 DOI: 10.26508/lsa.201900323] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 03/04/2019] [Accepted: 03/11/2019] [Indexed: 01/07/2023] Open
Abstract
The subunit p12 of human DNA polymerase delta (hPolδ) can dimerize, facilitating its interaction with PCNA and suggesting that hPolδ exists in a pentameric form in the cell. Human DNA polymerase delta (Polδ), a holoenzyme consisting of p125, p50, p68, and p12 subunits, plays an essential role in DNA replication, repair, and recombination. Herein, using multiple physicochemical and cellular approaches, we found that the p12 protein forms a dimer in solution. In vitro reconstitution and pull down of cellular Polδ by tagged p12 substantiate the pentameric nature of this critical holoenzyme. Furthermore, a consensus proliferating nuclear antigen (PCNA) interaction protein motif at the extreme carboxyl-terminal tail and a homodimerization domain at the amino terminus of the p12 subunit were identified. Mutational analyses of these motifs in p12 suggest that dimerization facilitates p12 binding to the interdomain connecting loop of PCNA. In addition, we observed that oligomerization of the smallest subunit of Polδ is evolutionarily conserved as Cdm1 of Schizosaccharomyces pombe also dimerizes. Thus, we suggest that human Polδ is a pentameric complex with a dimeric p12 subunit, and discuss implications of p12 dimerization in enzyme architecture and PCNA interaction during DNA replication.
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Affiliation(s)
- Prashant Khandagale
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Doureradjou Peroumal
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Kodavati Manohar
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Narottam Acharya
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
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16
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DNA Replication Through Strand Displacement During Lagging Strand DNA Synthesis in Saccharomyces cerevisiae. Genes (Basel) 2019; 10:genes10020167. [PMID: 30795600 PMCID: PMC6409922 DOI: 10.3390/genes10020167] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 02/14/2019] [Accepted: 02/18/2019] [Indexed: 01/21/2023] Open
Abstract
This review discusses a set of experimental results that support the existence of extended strand displacement events during budding yeast lagging strand DNA synthesis. Starting from introducing the mechanisms and factors involved in leading and lagging strand DNA synthesis and some aspects of the architecture of the eukaryotic replisome, we discuss studies on bacterial, bacteriophage and viral DNA polymerases with potent strand displacement activities. We describe proposed pathways of Okazaki fragment processing via short and long flaps, with a focus on experimental results obtained in Saccharomyces cerevisiae that suggest the existence of frequent and extended strand displacement events during eukaryotic lagging strand DNA synthesis, and comment on their implications for genome integrity.
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17
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Minobe A, Fukui K, Yonezu H, Ohshita K, Mizobuchi S, Morisawa T, Hakumai Y, Yano T, Ashiuchi M, Wakamatsu T. Biochemical characterization of mismatch-binding protein MutS1 and nicking endonuclease MutL from a euryarchaeon Methanosaeta thermophila. DNA Repair (Amst) 2019; 75:29-38. [PMID: 30711824 DOI: 10.1016/j.dnarep.2019.01.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 01/21/2019] [Accepted: 01/21/2019] [Indexed: 12/20/2022]
Abstract
In eukaryotes and most bacteria, the MutS1/MutL-dependent mismatch repair system (MMR) corrects DNA mismatches that arise as replication errors. MutS1 recognizes mismatched DNA and stimulates the nicking endonuclease activity of MutL to incise mismatch-containing DNA. In archaea, there has been no experimental evidence to support the existence of the MutS1/MutL-dependent MMR. Instead, it was revealed that a large part of archaea possess mismatch-specific endonuclease EndoMS, indicating that the EndoMS-dependent MMR is widely adopted in archaea. However, some archaeal genomes encode MutS1 and MutL homologs, and their molecular functions have not been revealed. In this study, we purified and characterized recombinant MutS1 and the C-terminal endonuclease domain of MutL from a methanogenic archaeon Methanosaeta thermophila (mtMutS1 and the mtMutL CTD, respectively). mtMutS1 bound to mismatched DNAs with a higher affinity than to perfectly-matched and other structured DNAs, which resembles the DNA-binding specificities of eukaryotic and bacterial MutS1 homologs. The mtMutL CTD showed a Mn2+/Ni2+/Co2+-dependent nicking endonuclease activity that introduces single-strand breaks into a circular double-stranded DNA. The nicking endonuclease activity of the mtMutL CTD was impaired by mutagenizing the metal-binding motif that is identical to those of eukaryotic and bacterial MutL endonucleases. These results raise the possibility that not only the EndoMS-dependent MMR but also the traditional MutS1/MutL-dependent MMR exist in archaea.
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Affiliation(s)
- Ai Minobe
- Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi, 783-8502, Japan
| | - Kenji Fukui
- Department of Biochemistry, Osaka Medical College, 2-7 Daigakumachi, Takatsuki, Osaka, 569-8686, Japan
| | - Hitomi Yonezu
- Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi, 783-8502, Japan
| | - Koki Ohshita
- Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi, 783-8502, Japan
| | - Saki Mizobuchi
- Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi, 783-8502, Japan
| | - Takashi Morisawa
- Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi, 783-8502, Japan
| | - Yuichi Hakumai
- Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi, 783-8502, Japan
| | - Takato Yano
- Department of Biochemistry, Osaka Medical College, 2-7 Daigakumachi, Takatsuki, Osaka, 569-8686, Japan
| | - Makoto Ashiuchi
- Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi, 783-8502, Japan
| | - Taisuke Wakamatsu
- Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi, 783-8502, Japan.
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18
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Deshmukh AL, Chandra S, Singh DK, Siddiqi MI, Banerjee D. Identification of human flap endonuclease 1 (FEN1) inhibitors using a machine learning based consensus virtual screening. MOLECULAR BIOSYSTEMS 2018; 13:1630-1639. [PMID: 28685785 DOI: 10.1039/c7mb00118e] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Human Flap endonuclease1 (FEN1) is an enzyme that is indispensable for DNA replication and repair processes and inhibition of its Flap cleavage activity results in increased cellular sensitivity to DNA damaging agents (cisplatin, temozolomide, MMS, etc.), with the potential to improve cancer prognosis. Reports of the high expression levels of FEN1 in several cancer cells support the idea that FEN1 inhibitors may target cancer cells with minimum side effects to normal cells. In this study, we used large publicly available, high-throughput screening data of small molecule compounds targeted against FEN1. Two machine learning algorithms, Support Vector Machine (SVM) and Random Forest (RF), were utilized to generate four classification models from huge PubChem bioassay data containing probable FEN1 inhibitors and non-inhibitors. We also investigated the influence of randomly selected Zinc-database compounds as negative data on the outcome of classification modelling. The results show that the SVM model with inactive compounds was superior to RF with Matthews's correlation coefficient (MCC) of 0.67 for the test set. A Maybridge database containing approximately 53 000 compounds was screened and top ranking 5 compounds were selected for enzyme and cell-based in vitro screening. The compound JFD00950 was identified as a novel FEN1 inhibitor with in vitro inhibition of flap cleavage activity as well as cytotoxic activity against a colon cancer cell line, DLD-1.
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Affiliation(s)
- Amit Laxmikant Deshmukh
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, B.S. 10/1, Janakipuram Extension, Sitapur Road, Lucknow, 226031, India.
| | - Sharat Chandra
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, B.S. 10/1, Janakipuram Extension, Sitapur Road, Lucknow, 226031, India. and AcSIR (Academy of Scientific and Innovative Research), India
| | - Deependra Kumar Singh
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, B.S. 10/1, Janakipuram Extension, Sitapur Road, Lucknow, 226031, India.
| | - Mohammad Imran Siddiqi
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, B.S. 10/1, Janakipuram Extension, Sitapur Road, Lucknow, 226031, India. and AcSIR (Academy of Scientific and Innovative Research), India
| | - Dibyendu Banerjee
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, B.S. 10/1, Janakipuram Extension, Sitapur Road, Lucknow, 226031, India. and AcSIR (Academy of Scientific and Innovative Research), India
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19
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Sisakova A, Altmannova V, Sebesta M, Krejci L. Role of PCNA and RFC in promoting Mus81-complex activity. BMC Biol 2017; 15:90. [PMID: 28969641 PMCID: PMC5625722 DOI: 10.1186/s12915-017-0429-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Accepted: 09/15/2017] [Indexed: 01/23/2023] Open
Abstract
Background Proper DNA replication is essential for faithful transmission of the genome. However, replication stress has serious impact on the integrity of the cell, leading to stalling or collapse of replication forks, and has been determined as a driving force of carcinogenesis. Mus81-Mms4 complex is a structure-specific endonuclease previously shown to be involved in processing of aberrant replication intermediates and promotes POLD3-dependent DNA synthesis via break-induced replication. However, how replication components might be involved in this process is not known. Results Herein, we show the interaction and robust stimulation of Mus81-Mms4 nuclease activity by heteropentameric replication factor C (RFC) complex, the processivity factor of replicative DNA polymerases that is responsible for loading of proliferating cell nuclear antigen (PCNA) during DNA replication and repair. This stimulation is enhanced by RFC-dependent ATP hydrolysis and by PCNA loading on the DNA. Moreover, this stimulation is not specific to Rfc1, the largest of subunit of this complex, thus indicating that alternative clamp loaders may also play a role in the stimulation. We also observed a targeting of Mus81 by RFC to the nick-containing DNA substrate and we provide further evidence that indicates cooperation between Mus81 and the RFC complex in the repair of DNA lesions generated by various DNA-damaging agents. Conclusions Identification of new interacting partners and modulators of Mus81-Mms4 nuclease, RFC, and PCNA imply the cooperation of these factors in resolution of stalled replication forks and branched DNA structures emanating from the restarted replication forks under conditions of replication stress. Electronic supplementary material The online version of this article (doi:10.1186/s12915-017-0429-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alexandra Sisakova
- Department of Biology, Masaryk University, Kamenice 5/A7, CZ-62500, Brno, Czech Republic.,National Centre for Biomolecular Research, Masaryk University, Kamenice 5/A4, CZ-62500, Brno, Czech Republic.,International Clinical Research Center, Center for Biomolecular and Cellular Engineering, St. Anne's University Hospital Brno, Pekarska 53, CZ-656 91, Brno, Czech Republic
| | - Veronika Altmannova
- Department of Biology, Masaryk University, Kamenice 5/A7, CZ-62500, Brno, Czech Republic.,International Clinical Research Center, Center for Biomolecular and Cellular Engineering, St. Anne's University Hospital Brno, Pekarska 53, CZ-656 91, Brno, Czech Republic
| | - Marek Sebesta
- Department of Biology, Masaryk University, Kamenice 5/A7, CZ-62500, Brno, Czech Republic.,National Centre for Biomolecular Research, Masaryk University, Kamenice 5/A4, CZ-62500, Brno, Czech Republic.,Present address: Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Lumir Krejci
- Department of Biology, Masaryk University, Kamenice 5/A7, CZ-62500, Brno, Czech Republic. .,National Centre for Biomolecular Research, Masaryk University, Kamenice 5/A4, CZ-62500, Brno, Czech Republic. .,International Clinical Research Center, Center for Biomolecular and Cellular Engineering, St. Anne's University Hospital Brno, Pekarska 53, CZ-656 91, Brno, Czech Republic.
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20
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Overexpression of PCNA Attenuates Oxidative Stress-Caused Delay of Gap-Filling during Repair of UV-Induced DNA Damage. J Nucleic Acids 2017; 2017:8154646. [PMID: 28116145 PMCID: PMC5237465 DOI: 10.1155/2017/8154646] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 10/12/2016] [Accepted: 11/15/2016] [Indexed: 01/05/2023] Open
Abstract
UVC irradiation-caused DNA lesions are repaired in mammalian cells solely by nucleotide excision repair (NER), which consists of sequential events including initial damage recognition, dual incision of damage site, gap-filling, and ligation. We have previously shown that gap-filling during the repair of UV-induced DNA lesions may be delayed by a subsequent treatment of oxidants or prooxidants such as hydrogen peroxide, flavonoids, and colcemid. We considered the delay as a result of competition for limiting protein/enzyme factor(s) during repair synthesis between NER and base excision repair (BER) induced by the oxidative chemicals. In this report, using colcemid as oxidative stress inducer, we showed that colcemid-caused delay of gap-filling during the repair of UV-induced DNA lesions was attenuated by overexpression of PCNA but not ligase-I. PCNA knockdown, as expected, delayed the gap-filling of NER but also impaired the repair of oxidative DNA damage. Fen-1 knockdown, however, did not affect the repair of oxidative DNA damage, suggesting repair of oxidative DNA damage is not of long patch BER. Furthermore, overexpression of XRCC1 delayed the gap-filling, and presumably increase of XRCC1 pulls PCNA away from gap-filling of NER for BER, consistent with our hypothesis that delay of gap-filling of NER attributes the competition between NER and BER.
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21
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Defect of Fe-S cluster binding by DNA polymerase δ in yeast suppresses UV-induced mutagenesis, but enhances DNA polymerase ζ - dependent spontaneous mutagenesis. DNA Repair (Amst) 2016; 49:60-69. [PMID: 28034630 DOI: 10.1016/j.dnarep.2016.11.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Revised: 11/30/2016] [Accepted: 11/30/2016] [Indexed: 11/21/2022]
Abstract
Eukaryotic genomes are duplicated by a complex machinery, utilizing high fidelity replicative B-family DNA polymerases (pols) α, δ and ε. Specialized error-prone pol ζ, the fourth B-family member, is recruited when DNA synthesis by the accurate trio is impeded by replication stress or DNA damage. The damage tolerance mechanism dependent on pol ζ prevents DNA/genome instability and cell death at the expense of increased mutation rates. The pol switches occurring during this specialized replication are not fully understood. The loss of pol ζ results in the absence of induced mutagenesis and suppression of spontaneous mutagenesis. Disruption of the Fe-S cluster motif that abolish the interaction of the C-terminal domain (CTD) of the catalytic subunit of pol ζ with its accessory subunits, which are shared with pol δ, leads to a similar defect in induced mutagenesis. Intriguingly, the pol3-13 mutation that affects the Fe-S cluster in the CTD of the catalytic subunit of pol δ also leads to defective induced mutagenesis, suggesting the possibility that Fe-S clusters are essential for the pol switches during replication of damaged DNA. We confirmed that yeast strains with the pol3-13 mutation are UV-sensitive and defective in UV-induced mutagenesis. However, they have increased spontaneous mutation rates. We found that this increase is dependent on functional pol ζ. In the pol3-13 mutant strain with defective pol δ, there is a sharp increase in transversions and complex mutations, which require functional pol ζ, and an increase in the occurrence of large deletions, whose size is controlled by pol ζ. Therefore, the pol3-13 mutation abrogates pol ζ-dependent induced mutagenesis, but allows for pol ζ recruitment for the generation of spontaneous mutations and prevention of larger deletions. These results reveal differential control of the two major types of pol ζ-dependent mutagenesis by the Fe-S cluster present in replicative pol δ.
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22
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Beaver JM, Lai Y, Rolle SJ, Liu Y. Proliferating cell nuclear antigen prevents trinucleotide repeat expansions by promoting repeat deletion and hairpin removal. DNA Repair (Amst) 2016; 48:17-29. [PMID: 27793507 DOI: 10.1016/j.dnarep.2016.10.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 10/11/2016] [Accepted: 10/21/2016] [Indexed: 11/26/2022]
Abstract
DNA base lesions and base excision repair (BER) within trinucleotide repeat (TNR) tracts modulate repeat instability through the coordination among the key BER enzymes DNA polymerase β, flap endonuclease 1 (FEN1) and DNA ligase I (LIG I). However, it remains unknown whether BER cofactors can also alter TNR stability. In this study, we discovered that proliferating cell nuclear antigen (PCNA), a cofactor of BER, promoted CAG repeat deletion and removal of a CAG repeat hairpin during BER in a duplex CAG repeat tract and CAG hairpin loop, respectively. We showed that PCNA stimulated LIG I activity on a nick across a small template loop during BER in a duplex (CAG)20 repeat tract promoting small repeat deletions. Surprisingly, we found that during BER in a hairpin loop, PCNA promoted reannealing of the upstream flap of a double-flap intermediate, thereby facilitating the formation of a downstream flap and stimulating FEN1 cleavage activity and hairpin removal. Our results indicate that PCNA plays a critical role in preventing CAG repeat expansions by modulating the structures of dynamic DNA via cooperation with BER enzymes. We provide the first evidence that PCNA prevents CAG repeat expansions during BER by promoting CAG repeat deletion and removal of a TNR hairpin.
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Affiliation(s)
- Jill M Beaver
- Biochemistry Ph.D. Program, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Yanhao Lai
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Shantell J Rolle
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Yuan Liu
- Biochemistry Ph.D. Program, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States; Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States; Biomolecular Sciences Institute, School of Integrated Sciences and Humanities, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States.
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23
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Sebesta M, Urulangodi M, Stefanovie B, Szakal B, Pacesa M, Lisby M, Branzei D, Krejci L. Esc2 promotes Mus81 complex-activity via its SUMO-like and DNA binding domains. Nucleic Acids Res 2016; 45:215-230. [PMID: 27694623 PMCID: PMC5224511 DOI: 10.1093/nar/gkw882] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 08/30/2016] [Accepted: 09/22/2016] [Indexed: 01/17/2023] Open
Abstract
Replication across damaged DNA templates is accompanied by transient formation of sister chromatid junctions (SCJs). Cells lacking Esc2, an adaptor protein containing no known enzymatic domains, are defective in the metabolism of these SCJs. However, how Esc2 is involved in the metabolism of SCJs remains elusive. Here we show interaction between Esc2 and a structure-specific endonuclease Mus81-Mms4 (the Mus81 complex), their involvement in the metabolism of SCJs, and the effects Esc2 has on the enzymatic activity of the Mus81 complex. We found that Esc2 specifically interacts with the Mus81 complex via its SUMO-like domains, stimulates enzymatic activity of the Mus81 complex in vitro, and is involved in the Mus81 complex-dependent resolution of SCJs in vivo. Collectively, our data point to the possibility that the involvement of Esc2 in the metabolism of SCJs is, in part, via modulation of the activity of the Mus81 complex.
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Affiliation(s)
- Marek Sebesta
- National Centre for Biomolecular Research, Masaryk University, Kamenice 5/A4, CZ-62500 Brno, Czech Republic.,Department of Biology, Masaryk University, Kamenice 5/A7, CZ-62500 Brno, Czech Republic.,IFOM, the FIRC Institute of Molecular Oncology, Via Adamello 16, IT-20139 Milan, Italy
| | | | - Barbora Stefanovie
- National Centre for Biomolecular Research, Masaryk University, Kamenice 5/A4, CZ-62500 Brno, Czech Republic.,Department of Biology, Masaryk University, Kamenice 5/A7, CZ-62500 Brno, Czech Republic.,International Clinical Research Center, Center for Biomolecular and Cellular Engineering, St. Anne's University Hospital Brno, Pekarska 53, CZ-656 91 Brno, Czech Republic
| | - Barnabas Szakal
- IFOM, the FIRC Institute of Molecular Oncology, Via Adamello 16, IT-20139 Milan, Italy
| | - Martin Pacesa
- National Centre for Biomolecular Research, Masaryk University, Kamenice 5/A4, CZ-62500 Brno, Czech Republic
| | - Michael Lisby
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Dana Branzei
- IFOM, the FIRC Institute of Molecular Oncology, Via Adamello 16, IT-20139 Milan, Italy
| | - Lumir Krejci
- National Centre for Biomolecular Research, Masaryk University, Kamenice 5/A4, CZ-62500 Brno, Czech Republic .,Department of Biology, Masaryk University, Kamenice 5/A7, CZ-62500 Brno, Czech Republic.,International Clinical Research Center, Center for Biomolecular and Cellular Engineering, St. Anne's University Hospital Brno, Pekarska 53, CZ-656 91 Brno, Czech Republic
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24
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Halmai M, Frittmann O, Szabo Z, Daraba A, Gali VK, Balint E, Unk I. Mutations at the Subunit Interface of Yeast Proliferating Cell Nuclear Antigen Reveal a Versatile Regulatory Domain. PLoS One 2016; 11:e0161307. [PMID: 27537501 PMCID: PMC4990258 DOI: 10.1371/journal.pone.0161307] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 08/03/2016] [Indexed: 11/19/2022] Open
Abstract
Proliferating cell nuclear antigen (PCNA) plays a key role in many cellular processes and due to that it interacts with a plethora of proteins. The main interacting surfaces of Saccharomyces cerevisiae PCNA have been mapped to the interdomain connecting loop and to the carboxy-terminal domain. Here we report that the subunit interface of yeast PCNA also has regulatory roles in the function of several DNA damage response pathways. Using site-directed mutagenesis we engineered mutations at both sides of the interface and investigated the effect of these alleles on DNA damage response. Genetic experiments with strains bearing the mutant alleles revealed that mutagenic translesion synthesis, nucleotide excision repair, and homologous recombination are all regulated through residues at the subunit interface. Moreover, genetic characterization of one of our mutants identifies a new sub-branch of nucleotide excision repair. Based on these results we conclude that residues at the subunit boundary of PCNA are not only important for the formation of the trimer structure of PCNA, but they constitute a regulatory protein domain that mediates different DNA damage response pathways, as well.
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Affiliation(s)
- Miklos Halmai
- The Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | - Orsolya Frittmann
- The Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | - Zoltan Szabo
- The Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | - Andreea Daraba
- The Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | - Vamsi K. Gali
- The Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | - Eva Balint
- The Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
| | - Ildiko Unk
- The Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
- * E-mail:
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25
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Deshmukh AL, Kumar C, Singh DK, Maurya P, Banerjee D. Dynamics of replication proteins during lagging strand synthesis: A crossroads for genomic instability and cancer. DNA Repair (Amst) 2016; 42:72-81. [DOI: 10.1016/j.dnarep.2016.04.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 04/22/2016] [Accepted: 04/22/2016] [Indexed: 01/18/2023]
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26
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Resolving individual steps of Okazaki-fragment maturation at a millisecond timescale. Nat Struct Mol Biol 2016; 23:402-8. [PMID: 27065195 PMCID: PMC4857878 DOI: 10.1038/nsmb.3207] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 03/18/2016] [Indexed: 11/08/2022]
Abstract
DNA polymerase delta (Pol δ) is responsible for elongation and maturation of Okazaki fragments. Pol δ and the flap endonuclease FEN1, coordinated by the PCNA clamp, remove RNA primers and produce ligatable nicks. We studied this process in the Saccharomyces cerevisiae machinery at millisecond resolution. During elongation, PCNA increased the Pol δ catalytic rate by >30-fold. When Pol δ invaded double-stranded RNA-DNA representing unmatured Okazaki fragments, the incorporation rate of each nucleotide decreased successively to 10-20% that of the preceding nucleotide. Thus, the nascent flap acts as a progressive molecular brake on the polymerase, and consequently FEN1 cuts predominantly single-nucleotide flaps. Kinetic and enzyme-trapping experiments support a model in which a stable PCNA-DNA-Pol δ-FEN1 complex moves processively through iterative steps of nick translation, ultimately completely removing primer RNA. Finally, whereas elongation rates are under dynamic dNTP control, maturation rates are buffered against changes in dNTP concentrations.
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27
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Duffy CM, Hilbert BJ, Kelch BA. A Disease-Causing Variant in PCNA Disrupts a Promiscuous Protein Binding Site. J Mol Biol 2015; 428:1023-1040. [PMID: 26688547 DOI: 10.1016/j.jmb.2015.11.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 11/10/2015] [Accepted: 11/21/2015] [Indexed: 11/27/2022]
Abstract
The eukaryotic DNA polymerase sliding clamp, proliferating cell nuclear antigen or PCNA, is a ring-shaped protein complex that surrounds DNA to act as a sliding platform for increasing processivity of cellular replicases and for coordinating various cellular pathways with DNA replication. A single point mutation, Ser228Ile, in the human PCNA gene was recently identified to cause a disease whose symptoms resemble those of DNA damage and repair disorders. The mutation lies near the binding site for most PCNA-interacting proteins. However, the structural consequences of the S228I mutation are unknown. Here, we describe the structure of the disease-causing variant, which reveals a large conformational change that dramatically transforms the binding pocket for PCNA client proteins. We show that the mutation markedly alters the binding energetics for some client proteins, while another, p21(CIP1), is only mildly affected. Structures of the disease variant bound to peptides derived from two PCNA partner proteins reveal that the binding pocket can adjust conformation to accommodate some ligands, indicating that the binding site is dynamic and pliable. Our work has implications for the plasticity of the binding site in PCNA and reveals how a disease mutation selectively alters interactions to a promiscuous binding site that is critical for DNA metabolism.
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Affiliation(s)
- Caroline M Duffy
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Brendan J Hilbert
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Brian A Kelch
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
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28
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Doerfler L, Schmidt KH. Exo1 phosphorylation status controls the hydroxyurea sensitivity of cells lacking the Pol32 subunit of DNA polymerases delta and zeta. DNA Repair (Amst) 2015; 24:26-36. [PMID: 25457771 DOI: 10.1016/j.dnarep.2014.10.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 09/29/2014] [Accepted: 10/02/2014] [Indexed: 11/16/2022]
Abstract
Exo1 belongs to the Rad2 family of structure-specific nucleases and possesses 5'-3' exonuclease activity on double-stranded DNA substrates. Exo1 interacts physically with the DNA mismatch repair (MMR) proteins Msh2 and Mlh1 and is involved in the excision of the mispaired nucleotide. Independent of its role in MMR, Exo1 contributes to long-range resection of DNA double-strand break (DSB) ends to facilitate their repair by homologous recombination (HR), and was recently identified as a component of error-free DNA damage tolerance pathways. Here, we show that Exo1 activity increases the hydroxyurea sensitivity of cells lacking Pol32, a subunit of DNA polymerases δ and ζ. Both, phospho-mimicking and dephospho-mimicking exo1 mutants act as hypermorphs, as evidenced by an increase in HU sensitivity of pol32Δ cells, suggesting that they are trapped in an active form and that phosphorylation of Exo1 at residues S372, S567, S587, S692 is necessary, but insufficient, for the accurate regulation of Exo1 activity at stalled replication forks. In contrast, neither phosphorylation status is important for Exo1's role in MMR or in the suppression of genome instability in cells lacking Sgs1 helicase. This ability of an EXO1 deletion to suppress the HU hypersensitivity of pol32Δ cells is in contrast to the negative genetic interaction between deletions of EXO1 and POL32 in MMS-treated cells as well as the role of EXO1 in DNA-damage treated rad53 and mec1 mutants.
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Affiliation(s)
- Lillian Doerfler
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, United States; Graduate Program in Cell and Molecular Biology, University of South Florida, Tampa, FL 33620, United States
| | - Kristina H Schmidt
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, United States; Cancer Biology and Evolution Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612, United States.
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29
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Levikova M, Cejka P. The Saccharomyces cerevisiae Dna2 can function as a sole nuclease in the processing of Okazaki fragments in DNA replication. Nucleic Acids Res 2015; 43:7888-97. [PMID: 26175049 PMCID: PMC4652754 DOI: 10.1093/nar/gkv710] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Accepted: 07/01/2015] [Indexed: 01/30/2023] Open
Abstract
During DNA replication, synthesis of the lagging strand occurs in stretches termed Okazaki fragments. Before adjacent fragments are ligated, any flaps resulting from the displacement of the 5' DNA end of the Okazaki fragment must be cleaved. Previously, Dna2 was implicated to function upstream of flap endonuclease 1 (Fen1 or Rad27) in the processing of long flaps bound by the replication protein A (RPA). Here we show that Dna2 efficiently cleaves long DNA flaps exactly at or directly adjacent to the base. A fraction of the flaps cleaved by Dna2 can be immediately ligated. When coupled with DNA replication, the flap processing activity of Dna2 leads to a nearly complete Okazaki fragment maturation at sub-nanomolar Dna2 concentrations. Our results indicate that a subsequent nucleolytic activity of Fen1 is not required in most cases. In contrast Dna2 is completely incapable to cleave short flaps. We show that also Dna2, like Fen1, interacts with proliferating cell nuclear antigen (PCNA). We propose a model where Dna2 alone is responsible for cleaving of RPA-bound long flaps, while Fen1 or exonuclease 1 (Exo1) cleave short flaps. Our results argue that Dna2 can function in a separate, rather than in a Fen1-dependent pathway.
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Affiliation(s)
- Maryna Levikova
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Petr Cejka
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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30
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Khanam T, Rai N, Ramachandran R. Mycobacterium tuberculosis class II apurinic/apyrimidinic-endonuclease/3'-5' exonuclease III exhibits DNA regulated modes of interaction with the sliding DNA β-clamp. Mol Microbiol 2015; 98:46-68. [PMID: 26103519 DOI: 10.1111/mmi.13102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/19/2015] [Indexed: 11/30/2022]
Abstract
The class-II AP-endonuclease (XthA) acts on abasic sites of damaged DNA in bacterial base excision repair. We identified that the sliding DNA β-clamp forms in vivo and in vitro complexes with XthA in Mycobacterium tuberculosis. A novel 239 QLRFPKK245 motif in the DNA-binding domain of XthA was found to be important for the interactions. Likewise, the peptide binding-groove (PBG) and the C-terminal of β-clamp located on different domains interact with XthA. The β-clamp-XthA complex can be disrupted by clamp binding peptides and also by a specific bacterial clamp inhibitor that binds at the PBG. We also identified that β-clamp stimulates the activities of XthA primarily by increasing its affinity for the substrate and its processivity. Additionally, loading of the β-clamp onto DNA is required for activity stimulation. A reduction in XthA activity stimulation was observed in the presence of β-clamp binding peptides supporting that direct interactions between the proteins are necessary to cause stimulation. Finally, we found that in the absence of DNA, the PBG located on the second domain of the β-clamp is important for interactions with XthA, while the C-terminal domain predominantly mediates functional interactions in the substrate's presence.
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Affiliation(s)
- Taran Khanam
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, Uttar Pradesh, 226031, India
| | - Niyati Rai
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, Uttar Pradesh, 226031, India
| | - Ravishankar Ramachandran
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, Uttar Pradesh, 226031, India
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31
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Sparks JL, Burgers PM. Error-free and mutagenic processing of topoisomerase 1-provoked damage at genomic ribonucleotides. EMBO J 2015; 34:1259-69. [PMID: 25777529 DOI: 10.15252/embj.201490868] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 02/25/2015] [Indexed: 11/09/2022] Open
Abstract
Genomic ribonucleotides incorporated during DNA replication are commonly repaired by RNase H2-dependent ribonucleotide excision repair (RER). When RNase H2 is compromised, such as in Aicardi-Goutières patients, genomic ribonucleotides either persist or are processed by DNA topoisomerase 1 (Top1) by either error-free or mutagenic repair. Here, we present a biochemical analysis of these pathways. Top1 cleavage at genomic ribonucleotides can produce ribonucleoside-2',3'-cyclic phosphate-terminated nicks. Remarkably, this nick is rapidly reverted by Top1, thereby providing another opportunity for repair by RER. However, the 2',3'-cyclic phosphate-terminated nick is also processed by Top1 incision, generally 2 nucleotides upstream of the nick, which produces a covalent Top1-DNA complex with a 2-nucleotide gap. We show that these covalent complexes can be processed by proteolysis, followed by removal of the phospho-peptide by Tdp1 and the 3'-phosphate by Tpp1 to mediate error-free repair. However, when the 2-nucleotide gap is associated with a dinucleotide repeat sequence, sequence slippage re-alignment followed by Top1-mediated religation can occur which results in 2-nucleotide deletion. The efficiency of deletion formation shows strong sequence-context dependence.
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Affiliation(s)
- Justin L Sparks
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
| | - Peter M Burgers
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
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32
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Sequential switching of binding partners on PCNA during in vitro Okazaki fragment maturation. Proc Natl Acad Sci U S A 2014; 111:14118-23. [PMID: 25228764 DOI: 10.1073/pnas.1321349111] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The homotrimeric sliding clamp proliferating cell nuclear antigen (PCNA) mediates Okazaki fragment maturation through tight coordination of the activities of DNA polymerase δ (Pol δ), flap endonuclease 1 (FEN1) and DNA ligase I (Lig1). Little is known regarding the mechanism of partner switching on PCNA and the involvement of PCNA's three binding sites in coordinating such processes. To shed new light on PCNA-mediated Okazaki fragment maturation, we developed a novel approach for the generation of PCNA heterotrimers containing one or two mutant monomers that are unable to bind and stimulate partners. These heterotrimers maintain the native oligomeric structure of PCNA and exhibit high stability under various conditions. Unexpectedly, we found that PCNA heterotrimers containing only one functional binding site enable Okazaki fragment maturation by efficiently coordinating the activities of Pol δ, FEN1, and Lig1. The efficiency of switching between partners on PCNA was not significantly impaired by limiting the number of available binding sites on the PCNA ring. Our results provide the first direct evidence, to our knowledge, that simultaneous binding of multiple partners to PCNA is unnecessary, and if it occurs, does not provide significant functional advantages for PCNA-mediated Okazaki fragment maturation in vitro. In contrast to the "toolbelt" model, which was demonstrated for bacterial and archaeal sliding clamps, our results suggest a mechanism of sequential switching of partners on the eukaryotic PCNA trimer during DNA replication and repair.
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33
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Pache RA, Aloy P. Increasing the precision of orthology-based complex prediction through network alignment. PeerJ 2014; 2:e413. [PMID: 24918034 PMCID: PMC4045337 DOI: 10.7717/peerj.413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 05/13/2014] [Indexed: 12/01/2022] Open
Abstract
Macromolecular assemblies play an important role in almost all cellular processes. However, despite several large-scale studies, our current knowledge about protein complexes is still quite limited, thus advocating the use of in silico predictions to gather information on complex composition in model organisms. Since protein–protein interactions present certain constraints on the functional divergence of macromolecular assemblies during evolution, it is possible to predict complexes based on orthology data. Here, we show that incorporating interaction information through network alignment significantly increases the precision of orthology-based complex prediction. Moreover, we performed a large-scale in silico screen for protein complexes in human, yeast and fly, through the alignment of hundreds of known complexes to whole organism interactomes. Systematic comparison of the resulting network alignments to all complexes currently known in those species revealed many conserved complexes, as well as several novel complex components. In addition to validating our predictions using orthogonal data, we were able to assign specific functional roles to the predicted complexes. In several cases, the incorporation of interaction data through network alignment allowed to distinguish real complex components from other orthologous proteins. Our analyses indicate that current knowledge of yeast protein complexes exceeds that in other organisms and that predicting complexes in fly based on human and yeast data is complementary rather than redundant. Lastly, assessing the conservation of protein complexes of the human pathogen Mycoplasma pneumoniae, we discovered that its complexes repertoire is different from that of eukaryotes, suggesting new points of therapeutic intervention, whereas targeting the pathogen’s Restriction enzyme complex might lead to adverse effects due to its similarity to ATP-dependent metalloproteases in the human host.
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Affiliation(s)
- Roland A Pache
- Joint IRB-BSC Program in Computational Biology, Institute for Research in Biomedicine (IRB Barcelona) , Barcelona , Spain
| | - Patrick Aloy
- Joint IRB-BSC Program in Computational Biology, Institute for Research in Biomedicine (IRB Barcelona) , Barcelona , Spain ; Institució Catalana de Recerca i Estudis Avançats (ICREA) , Barcelona , Spain
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34
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The cutting edges in DNA repair, licensing, and fidelity: DNA and RNA repair nucleases sculpt DNA to measure twice, cut once. DNA Repair (Amst) 2014; 19:95-107. [PMID: 24754999 DOI: 10.1016/j.dnarep.2014.03.022] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To avoid genome instability, DNA repair nucleases must precisely target the correct damaged substrate before they are licensed to incise. Damage identification is a challenge for all DNA damage response proteins, but especially for nucleases that cut the DNA and necessarily create a cleaved DNA repair intermediate, likely more toxic than the initial damage. How do these enzymes achieve exquisite specificity without specific sequence recognition or, in some cases, without a non-canonical DNA nucleotide? Combined structural, biochemical, and biological analyses of repair nucleases are revealing their molecular tools for damage verification and safeguarding against inadvertent incision. Surprisingly, these enzymes also often act on RNA, which deserves more attention. Here, we review protein-DNA structures for nucleases involved in replication, base excision repair, mismatch repair, double strand break repair (DSBR), and telomere maintenance: apurinic/apyrimidinic endonuclease 1 (APE1), Endonuclease IV (Nfo), tyrosyl DNA phosphodiesterase (TDP2), UV Damage endonuclease (UVDE), very short patch repair endonuclease (Vsr), Endonuclease V (Nfi), Flap endonuclease 1 (FEN1), exonuclease 1 (Exo1), RNase T and Meiotic recombination 11 (Mre11). DNA and RNA structure-sensing nucleases are essential to life with roles in DNA replication, repair, and transcription. Increasingly these enzymes are employed as advanced tools for synthetic biology and as targets for cancer prognosis and interventions. Currently their structural biology is most fully illuminated for DNA repair, which is also essential to life. How DNA repair enzymes maintain genome fidelity is one of the DNA double helix secrets missed by James Watson and Francis Crick, that is only now being illuminated though structural biology and mutational analyses. Structures reveal motifs for repair nucleases and mechanisms whereby these enzymes follow the old carpenter adage: measure twice, cut once. Furthermore, to measure twice these nucleases act as molecular level transformers that typically reshape the DNA and sometimes themselves to achieve extraordinary specificity and efficiency.
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35
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Li Z, Huang RYC, Yopp DC, Hileman TH, Santangelo TJ, Hurwitz J, Hudgens JW, Kelman Z. A novel mechanism for regulating the activity of proliferating cell nuclear antigen by a small protein. Nucleic Acids Res 2014; 42:5776-89. [PMID: 24728986 PMCID: PMC4027161 DOI: 10.1093/nar/gku239] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Proliferating cell nuclear antigen (PCNA) forms a trimeric ring that associates with and influences the activity of many proteins participating in DNA metabolic processes and cell cycle progression. Previously, an uncharacterized small protein, encoded by TK0808 in the archaeon Thermococcus kodakarensis, was shown to stably interact with PCNA in vivo. Here, we show that this protein, designated Thermococcales inhibitor of PCNA (TIP), binds to PCNA in vitro and inhibits PCNA-dependent activities likely by preventing PCNA trimerization. Using hydrogen/deuterium exchange mass spectrometry and site-directed mutagenesis, the interacting regions of PCNA and TIP were identified. Most proteins bind to PCNA via a PCNA-interacting peptide (PIP) motif that interacts with the inter domain connecting loop (IDCL) on PCNA. TIP, however, lacks any known PCNA-interacting motif, suggesting a new mechanism for PCNA binding and regulation of PCNA-dependent activities, which may support the development of a new subclass of therapeutic biomolecules for inhibiting PCNA.
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Affiliation(s)
- Zhuo Li
- Institute for Bioscience and Biotechnology Research, 9600 Gudelsky Drive, Rockville, MD 20850, USA
| | - Richard Y-C Huang
- Institute for Bioscience and Biotechnology Research, 9600 Gudelsky Drive, Rockville, MD 20850, USA National Institute of Standards and Technology, 9600 Gudelsky Drive, Rockville, MD 20850, USA
| | - Daniel C Yopp
- Department of Microbiology and Center for RNA Biology, Ohio State University, Columbus, OH 43210, USA
| | - Travis H Hileman
- Department of Microbiology and Center for RNA Biology, Ohio State University, Columbus, OH 43210, USA
| | - Thomas J Santangelo
- Department of Microbiology and Center for RNA Biology, Ohio State University, Columbus, OH 43210, USA
| | - Jerard Hurwitz
- Program of Molecular Biology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Jeffrey W Hudgens
- Institute for Bioscience and Biotechnology Research, 9600 Gudelsky Drive, Rockville, MD 20850, USA National Institute of Standards and Technology, 9600 Gudelsky Drive, Rockville, MD 20850, USA
| | - Zvi Kelman
- Institute for Bioscience and Biotechnology Research, 9600 Gudelsky Drive, Rockville, MD 20850, USA National Institute of Standards and Technology, 9600 Gudelsky Drive, Rockville, MD 20850, USA
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36
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Burgess RC, Sebesta M, Sisakova A, Marini VP, Lisby M, Damborsky J, Klein H, Rothstein R, Krejci L. The PCNA interaction protein box sequence in Rad54 is an integral part of its ATPase domain and is required for efficient DNA repair and recombination. PLoS One 2013; 8:e82630. [PMID: 24376557 PMCID: PMC3869717 DOI: 10.1371/journal.pone.0082630] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 10/25/2013] [Indexed: 11/19/2022] Open
Abstract
Rad54 is an ATP-driven translocase involved in the genome maintenance pathway of homologous recombination (HR). Although its activity has been implicated in several steps of HR, its exact role(s) at each step are still not fully understood. We have identified a new interaction between Rad54 and the replicative DNA clamp, proliferating cell nuclear antigen (PCNA). This interaction was only mildly weakened by the mutation of two key hydrophobic residues in the highly-conserved PCNA interaction motif (PIP-box) of Rad54 (Rad54-AA). Intriguingly, the rad54-AA mutant cells displayed sensitivity to DNA damage and showed HR defects similar to the null mutant, despite retaining its ability to interact with HR proteins and to be recruited to HR foci in vivo. We therefore surmised that the PCNA interaction might be impaired in vivo and was unable to promote repair synthesis during HR. Indeed, the Rad54-AA mutant was defective in primer extension at the MAT locus as well as in vitro, but additional biochemical analysis revealed that this mutant also had diminished ATPase activity and an inability to promote D-loop formation. Further mutational analysis of the putative PIP-box uncovered that other phenotypically relevant mutants in this domain also resulted in a loss of ATPase activity. Therefore, we have found that although Rad54 interacts with PCNA, the PIP-box motif likely plays only a minor role in stabilizing the PCNA interaction, and rather, this conserved domain is probably an extension of the ATPase domain III.
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Affiliation(s)
- Rebecca C. Burgess
- Department of Genetics & Development, Columbia University Medical Center, New York, New York, United States of America
| | - Marek Sebesta
- National Centre for Biomolecular Research, Masaryk University, Brno, Czech Republic
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
- International Clinical Research Centre, Centre for Biomolecular and Cellular Engineering, Saint Anne's University Hospital, Brno, Czech Republic
| | - Alexandra Sisakova
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
- International Clinical Research Centre, Centre for Biomolecular and Cellular Engineering, Saint Anne's University Hospital, Brno, Czech Republic
| | - Victoria P. Marini
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Michael Lisby
- Department of Molecular Biology, University of Copenhagen, Copenhagen N, Denmark
| | - Jiri Damborsky
- International Clinical Research Centre, Centre for Biomolecular and Cellular Engineering, Saint Anne's University Hospital, Brno, Czech Republic
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Hannah Klein
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York, United States of America
| | - Rodney Rothstein
- Department of Genetics & Development, Columbia University Medical Center, New York, New York, United States of America
| | - Lumir Krejci
- National Centre for Biomolecular Research, Masaryk University, Brno, Czech Republic
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
- International Clinical Research Centre, Centre for Biomolecular and Cellular Engineering, Saint Anne's University Hospital, Brno, Czech Republic
- * E-mail:
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37
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Waisertreiger ISR, Liston VG, Menezes MR, Kim HM, Lobachev KS, Stepchenkova EI, Tahirov TH, Rogozin IB, Pavlov YI. Modulation of mutagenesis in eukaryotes by DNA replication fork dynamics and quality of nucleotide pools. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2012; 53:699-724. [PMID: 23055184 PMCID: PMC3893020 DOI: 10.1002/em.21735] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 08/13/2012] [Accepted: 08/15/2012] [Indexed: 06/01/2023]
Abstract
The rate of mutations in eukaryotes depends on a plethora of factors and is not immediately derived from the fidelity of DNA polymerases (Pols). Replication of chromosomes containing the anti-parallel strands of duplex DNA occurs through the copying of leading and lagging strand templates by a trio of Pols α, δ and ϵ, with the assistance of Pol ζ and Y-family Pols at difficult DNA template structures or sites of DNA damage. The parameters of the synthesis at a given location are dictated by the quality and quantity of nucleotides in the pools, replication fork architecture, transcription status, regulation of Pol switches, and structure of chromatin. The result of these transactions is a subject of survey and editing by DNA repair.
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Affiliation(s)
- Irina S.-R. Waisertreiger
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
| | - Victoria G. Liston
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
| | - Miriam R. Menezes
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
| | - Hyun-Min Kim
- School of Biology and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, U.S.A
| | - Kirill S. Lobachev
- School of Biology and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, U.S.A
| | - Elena I. Stepchenkova
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
- Saint Petersburg Branch of Vavilov Institute of General Genetics, Universitetskaya emb. 7/9, St Petersburg, 199034, Russia
- Department of Genetics, Saint Petersburg University, Universitetskaya emb. 7/9, St Petersburg, 199034, Russia
| | - Tahir H. Tahirov
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
| | - Igor B. Rogozin
- National Center for Biotechnology Information NLM, National Institutes of Health, Bethesda, MD 20894, U.S.A
- Institute of Cytology and Genetics, 630090 Novosibirsk, Russia
| | - Youri. I. Pavlov
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
- Department of Genetics, Saint Petersburg University, Universitetskaya emb. 7/9, St Petersburg, 199034, Russia
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38
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Fridman Y, Gur E, Fleishman SJ, Aharoni A. Computational protein design suggests that human PCNA-partner interactions are not optimized for affinity. Proteins 2012; 81:341-8. [PMID: 23011891 DOI: 10.1002/prot.24190] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 09/14/2012] [Accepted: 09/19/2012] [Indexed: 11/06/2022]
Abstract
Increasing the affinity of binding proteins is invaluable for basic and applied biological research. Currently, directed protein evolution experiments are the main approach for generating such proteins through the construction and screening of large mutant libraries. Proliferating cell nuclear antigen (PCNA) is an essential hub protein that interacts with many different partners to tightly regulate DNA replication and repair in all eukaryotes. Here, we used computational design to generate human PCNA mutants with enhanced affinity for several different partners. We identified double mutations in PCNA, outside the main partner binding site, that were predicted to increase PCNA-partner binding affinities compared to the wild-type protein by forming additional hydrophobic interactions with conserved residues in the PCNA partners. Affinity increases were experimentally validated with four different PCNA partners, demonstrating that computational design can reveal unexpected regions where affinity enhancements in natural systems are possible. The designed PCNA mutants can be used as a valuable tool for further examination of the regulation of PCNA-partner interactions during DNA replication and repair both in vitro and in vivo. More broadly, the ability to engineer affinity increases toward several PCNA partners suggests that interaction affinity is not an evolutionarily optimized trait of this system.
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Affiliation(s)
- Yearit Fridman
- Departments of Life Sciences and the National Institute for Biotechnology in the Negev (NIBN), Ben-Gurion University of the Negev, Be'er Sheva 84105, Israel
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39
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Repair complexes of FEN1 endonuclease, DNA, and Rad9-Hus1-Rad1 are distinguished from their PCNA counterparts by functionally important stability. Proc Natl Acad Sci U S A 2012; 109:8528-33. [PMID: 22586102 DOI: 10.1073/pnas.1121116109] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Processivity clamps such as proliferating cell nuclear antigen (PCNA) and the checkpoint sliding clamp Rad9/Rad1/Hus1 (9-1-1) act as versatile scaffolds in the coordinated recruitment of proteins involved in DNA replication, cell-cycle control, and DNA repair. Association and handoff of DNA-editing enzymes, such as flap endonuclease 1 (FEN1), with sliding clamps are key processes in biology, which are incompletely understood from a mechanistic point of view. We have used an integrative computational and experimental approach to define the assemblies of FEN1 with double-flap DNA substrates and either proliferating cell nuclear antigen or the checkpoint sliding clamp 9-1-1. Fully atomistic models of these two ternary complexes were developed and refined through extensive molecular dynamics simulations to expose their conformational dynamics. Clustering analysis revealed the most dominant conformations accessible to the complexes. The cluster centroids were subsequently used in conjunction with single-particle electron microscopy data to obtain a 3D EM reconstruction of the human 9-1-1/FEN1/DNA assembly at 18-Å resolution. Comparing the structures of the complexes revealed key differences in the orientation and interactions of FEN1 and double-flap DNA with the two clamps that are consistent with their respective functions in providing inherent flexibility for lagging strand DNA replication or inherent stability for DNA repair.
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40
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Kukshal V, Khanam T, Chopra D, Singh N, Sanyal S, Ramachandran R. M. tuberculosis sliding β-clamp does not interact directly with the NAD+-dependent DNA ligase. PLoS One 2012; 7:e35702. [PMID: 22545130 PMCID: PMC3335792 DOI: 10.1371/journal.pone.0035702] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 03/20/2012] [Indexed: 11/26/2022] Open
Abstract
The sliding β-clamp, an important component of the DNA replication and repair machinery, is drawing increasing attention as a therapeutic target. We report the crystal structure of the M. tuberculosis β-clamp (Mtbβ-clamp) to 3.0 Å resolution. The protein crystallized in the space group C222(1) with cell-dimensions a = 72.7, b = 234.9 & c = 125.1 Å respectively. Mtbβ-clamp is a dimer, and exhibits head-to-tail association similar to other bacterial clamps. Each monomer folds into three domains with similar structures respectively and associates with its dimeric partner through 6 salt-bridges and about 21 polar interactions. Affinity experiments involving a blunt DNA duplex, primed-DNA and nicked DNA respectively show that Mtbβ-clamp binds specifically to primed DNA about 1.8 times stronger compared to the other two substrates and with an apparent K(d) of 300 nM. In bacteria like E. coli, the β-clamp is known to interact with subunits of the clamp loader, NAD(+)-dependent DNA ligase (LigA) and other partners. We tested the interactions of the Mtbβ-clamp with MtbLigA and the γ-clamp loader subunit through radioactive gel shift assays, size exclusion chromatography, yeast-two hybrid experiments and also functionally. Intriguingly while Mtbβ-clamp interacts in vitro with the γ-clamp loader, it does not interact with MtbLigA unlike in bacteria like E. coli where it does. Modeling studies involving earlier peptide complexes reveal that the peptide-binding site is largely conserved despite lower sequence identity between bacterial clamps. Overall the results suggest that other as-yet-unidentified factors may mediate interactions between the clamp, LigA and DNA in mycobacteria.
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Affiliation(s)
- Vandna Kukshal
- Molecular and Structural Biology Division, Central Drug Research Institute (Council of Scientific and Industrial Research), Lucknow, Uttar Pradesh, India
| | - Taran Khanam
- Molecular and Structural Biology Division, Central Drug Research Institute (Council of Scientific and Industrial Research), Lucknow, Uttar Pradesh, India
| | - Deepti Chopra
- Molecular and Structural Biology Division, Central Drug Research Institute (Council of Scientific and Industrial Research), Lucknow, Uttar Pradesh, India
| | - Nidhi Singh
- Drug Target Discovery and Development Division, Central Drug Research Institute (Council of Scientific and Industrial Research), Lucknow, Uttar Pradesh, India
| | - Sabyasachi Sanyal
- Drug Target Discovery and Development Division, Central Drug Research Institute (Council of Scientific and Industrial Research), Lucknow, Uttar Pradesh, India
| | - Ravishankar Ramachandran
- Molecular and Structural Biology Division, Central Drug Research Institute (Council of Scientific and Industrial Research), Lucknow, Uttar Pradesh, India
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41
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Creze C, Ligabue A, Laurent S, Lestini R, Laptenok SP, Khun J, Vos MH, Czjzek M, Myllykallio H, Flament D. Modulation of the Pyrococcus abyssi NucS endonuclease activity by replication clamp at functional and structural levels. J Biol Chem 2012; 287:15648-60. [PMID: 22431731 DOI: 10.1074/jbc.m112.346361] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pyrococcus abyssi NucS is the founding member of a new family of structure-specific DNA endonucleases that interact with the replication clamp proliferating cell nuclear antigen (PCNA). Using a combination of small angle x-ray scattering and surface plasmon resonance analyses, we demonstrate the formation of a stable complex in solution, in which one molecule of the PabNucS homodimer binds to the outside surface of the PabPCNA homotrimer. Using fluorescent labels, PCNA is shown to increase the binding affinity of NucS toward single-strand/double-strand junctions on 5' and 3' flaps, as well as to modulate the cleavage specificity on the branched DNA structures. Our results indicate that the presence of a single major contact between the PabNucS and PabPCNA proteins, together with the complex-induced DNA bending, facilitate conformational flexibility required for specific cleavage at the single-strand/double-strand DNA junction.
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Affiliation(s)
- Christophe Creze
- Ifremer, UMR6197, Laboratoire de Microbiologie des Environnements Extrêmes, 29280 Plouzané, France
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42
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Beattie TR, Bell SD. Coordination of multiple enzyme activities by a single PCNA in archaeal Okazaki fragment maturation. EMBO J 2012; 31:1556-67. [PMID: 22307085 PMCID: PMC3321178 DOI: 10.1038/emboj.2012.12] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 01/09/2012] [Indexed: 11/16/2022] Open
Abstract
In vitro reconstitution of Okazaki fragment processing shows that DNA polymerase, flap endonuclease and DNA ligase need to simultaneously bind to the same PCNA-sliding clamp molecule during DNA lagging strand replication. Chromosomal DNA replication requires one daughter strand—the lagging strand—to be synthesised as a series of discontinuous, RNA-primed Okazaki fragments, which must subsequently be matured into a single covalent DNA strand. Here, we describe the reconstitution of Okazaki fragment maturation in vitro using proteins derived from the archaeon Sulfolobus solfataricus. Six proteins are necessary and sufficient for coupled DNA synthesis, RNA primer removal and DNA ligation. PolB1, Fen1 and Lig1 provide the required catalytic activities, with coordination of their activities dependent upon the DNA sliding clamp, proliferating cell nuclear antigen (PCNA). S. solfataricus PCNA is a heterotrimer, with each subunit having a distinct specificity for binding PolB1, Fen1 or Lig1. Our data demonstrate that the most efficient coupling of activities occurs when a single PCNA ring organises PolB1, Fen1 and Lig1 into a complex.
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Affiliation(s)
- Thomas R Beattie
- Sir William Dunn School of Pathology, Oxford University, Oxford, UK
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43
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Havens CG, Shobnam N, Guarino E, Centore RC, Zou L, Kearsey SE, Walter JC. Direct role for proliferating cell nuclear antigen in substrate recognition by the E3 ubiquitin ligase CRL4Cdt2. J Biol Chem 2012; 287:11410-21. [PMID: 22303007 DOI: 10.1074/jbc.m111.337683] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The E3 ubiquitin ligase Cullin-ring ligase 4-Cdt2 (CRL4(Cdt2)) is emerging as an important cell cycle regulator that targets numerous proteins for destruction in S phase and after DNA damage, including Cdt1, p21, and Set8. CRL4(Cdt2) substrates contain a "PIP degron," which consists of a canonical proliferating cell nuclear antigen (PCNA) interaction motif (PIP box) and an adjacent basic amino acid. Substrates use their PIP box to form a binary complex with PCNA on chromatin and the basic residue to recruit CRL4(Cdt2) for substrate ubiquitylation. Using Xenopus egg extracts, we identify an acidic residue in PCNA that is essential to support destruction of all CRL4(Cdt2) substrates. This PCNA residue, which adjoins the basic amino acid of the bound PIP degron, is dispensable for substrate binding to PCNA but essential for CRL4(Cdt2) recruitment to chromatin. Our data show that the interaction of CRL4(Cdt2) with substrates requires molecular determinants not only in the substrate degron but also on PCNA. The results illustrate a potentially general mechanism by which E3 ligases can couple ubiquitylation to the formation of protein-protein interactions.
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Affiliation(s)
- Courtney G Havens
- Department of Biological Chemistry & Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA
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44
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Tight coevolution of proliferating cell nuclear antigen (PCNA)-partner interaction networks in fungi leads to interspecies network incompatibility. Proc Natl Acad Sci U S A 2012; 109:E406-14. [PMID: 22308326 DOI: 10.1073/pnas.1108633109] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The structure and connectivity of protein-protein interaction (PPI) networks are maintained throughout evolution by coordinated changes (coevolution) of network proteins. Despite extensive research, relatively little is known regarding the molecular basis and functional implications of the coevolution of PPI networks. Here, we used proliferating cell nuclear antigen, a hub protein that mediates DNA replication and repair in eukaryotes, as a model system to study the coevolution of PPI networks in fungi. Using a combined bioinformatics and experimental approach, we discovered that PCNA-partner interactions tightly coevolved in fungal species, leading to specific modes of recognition. We found that fungal proliferating cell nuclear antigen-partner interaction networks diverged into two distinct groups as a result of such coevolution and that hybrid networks of these groups are functionally noncompatible in Saccharomyces cerevisiae. Our results indicate that the coevolution of PPI networks can form functional barriers between fungal species, and thus can promote and fix speciation.
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45
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Abstract
The eukaryotic RFC clamp loader couples the energy of ATP hydrolysis to open and close the circular PCNA sliding clamp onto primed sites for use by DNA polymerases and repair factors. Structural studies reveal clamp loaders to be heteropentamers. Each subunit contains a region of homology to AAA+ proteins that defines two domains. The AAA+ domains form a right-handed spiral upon binding ATP. This spiral arrangement generates a DNA binding site within the center of RFC. DNA enters the central chamber through a gap between the AAA+ domains of two subunits. Specificity for a primed template junction is achieved by a third domain that blocks DNA, forcing it to bend sharply. Thus only DNA with a flexible joint can bind the central chamber. DNA entry also requires a slot in the PCNA clamp, which is opened upon binding the AAA+ domains of the clamp loader. ATP hydrolysis enables clamp closing and ejection of RFC, completing the clamp loading reaction.
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Affiliation(s)
- Nina Y Yao
- Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA,
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46
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López de Saro FJ. Regulation of interactions with sliding clamps during DNA replication and repair. Curr Genomics 2011; 10:206-15. [PMID: 19881914 PMCID: PMC2705854 DOI: 10.2174/138920209788185234] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 03/09/2009] [Accepted: 03/16/2009] [Indexed: 01/12/2023] Open
Abstract
The molecular machines that replicate the genome consist of many interacting components. Essential to the organization of the replication machinery are ring-shaped proteins, like PCNA (Proliferating Cell Nuclear Antigen) or the β- clamp, collectively named sliding clamps. They encircle the DNA molecule and slide on it freely and bidirectionally. Sliding clamps are typically associated to DNA polymerases and provide these enzymes with the processivity required to synthesize large chromosomes. Additionally, they interact with a large array of proteins that perform enzymatic reactions on DNA, targeting and orchestrating their functions. In recent years there have been a large number of studies that have analyzed the structural details of how sliding clamps interact with their ligands. However, much remains to be learned in relation to how these interactions are regulated to occur coordinately and sequentially. Since sliding clamps participate in reactions in which many different enzymes bind and then release from the clamp in an orchestrated way, it is critical to analyze how these changes in affinity take place. In this review I focus the attention on the mechanisms by which various types of enzymes interact with sliding clamps and what is known about the regulation of this binding. Especially I describe emerging paradigms on how enzymes switch places on sliding clamps during DNA replication and repair of prokaryotic and eukaryotic genomes.
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Affiliation(s)
- Francisco J López de Saro
- Laboratorio de Ecología Molecular, Centro de Astrobiología (CSIC-INTA), 28850 Torrejón de Ardoz, Madrid, Spain
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47
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Zheng L, Dai H, Hegde ML, Zhou M, Guo Z, Wu X, Wu J, Su L, Zhong X, Mitra S, Huang Q, Kernstine KH, Pfeifer GP, Shen B. Fen1 mutations that specifically disrupt its interaction with PCNA cause aneuploidy-associated cancer. Cell Res 2011; 21:1052-67. [PMID: 21383776 DOI: 10.1038/cr.2011.35] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
DNA replication and repair are critical processes for all living organisms to ensure faithful duplication and transmission of genetic information. Flap endonuclease 1 (Fen1), a structure-specific nuclease, plays an important role in multiple DNA metabolic pathways and maintenance of genome stability. Human FEN1 mutations that impair its exonuclease activity have been linked to cancer development. FEN1 interacts with multiple proteins, including proliferation cell nuclear antigen (PCNA), to form various functional complexes. Interactions with these proteins are considered to be the key molecular mechanisms mediating FEN1's key biological functions. The current challenge is to experimentally demonstrate the biological consequence of a specific interaction without compromising other functions of a desired protein. To address this issue, we established a mutant mouse model harboring a FEN1 point mutation (F343A/F344A, FFAA), which specifically abolishes the FEN1/PCNA interaction. We show that the FFAA mutation causes defects in RNA primer removal and long-patch base excision repair, even in the heterozygous state, resulting in numerous DNA breaks. These breaks activate the G2/M checkpoint protein, Chk1, and induce near-tetraploid aneuploidy, commonly observed in human cancer, consequently elevating the transformation frequency. Consistent with this, inhibition of aneuploidy formation by a Chk1 inhibitor significantly suppressed the cellular transformation. WT/FFAA FEN1 mutant mice develop aneuploidy-associated cancer at a high frequency. Thus, this study establishes an exemplary case for investigating the biological significance of protein-protein interactions by knock-in of a point mutation rather than knock-out of a whole gene.
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Affiliation(s)
- Li Zheng
- Department of Cancer Biology, City of Hope National Medical Center and Beckman Research Institute, Duarte, CA 91010, USA.
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48
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The role of the DNA sliding clamp in Okazaki fragment maturation in archaea and eukaryotes. Biochem Soc Trans 2011; 39:70-6. [DOI: 10.1042/bst0390070] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Efficient processing of Okazaki fragments generated during discontinuous lagging-strand DNA replication is critical for the maintenance of genome integrity. In eukaryotes, a number of enzymes co-ordinate to ensure the removal of initiating primers from the 5′-end of each fragment and the generation of a covalently linked daughter strand. Studies in eukaryotic systems have revealed that the co-ordination of DNA polymerase δ and FEN-1 (Flap Endonuclease 1) is sufficient to remove the majority of primers. Other pathways such as that involving Dna2 also operate under certain conditions, although, notably, Dna2 is not universally conserved between eukaryotes and archaea, unlike the other core factors. In addition to the catalytic components, the DNA sliding clamp, PCNA (proliferating-cell nuclear antigen), plays a pivotal role in binding and co-ordinating these enzymes at sites of lagging-strand replication. Structural studies in eukaryotic and archaeal systems have revealed that PCNA-binding proteins can adopt different conformations when binding PCNA. This conformational malleability may be key to the co-ordination of these enzymes' activities.
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49
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Fridman Y, Palgi N, Dovrat D, Ben-Aroya S, Hieter P, Aharoni A. Subtle alterations in PCNA-partner interactions severely impair DNA replication and repair. PLoS Biol 2010; 8:e1000507. [PMID: 20967232 PMCID: PMC2953525 DOI: 10.1371/journal.pbio.1000507] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Accepted: 08/24/2010] [Indexed: 11/24/2022] Open
Abstract
Dynamic switching of PCNA-partner interactions is essential for normal DNA replication and repair in yeast. The robustness of complex biological processes in the face of environmental and genetic perturbations is a key biological trait. However, while robustness has been extensively studied, little is known regarding the fragility of biological processes. Here, we have examined the susceptibility of DNA replication and repair processes mediated by the proliferating cell nuclear antigen (PCNA). Using protein directed evolution, biochemical, and genetic approaches, we have generated and characterized PCNA mutants with increased affinity for several key partners of the PCNA-partner network. We found that increases in PCNA-partner interaction affinities led to severe in vivo phenotypic defects. Surprisingly, such defects are much more severe than those induced by complete abolishment of the respective interactions. Thus, the subtle and tunable nature of these affinity perturbations produced different phenotypic effects than realized with traditional “on-off” analysis using gene knockouts. Our findings indicate that biological systems can be robust to one set of perturbations yet fragile to others. Many biological processes are mediated by complex protein-protein interaction networks. The most highly connected proteins in such networks, termed hub proteins, precisely regulate biological processes by the regulated and sequential binding and releasing of partner proteins. In the case of DNA replication and repair, proliferating cell nuclear antigen (PCNA) is a hub protein that encircles the DNA to dynamically bind and release a variety of DNA-modifying enzymes. In this work, we explored the impact of subtle alterations of PCNA-partner interaction affinities on DNA replication and repair in yeast. Using directed evolution approaches, we generated a large library of PCNA mutants and selected for those with enhanced affinity for five different PCNA partners. In vivo analysis of such mutants indicated the high sensitivity of DNA replication and repair processes to minor alterations in PCNA-partner interaction affinities. Importantly, we discovered that some of the defects observed in the strains with increased PCNA-partner protein interaction far exceed the defects observed when the same partner protein is deleted altogether. Our analysis suggests that the cost of misregulating biological processes through disruption of the carefully orchestrated action of hub-interacting proteins can be much higher than the cost of deleting parts of the network altogether, demonstrating both the fragility and robustness of biological processes.
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Affiliation(s)
- Yearit Fridman
- Departments of Life Sciences and the National Institute for Biotechnology in the Negev (NIBN), Ben-Gurion University of the Negev, Be'er Sheva, Israel
| | - Niv Palgi
- Departments of Life Sciences and the National Institute for Biotechnology in the Negev (NIBN), Ben-Gurion University of the Negev, Be'er Sheva, Israel
| | - Daniel Dovrat
- Departments of Life Sciences and the National Institute for Biotechnology in the Negev (NIBN), Ben-Gurion University of the Negev, Be'er Sheva, Israel
| | - Shay Ben-Aroya
- The Nano Center, The Mina and Everard Goodman Faculty of Life Sciences Bar-Ilan University, Ramat-Gan, Israel
| | - Philip Hieter
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - Amir Aharoni
- Departments of Life Sciences and the National Institute for Biotechnology in the Negev (NIBN), Ben-Gurion University of the Negev, Be'er Sheva, Israel
- * E-mail:
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50
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Groehler AL, Lannigan DA. A chromatin-bound kinase, ERK8, protects genomic integrity by inhibiting HDM2-mediated degradation of the DNA clamp PCNA. ACTA ACUST UNITED AC 2010; 190:575-86. [PMID: 20733054 PMCID: PMC2928013 DOI: 10.1083/jcb.201002124] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Proliferating cell nuclear antigen (PCNA) acts as a scaffold, coordinator, and stimulator of numerous processes required for faithful transmission of genetic information. Maintaining PCNA levels above a critical threshold is essential, but little is known about PCNA protein turnover. We now show that ERK8 (extracellular signal-regulated kinase 8) is required for PCNA protein stability. ERK8 contains a conserved PCNA-interacting protein (PIP) box. Chromatin-bound ERK8 (ERK8(CHROMATIN)) interacts via this motif with PCNA(CHROMATIN), which acts as a platform for numerous proteins involved in DNA metabolism. Silencing ERK8 decreases PCNA levels and increases DNA damage. Ectopic expression of PCNA blocks DNA damage induced by ERK8 loss. ERK8 prevents HDM2-mediated PCNA destruction by inhibiting the association of PCNA with HDM2. This regulation is physiologically relevant as ERK8 activity is inhibited in transformed mammary cells. Our results reveal an unanticipated mechanism to control PCNA levels in normal cycling mammary epithelial cells and implicate ERK8 in the regulation of genomic stability.
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Affiliation(s)
- Angela L Groehler
- Department of Microbiology and Center for Cell Signaling, University of Virginia, Charlottesville, VA 22908, USA
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