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Pal R, Paul N, Bhattacharya D, Rakshit S, Shanmugam G, Sarkar K. XPG in the Nucleotide Excision Repair and Beyond: a study on the different functional aspects of XPG and its associated diseases. Mol Biol Rep 2022; 49:7995-8006. [PMID: 35596054 DOI: 10.1007/s11033-022-07324-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 12/17/2021] [Accepted: 03/02/2022] [Indexed: 11/26/2022]
Abstract
Several proteins are involved in DNA repair mechanisms attempting to repair damages to the DNA continuously. One such protein is Xeroderma Pigmentosum Complementation Group G (XPG), a significant component in the Nucleotide Excision Repair (NER) pathway. XPG is accountable for making the 3' incision in the NER, while XPF-ERCC4 joins ERCC1 to form the XPF-ERCC1 complex. This complex makes a 5' incision to eliminate bulky DNA lesions. XPG is also known to function as a cofactor in the Base Excision Repair (BER) pathway by increasing hNth1 activity, apart from its crucial involvement in the NER. Reports suggest that XPG also plays a non-catalytic role in the Homologous Recombination Repair (HRR) pathway by forming higher-order complexes with BRCA1, BRCA2, Rad51, and PALB2, further influencing the activity of these molecules. Studies show that, apart from its vital role in repairing DNA damages, XPG is also responsible for R-loop formation, which facilitates exhibiting phenotypes of Werner Syndrome. Though XPG has a role in several DNA repair pathways and molecular mechanisms, it is primarily a NER protein. Unrepaired and prolonged DNA damage leads to genomic instability and facilitates neurological disorders, aging, pigmentation, and cancer susceptibility. This review explores the vital role of XPG in different DNA repair mechanisms which are continuously involved in repairing these damaged sites and its failure leading to XP-G, XP-G/CS complex phenotypes, and cancer progression.
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Affiliation(s)
- Riasha Pal
- Department of Biotechnology, SRM Institute of Science and Technology, 603203, Kattankulathur, Tamil Nadu, India
| | - Nilanjan Paul
- Department of Biotechnology, SRM Institute of Science and Technology, 603203, Kattankulathur, Tamil Nadu, India
| | - Deep Bhattacharya
- Department of Biotechnology, SRM Institute of Science and Technology, 603203, Kattankulathur, Tamil Nadu, India
| | - Sudeshna Rakshit
- Department of Biotechnology, SRM Institute of Science and Technology, 603203, Kattankulathur, Tamil Nadu, India
| | - Geetha Shanmugam
- Department of Biotechnology, SRM Institute of Science and Technology, 603203, Kattankulathur, Tamil Nadu, India
| | - Koustav Sarkar
- Department of Biotechnology, SRM Institute of Science and Technology, 603203, Kattankulathur, Tamil Nadu, India.
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2
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Lata K, Vishwakarma J, Kumar S, Khanam T, Ramachandran R. Mycobacterium tuberculosis Endonuclease VIII 2 (Nei2) forms a prereplicative BER complex with DnaN: Identification, characterization, and disruption of complex formation. Mol Microbiol 2021; 117:320-333. [PMID: 34820919 DOI: 10.1111/mmi.14848] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 11/18/2021] [Accepted: 11/19/2021] [Indexed: 12/12/2022]
Abstract
Mycobacterium tuberculosis Nei2 (Rv3297) is a BER glycosylase that removes oxidized base lesions from ssDNA and replication fork-mimicking substrates. We show that Endonuclease VIII 2 (Nei2) forms a BER complex with the β-clamp (DnaN, Rv0002) with a KD of 170 nM. The Nei2-β-clamp interactions enhance Nei2's activities up to several folds. SEC analysis shows that one molecule of Nei2 binds to a single β-clamp dimer. Nei2 interacts with subsites I and II of the β-clamp via a noncanonical 223 QGCRRCGTLIAY239 Clamp Interacting Protein (CIP) motif in the C-terminal zinc-finger domain, which was previously shown by us to be dispensable for intrinsic Nei2 activity. The 12-mer peptide alone exhibited a KD of 10.28 nM, suggesting that the motif is a key mediator of Nei2-β-clamp interactions. Finally, we identified inhibitors of Nei2-β-clamp interactions using rational methods, in vitro disruption, and SPR assays after querying a database of natural products. We found that Tubulosine, Fumitremorgin C, Toyocamycin, and Aleuritic acid exhibit IC50 values of 94.47, 83.49, 109.7, and 71.49 µM, respectively. They act by disrupting Nei2-β-clamp interactions and do not affect intrinsic Nei2 activity. Among other things, the present study gives insights into the role of Nei2 in bacterial prereplicative BER.
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Affiliation(s)
- Kiran Lata
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Lucknow, India
| | - Jyoti Vishwakarma
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Lucknow, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Sanjay Kumar
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Lucknow, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Taran Khanam
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Lucknow, India
| | - Ravishankar Ramachandran
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Lucknow, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
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3
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Dieckman L. Something’s gotta give: How PCNA alters its structure in response to mutations and the implications on cellular processes. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 163:46-59. [DOI: 10.1016/j.pbiomolbio.2020.10.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 10/19/2020] [Accepted: 10/29/2020] [Indexed: 12/19/2022]
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4
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Human XPG nuclease structure, assembly, and activities with insights for neurodegeneration and cancer from pathogenic mutations. Proc Natl Acad Sci U S A 2020; 117:14127-14138. [PMID: 32522879 PMCID: PMC7321962 DOI: 10.1073/pnas.1921311117] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
DNA repair is essential to life and to avoidance of genome instability and cancer. Xeroderma pigmentosum group G (XPG) protein acts in multiple DNA repair pathways, both as an active enzyme and as a scaffold for coordinating with other repair proteins. We present here the structure of the catalytic domain responsible for its DNA binding and nuclease activity. Our analysis provides structure-based hypotheses for how XPG recognizes its bubble DNA substrate and predictions of the structural impacts of XPG disease mutations associated with two phenotypically distinct diseases: xeroderma pigmentosum (XP, skin cancer prone) or Cockayne syndrome (XP/CS, severe progressive developmental defects). Xeroderma pigmentosum group G (XPG) protein is both a functional partner in multiple DNA damage responses (DDR) and a pathway coordinator and structure-specific endonuclease in nucleotide excision repair (NER). Different mutations in the XPG gene ERCC5 lead to either of two distinct human diseases: Cancer-prone xeroderma pigmentosum (XP-G) or the fatal neurodevelopmental disorder Cockayne syndrome (XP-G/CS). To address the enigmatic structural mechanism for these differing disease phenotypes and for XPG’s role in multiple DDRs, here we determined the crystal structure of human XPG catalytic domain (XPGcat), revealing XPG-specific features for its activities and regulation. Furthermore, XPG DNA binding elements conserved with FEN1 superfamily members enable insights on DNA interactions. Notably, all but one of the known pathogenic point mutations map to XPGcat, and both XP-G and XP-G/CS mutations destabilize XPG and reduce its cellular protein levels. Mapping the distinct mutation classes provides structure-based predictions for disease phenotypes: Residues mutated in XP-G are positioned to reduce local stability and NER activity, whereas residues mutated in XP-G/CS have implied long-range structural defects that would likely disrupt stability of the whole protein, and thus interfere with its functional interactions. Combined data from crystallography, biochemistry, small angle X-ray scattering, and electron microscopy unveil an XPG homodimer that binds, unstacks, and sculpts duplex DNA at internal unpaired regions (bubbles) into strongly bent structures, and suggest how XPG complexes may bind both NER bubble junctions and replication forks. Collective results support XPG scaffolding and DNA sculpting functions in multiple DDR processes to maintain genome stability.
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5
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Limpose KL, Trego KS, Li Z, Leung SW, Sarker AH, Shah JA, Ramalingam SS, Werner EM, Dynan WS, Cooper PK, Corbett AH, Doetsch PW. Overexpression of the base excision repair NTHL1 glycosylase causes genomic instability and early cellular hallmarks of cancer. Nucleic Acids Res 2018; 46:4515-4532. [PMID: 29522130 PMCID: PMC5961185 DOI: 10.1093/nar/gky162] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 02/18/2018] [Accepted: 02/21/2018] [Indexed: 12/22/2022] Open
Abstract
Base excision repair (BER), which is initiated by DNA N-glycosylase proteins, is the frontline for repairing potentially mutagenic DNA base damage. The NTHL1 glycosylase, which excises DNA base damage caused by reactive oxygen species, is thought to be a tumor suppressor. However, in addition to NTHL1 loss-of-function mutations, our analysis of cancer genomic datasets reveals that NTHL1 frequently undergoes amplification or upregulation in some cancers. Whether NTHL1 overexpression could contribute to cancer phenotypes has not yet been explored. To address the functional consequences of NTHL1 overexpression, we employed transient overexpression. Both NTHL1 and a catalytically-dead NTHL1 (CATmut) induce DNA damage and genomic instability in non-transformed human bronchial epithelial cells (HBEC) when overexpressed. Strikingly, overexpression of either NTHL1 or CATmut causes replication stress signaling and a decrease in homologous recombination (HR). HBEC cells that overexpress NTHL1 or CATmut acquire the ability to grow in soft agar and exhibit loss of contact inhibition, suggesting that a mechanism independent of NTHL1 catalytic activity contributes to acquisition of cancer-related cellular phenotypes. We provide evidence that NTHL1 interacts with the multifunctional DNA repair protein XPG suggesting that interference with HR is a possible mechanism that contributes to acquisition of early cellular hallmarks of cancer.
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Affiliation(s)
- Kristin L Limpose
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
- Graduate Program in Cancer Biology, Emory University, Atlanta, GA 30322, USA
| | - Kelly S Trego
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Zhentian Li
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
- Department of Radiation Oncology, Emory University School of Medicine, Atlanta, GA, USA
| | - Sara W Leung
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Altaf H Sarker
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Jason A Shah
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Suresh S Ramalingam
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA 30322, USA
- Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Erica M Werner
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - William S Dynan
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
- Department of Radiation Oncology, Emory University School of Medicine, Atlanta, GA, USA
- Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Priscilla K Cooper
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Anita H Corbett
- Department of Biology, Emory University, Atlanta, GA 30322, USA
- Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Paul W Doetsch
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
- Department of Radiation Oncology, Emory University School of Medicine, Atlanta, GA, USA
- Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
- Laboratory of Genome Integrity and Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Durham, NC 27709, USA
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Bj Rås KØ, Sousa MML, Sharma A, Fonseca DM, S Gaard CK, Bj Rås M, Otterlei M. Monitoring of the spatial and temporal dynamics of BER/SSBR pathway proteins, including MYH, UNG2, MPG, NTH1 and NEIL1-3, during DNA replication. Nucleic Acids Res 2017; 45:8291-8301. [PMID: 28575236 PMCID: PMC5737410 DOI: 10.1093/nar/gkx476] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 05/15/2017] [Indexed: 12/03/2022] Open
Abstract
Base lesions in DNA can stall the replication machinery or induce mutations if bypassed. Consequently, lesions must be repaired before replication or in a post-replicative process to maintain genomic stability. Base excision repair (BER) is the main pathway for repair of base lesions and is known to be associated with DNA replication, but how BER is organized during replication is unclear. Here we coupled the iPOND (isolation of proteins on nascent DNA) technique with targeted mass-spectrometry analysis, which enabled us to detect all proteins required for BER on nascent DNA and to monitor their spatiotemporal orchestration at replication forks. We demonstrate that XRCC1 and other BER/single-strand break repair (SSBR) proteins are enriched in replisomes in unstressed cells, supporting a cellular capacity of post-replicative BER/SSBR. Importantly, we identify for the first time the DNA glycosylases MYH, UNG2, MPG, NTH1, NEIL1, 2 and 3 on nascent DNA. Our findings suggest that a broad spectrum of DNA base lesions are recognized and repaired by BER in a post-replicative process.
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Affiliation(s)
- Karine Ø Bj Rås
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway
| | - Mirta M L Sousa
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway.,The Central Norway Regional Health Authority, N-7501 Stj⊘rdal, Norway
| | - Animesh Sharma
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway.,The Central Norway Regional Health Authority, N-7501 Stj⊘rdal, Norway.,Proteomics and Metabolomics Core Facility (PROMEC), Department of Cancer Research and Molecular Medicine, NTNU, N-7491 Trondheim, Norway
| | - Davi M Fonseca
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway.,The Central Norway Regional Health Authority, N-7501 Stj⊘rdal, Norway.,Proteomics and Metabolomics Core Facility (PROMEC), Department of Cancer Research and Molecular Medicine, NTNU, N-7491 Trondheim, Norway
| | - Caroline K S Gaard
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway
| | - Magnar Bj Rås
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway.,Department of Microbiology, Oslo University Hospital and University of Oslo, N-0027 Oslo, Norway
| | - Marit Otterlei
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway
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7
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Ormeño F, Barrientos C, Ramirez S, Ponce I, Valenzuela L, Sepúlveda S, Bitar M, Kemmerling U, Machado CR, Cabrera G, Galanti N. Expression and the Peculiar Enzymatic Behavior of the Trypanosoma cruzi NTH1 DNA Glycosylase. PLoS One 2016; 11:e0157270. [PMID: 27284968 PMCID: PMC4902261 DOI: 10.1371/journal.pone.0157270] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 05/26/2016] [Indexed: 02/06/2023] Open
Abstract
Trypanosoma cruzi, the etiological agent of Chagas’ disease, presents three cellular forms (trypomastigotes, epimastigotes and amastigotes), all of which are submitted to oxidative species in its hosts. However, T. cruzi is able to resist oxidative stress suggesting a high efficiency of its DNA repair machinery.The Base Excision Repair (BER) pathway is one of the main DNA repair mechanisms in other eukaryotes and in T. cruzi as well. DNA glycosylases are enzymes involved in the recognition of oxidative DNA damage and in the removal of oxidized bases, constituting the first step of the BER pathway. Here, we describe the presence and activity of TcNTH1, a nuclear T. cruzi DNA glycosylase. Surprisingly, purified recombinant TcNTH1 does not remove the thymine glycol base, but catalyzes the cleavage of a probe showing an AP site. The same activity was found in epimastigote and trypomastigote homogenates suggesting that the BER pathway is not involved in thymine glycol DNA repair. TcNTH1 DNA-binding properties assayed in silico are in agreement with the absence of a thymine glycol removing function of that parasite enzyme. Over expression of TcNTH1 decrease parasite viability when transfected epimastigotes are submitted to a sustained production of H2O2.Therefore, TcNTH1 is the only known NTH1 orthologous unable to eliminate thymine glycol derivatives but that recognizes and cuts an AP site, most probably by a beta-elimination mechanism. We cannot discard that TcNTH1 presents DNA glycosylase activity on other DNA base lesions. Accordingly, a different DNA repair mechanism should be expected leading to eliminate thymine glycol from oxidized parasite DNA. Furthermore, TcNTH1 may play a role in the AP site recognition and processing.
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Affiliation(s)
- Fernando Ormeño
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Camila Barrientos
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Santiago Ramirez
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Iván Ponce
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Lucía Valenzuela
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Sofía Sepúlveda
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Mainá Bitar
- Departamento de Bioquímica e Imunologia, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Ulrike Kemmerling
- Programa de Anatomía y Biología del Desarrollo, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Carlos Renato Machado
- Departamento de Bioquímica e Imunologia, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Gonzalo Cabrera
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- * E-mail: (GC); (NG)
| | - Norbel Galanti
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- * E-mail: (GC); (NG)
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8
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Bauer NC, Corbett AH, Doetsch PW. The current state of eukaryotic DNA base damage and repair. Nucleic Acids Res 2015; 43:10083-101. [PMID: 26519467 PMCID: PMC4666366 DOI: 10.1093/nar/gkv1136] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 10/16/2015] [Indexed: 12/15/2022] Open
Abstract
DNA damage is a natural hazard of life. The most common DNA lesions are base, sugar, and single-strand break damage resulting from oxidation, alkylation, deamination, and spontaneous hydrolysis. If left unrepaired, such lesions can become fixed in the genome as permanent mutations. Thus, evolution has led to the creation of several highly conserved, partially redundant pathways to repair or mitigate the effects of DNA base damage. The biochemical mechanisms of these pathways have been well characterized and the impact of this work was recently highlighted by the selection of Tomas Lindahl, Aziz Sancar and Paul Modrich as the recipients of the 2015 Nobel Prize in Chemistry for their seminal work in defining DNA repair pathways. However, how these repair pathways are regulated and interconnected is still being elucidated. This review focuses on the classical base excision repair and strand incision pathways in eukaryotes, considering both Saccharomyces cerevisiae and humans, and extends to some important questions and challenges facing the field of DNA base damage repair.
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Affiliation(s)
- Nicholas C Bauer
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA Graduate Program in Biochemistry, Cell, and Developmental Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Anita H Corbett
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Paul W Doetsch
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA 30322, USA Department of Radiation Oncology, Emory University School of Medicine, Atlanta, GA 30322, USA Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA 30322, USA
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9
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Cell-autonomous progeroid changes in conditional mouse models for repair endonuclease XPG deficiency. PLoS Genet 2014; 10:e1004686. [PMID: 25299392 PMCID: PMC4191938 DOI: 10.1371/journal.pgen.1004686] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 08/19/2014] [Indexed: 01/15/2023] Open
Abstract
As part of the Nucleotide Excision Repair (NER) process, the endonuclease XPG is involved in repair of helix-distorting DNA lesions, but the protein has also been implicated in several other DNA repair systems, complicating genotype-phenotype relationship in XPG patients. Defects in XPG can cause either the cancer-prone condition xeroderma pigmentosum (XP) alone, or XP combined with the severe neurodevelopmental disorder Cockayne Syndrome (CS), or the infantile lethal cerebro-oculo-facio-skeletal (COFS) syndrome, characterized by dramatic growth failure, progressive neurodevelopmental abnormalities and greatly reduced life expectancy. Here, we present a novel (conditional) Xpg−/− mouse model which -in a C57BL6/FVB F1 hybrid genetic background- displays many progeroid features, including cessation of growth, loss of subcutaneous fat, kyphosis, osteoporosis, retinal photoreceptor loss, liver aging, extensive neurodegeneration, and a short lifespan of 4–5 months. We show that deletion of XPG specifically in the liver reproduces the progeroid features in the liver, yet abolishes the effect on growth or lifespan. In addition, specific XPG deletion in neurons and glia of the forebrain creates a progressive neurodegenerative phenotype that shows many characteristics of human XPG deficiency. Our findings therefore exclude that both the liver as well as the neurological phenotype are a secondary consequence of derailment in other cell types, organs or tissues (e.g. vascular abnormalities) and support a cell-autonomous origin caused by the DNA repair defect itself. In addition they allow the dissection of the complex aging process in tissue- and cell-type-specific components. Moreover, our data highlight the critical importance of genetic background in mouse aging studies, establish the Xpg−/− mouse as a valid model for the severe form of human XPG patients and segmental accelerated aging, and strengthen the link between DNA damage and aging. Accumulation of DNA damage has been implicated in aging. Many premature aging syndromes are due to defective DNA repair systems. The endonuclease XPG is involved in repair of helix-distorting DNA lesions, and XPG defects cause the cancer-prone condition xeroderma pigmentosum (XP) alone or combined with the severe neurodevelopmental progeroid disorder Cockayne syndrome (CS). Here, we present a novel (conditional) Xpg−/− mouse model which -in a C57BL6/FVB F1 hybrid background- displays many progressive progeroid features, including early cessation of growth, cachexia, kyphosis, osteoporosis, neurodegeneration, liver aging, retinal degeneration, and reduced lifespan. In a constitutive mutant with a complex phenotype it is difficult to dissect cause and consequence. We have therefore generated liver- and forebrain-specific Xpg mutants and demonstrate that they exhibit progressive anisokaryosis and neurodegeneration, respectively, indicating that a cell-intrinsic repair defect in neurons can account for neuronal degeneration. These findings strengthen the link between DNA damage and the complex process of aging.
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10
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Vallabhaneni H, O'Callaghan N, Sidorova J, Liu Y. Defective repair of oxidative base lesions by the DNA glycosylase Nth1 associates with multiple telomere defects. PLoS Genet 2013; 9:e1003639. [PMID: 23874233 PMCID: PMC3715427 DOI: 10.1371/journal.pgen.1003639] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 06/03/2013] [Indexed: 02/07/2023] Open
Abstract
Telomeres are chromosome end structures and are essential for maintenance of genome stability. Highly repetitive telomere sequences appear to be susceptible to oxidative stress-induced damage. Oxidation may therefore have a severe impact on telomere integrity and function. A wide spectrum of oxidative pyrimidine-derivatives has been reported, including thymine glycol (Tg), that are primarily removed by a DNA glycosylase, Endonuclease III-like protein 1 (Nth1). Here, we investigate the effect of Nth1 deficiency on telomere integrity in mice. Nth1 null (Nth1(-/-) ) mouse tissues and primary MEFs harbor higher levels of Endonuclease III-sensitive DNA lesions at telomeric repeats, in comparison to a non-telomeric locus. Furthermore, oxidative DNA damage induced by acute exposure to an oxidant is repaired slowly at telomeres in Nth1(-/-) MEFs. Although telomere length is not affected in the hematopoietic tissues of Nth1(-/-) adult mice, telomeres suffer from attrition and increased recombination and DNA damage foci formation in Nth1(-/-) bone marrow cells that are stimulated ex vivo in the presence of 20% oxygen. Nth1 deficiency also enhances telomere fragility in mice. Lastly, in a telomerase null background, Nth1(-/-) bone marrow cells undergo severe telomere loss at some chromosome ends and cell apoptosis upon replicative stress. These results suggest that Nth1 plays an important role in telomere maintenance and base repair against oxidative stress-induced base modifications. The fact that telomerase deficiency can exacerbate telomere shortening in Nth1 deficient mouse cells supports that base excision repair cooperates with telomerase to maintain telomere integrity.
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Affiliation(s)
- Haritha Vallabhaneni
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | | | - Julia Sidorova
- Department of Pathology, University of Washington, Seattle, Washington, United States of America
| | - Yie Liu
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
- * E-mail:
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11
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Hanssen-Bauer A, Solvang-Garten K, Akbari M, Otterlei M. X-ray repair cross complementing protein 1 in base excision repair. Int J Mol Sci 2012; 13:17210-29. [PMID: 23247283 PMCID: PMC3546746 DOI: 10.3390/ijms131217210] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 12/06/2012] [Accepted: 12/07/2012] [Indexed: 12/20/2022] Open
Abstract
X-ray Repair Cross Complementing protein 1 (XRCC1) acts as a scaffolding protein in the converging base excision repair (BER) and single strand break repair (SSBR) pathways. XRCC1 also interacts with itself and rapidly accumulates at sites of DNA damage. XRCC1 can thus mediate the assembly of large multiprotein DNA repair complexes as well as facilitate the recruitment of DNA repair proteins to sites of DNA damage. Moreover, XRCC1 is present in constitutive DNA repair complexes, some of which associate with the replication machinery. Because of the critical role of XRCC1 in DNA repair, its common variants Arg194Trp, Arg280His and Arg399Gln have been extensively studied. However, the prevalence of these variants varies strongly in different populations, and their functional influence on DNA repair and disease remains elusive. Here we present the current knowledge about the role of XRCC1 and its variants in BER and human disease/cancer.
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Affiliation(s)
- Audun Hanssen-Bauer
- Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, N-7489 Trondheim, Norway; E-Mails: (A.H.-B.); (K.S.-G.)
| | - Karin Solvang-Garten
- Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, N-7489 Trondheim, Norway; E-Mails: (A.H.-B.); (K.S.-G.)
| | - Mansour Akbari
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 N, Denmark; E-Mail:
| | - Marit Otterlei
- Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, N-7489 Trondheim, Norway; E-Mails: (A.H.-B.); (K.S.-G.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +47-72573075; Fax: +47-72576400
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12
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Strzalka W, Ziemienowicz A. Proliferating cell nuclear antigen (PCNA): a key factor in DNA replication and cell cycle regulation. ANNALS OF BOTANY 2011; 107:1127-40. [PMID: 21169293 PMCID: PMC3091797 DOI: 10.1093/aob/mcq243] [Citation(s) in RCA: 468] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
BACKGROUND PCNA (proliferating cell nuclear antigen) has been found in the nuclei of yeast, plant and animal cells that undergo cell division, suggesting a function in cell cycle regulation and/or DNA replication. It subsequently became clear that PCNA also played a role in other processes involving the cell genome. SCOPE This review discusses eukaryotic PCNA, with an emphasis on plant PCNA, in terms of the protein structure and its biochemical properties as well as gene structure, organization, expression and function. PCNA exerts a tripartite function by operating as (1) a sliding clamp during DNA synthesis, (2) a polymerase switch factor and (3) a recruitment factor. Most of its functions are mediated by its interactions with various proteins involved in DNA synthesis, repair and recombination as well as in regulation of the cell cycle and chromatid cohesion. Moreover, post-translational modifications of PCNA play a key role in regulation of its functions. Finally, a phylogenetic comparison of PCNA genes suggests that the multi-functionality observed in most species is a product of evolution. CONCLUSIONS Most plant PCNAs exhibit features similar to those found for PCNAs of other eukaryotes. Similarities include: (1) a trimeric ring structure of the PCNA sliding clamp, (2) the involvement of PCNA in DNA replication and repair, (3) the ability to stimulate the activity of DNA polymerase δ and (4) the ability to interact with p21, a regulator of the cell cycle. However, many plant genomes seem to contain the second, probably functional, copy of the PCNA gene, in contrast to PCNA pseudogenes that are found in mammalian genomes.
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Affiliation(s)
- Wojciech Strzalka
- Department of Plant Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Krakow, Poland
| | - Alicja Ziemienowicz
- Department of Biological Sciences, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
- For correspondence. E-mail
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13
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Effects of base excision repair proteins on mutagenesis by 8-oxo-7,8-dihydroguanine (8-hydroxyguanine) paired with cytosine and adenine. DNA Repair (Amst) 2010; 9:542-50. [PMID: 20197241 DOI: 10.1016/j.dnarep.2010.02.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 02/03/2010] [Accepted: 02/03/2010] [Indexed: 11/21/2022]
Abstract
8-Oxo-7,8-dihydroguanine (8-oxo-Gua, also known as 8-hydroxyguanine) is a major base lesion that is generated by reactive oxygen species in both the DNA and nucleotide pool. The role of DNA glycosylases, which initiate base excision repair, in the mutagenic processes of 8-oxo-Gua in DNA and 8-oxo-7,8-dihydro-2'-deoxyguanosine 5'-triphosphate (8-oxo-dGTP, also known as 8-hydroxy-2'-deoxyguanosine 5'-triphosphate) were investigated using supF shuttle plasmids propagated in human cells. The DNA glycosylases, OGG1, MUTYH, NTH1, and NEIL1, in 293T cells were individually knocked-down by siRNAs and plasmid DNAs containing an 8-oxo-Gua:C/8-oxo-Gua:A pair, and 8-oxo-dGTP plus unmodified plasmid DNA were then introduced into the knocked-down cells. The knock-down of OGG1, MUTYH, NTH1, and NEIL1 resulted in a significant increase in G:C-->T:A transversions caused by the 8-oxo-Gua:C pair in the shuttle plasmid. The knock-down of MUTYH resulted in a reduction in A:T-->C:G transversions induced by 8-oxo-dGTP and the 8-oxo-Gua:A pair, but the knockdown of OGG1, NTH1, and NEIL1 had no effect on mutagenesis. These results indicate that all of the above DNA glycosylases suppress mutations caused by 8-oxo-Gua:C in DNA. In contrast, it appears that MUTYH enhances A:T-->C:G mutations caused by 8-oxo-dGTP.
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14
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Shell SM, Zou Y. Other proteins interacting with XP proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 637:103-12. [PMID: 19181115 DOI: 10.1007/978-0-387-09599-8_11] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Steven M Shell
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614, USA
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15
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Kiyonari S, Uchimura M, Shirai T, Ishino Y. Physical and functional interactions between uracil-DNA glycosylase and proliferating cell nuclear antigen from the euryarchaeon Pyrococcus furiosus. J Biol Chem 2008; 283:24185-93. [PMID: 18562313 PMCID: PMC3259797 DOI: 10.1074/jbc.m802837200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Revised: 06/10/2008] [Indexed: 01/27/2023] Open
Abstract
Uracil-DNA glycosylase (UDG) is an important repair enzyme in all organisms to remove uracil bases from DNA. Recent biochemical studies have revealed that human nuclear UDG (UNG2) forms a multiprotein complex in replication foci and initiates the base excision repair pathway by interacting with proliferating cell nuclear antigen (PCNA). Here, we show the physical and functional interactions between UDG and PCNA from the hyperthermophilic euryarchaeon, Pyrococcus furiosus. The physical interaction between the two proteins was identified by a surface plasmon resonance analysis. Furthermore, the uracil glycosylase activity of P. furiosus UDG is stimulated by P. furiosus PCNA (PfuPCNA) in vitro. This stimulatory effect was observed only when wild type PfuPCNA, but not a monomeric PCNA mutant, was present in the reaction. Mutational analyses revealed that our predicted PCNA-binding region (AKTLF) in P. furiosus UDG is actually important for the interaction with PfuPCNA. This is the first report describing the functional interaction between archaeal UDG and PCNA.
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Affiliation(s)
- Shinichi Kiyonari
- Department of Genetic
Resources Technology, Faculty of Agriculture, Kyushu University, and
BIRD-Japan Science and Technology
Agency, 6-10-1 Hakozaki, Fukuoka-shi, Fukuoka 812-8581, Japan and the
Department of Bioscience, Nagahama
Institute of Bio-Science and Technology and
BIRD-Japan Science and Technology
Agency, 1266 Tamura, Nagahama, Shiga 526-0829, Japan
| | - Maiko Uchimura
- Department of Genetic
Resources Technology, Faculty of Agriculture, Kyushu University, and
BIRD-Japan Science and Technology
Agency, 6-10-1 Hakozaki, Fukuoka-shi, Fukuoka 812-8581, Japan and the
Department of Bioscience, Nagahama
Institute of Bio-Science and Technology and
BIRD-Japan Science and Technology
Agency, 1266 Tamura, Nagahama, Shiga 526-0829, Japan
| | - Tsuyoshi Shirai
- Department of Genetic
Resources Technology, Faculty of Agriculture, Kyushu University, and
BIRD-Japan Science and Technology
Agency, 6-10-1 Hakozaki, Fukuoka-shi, Fukuoka 812-8581, Japan and the
Department of Bioscience, Nagahama
Institute of Bio-Science and Technology and
BIRD-Japan Science and Technology
Agency, 1266 Tamura, Nagahama, Shiga 526-0829, Japan
| | - Yoshizumi Ishino
- Department of Genetic
Resources Technology, Faculty of Agriculture, Kyushu University, and
BIRD-Japan Science and Technology
Agency, 6-10-1 Hakozaki, Fukuoka-shi, Fukuoka 812-8581, Japan and the
Department of Bioscience, Nagahama
Institute of Bio-Science and Technology and
BIRD-Japan Science and Technology
Agency, 1266 Tamura, Nagahama, Shiga 526-0829, Japan
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16
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Dou H, Theriot CA, Das A, Hegde ML, Matsumoto Y, Boldogh I, Hazra TK, Bhakat KK, Mitra S. Interaction of the human DNA glycosylase NEIL1 with proliferating cell nuclear antigen. The potential for replication-associated repair of oxidized bases in mammalian genomes. J Biol Chem 2007; 283:3130-3140. [PMID: 18032376 DOI: 10.1074/jbc.m709186200] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
NEIL1 and NEIL2 compose a family of DNA glycosylases that is distinct from that of the other two DNA glycosylases, OGG1 and NTH1, all of which are involved in repair of oxidized bases in mammalian genomes. That the NEIL proteins, unlike OGG1 and NTH1, are able to excise base lesions from single-stranded DNA regions suggests their preferential involvement in repair during replication and/or transcription. Previous studies showing S phase-specific activation of NEIL1, but not NEIL2, suggested NEIL1 involvement in the repair of replicating DNA. Here, we show that human NEIL1 stably interacts both in vivo and in vitro with proliferating cell nuclear antigen (PCNA), the sliding clamp for DNA replication. PCNA stimulates NEIL1 activity in excising the oxidized base 5-hydroxyuracil from single-stranded DNA sequences including fork structures. PCNA enhances NEIL1 loading on the substrate. In contrast, although present in the NEIL2 immunocomplex, PCNA does not stimulate NEIL2. NEIL1 interacts with PCNA via a domain that is located in a region near the C terminus, dispensable for base excision activity. The interacting sequence in NEIL1, which lacks the canonical PCNA-binding motif, includes a sequence conserved in DNA polymerase delta and implicated in its PCNA binding. Mammalian two-hybrid analysis confirmed PCNA interaction with NEIL1. The G127A mutation in PCNA reduces its stimulatory activity, suggesting that the interdomain connector loop, a common binding interface of PCNA, is involved in NEIL1 binding. These results strongly support in vivo function of NEIL1 in preferential repair of oxidized bases in DNA prior to replication.
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Affiliation(s)
- Hong Dou
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas 77555-1079, University of Texas Medical Branch, Galveston, Texas 77555-1079
| | - Corey A Theriot
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas 77555-1079, University of Texas Medical Branch, Galveston, Texas 77555-1079
| | - Aditi Das
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas 77555-1079, University of Texas Medical Branch, Galveston, Texas 77555-1079
| | - Muralidhar L Hegde
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas 77555-1079, University of Texas Medical Branch, Galveston, Texas 77555-1079
| | | | - Istvan Boldogh
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas 77555-1079
| | - Tapas K Hazra
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas 77555-1079, University of Texas Medical Branch, Galveston, Texas 77555-1079
| | - Kishor K Bhakat
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas 77555-1079, University of Texas Medical Branch, Galveston, Texas 77555-1079
| | - Sankar Mitra
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas 77555-1079, University of Texas Medical Branch, Galveston, Texas 77555-1079.
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17
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Abstract
Inheritance requires genome duplication, reproduction of chromatin and its epigenetic information, mechanisms to ensure genome integrity, and faithful transmission of the information to progeny. Proliferating cell nuclear antigen (PCNA)-a cofactor of DNA polymerases that encircles DNA-orchestrates several of these functions by recruiting crucial players to the replication fork. Remarkably, many factors that are involved in replication-linked processes interact with a particular face of PCNA and through the same interaction domain, indicating that these interactions do not occur simultaneously during replication. Switching of PCNA partners may be triggered by affinity-driven competition, phosphorylation, proteolysis, and modification of PCNA by ubiquitin and SUMO.
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Affiliation(s)
- George-Lucian Moldovan
- Department of Molecular Cell Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18 82152 Martinsried, Germany
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18
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Doré AS, Kilkenny ML, Jones SA, Oliver AW, Roe SM, Bell SD, Pearl LH. Structure of an archaeal PCNA1-PCNA2-FEN1 complex: elucidating PCNA subunit and client enzyme specificity. Nucleic Acids Res 2006; 34:4515-26. [PMID: 16945955 PMCID: PMC1636371 DOI: 10.1093/nar/gkl623] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The archaeal/eukaryotic proliferating cell nuclear antigen (PCNA) toroidal clamp interacts with a host of DNA modifying enzymes, providing a stable anchorage and enhancing their respective processivities. Given the broad range of enzymes with which PCNA has been shown to interact, relatively little is known about the mode of assembly of functionally meaningful combinations of enzymes on the PCNA clamp. We have determined the X-ray crystal structure of the Sulfolobus solfataricus PCNA1-PCNA2 heterodimer, bound to a single copy of the flap endonuclease FEN1 at 2.9 A resolution. We demonstrate the specificity of interaction of the PCNA subunits to form the PCNA1-PCNA2-PCNA3 heterotrimer, as well as providing a rationale for the specific interaction of the C-terminal PIP-box motif of FEN1 for the PCNA1 subunit. The structure explains the specificity of the individual archaeal PCNA subunits for selected repair enzyme 'clients', and provides insights into the co-ordinated assembly of sequential enzymatic steps in PCNA-scaffolded DNA repair cascades.
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Affiliation(s)
- Andrew S Doré
- CR-UK DNA Repair Enzymes Group, Section of Structural Biology, The Institute of Cancer Research, 237 Fulham Road, Chelsea, London, SW3 6JB, UK.
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19
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Prosperi E. The fellowship of the rings: distinct pools of proliferating cell nuclear antigen trimer at work. FASEB J 2006; 20:833-7. [PMID: 16675840 DOI: 10.1096/fj.05-5469hyp] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The proliferating cell nuclear antigen (PCNA) is a homotrimeric ring-shaped protein that, by encircling DNA, may function as a sliding platform for proteins participating in various DNA transactions. PCNA plays a fundamental role in DNA replication and repair, but also in postreplicative events, like DNA methylation, chromatin assembly and remodeling, sister chromatid cohesion, and coordinates these activities with cell cycle control. However, relevant aspects of PCNA function are still not well understood, like the role of PCNA in the association with partner proteins, and how multiple protein interactions are orchestrated. Based on emerging evidence, I suggest that 1) PCNA interacting proteins may be reclassified in three major categories, namely, a) cell cycle control; b) DNA replication/repair; c) chromatin regulation/transcription. 2) PCNA is a negative regulator, rather than a processivity/recruitment factor, of chromatin-modifying enzymes. 3) At DNA replication sites, PCNA function may be envisaged with a model of "dynamic hand-off" of interacting partners that rapidly and transiently exchange in a mutually exclusive manner, while cyclin-dependent kinase (Cdk) 2 (CDK2) is stably bound to PCNA. The partner exchange might occur through a conformational change of the PCNA/protein/DNA complex allowing CDK2 to phosphorylate the partner protein, thereby enabling its hand-off from PCNA.
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Affiliation(s)
- Ennio Prosperi
- Istituto di Genetica Molecolare del CNR, sez. Istochimica e Citometria, Dipartimento di Biologia Animale, Università di Pavia, Piazza Botta, 10, Pavia 27100, Italy.
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20
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Meira LB, Burgis NE, Samson LD. Base excision repair. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2006; 570:125-73. [PMID: 18727500 DOI: 10.1007/1-4020-3764-3_5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Lisiane B Meira
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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22
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Sugimoto T, Igawa E, Tanihigashi H, Matsubara M, Ide H, Ikeda S. Roles of base excision repair enzymes Nth1p and Apn2p from Schizosaccharomyces pombe in processing alkylation and oxidative DNA damage. DNA Repair (Amst) 2005; 4:1270-80. [PMID: 16076563 DOI: 10.1016/j.dnarep.2005.06.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2005] [Revised: 06/08/2005] [Accepted: 06/20/2005] [Indexed: 11/18/2022]
Abstract
Schizosaccharomyces pombe Nthpl, an ortholog of the endonuclease III family, is the sole bifunctional DNA glycosylase encoded in its genome. The enzyme removes oxidative pyrimidine and incises 3' to the apurinic/apyrimidinic (AP) site, leaving 3'-alpha,beta-unsaturated aldehyde. Analysis of nth1 cDNA revealed an intronless structure including 5'- and 3'-untranslated regions. An Nth1p-green fluorescent fusion protein was predominantly localized in the nuclei of yeast cells, indicating a nuclear function. Deletion of nth1 confirmed that Nth1p is responsible for the majority of activity for thymine glycol and AP site incision in the absence of metal ions, while nth1 mutants exhibit hypersensitivity to methylmethanesulfonate (MMS). Complementation of sensitivity by heterologous expression of various DNA glycosylases showed that the methyl-formamidopyrimidine (me-fapy) and/or AP sites are plausible substrates for Nth1p in repairing MMS damage. Apn2p, the major AP endonuclease in S. pombe, also greatly contributes to the repair of MMS damage. Deletion of nth1 from an apn2 mutant resulted in tolerance to MMS damage, indicating that Nth1p-induced 3'-blocks are responsible for MMS sensitivity in apn2 mutants. Overexpression of Apn2p in nth1 mutants failed to suppress MMS sensitivity. These results indicate that Nth1p, not Apn2p, primarily incises AP sites and that the resultant 3'-blocks are removed by the 3'-phosphodiesterase activity of Apn2p. Nth1p is dispensable for cell survival against low levels of oxidative stress, but wild-type yeast became more sensitive than the nth1 mutant at high levels. Overexpression of Nth1p in heavily damaged cells probably induced cell death via the formation of 3'-blocked single-strand breaks.
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Affiliation(s)
- Takanori Sugimoto
- Department of Biochemistry, Faculty of Science, Okayama University of Science, 1-1 Ridaicho, Okayama 700-0005, Japan
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