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Hsu SH, Chen SH, Kuo CC, Chang JY. Ubiquitin-conjugating enzyme E2 B regulates the ubiquitination of O 6-methylguanine-DNA methyltransferase and BCNU sensitivity in human nasopharyngeal carcinoma cells. Biochem Pharmacol 2018; 158:327-338. [PMID: 30449727 DOI: 10.1016/j.bcp.2018.10.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 10/25/2018] [Indexed: 02/06/2023]
Abstract
O6-Methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that removes the alkyl groups from the O6 position of guanine and is then degraded via ubiquitin-mediated degradation. Previous studies indicated that 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) facilitates the ubiquitination and degradation of MGMT in several types of cancer cells. However, the underlying mechanism of MGMT ubiquitination remains unclear. In this study, we demonstrated for the first time that ubiquitin-conjugating enzyme E2 B (UBE2B) is a novel regulator of MGMT ubiquitination mediated by BCNU in nasopharyngeal carcinoma (NPC) cells. The E3 ubiquitin ligase RAD18, a partner of UBE2B, is also involved in BCNU-mediated MGMT ubiquitination. Overexpression/knockdown of UBE2B enhanced/reduced BCNU-mediated MGMT ubiquitination. Surprisingly, UBE2B knockdown significantly increased BCNU cytotoxicity in NPC cells. Therefore, loss of UBE2B seems to disrupt ubiquitin-mediated degradation of alkylated MGMT. We found that UBE2B knockdown reduced MGMT activity, suggesting that loss of UBE2B leads to the accumulation of deactivated MGMT and suppresses MGMT protein turnover in BCNU-treated cells. These findings indicate that UBE2B modulates sensitivity to BCNU in NPC cells by regulating MGMT ubiquitination.
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Affiliation(s)
- Shih-Han Hsu
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan; National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan
| | - Shang-Hung Chen
- National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan; Division of Hematology/Oncology, Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Ching-Chuan Kuo
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Zhunan, Taiwan
| | - Jang-Yang Chang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan; National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan; Division of Hematology/Oncology, Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
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2
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Powers KT, Washington MT. Eukaryotic translesion synthesis: Choosing the right tool for the job. DNA Repair (Amst) 2018; 71:127-134. [PMID: 30174299 DOI: 10.1016/j.dnarep.2018.08.016] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Normal DNA replication is blocked by DNA damage in the template strand. Translesion synthesis is a major pathway for overcoming these replication blocks. In this process, multiple non-classical DNA polymerases are thought to form a complex at the stalled replication fork that we refer to as the mutasome. This hypothetical multi-protein complex is structurally organized by the replication accessory factor PCNA and the non-classical polymerase Rev1. One of the non-classical polymerases within this complex then catalyzes replication through the damage. Each non-classical polymerase has one or more cognate lesions, which the enzyme bypasses with high accuracy and efficiency. Thus, the accuracy and efficiency of translesion synthesis depends on which non-classical polymerase is chosen to bypass the damage. In this review article, we discuss how the most appropriate polymerase is chosen. In so doing, we examine the structural motifs that mediate the protein interactions in the mutasome; the multiple architectures that the mutasome can adopt, such as PCNA tool belts and Rev1 bridges; the intrinsically disordered regions that tether the polymerases to PCNA and to one another; and the kinetic selection model in which the most appropriate polymerase is chosen via a competition among the multiple polymerases within the mutasome.
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Affiliation(s)
- Kyle T Powers
- Department of Biochemistry, University of Iowa College of Medicine, Iowa City, IA 52242-1109, United States
| | - M Todd Washington
- Department of Biochemistry, University of Iowa College of Medicine, Iowa City, IA 52242-1109, United States.
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3
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Grebneva HA. Mechanisms of targeted frameshift mutations: Insertions arising during error-prone or SOS synthesis of DNA containing cis-syn cyclobutane thymine dimers. Mol Biol 2014. [DOI: 10.1134/s0026893314030066] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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4
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Liu C, Wang D, Wu J, Keller J, Ma T, Yu X. RNF168 forms a functional complex with RAD6 during the DNA damage response. J Cell Sci 2013; 126:2042-51. [PMID: 23525009 DOI: 10.1242/jcs.122945] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Protein ubiquitination plays an important role in initiating the DNA damage response. Following DNA damage, E2 ubiquitin conjugating enzymes are crucial for catalyzing substrate ubiquitination that recruits downstream DNA repair factors to DNA lesions. To identify novel E2 conjugating enzymes important for initiating the DNA-damage-induced ubiquitination cascade, we screened most of the known E2 enzymes and found that RAD6A and RAD6B function together with RNF168 in the ionizing radiation (IR)-induced DNA damage response. Similarly to RNF168-deficient cells, RAD6A- or RAD6B-deficient cells exhibit a reduction in DNA-damage-induced protein ubiquitination. Correspondingly, DNA-damage-induced foci formation of DNA damage repair proteins, such as BRCA1 and 53BP1, is impaired in the absence of RAD6A or RAD6B. Moreover, the RNF168-RAD6 complex targeted histone H1.2 for ubiquitination in vitro and regulated DNA-damage-induced histone H1.2 ubiquitination in vivo. Collectively, these data demonstrate that RNF168, in complex with RAD6A or RAD6B, is activated in the DNA-damage-induced protein ubiquitination cascade.
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Affiliation(s)
- Chao Liu
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, 200433, China
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5
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Halas A, Podlaska A, Derkacz J, McIntyre J, Skoneczna A, Sledziewska-Gojska E. The roles of PCNA SUMOylation, Mms2-Ubc13 and Rad5 in translesion DNA synthesis in Saccharomyces cerevisiae. Mol Microbiol 2011; 80:786-97. [PMID: 21362066 DOI: 10.1111/j.1365-2958.2011.07610.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Mms2, in concert with Ubc13 and Rad5, is responsible for polyubiquitination of replication processivity factor PCNA. This modification activates recombination-like DNA damage-avoidance mechanisms, which function in an error-free manner. Cells deprived of Mms2, Ubc13 or Rad5 exhibit mutator phenotypes as a result of the channelling of premutational DNA lesions to often error-prone translesion DNA synthesis (TLS). Here we show that Siz1-mediated PCNA SUMOylation is required for the stimulation of this TLS, despite the presence of PCNA monoubiquitination. The stimulation of spontaneous mutagenesis by Siz1 in cells carrying rad5 and/or mms2 mutations is connected with the known role of PCNA SUMOylation in the inhibition of Rad52-mediated recombination. However, following UV irradiation, Siz1 is engaged in additional, as yet undefined, mechanisms controlling genetic stability at the replication fork. We also demonstrate that in the absence of PCNA SUMOylation, Mms2-Ubc13 and Rad5 may, independently of each other, function in the stimulation of TLS. Based on this finding and on an analysis of the epistatic relationships between SIZ1, MMS2 and RAD5, with respect to UV sensitivity, we conclude that PCNA SUMOylation is responsible for the functional differences between the Mms2 and Rad5 homologues of Saccharomyces cerevisiae and Schizosaccharomyces pombe.
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Affiliation(s)
- Agnieszka Halas
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, 02-106 Warsaw, Poland
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6
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Hirota K, Sonoda E, Kawamoto T, Motegi A, Masutani C, Hanaoka F, Szüts D, Iwai S, Sale JE, Lehmann A, Takeda S. Simultaneous disruption of two DNA polymerases, Polη and Polζ, in Avian DT40 cells unmasks the role of Polη in cellular response to various DNA lesions. PLoS Genet 2010; 6. [PMID: 20949111 PMCID: PMC2951353 DOI: 10.1371/journal.pgen.1001151] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 09/08/2010] [Indexed: 12/18/2022] Open
Abstract
Replicative DNA polymerases are frequently stalled by DNA lesions. The resulting replication blockage is released by homologous recombination (HR) and translesion DNA synthesis (TLS). TLS employs specialized TLS polymerases to bypass DNA lesions. We provide striking in vivo evidence of the cooperation between DNA polymerase η, which is mutated in the variant form of the cancer predisposition disorder xeroderma pigmentosum (XP-V), and DNA polymerase ζ by generating POLη−/−/POLζ−/− cells from the chicken DT40 cell line. POLζ−/− cells are hypersensitive to a very wide range of DNA damaging agents, whereas XP-V cells exhibit moderate sensitivity to ultraviolet light (UV) only in the presence of caffeine treatment and exhibit no significant sensitivity to any other damaging agents. It is therefore widely believed that Polη plays a very specific role in cellular tolerance to UV-induced DNA damage. The evidence we present challenges this assumption. The phenotypic analysis of POLη−/−/POLζ−/− cells shows that, unexpectedly, the loss of Polη significantly rescued all mutant phenotypes of POLζ−/− cells and results in the restoration of the DNA damage tolerance by a backup pathway including HR. Taken together, Polη contributes to a much wide range of TLS events than had been predicted by the phenotype of XP-V cells. DNA replication is a fragile biochemical reaction, as the replicative DNA polymerases are readily stalled by DNA lesions. The resulting replication blockage is released by translesion DNA synthesis (TLS), which employs specialized TLS polymerases to bypass DNA lesions. There are at least seven TLS polymerases known in vertebrates. However, how they cooperate in vivo remains one of central questions in the field. We analyzed this functional interaction by genetically disrupting two of major TLS polymerases, Polη and Polζ, in the unique genetic model organism, chicken DT40 cells. Currently, it is widely believed that Polη plays a very specific role in cellular tolerance to ultraviolet light–induced DNA damage. Polζ, on the other hand, plays a key role in cellular tolerance to a very wide range of DNA–damaging agents, as POLζ−/− cells are hypersensitivity to a number of DNA damaging agents. Our phenotypic analysis of POLη−/−/POLζ−/− cells shows that, unexpectedly, the loss of Polη significantly rescued all mutant phenotypes of POLζ−/− cells. The genetic interaction shown here reveals a previously unappreciated role of human Polη in cellular response to a wide variety of DNA lesions and two-step collaborative action of Polymerase η and ζ.
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Affiliation(s)
- Kouji Hirota
- CREST Research Project, Japan Science and Technology, Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Eiichiro Sonoda
- CREST Research Project, Japan Science and Technology, Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Takuo Kawamoto
- CREST Research Project, Japan Science and Technology, Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Akira Motegi
- CREST Research Project, Japan Science and Technology, Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Chikahide Masutani
- Solution-Oriented Research for Science and Technology (SORST), Japan Science and Technology Agency, Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Fumio Hanaoka
- Solution-Oriented Research for Science and Technology (SORST), Japan Science and Technology Agency, Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Dávid Szüts
- St. George's, University of London, London, United Kingdom
| | - Shigenori Iwai
- Division of Chemistry, Graduate School of Engineering Science, Osaka University, Osaka, Japan
| | - Julian E. Sale
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Alan Lehmann
- Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Shunichi Takeda
- CREST Research Project, Japan Science and Technology, Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
- * E-mail:
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7
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Srs2 plays a critical role in reversible G2 arrest upon chronic and low doses of UV irradiation via two distinct homologous recombination-dependent mechanisms in postreplication repair-deficient cells. Mol Cell Biol 2010; 30:4840-50. [PMID: 20713444 DOI: 10.1128/mcb.00453-10] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Differential posttranslational modification of proliferating cell nuclear antigen (PCNA) by ubiquitin or SUMO plays an important role in coordinating the processes of DNA replication and DNA damage tolerance. Previously it was shown that the loss of RAD6-dependent error-free postreplication repair (PRR) results in DNA damage checkpoint-mediated G(2) arrest in cells exposed to chronic low-dose UV radiation (CLUV), whereas wild-type and nucleotide excision repair-deficient cells are largely unaffected. In this study, we report that suppression of homologous recombination (HR) in PRR-deficient cells by Srs2 and PCNA sumoylation is required for checkpoint activation and checkpoint maintenance during CLUV irradiation. Cyclin-dependent kinase (CDK1)-dependent phosphorylation of Srs2 did not influence checkpoint-mediated G(2) arrest or maintenance in PRR-deficient cells but was critical for HR-dependent checkpoint recovery following release from CLUV exposure. These results indicate that Srs2 plays an important role in checkpoint-mediated reversible G(2) arrest in PRR-deficient cells via two separate HR-dependent mechanisms. The first (required to suppress HR during PRR) is regulated by PCNA sumoylation, whereas the second (required for HR-dependent recovery following CLUV exposure) is regulated by CDK1-dependent phosphorylation.
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8
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Gong J, Siede W. SBF transcription factor complex positively regulates UV mutagenesis in Saccharomyces cerevisiae. Biochem Biophys Res Commun 2009; 379:1009-14. [PMID: 19150335 DOI: 10.1016/j.bbrc.2009.01.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2009] [Accepted: 01/03/2009] [Indexed: 11/19/2022]
Abstract
The collection of gene deletion mutants of Saccharomyces cerevisiae was used to screen for novel genes required for UV-induced mutagenesis. We found the SBF transcription factor (Swi4/Swi6 protein complex) to be required for wild-type levels of UV mutability in forward and reverse mutation assays. Expression of translesion polymerase zeta component Rev7 was identified as a target of SBF-dependent regulation.
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Affiliation(s)
- Jinjun Gong
- Department of Cell Biology and Genetics, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, Texas 76107, USA
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9
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Polyubiquitination of proliferating cell nuclear antigen by HLTF and SHPRH prevents genomic instability from stalled replication forks. Proc Natl Acad Sci U S A 2008; 105:12411-6. [PMID: 18719106 DOI: 10.1073/pnas.0805685105] [Citation(s) in RCA: 213] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Chronic stalling of DNA replication forks caused by DNA damage can lead to genomic instability. Cells have evolved lesion bypass pathways such as postreplication repair (PRR) to resolve these arrested forks. In yeast, one branch of PRR involves proliferating cell nuclear antigen (PCNA) polyubiquitination mediated by the Rad5-Ubc13-Mms2 complex that allows bypass of DNA lesion by a template-switching mechanism. Previously, we identified human SHPRH as a functional homologue of yeast Rad5 and revealed the existence of RAD5-like pathway in human cells. Here we report the identification of HLTF as a second RAD5 homologue in human cells. HLTF, like SHPRH, shares a unique domain architecture with Rad5 and promotes lysine 63-linked polyubiquitination of PCNA. Similar to yeast Rad5, HLTF is able to interact with UBC13 and PCNA, as well as SHPRH; and the reduction of either SHPRH or HLTF expression enhances spontaneous mutagenesis. Moreover, Hltf-deficient mouse embryonic fibroblasts show elevated chromosome breaks and fusions after methyl methane sulfonate treatment. Our results suggest that HLTF and SHPRH are functional homologues of yeast Rad5 that cooperatively mediate PCNA polyubiquitination and maintain genomic stability.
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10
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Chiolo I, Saponaro M, Baryshnikova A, Kim JH, Seo YS, Liberi G. The human F-Box DNA helicase FBH1 faces Saccharomyces cerevisiae Srs2 and postreplication repair pathway roles. Mol Cell Biol 2007; 27:7439-50. [PMID: 17724085 PMCID: PMC2169053 DOI: 10.1128/mcb.00963-07] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Saccharomyces cerevisiae Srs2 UvrD DNA helicase controls genome integrity by preventing unscheduled recombination events. While Srs2 orthologues have been identified in prokaryotic and lower eukaryotic organisms, human orthologues of Srs2 have not been described so far. We found that the human F-box DNA helicase hFBH1 suppresses specific recombination defects of S. cerevisiae srs2 mutants, consistent with the finding that the helicase domain of hFBH1 is highly conserved with that of Srs2. Surprisingly, hFBH1 in the absence of SRS2 also suppresses the DNA damage sensitivity caused by inactivation of postreplication repair-dependent functions leading to PCNA ubiquitylation. The F-box domain of hFBH1, which is not present in Srs2, is crucial for hFBH1 functions in substituting for Srs2 and postreplication repair factors. Furthermore, our findings indicate that an intact F-box domain, acting as an SCF ubiquitin ligase, is required for the DNA damage-induced degradation of hFBH1 itself. Overall, our findings suggest that the hFBH1 helicase is a functional human orthologue of budding yeast Srs2 that also possesses self-regulation properties necessary to execute its recombination functions.
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Affiliation(s)
- Irene Chiolo
- FIRC Institute of Molecular Oncology Foundation, Via Adamello 16, 20139 Milan, Italy
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11
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Tran PT, Fey JP, Erdeniz N, Gellon L, Boiteux S, Liskay RM. A mutation in EXO1 defines separable roles in DNA mismatch repair and post-replication repair. DNA Repair (Amst) 2007; 6:1572-83. [PMID: 17602897 PMCID: PMC2447855 DOI: 10.1016/j.dnarep.2007.05.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Revised: 05/10/2007] [Accepted: 05/11/2007] [Indexed: 01/27/2023]
Abstract
Replication forks stall at DNA lesions or as a result of an unfavorable replicative environment. These fork stalling events have been associated with recombination and gross chromosomal rearrangements. Recombination and fork bypass pathways are the mechanisms accountable for restart of stalled forks. An important lesion bypass mechanism is the highly conserved post-replication repair (PRR) pathway that is composed of error-prone translesion and error-free bypass branches. EXO1 codes for a Rad2p family member nuclease that has been implicated in a multitude of eukaryotic DNA metabolic pathways that include DNA repair, recombination, replication, and telomere integrity. In this report, we show EXO1 functions in the MMS2 error-free branch of the PRR pathway independent of the role of EXO1 in DNA mismatch repair (MMR). Consistent with the idea that EXO1 functions independently in two separate pathways, we defined a domain of Exo1p required for PRR distinct from those required for interaction with MMR proteins. We then generated a point mutant exo1 allele that was defective for the function of Exo1p in MMR due to disrupted interaction with Mlh1p, but still functional for PRR. Lastly, by using a compound exo1 mutant that was defective for interaction with Mlh1p and deficient for nuclease activity, we provide further evidence that Exo1p plays both structural and catalytic roles during MMR.
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Affiliation(s)
- Phuoc T. Tran
- Department of Radiation Oncology, Stanford Hospital & Clinics, Stanford, CA 94305, USA
- Corresponding Author: Phuoc T. Tran, 875 Blake Wilbur Drive, Stanford, CA 94305, e-mail:
| | - Julien P. Fey
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Naz Erdeniz
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Lionel Gellon
- Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Serge Boiteux
- Commissariat à l'Energie Atomique (CEA), Département de Radiobiologie et Radiopathologie, UMR217 CNRS/CEA Radiobiologie Moléculaire et Cellulaire, Fontenay aux Roses 92265, France
| | - R. Michael Liskay
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, USA
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