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Zhang D, Xu S, Luo Z, Lin Z. MOC1 cleaves Holliday junctions through a cooperative nick and counter-nick mechanism mediated by metal ions. Nat Commun 2024; 15:5140. [PMID: 38886375 PMCID: PMC11183143 DOI: 10.1038/s41467-024-49490-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 06/06/2024] [Indexed: 06/20/2024] Open
Abstract
Holliday junction resolution is a crucial process in homologous recombination and DNA double-strand break repair. Complete Holliday junction resolution requires two stepwise incisions across the center of the junction, but the precise mechanism of metal ion-catalyzed Holliday junction cleavage remains elusive. Here, we perform a metal ion-triggered catalysis in crystals to investigate the mechanism of Holliday junction cleavage by MOC1. We capture the structures of MOC1 in complex with a nicked Holliday junction at various catalytic states, including the ground state, the one-metal ion binding state, and the two-metal ion binding state. Moreover, we also identify a third metal ion that may aid in the nucleophilic attack on the scissile phosphate. Further structural and biochemical analyses reveal a metal ion-mediated allosteric regulation between the two active sites, contributing to the enhancement of the second strand cleavage following the first strand cleavage, as well as the precise symmetric cleavage across the Holliday junction. Our work provides insights into the mechanism of metal ion-catalyzed Holliday junction resolution by MOC1, with implications for understanding how cells preserve genome integrity during the Holliday junction resolution phase.
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Affiliation(s)
- Danping Zhang
- College of Chemistry, Fuzhou University, Fuzhou, 350108, China
| | - Shenjie Xu
- MOE Key Laboratory of Geriatric Diseases and Immunology, Institute of Molecular Enzymology, School of Biology and Basic Medical Sciences, Suzhou Medical College, Soochow University, Suzhou, 215123, China
| | - Zhipu Luo
- MOE Key Laboratory of Geriatric Diseases and Immunology, Institute of Molecular Enzymology, School of Biology and Basic Medical Sciences, Suzhou Medical College, Soochow University, Suzhou, 215123, China.
| | - Zhonghui Lin
- College of Chemistry, Fuzhou University, Fuzhou, 350108, China.
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Linder A, Westbom-Fremer S, Mateoiu C, Olsson Widjaja A, Österlund T, Veerla S, Ståhlberg A, Ulfenborg B, Hedenfalk I, Sundfeldt K. Genomic alterations in ovarian endometriosis and subsequently diagnosed ovarian carcinoma. Hum Reprod 2024; 39:1141-1154. [PMID: 38459814 PMCID: PMC11063555 DOI: 10.1093/humrep/deae043] [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: 09/18/2023] [Revised: 01/25/2024] [Indexed: 03/10/2024] Open
Abstract
STUDY QUESTION Can the alleged association between ovarian endometriosis and ovarian carcinoma be substantiated by genetic analysis of endometriosis diagnosed prior to the onset of the carcinoma? SUMMARY ANSWER The data suggest that ovarian carcinoma does not originate from ovarian endometriosis with a cancer-like genetic profile; however, a common precursor is probable. WHAT IS KNOWN ALREADY Endometriosis has been implicated as a precursor of ovarian carcinoma based on epidemiologic studies and the discovery of common driver mutations in synchronous disease at the time of surgery. Endometrioid ovarian carcinoma and clear cell ovarian carcinoma are the most common endometriosis-associated ovarian carcinomas (EAOCs). STUDY DESIGN, SIZE, DURATION The pathology biobanks of two university hospitals in Sweden were scrutinized to identify women with surgically removed endometrioma who subsequently developed ovarian carcinoma (1998-2016). Only 45 archival cases with EAOC and previous endometriosis were identified and after a careful pathology review, 25 cases were excluded due to reclassification into non-EAOC (n = 9) or because ovarian endometriosis could not be confirmed (n = 16). Further cases were excluded due to insufficient endometriosis tissue or poor DNA quality in either the endometriosis, carcinoma, or normal tissue (n = 9). Finally 11 cases had satisfactory DNA from all three locations and were eligible for further analysis. PARTICIPANTS/MATERIALS, SETTING, METHODS Epithelial cells were collected from formalin-fixed and paraffin-embedded (FFPE) sections by laser capture microdissection (endometrioma n = 11) or macrodissection (carcinoma n = 11) and DNA was extracted. Normal tissue from FFPE sections (n = 5) or blood samples collected at cancer diagnosis (n = 6) were used as the germline controls for each included patient. Whole-exome sequencing was performed (n = 33 samples). Somatic variants (single-nucleotide variants, indels, and copy number alterations) were characterized, and mutational signatures and kataegis were assessed. Microsatellite instability and mismatch repair status were confirmed with PCR and immunohistochemistry, respectively. MAIN RESULTS AND THE ROLE OF CHANCE The median age for endometriosis surgery was 42 years, and 54 years for the subsequent ovarian carcinoma diagnosis. The median time between the endometriosis and ovarian carcinoma was 10 (7-30) years. The data showed that all paired samples harbored one or more shared somatic mutations. Non-silent mutations in cancer-associated genes were frequent in endometriosis; however, the same mutations were never observed in subsequent carcinomas. The degree of clonal dominance, demonstrated by variant allele frequency, showed a positive correlation with the time to cancer diagnosis (Spearman's rho 0.853, P < 0.001). Mutations in genes associated with immune escape were the most conserved between paired samples, and regions harboring these genes were frequently affected by copy number alterations in both sample types. Mutational burdens and mutation signatures suggested faulty DNA repair mechanisms in all cases. LARGE SCALE DATA Datasets are available in the supplementary tables. LIMITATIONS, REASONS FOR CAUTION Even though we located several thousands of surgically removed endometriomas between 1998 and 2016, only 45 paired samples were identified and even fewer, 11 cases, were eligible for sequencing. The observed high level of intra- and inter-heterogeneity in both groups (endometrioma and carcinoma) argues for further studies of the alleged genetic association. WIDER IMPLICATIONS OF THE FINDINGS The observation of shared somatic mutations in all paired samples supports a common cellular origin for ovarian endometriosis and ovarian carcinoma. However, contradicting previous conclusions, our data suggest that cancer-associated mutations in endometriosis years prior to the carcinoma were not directly associated with the malignant transformation. Rather, a resilient ovarian endometriosis may delay tumorigenesis. Furthermore, the data indicate that genetic alterations affecting the immune response are early and significant events. STUDY FUNDING/COMPETING INTEREST(S) The present work has been funded by the Sjöberg Foundation (2021-01145 to K.S.; 2022-01-11:4 to A.S.), Swedish state under the agreement between the Swedish government and the county councils, the ALF-agreement (965552 to K.S.; 40615 to I.H.; 965065 to A.S.), Swedish Cancer Society (21-1848 to K.S.; 21-1684 to I.H.; 22-2080 to A.S.), BioCARE-A Strategic Research Area at Lund University (I.H. and S.W.-F.), Mrs Berta Kamprad's Cancer Foundation (FBKS-2019-28, I.H.), Cancer and Allergy Foundation (10381, I.H.), Region Västra Götaland (A.S.), Sweden's Innovation Agency (2020-04141, A.S.), Swedish Research Council (2021-01008, A.S.), Roche in collaboration with the Swedish Society of Gynecological Oncology (S.W.-F.), Assar Gabrielsson Foundation (FB19-86, C.M.), and the Lena Wäpplings Foundation (C.M.). A.S. declares stock ownership and is also a board member in Tulebovaasta, SiMSen Diagnostics, and Iscaff Pharma. A.S. has also received travel support from EMBL, Precision Medicine Forum, SLAS, and bioMCC. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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Affiliation(s)
- A Linder
- Department of Obstetrics and Gynecology, Sahlgrenska Center for Cancer Research, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - S Westbom-Fremer
- Division of Oncology, Department of Clinical Sciences Lund, Lund University, Lund, Sweden
- Lund University Cancer Centre (LUCC), Lund University, Lund, Sweden
| | - C Mateoiu
- Department of Pathology, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - A Olsson Widjaja
- Department of Obstetrics and Gynecology, Sahlgrenska Center for Cancer Research, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - T Österlund
- Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Gothenburg, Sweden
- Department of Clinical Genetics and Genomics, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - S Veerla
- Division of Oncology, Department of Clinical Sciences Lund, Lund University, Lund, Sweden
- Lund University Cancer Centre (LUCC), Lund University, Lund, Sweden
| | - A Ståhlberg
- Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Gothenburg, Sweden
- Department of Clinical Genetics and Genomics, Sahlgrenska University Hospital, Gothenburg, Sweden
- Department of Laboratory Medicine, Sahlgrenska Center for Cancer Research, Institute of Biomedicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - B Ulfenborg
- Department of Biology and Bioinformatics, Systems Biology Research Center, School of Bioscience, University of Skövde, Skövde, Sweden
| | - I Hedenfalk
- Division of Oncology, Department of Clinical Sciences Lund, Lund University, Lund, Sweden
- Lund University Cancer Centre (LUCC), Lund University, Lund, Sweden
| | - K Sundfeldt
- Department of Obstetrics and Gynecology, Sahlgrenska Center for Cancer Research, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
- Region Västra Götaland, Sahlgrenska University Hospital, Gothenburg, Sweden
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Du X, Wang C, Liu J, Yu M, Ju H, Xue S, Li Y, Liu J, Dai R, Chen J, Zhai Y, Rao J, Wang X, Sun Y, Sun L, Wu X, Xu H, Shen Q. GEN1 as a risk factor for human congenital anomalies of the kidney and urinary tract. Hum Genomics 2024; 18:41. [PMID: 38654324 PMCID: PMC11041010 DOI: 10.1186/s40246-024-00606-8] [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: 10/15/2023] [Accepted: 04/04/2024] [Indexed: 04/25/2024] Open
Abstract
BACKGROUND Congenital anomalies of the kidney and urinary tract (CAKUT) are prevalent birth defects. Although pathogenic CAKUT genes are known, they are insufficient to reveal the causes for all patients. Our previous studies indicated GEN1 as a pathogenic gene of CAKUT in mice, and this study further investigated the correlation between GEN1 and human CAKUT. METHODS In this study, DNA from 910 individuals with CAKUT was collected; 26 GEN1 rare variants were identified, and two GEN1 (missense) variants in a non-CAKUT group were found. Mainly due to the stability results of the predicted mutant on the website, in vitro, 10 variants (eight CAKUT, two non-CAKUT) were selected to verify mutant protein stability. In addition, mainly based on the division of the mutation site located in the functional region of the GEN1 protein, 8 variants (six CAKUT, two non-CAKUT) were selected to verify enzymatic hydrolysis, and the splice variant GEN1 (c.1071 + 3(IVS10) A > G) was selected to verify shear ability. Based on the results of in vitro experiments and higher frequency, three sites with the most significant functional change were selected to build mouse models. RESULTS Protein stability changed in six variants in the CAKUT group. Based on electrophoretic mobility shift assay of eight variants (six CAKUT, two non-CAKUT), the enzymatic hydrolysis and DNA-binding abilities of mutant proteins were impaired in the CAKUT group. The most serious functional damage was observed in the Gen1 variant that produced a truncated protein. A mini-gene splicing assay showed that the variant GEN1 (c.1071 + 3(IVS10) A > G) in the CAKUT group significantly affected splicing function. An abnormal exon10 was detected in the mini-gene splicing assay. Point-mutant mouse strains were constructed (Gen1: c.1068 + 3 A > G, p.R400X, and p.T105R) based on the variant frequency in the CAKUT group and functional impairment in vitro study and CAKUT phenotypes were replicated in each. CONCLUSION Overall, our findings indicated GEN1 as a risk factor for human CAKUT.
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Affiliation(s)
- Xuanjin Du
- Department of Nephrology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China
| | - Chunyan Wang
- Department of Nephrology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China
| | - Jialu Liu
- Department of Nephrology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China
| | - Minghui Yu
- Department of Nephrology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China
| | - Haixin Ju
- Department of Nephrology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China
| | - Shanshan Xue
- Department of Nephrology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China
| | - Yaxin Li
- Department of Nephrology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China
| | - Jiaojiao Liu
- Department of Nephrology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China
| | - Rufeng Dai
- Department of Nephrology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China
| | - Jing Chen
- Department of Nephrology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China
| | - Yihui Zhai
- Department of Nephrology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China
| | - Jia Rao
- Department of Nephrology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China
| | - Xiang Wang
- Department of Urology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China
| | - Yubo Sun
- Department of Urology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China
| | - Lei Sun
- Department of Nephrology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China
- State Key Laboratory of Genetic Engineering and National Center for International Research of Development and Disease, Institute of Developmental Biology and Molecular Medicine, Fudan University, 200433, Shanghai, China
| | - Xiaohui Wu
- Department of Nephrology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China
- State Key Laboratory of Genetic Engineering and National Center for International Research of Development and Disease, Institute of Developmental Biology and Molecular Medicine, Fudan University, 200433, Shanghai, China
| | - Hong Xu
- Department of Nephrology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China.
- National Key Laboratory of Kidney Diseases, 201102, Shanghai, China.
| | - Qian Shen
- Department of Nephrology, Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University, 201102, Shanghai, China.
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Alanazi AFR, Parkinson GN, Haider S. Structural Motifs at the Telomeres and Their Role in Regulatory Pathways. Biochemistry 2024; 63:827-842. [PMID: 38481135 PMCID: PMC10993422 DOI: 10.1021/acs.biochem.4c00023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Telomeres are specialized structures, found at the ends of linear chromosomes in eukaryotic cells, that play a crucial role in maintaining the stability and integrity of genomes. They are composed of repetitive DNA sequences, ssDNA overhangs, and several associated proteins. The length of telomeres is linked to cellular aging in humans, and deficiencies in their maintenance are associated with various diseases. Key structural motifs at the telomeres serve to protect vulnerable chromosomal ends. Telomeric DNA also has the ability to form diverse complex DNA higher-order structures, including T-loops, D-loops, R-loops, G-loops, G-quadruplexes, and i-motifs, in the complementary C-rich strand. While many essential proteins at telomeres have been identified, the intricacies of their interactions and structural details are still not fully understood. This Perspective highlights recent advancements in comprehending the structures associated with human telomeres. It emphasizes the significance of telomeres, explores various telomeric structural motifs, and delves into the structural biology surrounding telomeres and telomerase. Furthermore, telomeric loops, their topologies, and the associated proteins that contribute to the safeguarding of telomeres are discussed.
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Affiliation(s)
- Abeer F R Alanazi
- UCL School of Pharmacy, University College London, London WC1N 1AX, United Kingdom
| | - Gary N Parkinson
- UCL School of Pharmacy, University College London, London WC1N 1AX, United Kingdom
| | - Shozeb Haider
- UCL School of Pharmacy, University College London, London WC1N 1AX, United Kingdom
- UCL Centre for Advanced Research Computing, University College London, London WC1H 9RN, United Kingdom
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5
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Kim J, Yu J, Lee S, Kim S, Lee IS, Lee W, Chun S. Reverse Transcription-PCR-based Sanger Sequencing-confirmed Exon-skipping Effect of a Novel GEN1 Intronic Variant (c.1408+4A>G). Ann Lab Med 2024; 44:188-191. [PMID: 37840312 PMCID: PMC10628752 DOI: 10.3343/alm.2023.0163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Revised: 07/22/2023] [Accepted: 09/12/2023] [Indexed: 10/17/2023] Open
Affiliation(s)
- Jiyeon Kim
- Department of Laboratory Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Joonsang Yu
- Department of Laboratory Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Seunghoo Lee
- Department of Laboratory Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Sollip Kim
- Department of Laboratory Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - In-Seob Lee
- Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Woochang Lee
- Department of Laboratory Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Sail Chun
- Department of Laboratory Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
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6
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Swigonska S, Nynca A, Molcan T, Jablonska M, Ciereszko RE. Knock-down of aryl hydrocarbon receptor (AhR) affects the lncRNA-mediated response of porcine granulosa cells (AVG-16 cell line) to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Anim Reprod Sci 2023; 255:107277. [PMID: 37315452 DOI: 10.1016/j.anireprosci.2023.107277] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 05/25/2023] [Accepted: 06/05/2023] [Indexed: 06/16/2023]
Abstract
Recently, we found that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) - the most toxic dioxin - affected multiple cellular processes in AhR-knocked-down granulosa cells, including the expression of genes and the abundance of proteins. Such alterations may imply the involvement of noncoding RNAs in the remodeling of intracellular regulatory tracks. The aims of the current study were to examine the effects of TCDD on the expression of lncRNAs in AhR-knocked-down granulosa cells of pigs and to indicate potential target genes for differentially expressed lncRNAs (DELs). In the current study, the abundance of AhR protein in porcine granulosa cells was reduced by 98.9% at 24 h after AhR targeted siRNA transfection. Fifty-seven DELs were identified in the AhR-deficient cells treated with TCDD mostly after 3 h (3 h: 56, 12 h: 0, 24 h: 2) after the dioxin treatment. This number was 2.5 times higher than that of intact TCDD-treated granulosa cells. The high number of DELs identified in the early stages of the TCDD action may be associated with a rapid defensive response of cells to harmful actions of this persistent environmental pollutant. In contrast to intact TCDD-treated granulosa cells, AhR-deficient cells were characterized by a broader representation of DELs enriched in GO terms related to the immune response and regulation of transcription and cell cycle. The obtained results support the notion that TCDD may act in an AhR-independent manner. They increase our knowledge on the intracellular mechanism of TCDD action and may in the future contribute to better coping with detrimental consequences of human and animal exposure to TCDD.
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Affiliation(s)
- Sylwia Swigonska
- Laboratory of Molecular Diagnostics, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, Prawochenskiego 5, 10-720 Olsztyn, Poland.
| | - Anna Nynca
- Department of Animal Anatomy and Physiology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, Oczapowskiego 1A, 10-719 Olsztyn, Poland.
| | - Tomasz Molcan
- Molecular Biology Laboratory, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Olsztyn, Poland.
| | - Monika Jablonska
- Department of Human Nutrition, Faculty of Food Sciences, University of Warmia and Mazury in Olsztyn, Poland.
| | - Renata E Ciereszko
- Laboratory of Molecular Diagnostics, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, Prawochenskiego 5, 10-720 Olsztyn, Poland; Department of Animal Anatomy and Physiology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, Oczapowskiego 1A, 10-719 Olsztyn, Poland.
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7
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Song Q, Hu Y, Yin A, Wang H, Yin Q. DNA Holliday Junction: History, Regulation and Bioactivity. Int J Mol Sci 2022; 23:ijms23179730. [PMID: 36077130 PMCID: PMC9456528 DOI: 10.3390/ijms23179730] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 08/16/2022] [Accepted: 08/18/2022] [Indexed: 11/16/2022] Open
Abstract
DNA Holliday junction (HJ) is a four-way stranded DNA intermediate that formed in replication fork regression, homology-dependent repair and mitosis, performing a significant role in genomic stability. Failure to remove HJ can induce an acceptable replication fork stalling and DNA damage in normal cells, leading to a serious chromosomal aberration and even cell death in HJ nuclease-deficient tumor cells. Thus, HJ is becoming an attractive target in cancer therapy. However, the development of HJ-targeting ligand faces great challenges because of flexile cavities on the center of HJs. This review introduces the discovery history of HJ, elucidates the formation and dissociation procedures of HJ in corresponding bio-events, emphasizes the importance of prompt HJ-removing in genome stability, and summarizes recent advances in HJ-based ligand discovery. Our review indicate that target HJ is a promising approach in oncotherapy.
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Affiliation(s)
- Qinqin Song
- State/Key Laboratory of Microbial Technology, Shandong University, 72 Jimo Binhai Road, Qingdao 266237, China
| | - Yuemiao Hu
- Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, School of Pharmacy, Yantai University, 30 Qingquan Road, Yantai 264005, China
| | - Anqi Yin
- Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, School of Pharmacy, Yantai University, 30 Qingquan Road, Yantai 264005, China
| | - Hongbo Wang
- Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, School of Pharmacy, Yantai University, 30 Qingquan Road, Yantai 264005, China
| | - Qikun Yin
- Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, School of Pharmacy, Yantai University, 30 Qingquan Road, Yantai 264005, China
- Bohai Rim Advanced Research Institute for Drug Discovery, 198 Binhai East Road, Yantai 264005, China
- Correspondence:
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8
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Carreira R, Aguado FJ, Hurtado-Nieves V, Blanco MG. Canonical and novel non-canonical activities of the Holliday junction resolvase Yen1. Nucleic Acids Res 2021; 50:259-280. [PMID: 34928393 PMCID: PMC8754655 DOI: 10.1093/nar/gkab1225] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 11/12/2021] [Accepted: 12/01/2021] [Indexed: 11/14/2022] Open
Abstract
Yen1 and GEN1 are members of the Rad2/XPG family of nucleases that were identified as the first canonical nuclear Holliday junction (HJ) resolvases in budding yeast and humans due to their ability to introduce two symmetric, coordinated incisions on opposite strands of the HJ, yielding nicked DNA products that could be readily ligated. While GEN1 has been extensively characterized in vitro, much less is known about the biochemistry of Yen1. Here, we have performed the first in-depth characterization of purified Yen1. We confirmed that Yen1 resembles GEN1 in many aspects, including range of substrates targeted, position of most incisions they produce or the increase in the first incision rate by assembly of a dimer on a HJ, despite minor differences. However, we demonstrate that Yen1 is endowed with additional nuclease activities, like a nick-specific 5′-3′ exonuclease or HJ arm-chopping that could apparently blur its classification as a canonical HJ resolvase. Despite this, we show that Yen1 fulfils the requirements of a canonical HJ resolvase and hypothesize that its wider array of nuclease activities might contribute to its function in the removal of persistent recombination or replication intermediates.
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Affiliation(s)
- Raquel Carreira
- Department of Biochemistry and Molecular Biology, CIMUS, Universidade de Santiago de Compostela-Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela, A Coruña 15782, Spain
| | - F Javier Aguado
- Department of Biochemistry and Molecular Biology, CIMUS, Universidade de Santiago de Compostela-Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela, A Coruña 15782, Spain
| | - Vanesa Hurtado-Nieves
- Department of Biochemistry and Molecular Biology, CIMUS, Universidade de Santiago de Compostela-Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela, A Coruña 15782, Spain
| | - Miguel G Blanco
- Department of Biochemistry and Molecular Biology, CIMUS, Universidade de Santiago de Compostela-Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela, A Coruña 15782, Spain
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9
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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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10
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González-Corrochano R, Ruiz FM, Taylor NMI, Huecas S, Drakulic S, Spínola-Amilibia M, Fernández-Tornero C. The crystal structure of human XPG, the xeroderma pigmentosum group G endonuclease, provides insight into nucleotide excision DNA repair. Nucleic Acids Res 2020; 48:9943-9958. [PMID: 32821917 PMCID: PMC7515719 DOI: 10.1093/nar/gkaa688] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 08/04/2020] [Accepted: 08/06/2020] [Indexed: 01/14/2023] Open
Abstract
Nucleotide excision repair (NER) is an essential pathway to remove bulky lesions affecting one strand of DNA. Defects in components of this repair system are at the ground of genetic diseases such as xeroderma pigmentosum (XP) and Cockayne syndrome (CS). The XP complementation group G (XPG) endonuclease cleaves the damaged DNA strand on the 3′ side of the lesion coordinated with DNA re-synthesis. Here, we determined crystal structures of the XPG nuclease domain in the absence and presence of DNA. The overall fold exhibits similarities to other flap endonucleases but XPG harbors a dynamic helical arch that is uniquely oriented and defines a gateway. DNA binding through a helix-2-turn-helix motif, assisted by one flanking α-helix on each side, shows high plasticity, which is likely relevant for DNA scanning. A positively-charged canyon defined by the hydrophobic wedge and β-pin motifs provides an additional DNA-binding surface. Mutational analysis identifies helical arch residues that play critical roles in XPG function. A model for XPG participation in NER is proposed. Our structures and biochemical data represent a valuable tool to understand the atomic ground of XP and CS, and constitute a starting point for potential therapeutic applications.
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Affiliation(s)
| | - Federico M Ruiz
- Centro de Investigaciones Biológicas Margarita Salas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Nicholas M I Taylor
- Centro de Investigaciones Biológicas Margarita Salas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Sonia Huecas
- Centro de Investigaciones Biológicas Margarita Salas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Srdja Drakulic
- Centro de Investigaciones Biológicas Margarita Salas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | | | - Carlos Fernández-Tornero
- Centro de Investigaciones Biológicas Margarita Salas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
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11
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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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12
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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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13
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Yan J, Hong S, Guan Z, He W, Zhang D, Yin P. Structural insights into sequence-dependent Holliday junction resolution by the chloroplast resolvase MOC1. Nat Commun 2020; 11:1417. [PMID: 32184398 PMCID: PMC7078210 DOI: 10.1038/s41467-020-15242-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Accepted: 02/17/2020] [Indexed: 11/24/2022] Open
Abstract
Holliday junctions (HJs) are key DNA intermediates in genetic recombination and are eliminated by nuclease, termed resolvase, to ensure genome stability. HJ resolvases have been identified across all kingdoms of life, members of which exhibit sequence-dependent HJ resolution. However, the molecular basis of sequence selectivity remains largely unknown. Here, we present the chloroplast resolvase MOC1, which cleaves HJ in a cytosine-dependent manner. We determine the crystal structure of MOC1 with and without HJs. MOC1 exhibits an RNase H fold, belonging to the retroviral integrase family. MOC1 functions as a dimer, and the HJ is embedded into the basic cleft of the dimeric enzyme. We characterize a base recognition loop (BR loop) that protrudes into and opens the junction. Residues from the BR loop intercalate into the bases, disrupt the C-G base pairing at the crossover and recognize the cytosine, providing the molecular basis for sequence-dependent HJ resolution by a resolvase.
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Affiliation(s)
- Junjie Yan
- National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research, Huazhong Agricultural University, 430070, Wuhan, China
| | - Sixing Hong
- National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research, Huazhong Agricultural University, 430070, Wuhan, China
| | - Zeyuan Guan
- National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research, Huazhong Agricultural University, 430070, Wuhan, China
| | - Wenjing He
- National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research, Huazhong Agricultural University, 430070, Wuhan, China
| | - Delin Zhang
- National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research, Huazhong Agricultural University, 430070, Wuhan, China
| | - Ping Yin
- National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research, Huazhong Agricultural University, 430070, Wuhan, China.
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14
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Gaur V, Ziajko W, Nirwal S, Szlachcic A, Gapińska M, Nowotny M. Recognition and processing of branched DNA substrates by Slx1-Slx4 nuclease. Nucleic Acids Res 2019; 47:11681-11690. [PMID: 31584081 PMCID: PMC6902002 DOI: 10.1093/nar/gkz842] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 09/16/2019] [Accepted: 10/01/2019] [Indexed: 12/11/2022] Open
Abstract
Structure-selective endonucleases cleave branched DNA substrates. Slx1 is unique among structure-selective nucleases because it can cleave all branched DNA structures at multiple sites near the branch point. The mechanism behind this broad range of activity is unknown. The present study structurally and biochemically investigated fungal Slx1 to define a new protein interface that binds the non-cleaved arm of branched DNAs. The DNA arm bound at this new site was positioned at a sharp angle relative to the arm that was modeled to interact with the active site, implying that Slx1 uses DNA bending to localize the branch point as a flexible discontinuity in DNA. DNA binding at the new interface promoted a disorder-order transition in a region of the protein that was located in the vicinity of the active site, potentially participating in its formation. This appears to be a safety mechanism that ensures that DNA cleavage occurs only when the new interface is occupied by the non-cleaved DNA arm. Models of Slx1 that interacted with various branched DNA substrates were prepared. These models explain the way in which Slx1 cuts DNA toward the 3' end away from the branch point and elucidate the unique ability of Slx1 to cleave various DNA structures.
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Affiliation(s)
- Vineet Gaur
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Trojdena St., 02-109 Warsaw, Poland
| | - Weronika Ziajko
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Trojdena St., 02-109 Warsaw, Poland
| | - Shivlee Nirwal
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Trojdena St., 02-109 Warsaw, Poland
| | - Aleksandra Szlachcic
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Trojdena St., 02-109 Warsaw, Poland
| | - Marta Gapińska
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Trojdena St., 02-109 Warsaw, Poland
| | - Marcin Nowotny
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, 4 Trojdena St., 02-109 Warsaw, Poland
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15
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Bennet IA, Finger LD, Baxter NJ, Ambrose B, Hounslow AM, Thompson MJ, Exell JC, Shahari NNBM, Craggs TD, Waltho JP, Grasby JA. Regional conformational flexibility couples substrate specificity and scissile phosphate diester selectivity in human flap endonuclease 1. Nucleic Acids Res 2019; 46:5618-5633. [PMID: 29718417 PMCID: PMC6009646 DOI: 10.1093/nar/gky293] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 04/09/2018] [Indexed: 02/07/2023] Open
Abstract
Human flap endonuclease-1 (hFEN1) catalyzes the divalent metal ion-dependent removal of single-stranded DNA protrusions known as flaps during DNA replication and repair. Substrate selectivity involves passage of the 5'-terminus/flap through the arch and recognition of a single nucleotide 3'-flap by the α2-α3 loop. Using NMR spectroscopy, we show that the solution conformation of free and DNA-bound hFEN1 are consistent with crystal structures; however, parts of the arch region and α2-α3 loop are disordered without substrate. Disorder within the arch explains how 5'-flaps can pass under it. NMR and single-molecule FRET data show a shift in the conformational ensemble in the arch and loop region upon addition of DNA. Furthermore, the addition of divalent metal ions to the active site of the hFEN1-DNA substrate complex demonstrates that active site changes are propagated via DNA-mediated allostery to regions key to substrate differentiation. The hFEN1-DNA complex also shows evidence of millisecond timescale motions in the arch region that may be required for DNA to enter the active site. Thus, hFEN1 regional conformational flexibility spanning a range of dynamic timescales is crucial to reach the catalytically relevant ensemble.
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Affiliation(s)
- Ian A Bennet
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S3 7HF, UK
| | - L David Finger
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S3 7HF, UK
| | - Nicola J Baxter
- Department of Molecular Biology and Biotechnology, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S10 2TN, UK.,Manchester Institute of Biotechnology, School of Chemistry, The University of Manchester, Manchester M1 7DN, UK
| | - Benjamin Ambrose
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S3 7HF, UK
| | - Andrea M Hounslow
- Department of Molecular Biology and Biotechnology, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S10 2TN, UK
| | - Mark J Thompson
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S3 7HF, UK
| | - Jack C Exell
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S3 7HF, UK
| | - Nur Nazihah B Md Shahari
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S3 7HF, UK
| | - Timothy D Craggs
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S3 7HF, UK
| | - Jonathan P Waltho
- Department of Molecular Biology and Biotechnology, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S10 2TN, UK.,Manchester Institute of Biotechnology, School of Chemistry, The University of Manchester, Manchester M1 7DN, UK
| | - Jane A Grasby
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S3 7HF, UK
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16
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Falquet B, Rass U. Structure-Specific Endonucleases and the Resolution of Chromosome Underreplication. Genes (Basel) 2019; 10:E232. [PMID: 30893921 PMCID: PMC6470701 DOI: 10.3390/genes10030232] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 03/11/2019] [Accepted: 03/13/2019] [Indexed: 12/11/2022] Open
Abstract
Complete genome duplication in every cell cycle is fundamental for genome stability and cell survival. However, chromosome replication is frequently challenged by obstacles that impede DNA replication fork (RF) progression, which subsequently causes replication stress (RS). Cells have evolved pathways of RF protection and restart that mitigate the consequences of RS and promote the completion of DNA synthesis prior to mitotic chromosome segregation. If there is entry into mitosis with underreplicated chromosomes, this results in sister-chromatid entanglements, chromosome breakage and rearrangements and aneuploidy in daughter cells. Here, we focus on the resolution of persistent replication intermediates by the structure-specific endonucleases (SSEs) MUS81, SLX1-SLX4 and GEN1. Their actions and a recently discovered pathway of mitotic DNA repair synthesis have emerged as important facilitators of replication completion and sister chromatid detachment in mitosis. As RS is induced by oncogene activation and is a common feature of cancer cells, any advances in our understanding of the molecular mechanisms related to chromosome underreplication have important biomedical implications.
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Affiliation(s)
- Benoît Falquet
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland.
- Faculty of Natural Sciences, University of Basel, Petersplatz 10, CH-4003 Basel, Switzerland.
| | - Ulrich Rass
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK.
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17
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Sobhy MA, Bralić A, Raducanu VS, Takahashi M, Tehseen M, Rashid F, Zaher MS, Hamdan SM. Resolution of the Holliday junction recombination intermediate by human GEN1 at the single-molecule level. Nucleic Acids Res 2019; 47:1935-1949. [PMID: 30590761 PMCID: PMC6393306 DOI: 10.1093/nar/gky1280] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 11/19/2018] [Accepted: 12/13/2018] [Indexed: 01/18/2023] Open
Abstract
Human GEN1 is a cytosolic homologous recombination protein that resolves persisting four-way Holliday junctions (HJ) after the dissolution of the nuclear membrane. GEN1 dimerization has been suggested to play key role in the resolution of the HJ, but the kinetic details of its reaction remained elusive. Here, single-molecule FRET shows how human GEN1 binds the HJ and always ensures its resolution within the lifetime of the GEN1-HJ complex. GEN1 monomer generally follows the isomer bias of the HJ in its initial binding and subsequently distorts it for catalysis. GEN1 monomer remains tightly bound with no apparent dissociation until GEN1 dimer is formed and the HJ is fully resolved. Fast on- and slow off-rates of GEN1 dimer and its increased affinity to the singly-cleaved HJ enforce the forward reaction. Furthermore, GEN1 monomer binds singly-cleaved HJ tighter than intact HJ providing a fail-safe mechanism if GEN1 dimer or one of its monomers dissociates after the first cleavage. The tight binding of GEN1 monomer to intact- and singly-cleaved HJ empowers it as the last resort to process HJs that escape the primary mechanisms.
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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
| | - 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
| | - Vlad-Stefan Raducanu
- 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
| | - 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
| | - Fahad Rashid
- 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
| | - Manal S Zaher
- 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
| | - 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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18
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Liu Y, Freeman ADJ, Déclais AC, Lilley DMJ. A monovalent ion in the DNA binding interface of the eukaryotic junction-resolving enzyme GEN1. Nucleic Acids Res 2018; 46:11089-11098. [PMID: 30247722 PMCID: PMC6237754 DOI: 10.1093/nar/gky863] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/11/2018] [Accepted: 09/13/2018] [Indexed: 01/07/2023] Open
Abstract
GEN1 is a member of the FEN/EXO family of structure-selective nucleases that cleave 1 nt 3' to a variety of branchpoints. For each, the H2TH motif binds a monovalent ion and plays an important role in binding one helical arm of the substrates. We investigate here the importance of this metal ion on substrate specificity and GEN1 structure. In the presence of K+ ions the substrate specificity is wider than in Na+, yet four-way junctions remain the preferred substrate. In a combination of K+ and Mg2+ second strand cleavage is accelerated 17-fold, ensuring bilateral cleavage of the junction. We have solved crystal structures of Chaetomium thermophilum GEN1 with Cs+, K+ and Na+ bound. With bound Cs+ the loop of the H2TH motif extends toward the active site so that D199 coordinates a Mg2+, buttressed by an interaction of the adjacent Y200. With the lighter ions bound the H2TH loop changes conformation and retracts away from the active site. We hypothesize this conformational change might play a role in second strand cleavage acceleration.
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Affiliation(s)
- Yijin Liu
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Alasdair DJ Freeman
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Anne-Cécile Déclais
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - David M J Lilley
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, UK
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19
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Uson ML, Carl A, Goldgur Y, Shuman S. Crystal structure and mutational analysis of Mycobacterium smegmatis FenA highlight active site amino acids and three metal ions essential for flap endonuclease and 5' exonuclease activities. Nucleic Acids Res 2018; 46:4164-4175. [PMID: 29635474 PMCID: PMC5934675 DOI: 10.1093/nar/gky238] [Citation(s) in RCA: 5] [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: 01/17/2018] [Revised: 03/19/2018] [Accepted: 03/21/2018] [Indexed: 02/02/2023] Open
Abstract
Mycobacterium smegmatis FenA is a nucleic acid phosphodiesterase with flap endonuclease and 5' exonuclease activities. The 1.8 Å crystal structure of FenA reported here highlights as its closest homologs bacterial FEN-family enzymes ExoIX, the Pol1 exonuclease domain and phage T5 Fen. Mycobacterial FenA assimilates three active site manganese ions (M1, M2, M3) that are coordinated, directly and via waters, to a constellation of eight carboxylate side chains. We find via mutagenesis that the carboxylate contacts to all three manganese ions are essential for FenA's activities. Structures of nuclease-dead FenA mutants D125N, D148N and D208N reveal how they fail to bind one of the three active site Mn2+ ions, in a distinctive fashion for each Asn change. The structure of FenA D208N with a phosphate anion engaged by M1 and M2 in a state mimetic of a product complex suggests a mechanism for metal-catalyzed phosphodiester hydrolysis similar to that proposed for human Exo1. A distinctive feature of FenA is that it does not have the helical arch module found in many other FEN/FEN-like enzymes. Instead, this segment of FenA adopts a unique structure comprising a short 310 helix and surface β-loop that coordinates a fourth manganese ion (M4).
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Affiliation(s)
- Maria Loressa Uson
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Ayala Carl
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Yehuda Goldgur
- Structural Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
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20
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Liu Y, Freeman A, Déclais AC, Gartner A, Lilley DMJ. Biochemical and Structural Properties of Fungal Holliday Junction-Resolving Enzymes. Methods Enzymol 2018; 600:543-568. [PMID: 29458774 DOI: 10.1016/bs.mie.2017.11.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Four-way Holliday junctions in DNA are the central intermediates of genetic recombination and must be processed into regular duplex species. One mechanism for achieving this is called resolution, brought about by structure-selective nucleases. GEN1 is an important junction-resolving enzyme in eukaryotic cells, a member of the FEN1/EXO1 superfamily of nucleases. While human GEN1 is difficult to work with because of aggregation, orthologs from thermophilic fungi have been identified using bioinformatics and have proved to have excellent properties. Here, the expression and purification of this enzyme from Chaetomium thermophilum is described, together with the means of investigating its biochemical properties. The enzyme is quite similar to junction-resolving enzymes from lower organisms, binding to junctions in dimeric form, introducing symmetrical bilateral cleavages, the second of which is accelerated to promote productive resolution. Crystallization of C. thermophilum GEN1 is described, and the structure of a DNA-product complex. Juxtaposition of complexes in the crystal lattice suggests how the structure of a dimeric enzyme with an intact junction is organized.
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Affiliation(s)
- Yijin Liu
- Cancer Research UK Nucleic Acid Structure Research Group, The University of Dundee, Dundee, United Kingdom
| | - Alasdair Freeman
- Cancer Research UK Nucleic Acid Structure Research Group, The University of Dundee, Dundee, United Kingdom
| | - Anne-Cécile Déclais
- Cancer Research UK Nucleic Acid Structure Research Group, The University of Dundee, Dundee, United Kingdom
| | - Anton Gartner
- Cancer Research UK Nucleic Acid Structure Research Group, The University of Dundee, Dundee, United Kingdom
| | - David M J Lilley
- Cancer Research UK Nucleic Acid Structure Research Group, The University of Dundee, Dundee, United Kingdom.
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21
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Abstract
Successful chromosome segregation depends on the timely removal of DNA recombination and replication intermediates that interlink sister chromatids. These intermediates are acted upon by structure-selective endonucleases that promote incisions close to the junction point. GEN1, a member of the Rad2/XPG endonuclease family, was identified on the basis of its ability to cleave Holliday junction recombination intermediates. Resolution occurs by a nick and counter-nick mechanism in strands that are symmetrically related across the junction point, leading to the formation of ligatable nicked duplex products. The actions of GEN1 are, however, not restricted to HJs, as 5'-flaps and replication fork structures also serve as excellent in vitro substrates for the nuclease. In the cellular context, GEN1 activity is observed late in the cell cycle, as most of the protein is excluded from the nucleus, such that it gains access to DNA intermediates after the breakdown of nuclear envelope. Nuclear exclusion ensures the protection of replication forks and other DNA secondary structures important for normal metabolic processes. In this chapter, we describe the purification of recombinant GEN1 and detail biochemical assays involving the use of synthetic DNA substrates and cruciform-containing plasmids.
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22
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Phosphate steering by Flap Endonuclease 1 promotes 5'-flap specificity and incision to prevent genome instability. Nat Commun 2017; 8:15855. [PMID: 28653660 PMCID: PMC5490271 DOI: 10.1038/ncomms15855] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 05/05/2017] [Indexed: 12/13/2022] Open
Abstract
DNA replication and repair enzyme Flap Endonuclease 1 (FEN1) is vital for genome integrity, and FEN1 mutations arise in multiple cancers. FEN1 precisely cleaves single-stranded (ss) 5′-flaps one nucleotide into duplex (ds) DNA. Yet, how FEN1 selects for but does not incise the ss 5′-flap was enigmatic. Here we combine crystallographic, biochemical and genetic analyses to show that two dsDNA binding sites set the 5′polarity and to reveal unexpected control of the DNA phosphodiester backbone by electrostatic interactions. Via ‘phosphate steering’, basic residues energetically steer an inverted ss 5′-flap through a gateway over FEN1’s active site and shift dsDNA for catalysis. Mutations of these residues cause an 18,000-fold reduction in catalytic rate in vitro and large-scale trinucleotide (GAA)n repeat expansions in vivo, implying failed phosphate-steering promotes an unanticipated lagging-strand template-switch mechanism during replication. Thus, phosphate steering is an unappreciated FEN1 function that enforces 5′-flap specificity and catalysis, preventing genomic instability. Flap Endonuclease 1 is a DNA replication and repair enzyme indispensable for maintaining genomic stability. Here the authors provide mechanistic details on how FEN1 selects for 5′-flaps and promotes catalysis to avoid large-scale repeat expansion by a process termed ‘phosphate steering’.
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23
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Bellendir SP, Rognstad DJ, Morris LP, Zapotoczny G, Walton WG, Redinbo MR, Ramsden DA, Sekelsky J, Erie DA. Substrate preference of Gen endonucleases highlights the importance of branched structures as DNA damage repair intermediates. Nucleic Acids Res 2017; 45:5333-5348. [PMID: 28369583 PMCID: PMC5435919 DOI: 10.1093/nar/gkx214] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 02/16/2017] [Accepted: 03/21/2017] [Indexed: 11/20/2022] Open
Abstract
Human GEN1 and yeast Yen1 are endonucleases with the ability to cleave Holliday junctions (HJs), which are proposed intermediates in recombination. In vivo, GEN1 and Yen1 function secondarily to Mus81, which has weak activity on intact HJs. We show that the genetic relationship is reversed in Drosophila, with Gen mutants having more severe defects than mus81 mutants. In vitro, DmGen, like HsGEN1, efficiently cleaves HJs, 5΄ flaps, splayed arms, and replication fork structures. We find that the cleavage rates for 5΄ flaps are significantly higher than those for HJs for both DmGen and HsGEN1, even in vast excess of enzyme over substrate. Kinetic studies suggest that the difference in cleavage rates results from a slow, rate-limiting conformational change prior to HJ cleavage: formation of a productive dimer on the HJ. Despite the stark difference in vivo that Drosophila uses Gen over Mus81 and humans use MUS81 over GEN1, we find the in vitro activities of DmGen and HsGEN1 to be strikingly similar. These findings suggest that simpler branched structures may be more important substrates for Gen orthologs in vivo, and highlight the utility of using the Drosophila model system to further understand these enzymes.
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Affiliation(s)
| | | | - Lydia P. Morris
- Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
| | | | | | - Matthew R. Redinbo
- Department of Chemistry, Chapel Hill, NC 27599, USA
- Integrative Program for Biological and Genome Sciences, Chapel Hill, NC 27599, USA
| | - Dale A. Ramsden
- Curriculum in Genetics and Molecular Biology, Chapel Hill, NC 27599, USA
- Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
- Department of Biochemistry and Biophysics, Chapel Hill, NC 27599, USA
| | - Jeff Sekelsky
- Curriculum in Genetics and Molecular Biology, Chapel Hill, NC 27599, USA
- Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
- Integrative Program for Biological and Genome Sciences, Chapel Hill, NC 27599, USA
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Dorothy A. Erie
- Department of Chemistry, Chapel Hill, NC 27599, USA
- Integrative Program for Biological and Genome Sciences, Chapel Hill, NC 27599, USA
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24
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Lilley DMJ. Holliday junction-resolving enzymes-structures and mechanisms. FEBS Lett 2017; 591:1073-1082. [PMID: 27990631 DOI: 10.1002/1873-3468.12529] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Revised: 12/12/2016] [Accepted: 12/13/2016] [Indexed: 12/15/2022]
Abstract
Holliday junction-resolving enzymes are nucleases that are highly specific for the structure of the junction, to which they bind in dimeric form. Two symmetrically disposed cleavages are made. These are not simultaneous, but the second cleavage is accelerated relative to the first, so ensuring that bilateral cleavage occurs during the lifetime of the DNA-protein complex. In eukaryotic cells there are two known junction-resolving activities. GEN1 is similar to enzymes from lower organisms. A crystallographic structure of a fungal GEN1 bound to the product of resolution has been determined. These complexes are dimerized within the crystal lattice such that the strands of the products may be simply reconnected to form a junction. These structures suggest a trajectory for the resolution process.
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Affiliation(s)
- David M J Lilley
- Cancer Research UK Nucleic Acid Structure Research Group, The University of Dundee, UK
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25
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Rashid F, Harris PD, Zaher MS, Sobhy MA, Joudeh LI, Yan C, Piwonski H, Tsutakawa SE, Ivanov I, Tainer JA, Habuchi S, Hamdan SM. Single-molecule FRET unveils induced-fit mechanism for substrate selectivity in flap endonuclease 1. eLife 2017; 6. [PMID: 28230529 PMCID: PMC5358979 DOI: 10.7554/elife.21884] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 02/20/2017] [Indexed: 12/21/2022] Open
Abstract
Human flap endonuclease 1 (FEN1) and related structure-specific 5’nucleases precisely identify and incise aberrant DNA structures during replication, repair and recombination to avoid genomic instability. Yet, it is unclear how the 5’nuclease mechanisms of DNA distortion and protein ordering robustly mediate efficient and accurate substrate recognition and catalytic selectivity. Here, single-molecule sub-millisecond and millisecond analyses of FEN1 reveal a protein-DNA induced-fit mechanism that efficiently verifies substrate and suppresses off-target cleavage. FEN1 sculpts DNA with diffusion-limited kinetics to test DNA substrate. This DNA distortion mutually ‘locks’ protein and DNA conformation and enables substrate verification with extreme precision. Strikingly, FEN1 never misses cleavage of its cognate substrate while blocking probable formation of catalytically competent interactions with noncognate substrates and fostering their pre-incision dissociation. These findings establish FEN1 has practically perfect precision and that separate control of induced-fit substrate recognition sets up the catalytic selectivity of the nuclease active site for genome stability. DOI:http://dx.doi.org/10.7554/eLife.21884.001 When a cell divides it must copy its genetic information, which is found in the form of strands of DNA. Damage to the DNA may lead to cancer or a number of genetic diseases. However, every time a cell divides more than 10 million toxic “flaps” of excess DNA are generated. A protein called flap endonuclease 1 (FEN1) keeps the DNA in good repair by cutting off the flaps in a highly specific and selective manner. Many proteins that interact with DNA are attracted to specific genetic sequences within the DNA strands. However, this is not the case for FEN1 and several other “structure-specific” proteins that help to repair and replicate DNA strands. So how do these proteins select the correct regions of DNA to interact with? Rashid et al. used single-molecule fluorescence measurements to examine how purified FEN1 proteins interact with DNA flaps. The results show that FEN1 can perfectly recognize and correctly remove flaps through a process called “mutual-induced fit”, where the DNA and FEN1 are shaped by each other to produce a highly specific structure. Further work is now needed to examine whether other proteins that are related to FEN1 use a similar process to ensure that they always cut DNA in the same way. More detailed and direct examination of the structure of FEN1 through other experimental methods may also help to reveal how the mutual-induced fit process enables FEN1 to achieve such high levels of precision. This could increase our understanding of how problems with FEN1 and similar proteins lead to different genetic diseases. DOI:http://dx.doi.org/10.7554/eLife.21884.002
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Affiliation(s)
- Fahad Rashid
- Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Paul D Harris
- Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Manal S Zaher
- Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Mohamed A Sobhy
- Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Luay I Joudeh
- Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Chunli Yan
- Department of Chemistry, Georgia State University, Atlanta, United States.,Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, United States
| | - Hubert Piwonski
- Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | | | - Ivaylo Ivanov
- Department of Chemistry, Georgia State University, Atlanta, United States.,Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, United States
| | - John A Tainer
- Lawrence Berkeley National Laboratory, Berkeley, United States.,Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, United States
| | - Satoshi Habuchi
- Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Samir M Hamdan
- Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
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26
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Wang C, Higgins JD, He Y, Lu P, Zhang D, Liang W. Resolvase OsGEN1 Mediates DNA Repair by Homologous Recombination. PLANT PHYSIOLOGY 2017; 173:1316-1329. [PMID: 28049740 PMCID: PMC5291025 DOI: 10.1104/pp.16.01726] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 12/29/2016] [Indexed: 05/18/2023]
Abstract
Yen1/GEN1 are canonical Holliday junction resolvases that belong to the RAD2/XPG family. In eukaryotes, such as budding yeast, mice, worms, and humans, Yen1/GEN1 work together with Mus81-Mms4/MUS81-EME1 and Slx1-Slx4/SLX1-SLX4 in DNA repair by homologous recombination to maintain genome stability. In plants, the biological function of Yen1/GEN1 remains largely unclear. In this study, we characterized the loss of function mutants of OsGEN1 and OsSEND1, a pair of paralogs of Yen1/GEN1 in rice (Oryza sativa). We first investigated the role of OsGEN1 during meiosis and found a reduction in chiasma frequency by ∼6% in osgen1 mutants, compared to the wild type, suggesting a possible involvement of OsGEN1 in the formation of crossovers. Postmeiosis, OsGEN1 foci were detected in wild-type microspore nuclei, but not in the osgen1 mutant concomitant with an increase in double-strand breaks. Persistent double-strand breaks led to programmed cell death of the male gametes and complete male sterility. In contrast, depletion of OsSEND1 had no effects on plant development and did not enhance osgen1 defects. Our results indicate that OsGEN1 is essential for homologous recombinational DNA repair at two stages of microsporogenesis in rice.
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Affiliation(s)
- Chong Wang
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University-University of Adelaide Joint Centre for Agriculture and Health, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 20040, China (C.W., Y.H., D.Z., W.L.)
- Department of Genetics, University of Leicester, Leicester LE1 7RH, United Kingdom (J.D.H.)
- State Key Laboratory of Genetic Engineering and Collaborative Innovation Center of Genetics and Development, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai 200433, China (P.L.); and
- School of Agriculture, Food and Wine, University of Adelaide, Urrbrae, South Australia 5064, Australia (D.Z.)
| | - James D Higgins
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University-University of Adelaide Joint Centre for Agriculture and Health, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 20040, China (C.W., Y.H., D.Z., W.L.)
- Department of Genetics, University of Leicester, Leicester LE1 7RH, United Kingdom (J.D.H.)
- State Key Laboratory of Genetic Engineering and Collaborative Innovation Center of Genetics and Development, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai 200433, China (P.L.); and
- School of Agriculture, Food and Wine, University of Adelaide, Urrbrae, South Australia 5064, Australia (D.Z.)
| | - Yi He
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University-University of Adelaide Joint Centre for Agriculture and Health, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 20040, China (C.W., Y.H., D.Z., W.L.)
- Department of Genetics, University of Leicester, Leicester LE1 7RH, United Kingdom (J.D.H.)
- State Key Laboratory of Genetic Engineering and Collaborative Innovation Center of Genetics and Development, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai 200433, China (P.L.); and
- School of Agriculture, Food and Wine, University of Adelaide, Urrbrae, South Australia 5064, Australia (D.Z.)
| | - Pingli Lu
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University-University of Adelaide Joint Centre for Agriculture and Health, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 20040, China (C.W., Y.H., D.Z., W.L.)
- Department of Genetics, University of Leicester, Leicester LE1 7RH, United Kingdom (J.D.H.)
- State Key Laboratory of Genetic Engineering and Collaborative Innovation Center of Genetics and Development, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai 200433, China (P.L.); and
- School of Agriculture, Food and Wine, University of Adelaide, Urrbrae, South Australia 5064, Australia (D.Z.)
| | - Dabing Zhang
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University-University of Adelaide Joint Centre for Agriculture and Health, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 20040, China (C.W., Y.H., D.Z., W.L.)
- Department of Genetics, University of Leicester, Leicester LE1 7RH, United Kingdom (J.D.H.)
- State Key Laboratory of Genetic Engineering and Collaborative Innovation Center of Genetics and Development, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai 200433, China (P.L.); and
- School of Agriculture, Food and Wine, University of Adelaide, Urrbrae, South Australia 5064, Australia (D.Z.)
| | - Wanqi Liang
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University-University of Adelaide Joint Centre for Agriculture and Health, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 20040, China (C.W., Y.H., D.Z., W.L.);
- Department of Genetics, University of Leicester, Leicester LE1 7RH, United Kingdom (J.D.H.);
- State Key Laboratory of Genetic Engineering and Collaborative Innovation Center of Genetics and Development, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai 200433, China (P.L.); and
- School of Agriculture, Food and Wine, University of Adelaide, Urrbrae, South Australia 5064, Australia (D.Z.)
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27
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Shah Punatar R, Martin MJ, Wyatt HDM, Chan YW, West SC. Resolution of single and double Holliday junction recombination intermediates by GEN1. Proc Natl Acad Sci U S A 2017; 114:443-450. [PMID: 28049850 PMCID: PMC5255610 DOI: 10.1073/pnas.1619790114] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Genetic recombination provides an important mechanism for the repair of DNA double-strand breaks. Homologous pairing and strand exchange lead to the formation of DNA intermediates, in which sister chromatids or homologous chromosomes are covalently linked by four-way Holliday junctions (HJs). Depending on the type of recombination reaction that takes place, intermediates may have single or double HJs, and their resolution is essential for proper chromosome segregation. In mitotic cells, double HJs are primarily dissolved by the BLM helicase-TopoisomeraseIIIα-RMI1-RMI2 (BTR) complex, whereas single HJs (and double HJs that have escaped the attention of BTR) are resolved by structure-selective endonucleases known as HJ resolvases. These enzymes are ubiquitous in nature, because they are present in bacteriophage, bacteria, archaea, and simple and complex eukaryotes. The human HJ resolvase GEN1 is a member of the XPG/Rad2 family of 5'-flap endonucleases. Biochemical studies of GEN1 revealed that it cleaves synthetic DNA substrates containing a single HJ by a mechanism similar to that shown by the prototypic HJ resolvase, Escherichia coli RuvC protein, but it is unclear whether these substrates fully recapitulate the properties of recombination intermediates that arise within a physiological context. Here, we show that GEN1 efficiently cleaves both single and double HJs contained within large recombination intermediates. Moreover, we find that GEN1 exhibits a weak sequence preference for incision between two G residues that reside in a T-rich region of DNA. These results contrast with those obtained with RuvC, which exhibits a strict requirement for the consensus sequence 5'-A/TTTG/C-3'.
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Affiliation(s)
- Rajvee Shah Punatar
- DNA Recombination and Repair Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Maria Jose Martin
- DNA Recombination and Repair Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Haley D M Wyatt
- DNA Recombination and Repair Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Ying Wai Chan
- DNA Recombination and Repair Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Stephen C West
- DNA Recombination and Repair Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom
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28
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Wang X, Wang H, Guo B, Zhang Y, Gong Y, Zhang C, Xu H, Wu X. Gen1 and Eme1 Play Redundant Roles in DNA Repair and Meiotic Recombination in Mice. DNA Cell Biol 2016; 35:585-590. [PMID: 27383418 DOI: 10.1089/dna.2015.3022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Resolution of the Holliday junction (HJ) is essential for homologous recombination and DNA repair. In Saccharomyces cerevisiae, HJ resolvase Yen1 and the Mus81-Mms4 complex are redundant in DNA damage repair. In cultured mammalian cells, such redundancy also exists between Yen1 ortholog GEN1 and the Mus81-Mms1 ortholog MUS81-EME1. In this report, we further tested if GEN1 and EME1 redundantly affect HJ-related physiological processes in mice. We found that combined homozygous mutations of Gen1 and Eme1 led to synthetic lethality during early embryonic stages. Homozygous Gen1 mutations did not cause DNA repair deficiency in mouse embryonic fibroblast (MEF) cells, but made heterozygous Eme1 mutant MEFs more sensitive to various DNA-damaging reagents. Gen1 mutations also reduced the meiotic recombination efficiency in Eme1 mutant mice. These results suggest that Gen1 and Eme1 play redundant roles in DNA repair and meiotic recombination in vivo.
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Affiliation(s)
- Xiaowen Wang
- 1 Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University , Shanghai, China .,2 Department of Nephrology, Wuhan Medical and Healthcare Center for Women and Children , Wuhan, China
| | - Herui Wang
- 3 State Key Laboratory of Genetic Engineering and National Center for International Research of Development and Disease, Institute of Developmental Biology and Molecular Medicine, Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Fudan University , Shanghai, China .,4 Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health , Bethesda, Maryland
| | - Bin Guo
- 3 State Key Laboratory of Genetic Engineering and National Center for International Research of Development and Disease, Institute of Developmental Biology and Molecular Medicine, Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Fudan University , Shanghai, China
| | - Ya Zhang
- 1 Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University , Shanghai, China
| | - Yinv Gong
- 1 Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University , Shanghai, China
| | - Chi Zhang
- 3 State Key Laboratory of Genetic Engineering and National Center for International Research of Development and Disease, Institute of Developmental Biology and Molecular Medicine, Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Fudan University , Shanghai, China .,5 Department of Molecular, Cellular, and Developmental Biology, University of Colorado , Boulder, Colorado
| | - Hong Xu
- 1 Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University , Shanghai, China
| | - Xiaohui Wu
- 1 Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Children's Hospital of Fudan University , Shanghai, China .,3 State Key Laboratory of Genetic Engineering and National Center for International Research of Development and Disease, Institute of Developmental Biology and Molecular Medicine, Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Fudan University , Shanghai, China
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