1
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Mao EYC, Yen HY, Wu CC. Structural basis of how MGME1 processes DNA 5' ends to maintain mitochondrial genome integrity. Nucleic Acids Res 2024; 52:4067-4078. [PMID: 38471810 DOI: 10.1093/nar/gkae186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 02/29/2024] [Accepted: 03/05/2024] [Indexed: 03/14/2024] Open
Abstract
Mitochondrial genome maintenance exonuclease 1 (MGME1) helps to ensure mitochondrial DNA (mtDNA) integrity by serving as an ancillary 5'-exonuclease for DNA polymerase γ. Curiously, MGME1 exhibits unique bidirectionality in vitro, being capable of degrading DNA from either the 5' or 3' end. The structural basis of this bidirectionally and, particularly, how it processes DNA from the 5' end to assist in mtDNA maintenance remain unclear. Here, we present a crystal structure of human MGME1 in complex with a 5'-overhang DNA, revealing that MGME1 functions as a rigid DNA clamp equipped with a single-strand (ss)-selective arch, allowing it to slide on single-stranded DNA in either the 5'-to-3' or 3'-to-5' direction. Using a nuclease activity assay, we have dissected the structural basis of MGME1-derived DNA cleavage patterns in which the arch serves as a ruler to determine the cleavage site. We also reveal that MGME1 displays partial DNA-unwinding ability that helps it to better resolve 5'-DNA flaps, providing insights into MGME1-mediated 5'-end processing of nascent mtDNA. Our study builds on previously solved MGME1-DNA complex structures, finally providing the comprehensive functional mechanism of this bidirectional, ss-specific exonuclease.
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Affiliation(s)
- Eric Y C Mao
- Department of Chemistry, College of Science, National Cheng Kung University, Tainan City 701, Taiwan
| | - Han-Yi Yen
- Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, Tainan City 701, Taiwan
| | - Chyuan-Chuan Wu
- Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, Tainan City 701, Taiwan
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2
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Czarny P, Ziółkowska S, Kołodziej Ł, Watała C, Wigner-Jeziorska P, Bliźniewska-Kowalska K, Wachowska K, Gałecka M, Synowiec E, Gałecki P, Bijak M, Szemraj J, Śliwiński T. Single-Nucleotide Polymorphisms in Genes Maintaining the Stability of Mitochondrial DNA Affect the Occurrence, Onset, Severity and Treatment of Major Depressive Disorder. Int J Mol Sci 2023; 24:14752. [PMID: 37834200 PMCID: PMC10573273 DOI: 10.3390/ijms241914752] [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: 09/02/2023] [Revised: 09/26/2023] [Accepted: 09/27/2023] [Indexed: 10/15/2023] Open
Abstract
One of the key features of major depressive disorder (MDD, depression) is increased oxidative stress manifested by elevated levels of mtROS, a hallmark of mitochondrial dysfunction, which can arise from mitochondrial DNA (mtDNA) damage. Thus, the current study explores possibility that the single-nucleotide polymorphisms (SNPs) of genes encoding the three enzymes that are thought to be implicated in the replication, repair or degradation of mtDNA, i.e., POLG, ENDOG and EXOG, have an impact on the occurrence, onset, severity and treatment of MDD. Five SNPs were selected: EXOG c.-188T > G (rs9838614), EXOG c.*627G > A (rs1065800), POLG c.-1370T > A (rs1054875), ENDOG c.-394T > C (rs2977998) and ENDOG c.-220C > T (rs2997922), while genotyping was performed on 538 DNA samples (277 cases and 261 controls) using TaqMan probes. All SNPs of EXOG and ENDOG modulated the risk of depression, but the strongest effect was observed for rs1065800, while rs9838614 and rs2977998 indicate that they might influence the severity of symptoms, and, to a lesser extent, treatment effectiveness. Although the SNP located in POLG did not affect occurrence of the disease, the result suggests that it may influence the onset and treatment outcome. These findings further support the hypothesis that mtDNA damage and impairment in its metabolism play a crucial role not only in the development, but also in the treatment of depression.
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Affiliation(s)
- Piotr Czarny
- Department of Medical Biochemistry, Medical University of Lodz, 92-215 Lodz, Poland; (S.Z.); (J.S.)
| | - Sylwia Ziółkowska
- Department of Medical Biochemistry, Medical University of Lodz, 92-215 Lodz, Poland; (S.Z.); (J.S.)
| | - Łukasz Kołodziej
- Laboratory of Medical Genetics, Faculty of Biology and Environmental Protection, University of Lodz, 92-215 Lodz, Poland; (Ł.K.)
| | - Cezary Watała
- Department of Haemostatic Disorders, Medical University of Lodz, 92-215 Lodz, Poland;
| | - Paulina Wigner-Jeziorska
- Department of General Biochemistry, Faculty of Biology and Environmental Protection, University of Lodz, 90-136 Lodz, Poland;
| | | | - Katarzyna Wachowska
- Department of Adult Psychiatry, Medical University of Lodz, 91-229 Lodz, Poland; (K.B.-K.); (K.W.); (P.G.)
| | - Małgorzata Gałecka
- Department of Psychotherapy, Medical University of Lodz, 91-229 Lodz, Poland;
| | - Ewelina Synowiec
- Laboratory of Medical Genetics, Faculty of Biology and Environmental Protection, University of Lodz, 92-215 Lodz, Poland; (Ł.K.)
| | - Piotr Gałecki
- Department of Adult Psychiatry, Medical University of Lodz, 91-229 Lodz, Poland; (K.B.-K.); (K.W.); (P.G.)
| | - Michał Bijak
- Biohazard Prevention Centre, Faculty of Biology and Environmental Protection, University of Lodz, 90-136 Lodz, Poland;
| | - Janusz Szemraj
- Department of Medical Biochemistry, Medical University of Lodz, 92-215 Lodz, Poland; (S.Z.); (J.S.)
| | - Tomasz Śliwiński
- Laboratory of Medical Genetics, Faculty of Biology and Environmental Protection, University of Lodz, 92-215 Lodz, Poland; (Ł.K.)
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3
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Park J, Baruch-Torres N, Yin YW. Structural and Molecular Basis for Mitochondrial DNA Replication and Transcription in Health and Antiviral Drug Toxicity. Molecules 2023; 28:1796. [PMID: 36838782 PMCID: PMC9961925 DOI: 10.3390/molecules28041796] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 02/06/2023] [Accepted: 02/09/2023] [Indexed: 02/17/2023] Open
Abstract
Human mitochondrial DNA (mtDNA) is a 16.9 kbp double-stranded, circular DNA, encoding subunits of the oxidative phosphorylation electron transfer chain and essential RNAs for mitochondrial protein translation. The minimal human mtDNA replisome is composed of the DNA helicase Twinkle, DNA polymerase γ, and mitochondrial single-stranded DNA-binding protein. While the mitochondrial RNA transcription is carried out by mitochondrial RNA polymerase, mitochondrial transcription factors TFAM and TFB2M, and a transcription elongation factor, TEFM, both RNA transcriptions, and DNA replication machineries are intertwined and control mtDNA copy numbers, cellular energy supplies, and cellular metabolism. In this review, we discuss the mechanisms governing these main pathways and the mtDNA diseases that arise from mutations in transcription and replication machineries from a structural point of view. We also address the adverse effect of antiviral drugs mediated by mitochondrial DNA and RNA polymerases as well as possible structural approaches to develop nucleoside reverse transcriptase inhibitor and ribonucleosides analogs with reduced toxicity.
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Affiliation(s)
- Joon Park
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Noe Baruch-Torres
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Y. Whitney Yin
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
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4
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Mitochondrial DNA Repair in Neurodegenerative Diseases and Ageing. Int J Mol Sci 2022; 23:ijms231911391. [PMID: 36232693 PMCID: PMC9569545 DOI: 10.3390/ijms231911391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 09/20/2022] [Accepted: 09/21/2022] [Indexed: 11/17/2022] Open
Abstract
Mitochondria are the only organelles, along with the nucleus, that have their own DNA. Mitochondrial DNA (mtDNA) is a double-stranded circular molecule of ~16.5 kbp that can exist in multiple copies within the organelle. Both strands are translated and encode for 22 tRNAs, 2 rRNAs, and 13 proteins. mtDNA molecules are anchored to the inner mitochondrial membrane and, in association with proteins, form a structure called nucleoid, which exerts a structural and protective function. Indeed, mitochondria have evolved mechanisms necessary to protect their DNA from chemical and physical lesions such as DNA repair pathways similar to those present in the nucleus. However, there are mitochondria-specific mechanisms such as rapid mtDNA turnover, fission, fusion, and mitophagy. Nevertheless, mtDNA mutations may be abundant in somatic tissue due mainly to the proximity of the mtDNA to the oxidative phosphorylation (OXPHOS) system and, consequently, to the reactive oxygen species (ROS) formed during ATP production. In this review, we summarise the most common types of mtDNA lesions and mitochondria repair mechanisms. The second part of the review focuses on the physiological role of mtDNA damage in ageing and the effect of mtDNA mutations in neurodegenerative disorders such as Alzheimer’s and Parkinson’s disease. Considering the central role of mitochondria in maintaining cellular homeostasis, the analysis of mitochondrial function is a central point for developing personalised medicine.
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5
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Karlowicz A, Dubiel AB, Czerwinska J, Bledea A, Purzycki P, Grzelewska M, McAuley RJ, Szczesny RJ, Brzuska G, Krol E, Szczesny B, Szymanski MR. In vitro reconstitution reveals a key role of human mitochondrial EXOG in RNA primer processing. Nucleic Acids Res 2022; 50:7991-8007. [PMID: 35819194 PMCID: PMC9371904 DOI: 10.1093/nar/gkac581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 06/01/2022] [Accepted: 06/24/2022] [Indexed: 11/12/2022] Open
Abstract
The removal of RNA primers is essential for mitochondrial DNA (mtDNA) replication. Several nucleases have been implicated in RNA primer removal in human mitochondria, however, no conclusive mechanism has been elucidated. Here, we reconstituted minimal in vitro system capable of processing RNA primers into ligatable DNA ends. We show that human 5'-3' exonuclease, EXOG, plays a fundamental role in removal of the RNA primer. EXOG cleaves short and long RNA-containing flaps but also in cooperation with RNase H1, processes non-flap RNA-containing intermediates. Our data indicate that the enzymatic activity of both enzymes is necessary to process non-flap RNA-containing intermediates and that regardless of the pathway, EXOG-mediated RNA cleavage is necessary prior to ligation by DNA Ligase III. We also show that upregulation of EXOG levels in mitochondria increases ligation efficiency of RNA-containing substrates and discover physical interactions, both in vitro and in cellulo, between RNase H1 and EXOG, Pol γA, Pol γB and Lig III but not FEN1, which we demonstrate to be absent from mitochondria of human lung epithelial cells. Together, using human mtDNA replication enzymes, we reconstitute for the first time RNA primer removal reaction and propose a novel model for RNA primer processing in human mitochondria.
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Affiliation(s)
- Anna Karlowicz
- Structural Biology Laboratory, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, ul. Abrahama 58, 80-307 Gdansk, Poland
| | - Andrzej B Dubiel
- Structural Biology Laboratory, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, ul. Abrahama 58, 80-307 Gdansk, Poland
| | - Jolanta Czerwinska
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, ul. Pawinskiego 5A, 02-106 Warsaw, Poland.,Faculty of Biology, Institute of Genetics and Biotechnology, University of Warsaw, Warsaw 02-106, Poland
| | - Adela Bledea
- Structural Biology Laboratory, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, ul. Abrahama 58, 80-307 Gdansk, Poland
| | - Piotr Purzycki
- Structural Biology Laboratory, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, ul. Abrahama 58, 80-307 Gdansk, Poland
| | - Marta Grzelewska
- Structural Biology Laboratory, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, ul. Abrahama 58, 80-307 Gdansk, Poland
| | - Ryan J McAuley
- Department of Ophthalmology and Visual Sciences, The University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA
| | - Roman J Szczesny
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, ul. Pawinskiego 5A, 02-106 Warsaw, Poland
| | - Gabriela Brzuska
- Laboratory of Recombinant Vaccines, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, ul. Abrahama 58, 80-307 Gdansk, Poland
| | - Ewelina Krol
- Laboratory of Recombinant Vaccines, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, ul. Abrahama 58, 80-307 Gdansk, Poland
| | - Bartosz Szczesny
- Department of Ophthalmology and Visual Sciences, The University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA
| | - Michal R Szymanski
- Structural Biology Laboratory, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, ul. Abrahama 58, 80-307 Gdansk, Poland
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6
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Manils J, Marruecos L, Soler C. Exonucleases: Degrading DNA to Deal with Genome Damage, Cell Death, Inflammation and Cancer. Cells 2022; 11:cells11142157. [PMID: 35883600 PMCID: PMC9316158 DOI: 10.3390/cells11142157] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 06/30/2022] [Accepted: 07/07/2022] [Indexed: 01/27/2023] Open
Abstract
Although DNA degradation might seem an unwanted event, it is essential in many cellular processes that are key to maintaining genomic stability and cell and organism homeostasis. The capacity to cut out nucleotides one at a time from the end of a DNA chain is present in enzymes called exonucleases. Exonuclease activity might come from enzymes with multiple other functions or specialized enzymes only dedicated to this function. Exonucleases are involved in central pathways of cell biology such as DNA replication, repair, and death, as well as tuning the immune response. Of note, malfunctioning of these enzymes is associated with immune disorders and cancer. In this review, we will dissect the impact of DNA degradation on the DNA damage response and its links with inflammation and cancer.
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Affiliation(s)
- Joan Manils
- Serra Húnter Programme, Immunology Unit, Department of Pathology and Experimental Therapy, School of Medicine, Universitat de Barcelona, Feixa Llarga s/n, 08907 L’Hospitalet de Llobregat, Spain;
- Immunity, Inflammation and Cancer Group, Oncobell Program, Institut d’Investigació Biomèdica de Bellvitge—IDIBELL, 08907 L’Hospitalet de Llobregat, Spain
| | - Laura Marruecos
- Breast Cancer Laboratory, Cancer Biology and Stem Cells Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia;
| | - Concepció Soler
- Immunity, Inflammation and Cancer Group, Oncobell Program, Institut d’Investigació Biomèdica de Bellvitge—IDIBELL, 08907 L’Hospitalet de Llobregat, Spain
- Immunology Unit, Department of Pathology and Experimental Therapy, School of Medicine, Universitat de Barcelona, 08007 Barcelona, Spain
- Correspondence:
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7
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Abstract
R-loops forming inadvertently during transcription can threaten genome stability, but R-loops are also formed intentionally, as a means of regulating transcription and other aspects of DNA metabolism. The study of R-loops in mitochondria is in its infancy, and yet there is already clear evidence that they are predominantly located in the major regulatory region of the mammalian mitochondrial genome. Here, we describe how mitochondrial R-loops have been characterized to date, with the emphasis on the problems of their being extremely labile, and how to minimize their loss during extraction. The oft-overlooked issues of RNA-DNA hybrids not being synonymous with R-loops, and adventitious RNA hybridization to DNA, are tackled head on; and possible new approaches are described and placed in the context of future research lines that could reveal the detailed roles of R-loops in the metabolism of mitochondrial DNA.
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Affiliation(s)
- Ian J Holt
- Biodonostia Health Research Institute, San Sebastián, Spain.
- CIBERNED (Center for Networked Biomedical Research on Neurodegenerative Diseases, Ministry of Economy and Competitiveness, Institute Carlos III), Madrid, Spain.
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
- Universidad de País Vasco, Bilbao, Spain.
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8
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Sullivan ED, Longley MJ, Copeland WC. Polymerase γ efficiently replicates through many natural template barriers but stalls at the HSP1 quadruplex. J Biol Chem 2021; 295:17802-17815. [PMID: 33454015 DOI: 10.1074/jbc.ra120.015390] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 10/05/2020] [Indexed: 12/27/2022] Open
Abstract
Faithful replication of the mitochondrial genome is carried out by a set of key nuclear-encoded proteins. DNA polymerase γ is a core component of the mtDNA replisome and the only replicative DNA polymerase localized to mitochondria. The asynchronous mechanism of mtDNA replication predicts that the replication machinery encounters dsDNA and unique physical barriers such as structured genes, G-quadruplexes, and other obstacles. In vitro experiments here provide evidence that the polymerase γ heterotrimer is well-adapted to efficiently synthesize DNA, despite the presence of many naturally occurring roadblocks. However, we identified a specific G-quadruplex-forming sequence at the heavy-strand promoter (HSP1) that has the potential to cause significant stalling of mtDNA replication. Furthermore, this structured region of DNA corresponds to the break site for a large (3,895 bp) deletion observed in mitochondrial disease patients. The presence of this deletion in humans correlates with UV exposure, and we have found that efficiency of polymerase γ DNA synthesis is reduced after this quadruplex is exposed to UV in vitro.
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Affiliation(s)
- Eric D Sullivan
- Mitochondrial DNA Replication Group, Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - Matthew J Longley
- Mitochondrial DNA Replication Group, Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - William C Copeland
- Mitochondrial DNA Replication Group, Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina, USA.
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9
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Wu CC, Lin JL, Yuan HS. Structures, Mechanisms, and Functions of His-Me Finger Nucleases. Trends Biochem Sci 2020; 45:935-946. [DOI: 10.1016/j.tibs.2020.07.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 06/30/2020] [Accepted: 07/15/2020] [Indexed: 02/06/2023]
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10
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Falkenberg M, Gustafsson CM. Mammalian mitochondrial DNA replication and mechanisms of deletion formation. Crit Rev Biochem Mol Biol 2020; 55:509-524. [DOI: 10.1080/10409238.2020.1818684] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Claes M. Gustafsson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
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11
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Park KH, Yoon SM, Song HN, Yang JH, Ryu SE, Woo EJ. Crystal structure of the mouse endonuclease G. Biochem Biophys Res Commun 2020; 526:35-40. [PMID: 32192768 DOI: 10.1016/j.bbrc.2020.03.060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 03/10/2020] [Indexed: 10/24/2022]
Abstract
Endonuclease G (EndoG) is a mitochondrial enzyme that responds to apoptotic stimuli by translocating to the nucleus and cleaving the chromatin DNA. The molecular mechanism of EndoG still remains unknown in higher organisms. Here, we determined the crystal structure of mouse EndoG at ∼1.96 Å resolution. The EndoG shows an altered dimeric configuration in which N-terminal region of one subunit interact to the other subunit in dimer. The deletion of this region that is highly conserved in mammalian EndoGs resulted in a monomer with significantly reduced activity suggesting the association of the dimeric arrangement into the nuclease activity. Furthermore, we observed a large conformational change in the loop of the active site groove in EndoG, which corresponds to the DNA binding region. Intriguingly, EndoG dimers are linked by oxidation of the reactive cysteine 110 in this flexible loop to form a long oligomeric chain in the crystal lattice. The structural analysis and ensuing biochemical data suggest that this flexible loop region in the active site is important to the regulation of EndoG nuclease function in mouse.
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Affiliation(s)
- Kwang-Hyun Park
- Disease Target Structure Research Center, Korea Research Institute of Bioscience & Biotechnology (KRIBB), Daejeon, 305-806, Republic of Korea
| | - Sei Mee Yoon
- Disease Target Structure Research Center, Korea Research Institute of Bioscience & Biotechnology (KRIBB), Daejeon, 305-806, Republic of Korea
| | - Hyung Nam Song
- Disease Target Structure Research Center, Korea Research Institute of Bioscience & Biotechnology (KRIBB), Daejeon, 305-806, Republic of Korea
| | - Joon-Hyuck Yang
- Disease Target Structure Research Center, Korea Research Institute of Bioscience & Biotechnology (KRIBB), Daejeon, 305-806, Republic of Korea; Department of Health Informatics and Management, College of Medicine, Chungbuk National University, Cheongju, Republic of Korea
| | - Seong Eon Ryu
- Department of Bioengineering, College of Engineering, Hanyang University, Seoul, 04673, Republic of Korea.
| | - Eui-Jeon Woo
- Disease Target Structure Research Center, Korea Research Institute of Bioscience & Biotechnology (KRIBB), Daejeon, 305-806, Republic of Korea; Department of Proteome Structural Biology, KRIBB School of Bioscience, University of Science and Technology (UST), Daejeon, 305-333, Republic of Korea.
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12
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Donati E, Genna V, De Vivo M. Recruiting Mechanism and Functional Role of a Third Metal Ion in the Enzymatic Activity of 5' Structure-Specific Nucleases. J Am Chem Soc 2020; 142:2823-2834. [PMID: 31939291 PMCID: PMC7993637 DOI: 10.1021/jacs.9b10656] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
![]()
Enzymes of the 5′ structure-specific
nuclease family are crucial for DNA repair, replication, and recombination.
One such enzyme is the human exonuclease 1 (hExo1) metalloenzyme,
which cleaves DNA strands, acting primarily as a processive 5′-3′
exonuclease and secondarily as a 5′-flap endonuclease. Recently,
in crystallo reaction intermediates have elucidated how hExo1 exerts
hydrolysis of DNA phosphodiester bonds. These hExo1 structures show
a third metal ion intermittently bound close to the two-metal-ion
active site, to which recessed ends or 5′-flap substrates bind.
Evidence of this third ion has been observed in several nucleic-acid-processing
metalloenzymes. However, there is still debate over what triggers
the (un)binding of this transient third ion during catalysis and whether
this ion has a catalytic function. Using extended molecular dynamics
and enhanced sampling free-energy simulations, we observed that the
carboxyl side chain of Glu89 (located along the arch motif in hExo1)
flips frequently from the reactant state to the product state. The
conformational flipping of Glu89 allows one metal ion to be recruited
from the bulk and promptly positioned near the catalytic center. This
is in line with the structural evidence. Additionally, our simulations
show that the third metal ion assists the departure, through the mobile
arch, of the nucleotide monophosphate product from the catalytic site.
Structural comparisons of nuclease enzymes suggest that this Glu(Asp)-mediated
mechanism for third ion recruitment and nucleic acid hydrolysis may
be shared by other 5′ structure-specific nucleases.
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Affiliation(s)
- Elisa Donati
- Laboratory of Molecular Modelling & Drug Discovery , Istituto Italiano di Tecnologia , Via Morego 30 , 16163 Genoa , Italy
| | - Vito Genna
- Laboratory of Molecular Modelling & Drug Discovery , Istituto Italiano di Tecnologia , Via Morego 30 , 16163 Genoa , Italy
| | - Marco De Vivo
- Laboratory of Molecular Modelling & Drug Discovery , Istituto Italiano di Tecnologia , Via Morego 30 , 16163 Genoa , Italy
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13
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Brieba LG. Structure-Function Analysis Reveals the Singularity of Plant Mitochondrial DNA Replication Components: A Mosaic and Redundant System. PLANTS 2019; 8:plants8120533. [PMID: 31766564 PMCID: PMC6963530 DOI: 10.3390/plants8120533] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 11/18/2019] [Accepted: 11/19/2019] [Indexed: 02/06/2023]
Abstract
Plants are sessile organisms, and their DNA is particularly exposed to damaging agents. The integrity of plant mitochondrial and plastid genomes is necessary for cell survival. During evolution, plants have evolved mechanisms to replicate their mitochondrial genomes while minimizing the effects of DNA damaging agents. The recombinogenic character of plant mitochondrial DNA, absence of defined origins of replication, and its linear structure suggest that mitochondrial DNA replication is achieved by a recombination-dependent replication mechanism. Here, I review the mitochondrial proteins possibly involved in mitochondrial DNA replication from a structural point of view. A revision of these proteins supports the idea that mitochondrial DNA replication could be replicated by several processes. The analysis indicates that DNA replication in plant mitochondria could be achieved by a recombination-dependent replication mechanism, but also by a replisome in which primers are synthesized by three different enzymes: Mitochondrial RNA polymerase, Primase-Helicase, and Primase-Polymerase. The recombination-dependent replication model and primers synthesized by the Primase-Polymerase may be responsible for the presence of genomic rearrangements in plant mitochondria.
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Affiliation(s)
- Luis Gabriel Brieba
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato, Guanajuato C.P. 36821, Mexico
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14
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Nicholls TJ, Spåhr H, Jiang S, Siira SJ, Koolmeister C, Sharma S, Kauppila JHK, Jiang M, Kaever V, Rackham O, Chabes A, Falkenberg M, Filipovska A, Larsson NG, Gustafsson CM. Dinucleotide Degradation by REXO2 Maintains Promoter Specificity in Mammalian Mitochondria. Mol Cell 2019; 76:784-796.e6. [PMID: 31588022 PMCID: PMC6900737 DOI: 10.1016/j.molcel.2019.09.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 07/12/2019] [Accepted: 09/04/2019] [Indexed: 12/12/2022]
Abstract
Oligoribonucleases are conserved enzymes that degrade short RNA molecules of up to 5 nt in length and are assumed to constitute the final stage of RNA turnover. Here we demonstrate that REXO2 is a specialized dinucleotide-degrading enzyme that shows no preference between RNA and DNA dinucleotide substrates. A heart- and skeletal-muscle-specific knockout mouse displays elevated dinucleotide levels and alterations in gene expression patterns indicative of aberrant dinucleotide-primed transcription initiation. We find that dinucleotides act as potent stimulators of mitochondrial transcription initiation in vitro. Our data demonstrate that increased levels of dinucleotides can be used to initiate transcription, leading to an increase in transcription levels from both mitochondrial promoters and other, nonspecific sequence elements in mitochondrial DNA. Efficient RNA turnover by REXO2 is thus required to maintain promoter specificity and proper regulation of transcription in mammalian mitochondria.
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Affiliation(s)
- Thomas J Nicholls
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, Gothenburg 405 30, Sweden
| | - Henrik Spåhr
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany; Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm 17177, Sweden; Max Planck Institute for Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm 17177, Sweden
| | - Shan Jiang
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm 17177, Sweden; Max Planck Institute for Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm 17177, Sweden
| | - Stefan J Siira
- Harry Perkins Institute of Medical Research, Nedlands, WA 6009, Australia; Centre for Medical Research, The University of Western Australia, Nedlands, WA 6009, Australia
| | - Camilla Koolmeister
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm 17177, Sweden; Max Planck Institute for Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm 17177, Sweden
| | - Sushma Sharma
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå 901 87, Sweden
| | - Johanna H K Kauppila
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Min Jiang
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Volkhard Kaever
- Research Core Unit Metabolomics, Hannover Medical School, 30625 Hannover, Germany
| | - Oliver Rackham
- Harry Perkins Institute of Medical Research, Nedlands, WA 6009, Australia; School of Pharmacy and Biomedical Sciences, Curtin University, Bentley, WA 6102, Australia; Curtin Health Innovation Research Institute, Curtin University, Bentley, WA 6102, Australia
| | - Andrei Chabes
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå 901 87, Sweden
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, Gothenburg 405 30, Sweden
| | - Aleksandra Filipovska
- Harry Perkins Institute of Medical Research, Nedlands, WA 6009, Australia; School of Molecular Sciences, The University of Western Australia, Nedlands, WA, Australia
| | - Nils-Göran Larsson
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm 17177, Sweden; Max Planck Institute for Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm 17177, Sweden.
| | - Claes M Gustafsson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, Gothenburg 405 30, Sweden.
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15
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Holt IJ. The Jekyll and Hyde character of RNase H1 and its multiple roles in mitochondrial DNA metabolism. DNA Repair (Amst) 2019; 84:102630. [PMID: 31178343 DOI: 10.1016/j.dnarep.2019.06.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 06/03/2019] [Accepted: 06/03/2019] [Indexed: 02/06/2023]
Abstract
The activity and specificity of ribonuclease H1, RNase H1, has been known for over half a century; like all enzymes in its class, it degrades RNA only when it is hybridized to DNA. However, the essential role of RNase H1 in mitochondrial DNA maintenance was not recognized until 2003, and empirical evidence that it is required to process RNA primers of mitochondrial DNA had to wait until 2015. In the same year, mutations in the RNASEH1 gene were linked to human mitochondrial diseases. The most recent studies suggest that in addition to primer-processing, RNase H1 determines the fate of R-loops, although not primarily those that might present an obstacle to DNA replication, but ones that contribute to the organization of mitochondrial DNA and the unusual mechanism of replication in mitochondria that utilizes transcripts for the strand-asynchronous mechanism of mitochondrial DNA replication. A full understanding of the role of RNase H1 in mtDNA metabolism will depend on further study, including careful consideration of its ability to stabilize, as well as to degrade RNA/DNA hybrids, and its regulation by oxidation or other mechanisms. Nevertheless, RNase H1 is already staking a strong claim to be the most versatile factor involved in propagating the DNA in the mitochondria.
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Affiliation(s)
- Ian J Holt
- Biodonostia Health Research Institute, 20014 San Sebastián, Spain; IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain; Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Royal Free Campus, London, NW3 2PF, UK; CIBERNED (Center for Networked Biomedical Research on Neurodegenerative Diseases, Ministry of Economy and Competitiveness, Institute Carlos III), Madrid, Spain.
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