1
|
Singh A, Patel G, Patel SS. Twinkle-Catalyzed Toehold-Mediated DNA Strand Displacement Reaction. J Am Chem Soc 2023:10.1021/jacs.3c04970. [PMID: 37917930 PMCID: PMC11063129 DOI: 10.1021/jacs.3c04970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2023]
Abstract
Strand exchange between homologous nucleic acid sequences is the basis for cellular DNA repair, recombination, and genome editing technologies. Specialized enzymes catalyze cellular strand exchange; however, the reaction occurs spontaneously when a single-stranded DNA toehold can dock the invader strand on the target DNA to initiate strand exchange through branch migration. Due to its precise response, the spontaneous toehold-mediated strand displacement (TMSD) reaction is widely employed in DNA nanotechnology. However, enzyme-free TMSD suffers from slow rates, resulting in slow response times. Here, we show that human mitochondrial DNA helicase Twinkle can accelerate TMSD up to 6000-fold. Mechanistic studies indicate that Twinkle accelerates TMSD by catalyzing the docking step, which typically limits spontaneous reactions. The catalysis occurs without ATP, and Twinkle-catalyzed TMSD rates remain sensitive to base-pair mismatches. The simple catalysis, tunability, and speed improvement of the catalyzed TMSD can be leveraged in nanotechnology, requiring sensitive detection and faster response times.
Collapse
Affiliation(s)
- Anupam Singh
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey, USA
| | - Gayatri Patel
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey, USA
| | - Smita S. Patel
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey, USA
| |
Collapse
|
2
|
Uhler JP, Alexandersson U, Falkenberg M. In Vitro Assays of TWINKLE Function. Methods Mol Biol 2023; 2615:191-201. [PMID: 36807793 DOI: 10.1007/978-1-0716-2922-2_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
TWINKLE is an essential helicase that unwinds the duplex mitochondrial genome during DNA replication. In vitro assays using purified recombinant forms of the protein have been an instrumental tool for gaining mechanistic insights about TWINKLE and its function at the replication fork. Here we present methods to probe the helicase and ATPase activities of TWINKLE. For the helicase assay, TWINKLE is incubated with a radiolabeled oligonucleotide annealed to an M13mp18 single-stranded DNA template. TWINKLE will displace the oligonucleotide, which is then visualized by gel electrophoresis and autoradiography. To measure the ATPase activity of TWINKLE, a colorimetric assay is used, which quantifies the release of phosphate upon ATP hydrolysis by TWINKLE.
Collapse
Affiliation(s)
- Jay P Uhler
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Ulrika Alexandersson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden.
| |
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
The N-terminal domain of human mitochondrial helicase Twinkle has DNA-binding activity crucial for supporting processive DNA synthesis by polymerase γ. J Biol Chem 2022; 299:102797. [PMID: 36528058 PMCID: PMC9860392 DOI: 10.1016/j.jbc.2022.102797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/30/2022] [Accepted: 12/03/2022] [Indexed: 12/15/2022] Open
Abstract
Twinkle is the ring-shaped replicative helicase within the human mitochondria with high homology to bacteriophage T7 gp4 helicase-primase. Unlike many orthologs of Twinkle, the N-terminal domain (NTD) of human Twinkle has lost its primase activity through evolutionarily acquired mutations. The NTD has no demonstrated activity thus far; its role has remained unclear. Here, we biochemically characterize the isolated NTD and C-terminal domain (CTD) with linker to decipher their contributions to full-length Twinkle activities. This novel CTD construct hydrolyzes ATP, has weak DNA unwinding activity, and assists DNA polymerase γ (Polγ)-catalyzed strand-displacement synthesis on short replication forks. However, CTD fails to promote multikilobase length product formation by Polγ in rolling-circle DNA synthesis. Thus, CTD retains all the motor functions but struggles to implement them for processive translocation. We show that NTD has DNA-binding activity, and its presence stabilizes Twinkle oligomerization. CTD oligomerizes on its own, but the loss of NTD results in heterogeneously sized oligomeric species. The CTD also exhibits weaker and salt-sensitive DNA binding compared with full-length Twinkle. Based on these results, we propose that NTD directly contributes to DNA binding and holds the DNA in place behind the central channel of the CTD like a "doorstop," preventing helicase slippages and sustaining processive unwinding. Consistent with this model, mitochondrial single-stranded DNA-binding protein (mtSSB) compensate for the NTD loss and partially restore kilobase length DNA synthesis by CTD and Polγ. The implications of our studies are foundational for understanding the mechanisms of disease-causing Twinkle mutants that lie in the NTD.
Collapse
|
5
|
Wang L, Yang Z, He X, Pu S, Yang C, Wu Q, Zhou Z, Cen X, Zhao H. Mitochondrial protein dysfunction in pathogenesis of neurological diseases. Front Mol Neurosci 2022; 15:974480. [PMID: 36157077 PMCID: PMC9489860 DOI: 10.3389/fnmol.2022.974480] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 08/08/2022] [Indexed: 11/21/2022] Open
Abstract
Mitochondria are essential organelles for neuronal function and cell survival. Besides the well-known bioenergetics, additional mitochondrial roles in calcium signaling, lipid biogenesis, regulation of reactive oxygen species, and apoptosis are pivotal in diverse cellular processes. The mitochondrial proteome encompasses about 1,500 proteins encoded by both the nuclear DNA and the maternally inherited mitochondrial DNA. Mutations in the nuclear or mitochondrial genome, or combinations of both, can result in mitochondrial protein deficiencies and mitochondrial malfunction. Therefore, mitochondrial quality control by proteins involved in various surveillance mechanisms is critical for neuronal integrity and viability. Abnormal proteins involved in mitochondrial bioenergetics, dynamics, mitophagy, import machinery, ion channels, and mitochondrial DNA maintenance have been linked to the pathogenesis of a number of neurological diseases. The goal of this review is to give an overview of these pathways and to summarize the interconnections between mitochondrial protein dysfunction and neurological diseases.
Collapse
Affiliation(s)
- Liang Wang
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu, China
| | - Ziyun Yang
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu, China
- School of Life Sciences, Guangxi Normal University, Guilin, China
- Guangxi Universities, Key Laboratory of Stem Cell and Biopharmaceutical Technology, Guangxi Normal University, Guilin, China
- Research Center for Biomedical Sciences, Guangxi Normal University, Guilin, China
| | - Xiumei He
- School of Life Sciences, Guangxi Normal University, Guilin, China
- Guangxi Universities, Key Laboratory of Stem Cell and Biopharmaceutical Technology, Guangxi Normal University, Guilin, China
- Research Center for Biomedical Sciences, Guangxi Normal University, Guilin, China
| | - Shiming Pu
- School of Life Sciences, Guangxi Normal University, Guilin, China
- Guangxi Universities, Key Laboratory of Stem Cell and Biopharmaceutical Technology, Guangxi Normal University, Guilin, China
- Research Center for Biomedical Sciences, Guangxi Normal University, Guilin, China
| | - Cheng Yang
- School of Life Sciences, Guangxi Normal University, Guilin, China
- Guangxi Universities, Key Laboratory of Stem Cell and Biopharmaceutical Technology, Guangxi Normal University, Guilin, China
- Research Center for Biomedical Sciences, Guangxi Normal University, Guilin, China
| | - Qiong Wu
- School of Life Sciences, Guangxi Normal University, Guilin, China
- Guangxi Universities, Key Laboratory of Stem Cell and Biopharmaceutical Technology, Guangxi Normal University, Guilin, China
- Research Center for Biomedical Sciences, Guangxi Normal University, Guilin, China
| | - Zuping Zhou
- Guangxi Universities, Key Laboratory of Stem Cell and Biopharmaceutical Technology, Guangxi Normal University, Guilin, China
- Research Center for Biomedical Sciences, Guangxi Normal University, Guilin, China
| | - Xiaobo Cen
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu, China
| | - Hongxia Zhao
- School of Life Sciences, Guangxi Normal University, Guilin, China
- Guangxi Universities, Key Laboratory of Stem Cell and Biopharmaceutical Technology, Guangxi Normal University, Guilin, China
- Research Center for Biomedical Sciences, Guangxi Normal University, Guilin, China
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| |
Collapse
|
6
|
Abstract
Abstract
Mitochondria, the cell powerhouse, are membrane-bound organelles present in the cytoplasm of almost all the eukaryotic cells. Their main function is to generate energy in the form of adenosine triphosphate (ATP). In addition, mitochondria store calcium for the cell signaling activities, generate heat, harbor pathways of intermediate metabolism and mediate cell growth and death. Primary mitochondrial diseases (MDs) form a clinically as well as genetically heterogeneous group of inherited disorders that result from the mitochondrial energetic metabolism malfunctions. The lifetime risk of the MDs development is estimated at 1:1470 of newborns, which makes them one of the most recurrent groups of inherited disorders with an important burden for society.
MDs are progressive with wide range of symptoms of variable severity that can emerge congenitally or anytime during the life. MD can be caused by mutations in the mitochondrial DNA (mtDNA) or nuclear DNA genes. Mutations inducing impairment of mitochondrial function have been found in more than 400 genes. Furthermore, more than 1200 nuclear genes, which could play a role in the MDs’ genetic etiology, are involved in the mitochondrial activities. However, the knowledge regarding the mechanism of the mitochondrial pathogenicity appears to be most essential for the development of effective patient’s treatment suffering from the mitochondrial disease. This is an overview update focused on the mitochondrial biology and the mitochondrial diseases associated genes.
Collapse
|
7
|
Roy A, Kandettu A, Ray S, Chakrabarty S. Mitochondrial DNA replication and repair defects: Clinical phenotypes and therapeutic interventions. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148554. [PMID: 35341749 DOI: 10.1016/j.bbabio.2022.148554] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 03/06/2022] [Accepted: 03/16/2022] [Indexed: 12/15/2022]
Abstract
Mitochondria is a unique cellular organelle involved in multiple cellular processes and is critical for maintaining cellular homeostasis. This semi-autonomous organelle contains its circular genome - mtDNA (mitochondrial DNA), that undergoes continuous cycles of replication and repair to maintain the mitochondrial genome integrity. The majority of the mitochondrial genes, including mitochondrial replisome and repair genes, are nuclear-encoded. Although the repair machinery of mitochondria is quite efficient, the mitochondrial genome is highly susceptible to oxidative damage and other types of exogenous and endogenous agent-induced DNA damage, due to the absence of protective histones and their proximity to the main ROS production sites. Mutations in replication and repair genes of mitochondria can result in mtDNA depletion and deletions subsequently leading to mitochondrial genome instability. The combined action of mutations and deletions can result in compromised mitochondrial genome maintenance and lead to various mitochondrial disorders. Here, we review the mechanism of mitochondrial DNA replication and repair process, key proteins involved, and their altered function in mitochondrial disorders. The focus of this review will be on the key genes of mitochondrial DNA replication and repair machinery and the clinical phenotypes associated with mutations in these genes.
Collapse
Affiliation(s)
- Abhipsa Roy
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | - Amoolya Kandettu
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | - Swagat Ray
- Department of Life Sciences, School of Life and Environmental Sciences, University of Lincoln, Lincoln LN6 7TS, United Kingdom
| | - Sanjiban Chakrabarty
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India.
| |
Collapse
|
8
|
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
| |
Collapse
|
9
|
Kaur P, Longley MJ, Pan H, Wang W, Countryman P, Wang H, Copeland WC. Single-molecule level structural dynamics of DNA unwinding by human mitochondrial Twinkle helicase. J Biol Chem 2020; 295:5564-5576. [PMID: 32213598 PMCID: PMC7186178 DOI: 10.1074/jbc.ra120.012795] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 03/24/2020] [Indexed: 11/06/2022] Open
Abstract
Knowledge of the molecular events in mitochondrial DNA (mtDNA) replication is crucial to understanding the origins of human disorders arising from mitochondrial dysfunction. Twinkle helicase is an essential component of mtDNA replication. Here, we employed atomic force microscopy imaging in air and liquids to visualize ring assembly, DNA binding, and unwinding activity of individual Twinkle hexamers at the single-molecule level. We observed that the Twinkle subunits self-assemble into hexamers and higher-order complexes that can switch between open and closed-ring configurations in the absence of DNA. Our analyses helped visualize Twinkle loading onto and unloading from DNA in an open-ringed configuration. They also revealed that closed-ring conformers bind and unwind several hundred base pairs of duplex DNA at an average rate of ∼240 bp/min. We found that the addition of mitochondrial single-stranded (ss) DNA-binding protein both influences the ways Twinkle loads onto defined DNA substrates and stabilizes the unwound ssDNA product, resulting in a ∼5-fold stimulation of the apparent DNA-unwinding rate. Mitochondrial ssDNA-binding protein also increased the estimated translocation processivity from 1750 to >9000 bp before helicase disassociation, suggesting that more than half of the mitochondrial genome could be unwound by Twinkle during a single DNA-binding event. The strategies used in this work provide a new platform to examine Twinkle disease variants and the core mtDNA replication machinery. They also offer an enhanced framework to investigate molecular mechanisms underlying deletion and depletion of the mitochondrial genome as observed in mitochondrial diseases.
Collapse
Affiliation(s)
- Parminder Kaur
- Physics Department, North Carolina State University, Raleigh, North Carolina 27695; Center for Human Health and the Environment, North Carolina State University, Raleigh, North Carolina 27695.
| | - Matthew J Longley
- Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709
| | - Hai Pan
- Physics Department, North Carolina State University, Raleigh, North Carolina 27695
| | - Wendy Wang
- Physics Department, North Carolina State University, Raleigh, North Carolina 27695
| | - Preston Countryman
- Physics Department, North Carolina State University, Raleigh, North Carolina 27695
| | - Hong Wang
- Physics Department, North Carolina State University, Raleigh, North Carolina 27695; Center for Human Health and the Environment, North Carolina State University, Raleigh, North Carolina 27695; Toxicology Program, North Carolina State University, Raleigh, North Carolina 27695
| | - William C Copeland
- Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709.
| |
Collapse
|
10
|
Peter B, Falkenberg M. TWINKLE and Other Human Mitochondrial DNA Helicases: Structure, Function and Disease. Genes (Basel) 2020; 11:genes11040408. [PMID: 32283748 PMCID: PMC7231222 DOI: 10.3390/genes11040408] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 04/06/2020] [Accepted: 04/07/2020] [Indexed: 12/30/2022] Open
Abstract
Mammalian mitochondria contain a circular genome (mtDNA) which encodes subunits of the oxidative phosphorylation machinery. The replication and maintenance of mtDNA is carried out by a set of nuclear-encoded factors—of which, helicases form an important group. The TWINKLE helicase is the main helicase in mitochondria and is the only helicase required for mtDNA replication. Mutations in TWINKLE cause a number of human disorders associated with mitochondrial dysfunction, neurodegeneration and premature ageing. In addition, a number of other helicases with a putative role in mitochondria have been identified. In this review, we discuss our current knowledge of TWINKLE structure and function and its role in diseases of mtDNA maintenance. We also briefly discuss other potential mitochondrial helicases and postulate on their role(s) in mitochondria.
Collapse
|
11
|
Kume K, Morino H, Miyamoto R, Matsuda Y, Ohsawa R, Kanaya Y, Tada Y, Kurashige T, Kawakami H. Middle-age-onset cerebellar ataxia caused by a homozygous TWNK variant: a case report. BMC MEDICAL GENETICS 2020; 21:68. [PMID: 32234020 PMCID: PMC7110654 DOI: 10.1186/s12881-020-01002-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 03/18/2020] [Indexed: 11/21/2022]
Abstract
Background The TWNK gene encodes the twinkle protein, which is a mitochondrial helicase for DNA replication. The dominant TWNK variants cause progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 3, while the recessive variants cause mitochondrial DNA depletion syndrome 7 and Perrault syndrome 5. Perrault syndrome is characterized by sensorineural hearing loss in both males and females and gonadal dysfunction in females. Patients with Perrault syndrome may present early-onset cerebellar ataxia, whereas middle-age-onset cerebellar ataxia caused by TWNK variants is rare. Case presentation A Japanese female born to consanguineous parents presented hearing loss at age 48, a staggering gait at age 53, and numbness in her distal extremities at age 57. Neurological examination revealed sensorineural hearing loss, cerebellar ataxia, decreased deep tendon reflexes, and sensory disturbance in the distal extremities. Laboratory tests showed no abnormal findings other than a moderate elevation of pyruvate concentration levels. Brain magnetic resonance imaging revealed mild cerebellar atrophy. Using exome sequencing, we identified a homozygous TWNK variant (NM_021830: c.1358G>A, p.R453Q). Conclusions TWNK variants could cause middle-age-onset cerebellar ataxia. Screening for TWNK variants should be considered in cases of cerebellar ataxia associated with deafness and/or peripheral neuropathy, even if the onset is not early.
Collapse
Affiliation(s)
- Kodai Kume
- Department of Epidemiology, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan
| | - Hiroyuki Morino
- Department of Epidemiology, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan.
| | - Ryosuke Miyamoto
- Department of Clinical Neuroscience, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-0042, Japan
| | - Yukiko Matsuda
- Department of Epidemiology, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan
| | - Ryosuke Ohsawa
- Department of Epidemiology, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan
| | - Yuhei Kanaya
- Department of Epidemiology, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan
| | - Yui Tada
- Department of Epidemiology, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan
| | - Takashi Kurashige
- Department of Neurology, National Hospital Organization Kure Medical Center and Chugoku Cancer Center, 3-1 Aoyama-cho, Kure, 737-0023, Japan
| | - Hideshi Kawakami
- Department of Epidemiology, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan
| |
Collapse
|
12
|
Matkarimov BT, Saparbaev MK. DNA Repair and Mutagenesis in Vertebrate Mitochondria: Evidence for Asymmetric DNA Strand Inheritance. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1241:77-100. [DOI: 10.1007/978-3-030-41283-8_6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
13
|
Domínguez-Ruiz M, García-Martínez A, Corral-Juan M, Pérez-Álvarez ÁI, Plasencia AM, Villamar M, Moreno-Pelayo MA, Matilla-Dueñas A, Menéndez-González M, Del Castillo I. Perrault syndrome with neurological features in a compound heterozygote for two TWNK mutations: overlap of TWNK-related recessive disorders. J Transl Med 2019; 17:290. [PMID: 31455392 PMCID: PMC6712801 DOI: 10.1186/s12967-019-2041-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 08/18/2019] [Indexed: 01/22/2023] Open
Abstract
Background Perrault syndrome is a rare autosomal recessive disorder that is characterized by the association of sensorineural hearing impairment and ovarian dysgenesis in females, whereas males have only hearing impairment. In some cases, patients present with a diversity of neurological signs. To date, mutations in six genes are known to cause Perrault syndrome, but they do not explain all clinically-diagnosed cases. In addition, the number of reported cases and the spectra of mutations are still small to establish conclusive genotype–phenotype correlations. Methods Affected siblings from family SH19, who presented with features that were suggestive of Perrault syndrome, were subjected to audiological, neurological and gynecological examination. The genetic study included genotyping and haplotype analysis for microsatellite markers close to the genes involved in Perrault syndrome, whole-exome sequencing, and Sanger sequencing of the coding region of the TWNK gene. Results Three siblings from family SH19 shared similar clinical features: childhood-onset bilateral sensorineural hearing impairment, which progressed to profound deafness in the second decade of life; neurological signs (spinocerebellar ataxia, polyneuropathy), with onset in the fourth decade of life in the two females and at age 20 years in the male; gonadal dysfunction with early cessation of menses in the two females. The genetic study revealed two compound heterozygous pathogenic mutations in the TWNK gene in the three affected subjects: c.85C>T (p.Arg29*), previously reported in a case of hepatocerebral syndrome; and a novel missense mutation, c.1886C>T (p.Ser629Phe). Mutations segregated in the family according to an autosomal recessive inheritance pattern. Conclusions Our results further illustrate the utility of genetic testing as a tool to confirm a tentative clinical diagnosis of Perrault syndrome. Studies on genotype–phenotype correlation from the hitherto reported cases indicate that patients with Perrault syndrome caused by TWNK mutations will manifest neurological signs in adulthood. Molecular and clinical characterization of novel cases of recessive disorders caused by TWNK mutations is strongly needed to get further insight into the genotype–phenotype correlations of a phenotypic continuum encompassing Perrault syndrome, infantile-onset spinocerebellar ataxia, and hepatocerebral syndrome.
Collapse
Affiliation(s)
- María Domínguez-Ruiz
- Servicio de Genética, Hospital Universitario Ramón y Cajal, IRYCIS, Carretera de Colmenar km 9.100, 28034, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Alberto García-Martínez
- Department of Neurology, Servicio de Neurología, Hospital Universitario Central de Asturias, Avenida Roma sn, 33011, Oviedo, Spain
| | - Marc Corral-Juan
- Functional and Translational Neurogenetics Unit, Department of Neuroscience, Health Sciences Research Institute Germans Trias i Pujol (IGTP), Universitat Autónoma de Barcelona, Can Ruti Campus, Badalona, Barcelona, Spain
| | - Ángel I Pérez-Álvarez
- Department of Neurology, Servicio de Neurología, Hospital Universitario Central de Asturias, Avenida Roma sn, 33011, Oviedo, Spain
| | - Ana M Plasencia
- Servicio de Pediatría, Hospital Universitario Central de Asturias, Oviedo, Spain
| | - Manuela Villamar
- Servicio de Genética, Hospital Universitario Ramón y Cajal, IRYCIS, Carretera de Colmenar km 9.100, 28034, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Miguel A Moreno-Pelayo
- Servicio de Genética, Hospital Universitario Ramón y Cajal, IRYCIS, Carretera de Colmenar km 9.100, 28034, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Antoni Matilla-Dueñas
- Functional and Translational Neurogenetics Unit, Department of Neuroscience, Health Sciences Research Institute Germans Trias i Pujol (IGTP), Universitat Autónoma de Barcelona, Can Ruti Campus, Badalona, Barcelona, Spain
| | - Manuel Menéndez-González
- Department of Neurology, Servicio de Neurología, Hospital Universitario Central de Asturias, Avenida Roma sn, 33011, Oviedo, Spain.
| | - Ignacio Del Castillo
- Servicio de Genética, Hospital Universitario Ramón y Cajal, IRYCIS, Carretera de Colmenar km 9.100, 28034, Madrid, Spain. .,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain.
| |
Collapse
|
14
|
Peter B, Farge G, Pardo-Hernandez C, Tångefjord S, Falkenberg M. Structural basis for adPEO-causing mutations in the mitochondrial TWINKLE helicase. Hum Mol Genet 2019; 28:1090-1099. [PMID: 30496414 PMCID: PMC6423418 DOI: 10.1093/hmg/ddy415] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 11/27/2018] [Accepted: 11/28/2018] [Indexed: 11/13/2022] Open
Abstract
TWINKLE is the helicase involved in replication and maintenance of mitochondrial DNA (mtDNA) in mammalian cells. Structurally, TWINKLE is closely related to the bacteriophage T7 gp4 protein and comprises a helicase and primase domain joined by a flexible linker region. Mutations in and around this linker region are responsible for autosomal dominant progressive external ophthalmoplegia (adPEO), a neuromuscular disorder associated with deletions in mtDNA. The underlying molecular basis of adPEO-causing mutations remains unclear, but defects in TWINKLE oligomerization are thought to play a major role. In this study, we have characterized these disease variants by single-particle electron microscopy and can link the diminished activities of the TWINKLE variants to altered oligomeric properties. Our results suggest that the mutations can be divided into those that (i) destroy the flexibility of the linker region, (ii) inhibit ring closure and (iii) change the number of subunits within a helicase ring. Furthermore, we demonstrate that wild-type TWINKLE undergoes large-scale conformational changes upon nucleoside triphosphate binding and that this ability is lost in the disease-causing variants. This represents a substantial advancement in the understanding of the molecular basis of adPEO and related pathologies and may aid in the development of future therapeutic strategies.
Collapse
Affiliation(s)
- Bradley Peter
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Sweden
| | - Geraldine Farge
- Centre Nacionale de la Recherche Scientifique/Institut National de Physique Nucléaire et des Particules, Laboratoire de Physique de Clermont, Université Clermont Auvergne, BP 10448, Clermont-Ferrand, France
| | | | - Stefan Tångefjord
- Discovery Sciences, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Sweden
| |
Collapse
|
15
|
Harman A, Barth C. The Dictyostelium discoideum homologue of Twinkle, Twm1, is a mitochondrial DNA helicase, an active primase and promotes mitochondrial DNA replication. BMC Mol Biol 2018; 19:12. [PMID: 30563453 PMCID: PMC6299598 DOI: 10.1186/s12867-018-0114-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Accepted: 11/07/2018] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND DNA replication requires contributions from various proteins, such as DNA helicases; in mitochondria Twinkle is important for maintaining and replicating mitochondrial DNA. Twinkle helicases are predicted to also possess primase activity, as has been shown in plants; however this activity appears to have been lost in metazoans. Given this, the study of Twinkle in other organisms is required to better understand the evolution of this family and the roles it performs within mitochondria. RESULTS Here we describe the characterization of a Twinkle homologue, Twm1, in the amoeba Dictyostelium discoideum, a model organism for mitochondrial genetics and disease. We show that Twm1 is important for mitochondrial function as it maintains mitochondrial DNA copy number in vivo. Twm1 is a helicase which unwinds DNA resembling open forks, although it can act upon substrates with a single 3' overhang, albeit less efficiently. Furthermore, unlike human Twinkle, Twm1 has primase activity in vitro. Finally, using a novel in bacterio approach, we demonstrated that Twm1 promotes DNA replication. CONCLUSIONS We conclude that Twm1 is a replicative mitochondrial DNA helicase which is capable of priming DNA for replication. Our results also suggest that non-metazoan Twinkle could function in the initiation of mitochondrial DNA replication. While further work is required, this study has illuminated several alternative processes of mitochondrial DNA maintenance which might also be performed by the Twinkle family of helicases.
Collapse
Affiliation(s)
- Ashley Harman
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, VIC Australia
- Present Address: Cell Biology Unit, Children’s Medical Research Institute, University of Sydney, Westmead, NSW Australia
| | - Christian Barth
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, VIC Australia
| |
Collapse
|
16
|
Mitochondrial DNA replication in mammalian cells: overview of the pathway. Essays Biochem 2018; 62:287-296. [PMID: 29880722 PMCID: PMC6056714 DOI: 10.1042/ebc20170100] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 05/18/2018] [Accepted: 05/21/2018] [Indexed: 12/27/2022]
Abstract
Mammalian mitochondria contain multiple copies of a circular, double-stranded DNA genome and a dedicated DNA replication machinery is required for its maintenance. Many disease-causing mutations affect mitochondrial replication factors and a detailed understanding of the replication process may help to explain the pathogenic mechanisms underlying a number of mitochondrial diseases. We here give a brief overview of DNA replication in mammalian mitochondria, describing our current understanding of this process and some unanswered questions remaining.
Collapse
|
17
|
Chan SSL. Inherited mitochondrial genomic instability and chemical exposures. Toxicology 2017; 391:75-83. [PMID: 28756246 DOI: 10.1016/j.tox.2017.07.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 06/12/2017] [Accepted: 07/24/2017] [Indexed: 12/21/2022]
Abstract
There are approximately 1500 proteins that are needed for mitochondrial structure and function, most of which are encoded in the nuclear genome (Calvo et al., 2006). Each mitochondrion has its own genome (mtDNA), which in humans encodes 13 polypeptides, 22 tRNAs and 2 rRNAs required for oxidative phosphorylation. The mitochondrial genome of humans and most vertebrates is approximately 16.5kbp, double-stranded, circular, with few non-coding bases. Thus, maintaining mtDNA stability, that is, the ability of the cell to maintain adequate levels of mtDNA template for oxidative phosphorylation is essential and can be impacted by the level of mtDNA mutation currently within the cell or mitochondrion, but also from errors made during normal mtDNA replication, defects in mitochondrial quality control mechanisms, and exacerbated by exposures to exogenous and/or endogenous genotoxic agents. In this review, we expand on the origins and consequences of mtDNA instability, the current state of research regarding the mechanisms by which mtDNA instability can be overcome by cellular and chemical interventions, and the future of research and treatments for mtDNA instability.
Collapse
Affiliation(s)
- Sherine S L Chan
- Drug Discovery and Biomedical Sciences, College of Pharmacy, Medical University of South Carolina, Charleston, SC 29425, United States; Neuroene Therapeutics, Mt. Pleasant, SC 29464, United States.
| |
Collapse
|
18
|
DeBalsi KL, Hoff KE, Copeland WC. Role of the mitochondrial DNA replication machinery in mitochondrial DNA mutagenesis, aging and age-related diseases. Ageing Res Rev 2017; 33:89-104. [PMID: 27143693 DOI: 10.1016/j.arr.2016.04.006] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 04/19/2016] [Accepted: 04/19/2016] [Indexed: 12/19/2022]
Abstract
As regulators of bioenergetics in the cell and the primary source of endogenous reactive oxygen species (ROS), dysfunctional mitochondria have been implicated for decades in the process of aging and age-related diseases. Mitochondrial DNA (mtDNA) is replicated and repaired by nuclear-encoded mtDNA polymerase γ (Pol γ) and several other associated proteins, which compose the mtDNA replication machinery. Here, we review evidence that errors caused by this replication machinery and failure to repair these mtDNA errors results in mtDNA mutations. Clonal expansion of mtDNA mutations results in mitochondrial dysfunction, such as decreased electron transport chain (ETC) enzyme activity and impaired cellular respiration. We address the literature that mitochondrial dysfunction, in conjunction with altered mitochondrial dynamics, is a major driving force behind aging and age-related diseases. Additionally, interventions to improve mitochondrial function and attenuate the symptoms of aging are examined.
Collapse
Affiliation(s)
- Karen L DeBalsi
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Kirsten E Hoff
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - William C Copeland
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
| |
Collapse
|
19
|
Abstract
Recent advances in the field of mitochondrial DNA (mtDNA) replication highlight the diversity of both the mechanisms utilized and the structural and functional organization of the proteins at mtDNA replication fork, despite the relative simplicity of the animal mtDNA genome. DNA polymerase γ, mtDNA helicase and mitochondrial single-stranded DNA-binding protein-the key replisome proteins, have evolved distinct structural features and biochemical properties. These appear to be correlated with mtDNA genomic features in different metazoan taxa and with their modes of DNA replication, although substantial integrative research is warranted to establish firmly these links. To date, several modes of mtDNA replication have been described for animals: rolling circle, theta, strand-displacement, and RITOLS/bootlace. Resolution of a continuing controversy relevant to mtDNA replication in mammals/vertebrates will have a direct impact on the mechanistic interpretation of mtDNA-related human diseases. Here we review these subjects, integrating earlier and recent data to provide a perspective on the major challenges for future research.
Collapse
Affiliation(s)
- G L Ciesielski
- Institute of Biosciences and Medical Technology, University of Tampere, Tampere, Finland; Michigan State University, East Lansing, MI, United States
| | - M T Oliveira
- Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista "Júlio de Mesquita Filho", Jaboticabal, SP, Brazil
| | - L S Kaguni
- Institute of Biosciences and Medical Technology, University of Tampere, Tampere, Finland; Michigan State University, East Lansing, MI, United States.
| |
Collapse
|
20
|
Young MJ, Copeland WC. Human mitochondrial DNA replication machinery and disease. Curr Opin Genet Dev 2016; 38:52-62. [PMID: 27065468 DOI: 10.1016/j.gde.2016.03.005] [Citation(s) in RCA: 129] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 03/03/2016] [Accepted: 03/08/2016] [Indexed: 12/21/2022]
Abstract
The human mitochondrial genome is replicated by DNA polymerase γ in concert with key components of the mitochondrial DNA (mtDNA) replication machinery. Defects in mtDNA replication or nucleotide metabolism cause deletions, point mutations, or depletion of mtDNA. The resulting loss of cellular respiration ultimately induces mitochondrial genetic diseases, including mtDNA depletion syndromes (MDS) such as Alpers or early infantile hepatocerebral syndromes, and mtDNA deletion disorders such as progressive external ophthalmoplegia, ataxia-neuropathy, or mitochondrial neurogastrointestinal encephalomyopathy. Here we review the current literature regarding human mtDNA replication and heritable disorders caused by genetic changes of the POLG, POLG2, Twinkle, RNASEH1, DNA2, and MGME1 genes.
Collapse
Affiliation(s)
- Matthew J Young
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, P.O. Box 12233, Research Triangle Park, NC 27709, United States
| | - William C Copeland
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, P.O. Box 12233, Research Triangle Park, NC 27709, United States.
| |
Collapse
|
21
|
Abstract
Mammalian mitochondrial DNA (mtDNA) encodes 13 proteins that are essential for the function of the oxidative phosphorylation system, which is composed of four respiratory-chain complexes and adenosine triphosphate (ATP) synthase. Remarkably, the maintenance and expression of mtDNA depend on the mitochondrial import of hundreds of nuclear-encoded proteins that control genome maintenance, replication, transcription, RNA maturation, and mitochondrial translation. The importance of this complex regulatory system is underscored by the identification of numerous mutations of nuclear genes that impair mtDNA maintenance and expression at different levels, causing human mitochondrial diseases with pleiotropic clinical manifestations. The basic scientific understanding of the mechanisms controlling mtDNA function has progressed considerably during the past few years, thanks to advances in biochemistry, genetics, and structural biology. The challenges for the future will be to understand how mtDNA maintenance and expression are regulated and to what extent direct intramitochondrial cross talk between different processes, such as transcription and translation, is important.
Collapse
Affiliation(s)
- Claes M Gustafsson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, 405 30 Gothenburg, Sweden; ,
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, 405 30 Gothenburg, Sweden; ,
| | - Nils-Göran Larsson
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany; .,Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
| |
Collapse
|
22
|
Uittenbogaard M, Chiaramello A. Novel subcellular localization of the DNA helicase Twinkle at the kinetochore complex during mitosis in neuronal-like progenitor cells. Histochem Cell Biol 2015; 145:275-86. [PMID: 26678504 DOI: 10.1007/s00418-015-1388-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/20/2015] [Indexed: 11/28/2022]
Abstract
During mitosis, the kinetochore, a multi-protein structure located on the centromeric DNA, is responsible for proper segregation of the replicated genome. More specifically, the outer kinetochore complex component Ndc80/Hec1 plays a critical role in regulating microtubule attachment to the spindle for accurate sister chromatid segregation. In addition, DNA helicases play a key contribution for precise and complete disjunction of sister chromatids held together through double-stranded DNA catenations until anaphase. In this study, we focused our attention on the nuclear-encoded DNA helicase Twinkle, which functions as an essential helicase for replication of mitochondrial DNA. It regulates the copy number of the mitochondrial genome, while maintaining its integrity, two processes essential for mitochondrial biogenesis and bioenergetic functions. Although the majority of the Twinkle protein is imported into mitochondria, a small fraction remains cytosolic with an unknown function. In this study, we report a novel expression pattern of Twinkle during chromosomal segregation at distinct mitotic phases. By immunofluorescence microscopy, we found that Twinkle protein colocalizes with the outer kinetochore protein HEC1 as early as prophase until late anaphase in neuronal-like progenitor cells. Thus, our collective results have revealed an unexpected cell cycle-regulated expression pattern of the DNA helicase Twinkle, known for its role in mtDNA replication. Therefore, its recruitment to the kinetochore suggests an evolutionary conserved function for both mitochondrial and nuclear genomic inheritance.
Collapse
Affiliation(s)
- Martine Uittenbogaard
- Department of Anatomy and Regenerative Biology, George Washington University Medical Center, 2300 I Street N.W., Washington, DC, 20037, USA
| | - Anne Chiaramello
- Department of Anatomy and Regenerative Biology, George Washington University Medical Center, 2300 I Street N.W., Washington, DC, 20037, USA.
| |
Collapse
|
23
|
Kaguni LS, Oliveira MT. Structure, function and evolution of the animal mitochondrial replicative DNA helicase. Crit Rev Biochem Mol Biol 2015; 51:53-64. [PMID: 26615986 DOI: 10.3109/10409238.2015.1117056] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The mitochondrial replicative DNA helicase is essential for animal mitochondrial DNA (mtDNA) maintenance. Deleterious mutations in the gene that encodes it cause mitochondrial dysfunction manifested in developmental delays, defects and arrest, limited life span, and a number of human pathogenic phenotypes that are recapitulated in animals across taxa. In fact, the replicative mtDNA helicase was discovered with the identification of human disease mutations in its nuclear gene, and based upon its deduced amino acid sequence homology with bacteriophage T7 gene 4 protein (T7 gp4), a bi-functional primase-helicase. Since that time, numerous investigations of its structure, mechanism, and physiological relevance have been reported, and human disease alleles have been modeled in the human, mouse, and Drosophila systems. Here, we review this literature and draw evolutionary comparisons that serve to shed light on its divergent features.
Collapse
Affiliation(s)
- Laurie S Kaguni
- a Department of Biochemistry and Molecular Biology and Center for Mitochondrial Science and Medicine , Michigan State University , East Lansing , MI , USA .,b Institute of Biosciences and Medical Technology, University of Tampere , Tampere , Finland , and
| | - Marcos T Oliveira
- c Departamento de Tecnologia , Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista "Júlio de Mesquita Filho" , Jaboticabal , Brazil
| |
Collapse
|
24
|
Akhmedov AT, Marín-García J. Mitochondrial DNA maintenance: an appraisal. Mol Cell Biochem 2015; 409:283-305. [DOI: 10.1007/s11010-015-2532-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 08/06/2015] [Indexed: 12/13/2022]
|
25
|
Ding L, Liu Y. Borrowing nuclear DNA helicases to protect mitochondrial DNA. Int J Mol Sci 2015; 16:10870-87. [PMID: 25984607 PMCID: PMC4463680 DOI: 10.3390/ijms160510870] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 05/09/2015] [Accepted: 05/11/2015] [Indexed: 01/20/2023] Open
Abstract
In normal cells, mitochondria are the primary organelles that generate energy, which is critical for cellular metabolism. Mitochondrial dysfunction, caused by mitochondrial DNA (mtDNA) mutations or an abnormal mtDNA copy number, is linked to a range of human diseases, including Alzheimer's disease, premature aging and cancer. mtDNA resides in the mitochondrial lumen, and its duplication requires the mtDNA replicative helicase, Twinkle. In addition to Twinkle, many DNA helicases, which are encoded by the nuclear genome and are crucial for nuclear genome integrity, are transported into the mitochondrion to also function in mtDNA replication and repair. To date, these helicases include RecQ-like helicase 4 (RECQ4), petite integration frequency 1 (PIF1), DNA replication helicase/nuclease 2 (DNA2) and suppressor of var1 3-like protein 1 (SUV3). Although the nuclear functions of some of these DNA helicases have been extensively studied, the regulation of their mitochondrial transport and the mechanisms by which they contribute to mtDNA synthesis and maintenance remain largely unknown. In this review, we attempt to summarize recent research progress on the role of mammalian DNA helicases in mitochondrial genome maintenance and the effects on mitochondria-associated diseases.
Collapse
Affiliation(s)
- Lin Ding
- Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010-3000, USA.
| | - Yilun Liu
- Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010-3000, USA.
| |
Collapse
|
26
|
Morino H, Pierce SB, Matsuda Y, Walsh T, Ohsawa R, Newby M, Hiraki-Kamon K, Kuramochi M, Lee MK, Klevit RE, Martin A, Maruyama H, King MC, Kawakami H. Mutations in Twinkle primase-helicase cause Perrault syndrome with neurologic features. Neurology 2014; 83:2054-61. [PMID: 25355836 DOI: 10.1212/wnl.0000000000001036] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
OBJECTIVE To identify the genetic cause in 2 families of progressive ataxia, axonal neuropathy, hyporeflexia, and abnormal eye movements, accompanied by progressive hearing loss and ovarian dysgenesis, with a clinical diagnosis of Perrault syndrome. METHODS Whole-exome sequencing was performed to identify causative mutations in the 2 affected sisters in each family. Family 1 is of Japanese ancestry, and family 2 is of European ancestry. RESULTS In family 1, affected individuals were compound heterozygous for chromosome 10 open reading frame 2 (C10orf2) p.Arg391His and p.Asn585Ser. In family 2, affected individuals were compound heterozygous for C10orf2 p.Trp441Gly and p.Val507Ile. C10orf2 encodes Twinkle, a primase-helicase essential for replication of mitochondrial DNA. Conservation and structural modeling support the causality of the mutations. Twinkle is known also to harbor multiple mutations, nearly all missenses, leading to dominant progressive external ophthalmoplegia type 3 and to recessive mitochondrial DNA depletion syndrome 7, also known as infantile-onset spinocerebellar ataxia. CONCLUSIONS Our study identifies Twinkle mutations as a cause of Perrault syndrome accompanied by neurologic features and expands the phenotypic spectrum of recessive disease caused by mutations in Twinkle. The phenotypic heterogeneity of conditions caused by Twinkle mutations and the genetic heterogeneity of Perrault syndrome call for genomic definition of these disorders.
Collapse
Affiliation(s)
- Hiroyuki Morino
- From the Department of Epidemiology, Research Institute for Radiation Biology and Medicine (H. Morino, Y.M., R.O., K.H.-K., M.K., H.K.), and Department of Clinical Neuroscience & Therapeutics (H. Maruyama), Hiroshima University, Japan; Departments of Medicine (Medical Genetics) and Genome Sciences (S.B.P., T.W., M.K.L., M.-C.K.) and Biochemistry (R.E.K.), University of Washington, Seattle; and Neuromuscular Center (M.N., A.M.), Texas Health Presbyterian Hospital, Dallas
| | - Sarah B Pierce
- From the Department of Epidemiology, Research Institute for Radiation Biology and Medicine (H. Morino, Y.M., R.O., K.H.-K., M.K., H.K.), and Department of Clinical Neuroscience & Therapeutics (H. Maruyama), Hiroshima University, Japan; Departments of Medicine (Medical Genetics) and Genome Sciences (S.B.P., T.W., M.K.L., M.-C.K.) and Biochemistry (R.E.K.), University of Washington, Seattle; and Neuromuscular Center (M.N., A.M.), Texas Health Presbyterian Hospital, Dallas.
| | - Yukiko Matsuda
- From the Department of Epidemiology, Research Institute for Radiation Biology and Medicine (H. Morino, Y.M., R.O., K.H.-K., M.K., H.K.), and Department of Clinical Neuroscience & Therapeutics (H. Maruyama), Hiroshima University, Japan; Departments of Medicine (Medical Genetics) and Genome Sciences (S.B.P., T.W., M.K.L., M.-C.K.) and Biochemistry (R.E.K.), University of Washington, Seattle; and Neuromuscular Center (M.N., A.M.), Texas Health Presbyterian Hospital, Dallas
| | - Tom Walsh
- From the Department of Epidemiology, Research Institute for Radiation Biology and Medicine (H. Morino, Y.M., R.O., K.H.-K., M.K., H.K.), and Department of Clinical Neuroscience & Therapeutics (H. Maruyama), Hiroshima University, Japan; Departments of Medicine (Medical Genetics) and Genome Sciences (S.B.P., T.W., M.K.L., M.-C.K.) and Biochemistry (R.E.K.), University of Washington, Seattle; and Neuromuscular Center (M.N., A.M.), Texas Health Presbyterian Hospital, Dallas
| | - Ryosuke Ohsawa
- From the Department of Epidemiology, Research Institute for Radiation Biology and Medicine (H. Morino, Y.M., R.O., K.H.-K., M.K., H.K.), and Department of Clinical Neuroscience & Therapeutics (H. Maruyama), Hiroshima University, Japan; Departments of Medicine (Medical Genetics) and Genome Sciences (S.B.P., T.W., M.K.L., M.-C.K.) and Biochemistry (R.E.K.), University of Washington, Seattle; and Neuromuscular Center (M.N., A.M.), Texas Health Presbyterian Hospital, Dallas
| | - Marta Newby
- From the Department of Epidemiology, Research Institute for Radiation Biology and Medicine (H. Morino, Y.M., R.O., K.H.-K., M.K., H.K.), and Department of Clinical Neuroscience & Therapeutics (H. Maruyama), Hiroshima University, Japan; Departments of Medicine (Medical Genetics) and Genome Sciences (S.B.P., T.W., M.K.L., M.-C.K.) and Biochemistry (R.E.K.), University of Washington, Seattle; and Neuromuscular Center (M.N., A.M.), Texas Health Presbyterian Hospital, Dallas
| | - Keiko Hiraki-Kamon
- From the Department of Epidemiology, Research Institute for Radiation Biology and Medicine (H. Morino, Y.M., R.O., K.H.-K., M.K., H.K.), and Department of Clinical Neuroscience & Therapeutics (H. Maruyama), Hiroshima University, Japan; Departments of Medicine (Medical Genetics) and Genome Sciences (S.B.P., T.W., M.K.L., M.-C.K.) and Biochemistry (R.E.K.), University of Washington, Seattle; and Neuromuscular Center (M.N., A.M.), Texas Health Presbyterian Hospital, Dallas
| | - Masahito Kuramochi
- From the Department of Epidemiology, Research Institute for Radiation Biology and Medicine (H. Morino, Y.M., R.O., K.H.-K., M.K., H.K.), and Department of Clinical Neuroscience & Therapeutics (H. Maruyama), Hiroshima University, Japan; Departments of Medicine (Medical Genetics) and Genome Sciences (S.B.P., T.W., M.K.L., M.-C.K.) and Biochemistry (R.E.K.), University of Washington, Seattle; and Neuromuscular Center (M.N., A.M.), Texas Health Presbyterian Hospital, Dallas
| | - Ming K Lee
- From the Department of Epidemiology, Research Institute for Radiation Biology and Medicine (H. Morino, Y.M., R.O., K.H.-K., M.K., H.K.), and Department of Clinical Neuroscience & Therapeutics (H. Maruyama), Hiroshima University, Japan; Departments of Medicine (Medical Genetics) and Genome Sciences (S.B.P., T.W., M.K.L., M.-C.K.) and Biochemistry (R.E.K.), University of Washington, Seattle; and Neuromuscular Center (M.N., A.M.), Texas Health Presbyterian Hospital, Dallas
| | - Rachel E Klevit
- From the Department of Epidemiology, Research Institute for Radiation Biology and Medicine (H. Morino, Y.M., R.O., K.H.-K., M.K., H.K.), and Department of Clinical Neuroscience & Therapeutics (H. Maruyama), Hiroshima University, Japan; Departments of Medicine (Medical Genetics) and Genome Sciences (S.B.P., T.W., M.K.L., M.-C.K.) and Biochemistry (R.E.K.), University of Washington, Seattle; and Neuromuscular Center (M.N., A.M.), Texas Health Presbyterian Hospital, Dallas
| | - Alan Martin
- From the Department of Epidemiology, Research Institute for Radiation Biology and Medicine (H. Morino, Y.M., R.O., K.H.-K., M.K., H.K.), and Department of Clinical Neuroscience & Therapeutics (H. Maruyama), Hiroshima University, Japan; Departments of Medicine (Medical Genetics) and Genome Sciences (S.B.P., T.W., M.K.L., M.-C.K.) and Biochemistry (R.E.K.), University of Washington, Seattle; and Neuromuscular Center (M.N., A.M.), Texas Health Presbyterian Hospital, Dallas
| | - Hirofumi Maruyama
- From the Department of Epidemiology, Research Institute for Radiation Biology and Medicine (H. Morino, Y.M., R.O., K.H.-K., M.K., H.K.), and Department of Clinical Neuroscience & Therapeutics (H. Maruyama), Hiroshima University, Japan; Departments of Medicine (Medical Genetics) and Genome Sciences (S.B.P., T.W., M.K.L., M.-C.K.) and Biochemistry (R.E.K.), University of Washington, Seattle; and Neuromuscular Center (M.N., A.M.), Texas Health Presbyterian Hospital, Dallas
| | - Mary-Claire King
- From the Department of Epidemiology, Research Institute for Radiation Biology and Medicine (H. Morino, Y.M., R.O., K.H.-K., M.K., H.K.), and Department of Clinical Neuroscience & Therapeutics (H. Maruyama), Hiroshima University, Japan; Departments of Medicine (Medical Genetics) and Genome Sciences (S.B.P., T.W., M.K.L., M.-C.K.) and Biochemistry (R.E.K.), University of Washington, Seattle; and Neuromuscular Center (M.N., A.M.), Texas Health Presbyterian Hospital, Dallas
| | - Hideshi Kawakami
- From the Department of Epidemiology, Research Institute for Radiation Biology and Medicine (H. Morino, Y.M., R.O., K.H.-K., M.K., H.K.), and Department of Clinical Neuroscience & Therapeutics (H. Maruyama), Hiroshima University, Japan; Departments of Medicine (Medical Genetics) and Genome Sciences (S.B.P., T.W., M.K.L., M.-C.K.) and Biochemistry (R.E.K.), University of Washington, Seattle; and Neuromuscular Center (M.N., A.M.), Texas Health Presbyterian Hospital, Dallas.
| |
Collapse
|
27
|
Abstract
Mitochondrial DNA is replicated by DNA polymerase γ in concert with accessory proteins such as the mitochondrial DNA helicase, single-stranded DNA binding protein, topoisomerase, and initiating factors. Defects in mitochondrial DNA replication or nucleotide metabolism can cause mitochondrial genetic diseases due to mitochondrial DNA deletions, point mutations, or depletion, which ultimately cause loss of oxidative phosphorylation. These genetic diseases include mitochondrial DNA depletion syndromes such as Alpers or early infantile hepatocerebral syndromes, and mitochondrial DNA deletion disorders, such as progressive external ophthalmoplegia, ataxia-neuropathy, or mitochondrial neurogastrointestinal encephalomyopathy. This review focuses on our current knowledge of genetic defects of mitochondrial DNA replication (POLG, POLG2, C10orf2, and MGME1) that cause instability of mitochondrial DNA and mitochondrial disease.
Collapse
Affiliation(s)
- William C. Copeland
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| |
Collapse
|
28
|
Park MH, Woo HM, Hong YB, Park JH, Yoon BR, Park JM, Yoo JH, Koo H, Chae JH, Chung KW, Choi BO, Koo SK. Recessive C10orf2 mutations in a family with infantile-onset spinocerebellar ataxia, sensorimotor polyneuropathy, and myopathy. Neurogenetics 2014; 15:171-82. [PMID: 24816431 PMCID: PMC4102772 DOI: 10.1007/s10048-014-0405-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 04/25/2014] [Indexed: 01/09/2023]
Abstract
Recessive mutations in chromosome 10 open reading frame 2 (C10orf2) are relevant in infantile-onset spinocerebellar ataxia (IOSCA). In this study, we investigated the causative mutation in a Korean family with combined phenotypes of IOSCA, sensorimotor polyneuropathy, and myopathy. We investigated recessive mutations in a Korean family with two individuals affected by IOSCA. Causative mutations were investigated using whole exome sequencing. Electrophysiological analyses and muscle and nerve biopsies were performed, along with magnetic resonance imaging (MRI) of the brain and lower extremities. Compound heterozygous mutations c.1460C>T and c.1485-1G>A in C10orf2 were identified as causative of IOSCA. Skeletal muscle showed mitochondrial DNA (mtDNA) deletions. Both patients showed a period of normal development until 12–15 months, followed by ataxia, athetosis, hearing loss, and intellectual disability. Electrophysiological findings indicated motor and sensory polyneuropathies. Muscle biopsy revealed variations in the size and shape of myofibers with scattered, small, and angulated degenerating myofibers containing abnormal mitochondria; these observations are consistent with myopathy and may be the result of mtDNA deletions. Sural nerve biopsy revealed an axonal neuropathy. High-signal-intensity lesions in the middle cerebellar peduncles were correlated with clinical severity, and MRI of the lower legs was compatible with the hypothesis of length-dependent axonal degeneration. We identified novel compound heterozygous mutations of the C10orf2 gene as the cause of IOSCA with sensorimotor polyneuropathy and myopathy. Signs of motor neuropathy and myopathy were discovered for the first time in IOSCA patients with C10orf2 mutations. These results suggest that the clinical spectrum of IOSCA caused by C10orf2 mutations may be more variable than previously reported.
Collapse
Affiliation(s)
- Mi-Hyun Park
- Division of Intractable Diseases, Center for Biomedical Sciences, National Institute of Health, Osong Health Technology Administration Complex 643, Yeonje-ri, Osong-eup, Cheongwon-gun, Chungcheongbuk-do, 363-951, South Korea
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Meersseman C, Léjard V, Rebours E, Boussaha M, Maftah A, Petit D, Rocha D. Bovine TWINKLE and mitochondrial ribosomal protein L43 genes are regulated by an evolutionary conserved bidirectional promoter. Gene 2013; 537:154-63. [PMID: 24361965 DOI: 10.1016/j.gene.2013.11.088] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 11/30/2013] [Indexed: 11/16/2022]
Abstract
TWINKLE is a mitochondrial DNA helicase playing an important role in mitochondrial DNA replication. In human, mutations in this gene cause progressive external ophtalmoplegia and mitochondrial DNA depletion syndrome-7. TWINKLE is well conserved among multicellular eukaryotes and is believed to be a key regulator of mitochondrial DNA copy number in mammals. Despite its involvement in several diseases and its important function in mitochondrial DNA metabolism, nothing is known about the regulation of the expression of TWINKLE. We have analysed the 5'-flanking genomic region of the bovine TWINKLE gene and found it was localised adjacent to the MRPL43 gene in a head-to-head orientation, suggesting that both genes are regulated by a shared bidirectional promoter. The bovine 75-bp long intergenic region shows substantial homology across different species and contains several conserved putative transcription factor binding sites. A TATA box, however, was lacking. Using a dual fluorescent reporter system and transient transfection assays, we have analysed the bovine intergenic region between TWINKLE and MRPL43. This small genomic fragment showed a bidirectional promoter activity. As the TWINKLE/MRPL43 bidirectional promoter tested was highly conserved, it is likely that the results we obtained here in cattle may be extended to the other species.
Collapse
Affiliation(s)
- Cédric Meersseman
- INRA, UMR1313, Unité Génétique Animale et Biologie Intégrative, Domaine de Vilvert, F-78352 Jouy-en-Josas, France; AgroParisTech, UMR1313, Unité Génétique Animale et Biologie Intégrative, Domaine de Vilvert, F-78352 Jouy-en-Josas, France; INRA, UMR1061 Génétique Moléculaire Animale, F-87060 Limoges, France; Université de Limoges, UMR1061 Génétique Moléculaire Animale, F-87060 Limoges, France
| | - Véronique Léjard
- INRA, UMR1313, Unité Génétique Animale et Biologie Intégrative, Domaine de Vilvert, F-78352 Jouy-en-Josas, France; AgroParisTech, UMR1313, Unité Génétique Animale et Biologie Intégrative, Domaine de Vilvert, F-78352 Jouy-en-Josas, France
| | - Emmanuelle Rebours
- INRA, UMR1313, Unité Génétique Animale et Biologie Intégrative, Domaine de Vilvert, F-78352 Jouy-en-Josas, France; AgroParisTech, UMR1313, Unité Génétique Animale et Biologie Intégrative, Domaine de Vilvert, F-78352 Jouy-en-Josas, France
| | - Mekki Boussaha
- INRA, UMR1313, Unité Génétique Animale et Biologie Intégrative, Domaine de Vilvert, F-78352 Jouy-en-Josas, France; AgroParisTech, UMR1313, Unité Génétique Animale et Biologie Intégrative, Domaine de Vilvert, F-78352 Jouy-en-Josas, France
| | - Abderrahman Maftah
- INRA, UMR1061 Génétique Moléculaire Animale, F-87060 Limoges, France; Université de Limoges, UMR1061 Génétique Moléculaire Animale, F-87060 Limoges, France
| | - Daniel Petit
- INRA, UMR1061 Génétique Moléculaire Animale, F-87060 Limoges, France; Université de Limoges, UMR1061 Génétique Moléculaire Animale, F-87060 Limoges, France
| | - Dominique Rocha
- INRA, UMR1313, Unité Génétique Animale et Biologie Intégrative, Domaine de Vilvert, F-78352 Jouy-en-Josas, France; AgroParisTech, UMR1313, Unité Génétique Animale et Biologie Intégrative, Domaine de Vilvert, F-78352 Jouy-en-Josas, France.
| |
Collapse
|
30
|
Twinkle mutations in two Chinese families with autosomal dominant progressive external ophthalmoplegia. Neurol Sci 2013; 35:443-8. [PMID: 24091712 DOI: 10.1007/s10072-013-1557-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 09/20/2013] [Indexed: 10/26/2022]
Abstract
Autosomal dominant progressive external ophthalmoplegia (adPEO) is a common adult onset mitochondrial disease caused by mutations in nuclear DNA (nDNA). Twinkle is one of the nuclear genes associated with adPEO. Clinical, histochemical, and molecular genetics findings of 6 patients from two Chinese families with adPEO were reported. Two point mutations (c.1423G>C, p.A475P and c.1061G>C, p.R354P) of Twinkle gene have been found. Multiple mtDNA deletions were also detected in patient's muscle and fibroblasts. This study confirms two mutations in Chinese adPEO families, which were first reported in the Chinese population.
Collapse
|
31
|
Milenkovic D, Matic S, Kühl I, Ruzzenente B, Freyer C, Jemt E, Park CB, Falkenberg M, Larsson NG. TWINKLE is an essential mitochondrial helicase required for synthesis of nascent D-loop strands and complete mtDNA replication. Hum Mol Genet 2013; 22:1983-93. [PMID: 23393161 PMCID: PMC3633371 DOI: 10.1093/hmg/ddt051] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Replication of the mammalian mitochondrial DNA (mtDNA) is dependent on the minimal replisome, consisting of the heterotrimeric mtDNA polymerase (POLG), the hexameric DNA helicase TWINKLE and the tetrameric single-stranded DNA-binding protein (mtSSB). TWINKLE has been shown to unwind DNA during the replication process and many disease-causing mutations have been mapped to its gene. Patients carrying Twinkle mutations develop multiple deletions of mtDNA, deficient respiratory chain function and neuromuscular symptoms. Despite its importance in human disease, it has been unclear whether TWINKLE is the only replicative DNA helicase in mammalian mitochondria. Furthermore, a substantial portion of mtDNA replication events is prematurely terminated at the end of mitochondrial control region (D-loop) and it is unknown whether TWINKLE also has a role in this abortive replication. Here, we present a conditional mouse knockout for Twinkle and demonstrate that TWINKLE is essential for mouse embryonic development and thus is the only replicative DNA helicase in mammalian mitochondria. Conditional knockout of Twinkle results in severe and rapid mtDNA depletion in heart and skeletal muscle. No replication intermediates or deleted mtDNA molecules are observed after Twinkle knockout, suggesting that TWINKLE once loaded is very processive. We also demonstrate that TWINKLE is essential for nascent H-strand synthesis in the D-loop, thus showing that there is no separate DNA helicase responsible for replication of this region. Our data thus suggest that the relative levels of abortive D-loop synthesis versus complete mtDNA replication are regulated and may provide a mechanism to control progression to complete mtDNA replication.
Collapse
Affiliation(s)
- Dusanka Milenkovic
- Max Planck Institute for Biology of Ageing, Robert-Koch-Strasse 21, Cologne, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Sanchez-Martinez A, Calleja M, Peralta S, Matsushima Y, Hernandez-Sierra R, Whitworth AJ, Kaguni LS, Garesse R. Modeling pathogenic mutations of human twinkle in Drosophila suggests an apoptosis role in response to mitochondrial defects. PLoS One 2012; 7:e43954. [PMID: 22952820 PMCID: PMC3429445 DOI: 10.1371/journal.pone.0043954] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 07/27/2012] [Indexed: 01/31/2023] Open
Abstract
The human gene C10orf2 encodes the mitochondrial replicative DNA helicase Twinkle, mutations of which are responsible for a significant fraction of cases of autosomal dominant progressive external ophthalmoplegia (adPEO), a human mitochondrial disease caused by defects in intergenomic communication. We report the analysis of orthologous mutations in the Drosophila melanogaster mitochondrial DNA (mtDNA) helicase gene, d-mtDNA helicase. Increased expression of wild type d-mtDNA helicase using the UAS-GAL4 system leads to an increase in mtDNA copy number throughout adult life without any noteworthy phenotype, whereas overexpression of d-mtDNA helicase containing the K388A mutation in the helicase active site results in a severe depletion of mtDNA and a lethal phenotype. Overexpression of two d-mtDNA helicase variants equivalent to two human adPEO mutations shows differential effects. The A442P mutation exhibits a dominant negative effect similar to that of the active site mutant. In contrast, overexpression of d-mtDNA helicase containing the W441C mutation results in a slight decrease in mtDNA copy number during the third instar larval stage, and a moderate decrease in life span in the adult population. Overexpression of d-mtDNA helicase containing either the K388A or A442P mutations causes a mitochondrial oxidative phosphorylation (OXPHOS) defect that significantly reduces cell proliferation. The mitochondrial impairment caused by these mutations promotes apoptosis, arguing that mitochondria regulate programmed cell death in Drosophila. Our study of d-mtDNA helicase overexpression provides a tractable Drosophila model for understanding the cellular and molecular effects of human adPEO mutations.
Collapse
Affiliation(s)
- Alvaro Sanchez-Martinez
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas “Alberto Sols” Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, and Centro de Investigación Biomédica en Red en Enfermedades Raras, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
- Instituto de Investigación Santitaria Hospital 12 de Octubre (i+12), Madrid, Spain
| | - Manuel Calleja
- Centro de Biología Molecular “Severo Ochoa” Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Susana Peralta
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas “Alberto Sols” Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, and Centro de Investigación Biomédica en Red en Enfermedades Raras, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
- Instituto de Investigación Santitaria Hospital 12 de Octubre (i+12), Madrid, Spain
| | - Yuichi Matsushima
- Department of Biochemistry and Molecular Biology and Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, Michigan, United States of America
| | - Rosana Hernandez-Sierra
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas “Alberto Sols” Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, and Centro de Investigación Biomédica en Red en Enfermedades Raras, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
- Instituto de Investigación Santitaria Hospital 12 de Octubre (i+12), Madrid, Spain
| | - Alexander J. Whitworth
- Department of Biomedical Sciences, MRC Centre for Developmental and Biomedical Genetics, University of Sheffield, Sheffield, United Kingdom
| | - Laurie S. Kaguni
- Department of Biochemistry and Molecular Biology and Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, Michigan, United States of America
| | - Rafael Garesse
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas “Alberto Sols” Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, and Centro de Investigación Biomédica en Red en Enfermedades Raras, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
- Instituto de Investigación Santitaria Hospital 12 de Octubre (i+12), Madrid, Spain
- * E-mail:
| |
Collapse
|
33
|
Abstract
Mitochondrial DNA (mtDNA) is replicated by the DNA polymerase g in concert with accessory proteins such as the mtDNA helicase, single stranded DNA binding protein, topoisomerase, and initiating factors. Nucleotide precursors for mtDNA replication arise from the mitochondrial salvage pathway originating from transport of nucleosides, or alternatively from cytoplasmic reduction of ribonucleotides. Defects in mtDNA replication or nucleotide metabolism can cause mitochondrial genetic diseases due to mtDNA deletions, point mutations, or depletion which ultimately cause loss of oxidative phosphorylation. These genetic diseases include mtDNA depletion syndromes such as Alpers or early infantile hepatocerebral syndromes, and mtDNA deletion disorders, such as progressive external ophthalmoplegia (PEO), ataxia-neuropathy, or mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). This review focuses on our current knowledge of genetic defects of mtDNA replication (POLG, POLG2, C10orf2) and nucleotide metabolism (TYMP, TK2, DGOUK, and RRM2B) that cause instability of mtDNA and mitochondrial disease.
Collapse
Affiliation(s)
- William C Copeland
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Durham, North Carolina 27709, USA.
| |
Collapse
|
34
|
Dündar H, Ozgül RK, Yalnızoğlu D, Erdem S, Oğuz KK, Tuncel D, Temuçin CM, Dursun A. Identification of a novel Twinkle mutation in a family with infantile onset spinocerebellar ataxia by whole exome sequencing. Pediatr Neurol 2012; 46:172-7. [PMID: 22353293 DOI: 10.1016/j.pediatrneurol.2011.12.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 12/22/2011] [Indexed: 01/29/2023]
Abstract
Whole exome sequencing combined with homozygosity mapping comprises a genetic diagnostic tool to identify genetic defects in families with multiple affected members, compatible with presumed autosomal recessively inherited neurometabolic/neurogenetic disease. These tools were applied to a family with two individuals manifesting ataxia, associated with peripheral sensory neuropathy, athetosis, seizures, deafness, and ophthalmoplegia. A novel homozygous missense mutation c.1366C>G (L456V) in C10orf2 (the Twinkle gene) was identified, confirming infantile onset spinocerebellar ataxia in the probands. Signs in infantile onset spinocerebellar ataxia follow a fairly distinct pattern, affecting early development, followed by ataxia and loss of skills. However, this very rare disease was previously reported only in Finland. We suggest that infantile onset spinocerebellar ataxia should be more frequently considered in the differential diagnosis of neurometabolic diseases in childhood. Next-generation sequencing and its use along with homozygosity mapping offer highly promising techniques for molecular diagnosis, especially in small families affected with very rare neurometabolic disorders such as infantile onset spinocerebellar ataxia.
Collapse
Affiliation(s)
- Halil Dündar
- Metabolism Unit, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Sıhhiye, Ankara, Turkey
| | | | | | | | | | | | | | | |
Collapse
|
35
|
Sen D, Nandakumar D, Tang GQ, Patel SS. Human mitochondrial DNA helicase TWINKLE is both an unwinding and annealing helicase. J Biol Chem 2012; 287:14545-56. [PMID: 22383523 DOI: 10.1074/jbc.m111.309468] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
TWINKLE is a nucleus-encoded human mitochondrial (mt)DNA helicase. Point mutations in TWINKLE are associated with heritable neuromuscular diseases characterized by deletions in the mtDNA. To understand the biochemical basis of these diseases, it is important to define the roles of TWINKLE in mtDNA metabolism by studying its enzymatic activities. To this end, we purified native TWINKLE from Escherichia coli. The recombinant TWINKLE assembles into hexamers and higher oligomers, and addition of MgUTP stabilizes hexamers over higher oligomers. Probing into the DNA unwinding activity, we discovered that the efficiency of unwinding is greatly enhanced in the presence of a heterologous single strand-binding protein or a single-stranded (ss) DNA that is complementary to the unwound strand. We show that TWINKLE, although a helicase, has an antagonistic activity of annealing two complementary ssDNAs that interferes with unwinding in the absence of gp2.5 or ssDNA trap. Furthermore, only ssDNA and not double-stranded (ds)DNA competitively inhibits the annealing activity, although both DNAs bind with high affinities. This implies that dsDNA binds to a site that is distinct from the ssDNA-binding site that promotes annealing. Fluorescence anisotropy competition binding experiments suggest that TWINKLE has more than one ssDNA-binding sites, and we speculate that a surface-exposed ssDNA-specific site is involved in catalyzing DNA annealing. We propose that the strand annealing activity of TWINKLE may play a role in recombination-mediated replication initiation found in the mitochondria of mammalian brain and heart or in replication fork regression during repair of damaged DNA replication forks.
Collapse
Affiliation(s)
- Doyel Sen
- Department of Biochemistry, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
| | | | | | | |
Collapse
|
36
|
Kasiviswanathan R, Collins TRL, Copeland WC. The interface of transcription and DNA replication in the mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1819:970-8. [PMID: 22207204 DOI: 10.1016/j.bbagrm.2011.12.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2011] [Revised: 12/09/2011] [Accepted: 12/12/2011] [Indexed: 11/30/2022]
Abstract
DNA replication of the mitochondrial genome is unique in that replication is not primed by RNA derived from dedicated primases, but instead by extension of processed RNA transcripts laid down by the mitochondrial RNA polymerase. Thus, the RNA polymerase serves not only to generate the transcripts but also the primers needed for mitochondrial DNA replication. The interface between this transcription and DNA replication is not well understood but must be highly regulated and coordinated to carry out both mitochondrial DNA replication and transcription. This review focuses on the extension of RNA primers for DNA replication by the replication machinery and summarizes the current models of DNA replication in mitochondria as well as the proteins involved in mitochondrial DNA replication, namely, the DNA polymerase γ and its accessory subunit, the mitochondrial DNA helicase, the single-stranded DNA binding protein, topoisomerase I and IIIα and RNaseH1. This article is part of a Special Issue entitled: Mitochondrial Gene Expression.
Collapse
Affiliation(s)
- Rajesh Kasiviswanathan
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | | | | |
Collapse
|
37
|
Oliveira MT, Kaguni LS. Reduced stimulation of recombinant DNA polymerase γ and mitochondrial DNA (mtDNA) helicase by variants of mitochondrial single-stranded DNA-binding protein (mtSSB) correlates with defects in mtDNA replication in animal cells. J Biol Chem 2011; 286:40649-58. [PMID: 21953457 DOI: 10.1074/jbc.m111.289983] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mitochondrial single-stranded DNA-binding protein (mtSSB) is believed to coordinate the functions of DNA polymerase γ (pol γ) and the mitochondrial DNA (mtDNA) helicase at the mtDNA replication fork. We generated five variants of the human mtSSB bearing mutations in amino acid residues specific to metazoans that map on the protein surface, removed from the single-stranded DNA (ssDNA) binding groove. Although the mtSSB variants bound ssDNA with only slightly different affinities, they exhibited distinct capacities to stimulate the DNA polymerase activity of human pol γ and the DNA unwinding activity of human mtDNA helicase in vitro. Interestingly, we observed that the variants with defects in stimulating pol γ had unaltered capacities to stimulate the mtDNA helicase; at the same time, variants showing reduced stimulation of the mtDNA helicase activity promoted DNA synthesis by pol γ similarly to the wild-type mtSSB. The overexpression of the equivalent variants of Drosophila melanogaster mtSSB in S2 cells in culture caused mtDNA depletion under conditions of mitochondrial homeostasis. Furthermore, we observed more severe reduction of mtDNA copy number upon expression of these proteins during recovery from treatment with ethidium bromide, when mtDNA replication is stimulated in vivo. Our findings suggest that mtSSB uses distinct structural elements to interact functionally with its mtDNA replisome partners and to promote proper mtDNA replication in animal cells.
Collapse
Affiliation(s)
- Marcos T Oliveira
- Department of Biochemistry and Molecular Biology, Center for Mitochondrial Science and Medicine, and Graduate Program in Genetics, Michigan State University, East Lansing, Michigan 48824-1319, USA
| | | |
Collapse
|
38
|
Nakhro K, Chung KW, Kim SM, Sunwoo IN, Cho EM, Park SW, Hwang JH, Choi BO. Compound mutations of PEO1 and TYMP in a progressive external ophthalmoplegia patient with incomplete mitochondrial neurogastrointestinal encephalomyopathy phenotype. Genes Genomics 2011. [DOI: 10.1007/s13258-011-0089-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
39
|
Jemt E, Farge G, Bäckström S, Holmlund T, Gustafsson CM, Falkenberg M. The mitochondrial DNA helicase TWINKLE can assemble on a closed circular template and support initiation of DNA synthesis. Nucleic Acids Res 2011; 39:9238-49. [PMID: 21840902 PMCID: PMC3241658 DOI: 10.1093/nar/gkr653] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mitochondrial DNA replication is performed by a simple machinery, containing the TWINKLE DNA helicase, a single-stranded DNA-binding protein, and the mitochondrial DNA polymerase γ. In addition, mitochondrial RNA polymerase is required for primer formation at the origins of DNA replication. TWINKLE adopts a hexameric ring-shaped structure that must load on the closed circular mtDNA genome. In other systems, a specialized helicase loader often facilitates helicase loading. We here demonstrate that TWINKLE can function without a specialized loader. We also show that the mitochondrial replication machinery can assemble on a closed circular DNA template and efficiently elongate a DNA primer in a manner that closely resembles initiation of mtDNA synthesis in vivo.
Collapse
Affiliation(s)
- Elisabeth Jemt
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, SE-405 30 Gothenburg, Sweden
| | | | | | | | | | | |
Collapse
|
40
|
Patel G, Johnson DS, Sun B, Pandey M, Yu X, Egelman EH, Wang MD, Patel SS. A257T linker region mutant of T7 helicase-primase protein is defective in DNA loading and rescued by T7 DNA polymerase. J Biol Chem 2011; 286:20490-9. [PMID: 21515672 DOI: 10.1074/jbc.m110.201657] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The helicase and primase activities of the hexameric ring-shaped T7 gp4 protein reside in two separate domains connected by a linker region. This linker region is part of the subunit interface between monomers, and point mutations in this region have deleterious effects on the helicase functions. One such linker region mutant, A257T, is analogous to the A359T mutant of the homologous human mitochondrial DNA helicase Twinkle, which is linked to diseases such as progressive external opthalmoplegia. Electron microscopy studies show that A257T gp4 is normal in forming rings with dTTP, but the rings do not assemble efficiently on the DNA. Therefore, A257T, unlike the WT gp4, does not preassemble on the unwinding DNA substrate with dTTP without Mg(II), and its DNA unwinding activity in ensemble assays is slow and limited by the DNA loading rate. Single molecule assays measured a 45 times slower rate of A257T loading on DNA compared with WT gp4. Interestingly, once loaded, A257T has almost WT-like translocation and DNA unwinding activities. Strikingly, A257T preassembles stably on the DNA in the presence of T7 DNA polymerase, which restores the ensemble unwinding activity of A257T to ∼75% of WT, and the rescue does not require DNA synthesis. The DNA loading rate of A257T, however, remains slow even in the presence of the polymerase, which explains why A257T does not support T7 phage growth. Similar types of defects in the related human mitochondrial DNA helicase may be responsible for inefficient DNA replication leading to the disease states.
Collapse
Affiliation(s)
- Gayatri Patel
- Department of Biochemistry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey 08854, USA
| | | | | | | | | | | | | | | |
Collapse
|
41
|
Longley MJ, Humble MM, Sharief FS, Copeland WC. Disease variants of the human mitochondrial DNA helicase encoded by C10orf2 differentially alter protein stability, nucleotide hydrolysis, and helicase activity. J Biol Chem 2010; 285:29690-702. [PMID: 20659899 DOI: 10.1074/jbc.m110.151795] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Missense mutations in the human C10orf2 gene, encoding the mitochondrial DNA (mtDNA) helicase, co-segregate with mitochondrial diseases such as adult-onset progressive external ophthalmoplegia, hepatocerebral syndrome with mtDNA depletion syndrome, and infantile-onset spinocerebellar ataxia. To understand the biochemical consequences of C10orf2 mutations, we overproduced wild type and 20 mutant forms of human mtDNA helicase in Escherichia coli and developed novel schemes to purify the recombinant enzymes to near homogeneity. A combination of molecular crowding, non-ionic detergents, Mg(2+) ions, and elevated ionic strength was required to combat insolubility and intrinsic instability of certain mutant variants. A systematic biochemical assessment of the enzymes included analysis of DNA binding affinity, DNA helicase activity, the kinetics of nucleotide hydrolysis, and estimates of thermal stability. In contrast to other studies, we found that all 20 mutant variants retain helicase function under optimized in vitro conditions despite partial reductions in DNA binding affinity, nucleotide hydrolysis, or thermal stability for some mutants. Such partial defects are consistent with the delayed presentation of mitochondrial diseases associated with mutation of C10orf2.
Collapse
Affiliation(s)
- Matthew J Longley
- Laboratory of Molecular Genetics, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA
| | | | | | | |
Collapse
|
42
|
Abstract
Some cases of mitochondrial diseases are due to mitochondrial DNA instability: multiple deletions or depletions. These anomalies are responsible for a mitochondrial respiratory chain impairment leading to various clinical involvements ranging from mild features with multiple mtDNA deletions to severe organ failure and premature death caused by mtDNA depletions. Both, deletions and depletions share an important and common feature between these two specificities: indeed, both are expressed in a tissue-specific manner.
Collapse
Affiliation(s)
- Emmanuelle Sarzi
- Inserm U781, Hôpital Necker Enfants malades, 75015 Paris, France.
| | | |
Collapse
|
43
|
Wanrooij S, Falkenberg M. The human mitochondrial replication fork in health and disease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1378-88. [PMID: 20417176 DOI: 10.1016/j.bbabio.2010.04.015] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 04/13/2010] [Accepted: 04/15/2010] [Indexed: 11/16/2022]
Abstract
Mitochondria are organelles whose main function is to generate power by oxidative phosphorylation. Some of the essential genes required for this energy production are encoded by the mitochondrial genome, a small circular double stranded DNA molecule. Human mtDNA is replicated by a specialized machinery distinct from the nuclear replisome. Defects in the mitochondrial replication machinery can lead to loss of genetic information by deletion and/or depletion of the mtDNA, which subsequently may cause disturbed oxidative phosphorylation and neuromuscular symptoms in patients. We discuss here the different components of the mitochondrial replication machinery and their role in disease. We also review the mode of mammalian mtDNA replication.
Collapse
Affiliation(s)
- Sjoerd Wanrooij
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, SE-40530 Gothenburg, Sweden.
| | | |
Collapse
|
44
|
Bohlega S, Van Goethem G, Al Semari A, Löfgren A, Al Hamed M, Van Broeckhoven C, Kambouris M. Novel Twinkle gene mutation in autosomal dominant progressive external ophthalmoplegia and multisystem failure. Neuromuscul Disord 2009; 19:845-8. [PMID: 19853444 DOI: 10.1016/j.nmd.2009.10.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 08/29/2009] [Accepted: 10/02/2009] [Indexed: 10/20/2022]
Abstract
A Saudi Arabian family presented with adult onset autosomal dominant progressive external ophthalmoplegia (adPEO) complicated by late onset reversible failure of the CNS, respiratory, hepatic, and endocrine systems. Clinical findings were suggestive of mitochondrial dysfunction and multiple mitochondrial DNA deletions were demonstrated on long range and real time polymerase chain reaction assays but not on Southern blotting. The disorder is caused by a novel heterozygous PEO1 mutation predicting a Leu360Gly substitution in the twinkle protein. The peculiar clinical presentation expands the variable phenotype observed in adPEO and Twinkle gene mutations.
Collapse
Affiliation(s)
- S Bohlega
- Department of Neurosciences, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
| | | | | | | | | | | | | |
Collapse
|
45
|
Hong D, Bi H, Yao S, Wang Z, Yuan Y. Clinical phenotype of autosomal dominant progressive external ophthalmoplegia in a family with a novel mutation in the C10orf2 gene. Muscle Nerve 2009; 41:92-9. [DOI: 10.1002/mus.21439] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
46
|
A novel variation in the Twinkle linker region causing late-onset dementia. Neurogenetics 2009; 11:21-5. [DOI: 10.1007/s10048-009-0202-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2009] [Accepted: 06/02/2009] [Indexed: 10/20/2022]
|
47
|
Holmlund T, Farge G, Pande V, Korhonen J, Nilsson L, Falkenberg M. Structure-function defects of the twinkle amino-terminal region in progressive external ophthalmoplegia. Biochim Biophys Acta Mol Basis Dis 2008; 1792:132-9. [PMID: 19084593 DOI: 10.1016/j.bbadis.2008.11.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Revised: 11/05/2008] [Accepted: 11/06/2008] [Indexed: 11/28/2022]
Abstract
TWINKLE is a DNA helicase needed for mitochondrial DNA replication. In lower eukaryotes the protein also harbors a primase activity, which is lost from TWINKLE encoded by mammalian cells. Mutations in TWINKLE underlie autosomal dominant progressive external ophthalmoplegia (adPEO), a disorder associated with multiple deletions in the mtDNA. Four different adPEO-causing mutations (W315L, K319T, R334Q, and P335L) are located in the N-terminal domain of TWINKLE. The mutations cause a dramatic decrease in ATPase activity, which is partially overcome in the presence of single-stranded DNA. The mutated proteins have defects in DNA helicase activity and cannot support normal levels of DNA replication. To explain the phenotypes, we use a molecular model of TWINKLE based on sequence similarities with the phage T7 gene 4 protein. The four adPEO-causing mutations are located in a region required to bind single-stranded DNA. These mutations may therefore impair an essential element of the catalytic cycle in hexameric helicases, i.e. the interplay between single-stranded DNA binding and ATP hydrolysis.
Collapse
Affiliation(s)
- Teresa Holmlund
- Department of Laboratory Medicine, Division of Metabolic Diseases, Karolinska Institutet, Novum, SE-141 86 Stockholm, Sweden
| | | | | | | | | | | |
Collapse
|
48
|
Functional importance of the conserved N-terminal domain of the mitochondrial replicative DNA helicase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1787:290-5. [PMID: 19063859 DOI: 10.1016/j.bbabio.2008.11.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 11/10/2008] [Accepted: 11/11/2008] [Indexed: 11/23/2022]
Abstract
The mitochondrial replicative DNA helicase is an essential cellular protein that shows high similarity with the bifunctional primase-helicase of bacteriophage T7, the gene 4 protein (T7 gp4). The N-terminal primase domain of T7 gp4 comprises seven conserved sequence motifs, I, II, III, IV, V, VI, and an RNA polymerase basic domain. The putative primase domain of metazoan mitochondrial DNA helicases has diverged from T7 gp4 and in particular, the primase domain of vertebrates lacks motif I, which comprises a zinc binding domain. Interestingly, motif I is conserved in insect mtDNA helicases. Here, we evaluate the effects of overexpression in Drosophila cell culture of variants carrying mutations in conserved amino acids in the N-terminal region, including the zinc binding domain. Overexpression of alanine substitution mutants of conserved amino acids in motifs I, IV, V and VI and the RNA polymerase basic domain results in increased mtDNA copy number as is observed with overexpression of the wild type enzyme. In contrast, overexpression of three N-terminal mutants W282L, R301Q and P302L that are analogous to human autosomal dominant progressive external ophthalmoplegia mutations results in mitochondrial DNA depletion, and in the case of R301Q, a dominant negative cellular phenotype. Thus whereas our data suggest lack of a DNA primase activity in Drosophila mitochondrial DNA helicase, they show that specific N-terminal amino acid residues that map close to the central linker region likely play a physiological role in the C-terminal helicase function of the protein.
Collapse
|
49
|
Goffart S, Cooper HM, Tyynismaa H, Wanrooij S, Suomalainen A, Spelbrink JN. Twinkle mutations associated with autosomal dominant progressive external ophthalmoplegia lead to impaired helicase function and in vivo mtDNA replication stalling. Hum Mol Genet 2008; 18:328-40. [PMID: 18971204 PMCID: PMC2638771 DOI: 10.1093/hmg/ddn359] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mutations in the mitochondrial helicase Twinkle underlie autosomal dominant progressive external ophthalmoplegia (PEO), as well as recessively inherited infantile-onset spinocerebellar ataxia and rare forms of mitochondrial DNA (mtDNA) depletion syndrome. Familial PEO is typically associated with the occurrence of multiple mtDNA deletions, but the mechanism by which Twinkle dysfunction induces deletion formation has been under debate. Here we looked at the effects of Twinkle adPEO mutations in human cell culture and studied the mtDNA replication in the Deletor mouse model, which expresses a dominant PEO mutation in Twinkle and accumulates multiple mtDNA deletions during life. We show that expression of dominant Twinkle mutations results in the accumulation of mtDNA replication intermediates in cell culture. This indicated severe replication pausing or stalling and caused mtDNA depletion. A strongly enhanced accumulation of replication intermediates was evident also in six-week-old Deletor mice compared with wild-type littermates, even though mtDNA deletions accumulate in a late-onset fashion in this model. In addition, our results in cell culture pointed to a problem of transcription that preceded the mtDNA depletion phenotype and might be of relevance in adPEO pathophysiology. Finally, in vitro assays showed functional defects in the various Twinkle mutants and broadly agreed with the cell culture phenotypes such as the level of mtDNA depletion and the level of accumulation of replication intermediates. On the basis of our results we suggest that mtDNA replication pausing or stalling is the common consequence of Twinkle PEO mutations that predisposes to multiple deletion formation.
Collapse
Affiliation(s)
- Steffi Goffart
- Institute of Medical Technology and Tampere University Hospital, Biokatu 6, 33014, Tampere, Finland
| | | | | | | | | | | |
Collapse
|
50
|
Hakonen AH, Goffart S, Marjavaara S, Paetau A, Cooper H, Mattila K, Lampinen M, Sajantila A, Lonnqvist T, Spelbrink JN, Suomalainen A. Infantile-onset spinocerebellar ataxia and mitochondrial recessive ataxia syndrome are associated with neuronal complex I defect and mtDNA depletion. Hum Mol Genet 2008; 17:3822-35. [DOI: 10.1093/hmg/ddn280] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|