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Martucci M, Moretton A, Tarrés-Solé A, Ropars V, Lambert L, Vernet P, Solà M, Falkenberg M, Farge G, van den Wildenberg S. The mutation R107Q alters mtSSB ssDNA compaction ability and binding dynamics. Nucleic Acids Res 2024; 52:5912-5927. [PMID: 38742632 PMCID: PMC11162770 DOI: 10.1093/nar/gkae354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Revised: 04/02/2024] [Accepted: 04/22/2024] [Indexed: 05/16/2024] Open
Abstract
Mitochondrial single-stranded DNA-binding protein (mtSSB) is essential for mitochondrial DNA (mtDNA) replication. Recently, several mtSSB variants have been associated with autosomal dominant mitochondrial optic atrophy and retinal dystrophy. Here, we have studied at the molecular level the functional consequences of one of the most severe mtSSB variants, R107Q. We first studied the oligomeric state of this variant and observed that the mtSSBR107Q mutant forms stable tetramers in vitro. On the other hand, we showed, using complementary single-molecule approaches, that mtSSBR107Q displays a lower intramolecular ssDNA compaction ability and a higher ssDNA dissociation rate than the WT protein. Real-time competition experiments for ssDNA-binding showed a marked advantage of mtSSBWT over mtSSBR107Q. Combined, these results show that the R107Q mutation significantly impaired the ssDNA-binding and compacting ability of mtSSB, likely by weakening mtSSB ssDNA wrapping efficiency. These features are in line with our molecular modeling of ssDNA on mtSSB showing that the R107Q mutation may destabilize local interactions and results in an electronegative spot that interrupts an ssDNA-interacting-electropositive patch, thus reducing the potential mtSSB-ssDNA interaction sites.
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Affiliation(s)
- Martial Martucci
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
| | - Amandine Moretton
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
| | - Aleix Tarrés-Solé
- Structural MitoLab, Molecular Biology Institute Barcelona (IBMB-CSIC), Barcelona Science Park, Barcelona 08028, Spain
| | - Virginie Ropars
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Louise Lambert
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, SE-405 30 Gothenburg, Sweden
| | - Patrick Vernet
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
| | - Maria Solà
- Structural MitoLab, Molecular Biology Institute Barcelona (IBMB-CSIC), Barcelona Science Park, Barcelona 08028, Spain
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, SE-405 30 Gothenburg, Sweden
| | - Geraldine Farge
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
| | - Siet van den Wildenberg
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
- Université Clermont Auvergne, CNRS, IRD, Université Jean Monnet Saint Etienne, LMV, F-63000 Clermont-Ferrand, France
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2
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Bernardino Gomes TM, Vincent AE, Menger KE, Stewart JB, Nicholls TJ. Mechanisms and pathologies of human mitochondrial DNA replication and deletion formation. Biochem J 2024; 481:683-715. [PMID: 38804971 DOI: 10.1042/bcj20230262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 05/13/2024] [Accepted: 05/14/2024] [Indexed: 05/29/2024]
Abstract
Human mitochondria possess a multi-copy circular genome, mitochondrial DNA (mtDNA), that is essential for cellular energy metabolism. The number of copies of mtDNA per cell, and their integrity, are maintained by nuclear-encoded mtDNA replication and repair machineries. Aberrant mtDNA replication and mtDNA breakage are believed to cause deletions within mtDNA. The genomic location and breakpoint sequences of these deletions show similar patterns across various inherited and acquired diseases, and are also observed during normal ageing, suggesting a common mechanism of deletion formation. However, an ongoing debate over the mechanism by which mtDNA replicates has made it difficult to develop clear and testable models for how mtDNA rearrangements arise and propagate at a molecular and cellular level. These deletions may impair energy metabolism if present in a high proportion of the mtDNA copies within the cell, and can be seen in primary mitochondrial diseases, either in sporadic cases or caused by autosomal variants in nuclear-encoded mtDNA maintenance genes. These mitochondrial diseases have diverse genetic causes and multiple modes of inheritance, and show notoriously broad clinical heterogeneity with complex tissue specificities, which further makes establishing genotype-phenotype relationships challenging. In this review, we aim to cover our current understanding of how the human mitochondrial genome is replicated, the mechanisms by which mtDNA replication and repair can lead to mtDNA instability in the form of large-scale rearrangements, how rearranged mtDNAs subsequently accumulate within cells, and the pathological consequences when this occurs.
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Affiliation(s)
- Tiago M Bernardino Gomes
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- NHS England Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, U.K
| | - Amy E Vincent
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Katja E Menger
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - James B Stewart
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Thomas J Nicholls
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
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3
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Eshraghi R, Shafie D, Raisi A, Goleij P, Mirzaei H. Circular RNAs: a small piece in the heart failure puzzle. Funct Integr Genomics 2024; 24:102. [PMID: 38760573 DOI: 10.1007/s10142-024-01386-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Revised: 04/15/2024] [Accepted: 05/13/2024] [Indexed: 05/19/2024]
Abstract
Cardiovascular disease, specifically heart failure (HF), remains a significant concern in the realm of healthcare, necessitating the development of new treatments and biomarkers. The RNA family consists of various subgroups, including microRNAs, PIWI-interacting RNAs (piRAN) and long non-coding RNAs, which have shown potential in advancing personalized healthcare for HF patients. Recent research suggests that circular RNAs, a lesser-known subgroup of RNAs, may offer a novel set of targets and biomarkers for HF. This review will discuss the biogenesis of circular RNAs, their unique characteristics relevant to HF, their role in heart function, and their potential use as biomarkers in the bloodstream. Furthermore, future research directions in this field will be outlined. The stability of exosomal circRNAs makes them suitable as biomarkers, pathogenic regulators, and potential treatments for cardiovascular diseases such as atherosclerosis, acute coronary syndrome, ischemia/reperfusion injury, HF, and peripheral artery disease. Herein, we summarized the role of circular RNAs and their exosomal forms in HF diseases.
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Affiliation(s)
- Reza Eshraghi
- Student Research Committee, Kashan University of Medical Sciences, Kashan, Iran
| | - Davood Shafie
- Heart Failure Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Arash Raisi
- Student Research Committee, Kashan University of Medical Sciences, Kashan, Iran
| | - Pouya Goleij
- Department of Genetics, Faculty of Biology, Sana Institute of Higher Education, Sari, Iran.
- USERN Office, Kermanshah University of Medical Sciences, Kermanshah, Iran.
| | - Hamed Mirzaei
- Research Center for Biochemistry and Nutrition in Metabolic Diseases, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran.
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Tan DX. Mitochondrial dysfunction, a weakest link of network of aging, relation to innate intramitochondrial immunity of DNA recognition receptors. Mitochondrion 2024; 76:101886. [PMID: 38663836 DOI: 10.1016/j.mito.2024.101886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Revised: 04/21/2024] [Accepted: 04/22/2024] [Indexed: 04/30/2024]
Abstract
Aging probably is the most complexed process in biology. It is manifested by a variety of hallmarks. These hallmarks weave a network of aging; however, each hallmark is not uniformly strong for the network. It is the weakest link determining the strengthening of the network of aging, or the maximum lifespan of an organism. Therefore, only improvement of the weakest link has the chance to increase the maximum lifespan but not others. We hypothesize that mitochondrial dysfunction is the weakest link of the network of aging. It may origin from the innate intramitochondrial immunity related to the activities of pathogen DNA recognition receptors. These receptors recognize mtDNA as the PAMP or DAMP to initiate the immune or inflammatory reactions. Evidence has shown that several of these receptors including TLR9, cGAS and IFI16 can be translocated into mitochondria. The potentially intramitochondrial presented pathogen DNA recognition receptors have the capacity to attack the exposed second structures of the mtDNA during its transcriptional or especially the replicational processes, leading to the mtDNA mutation, deletion, heteroplasmy colonization, mitochondrial dysfunction, and alterations of other hallmarks, as well as aging. Pre-consumption of the intramitochondrial presented pathogen DNA recognition receptors by medical interventions including development of mitochondrial targeted small molecule which can neutralize these receptors may retard or even reverse the aging to significantly improve the maximum lifespan of the organisms.
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Affiliation(s)
- Dun-Xian Tan
- Department of Cell Systems and Anatomy, UT Health San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
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Johnson KA. You get what you screen for: Standards for experimental design and data fitting in drug discovery. Methods Enzymol 2023; 690:131-157. [PMID: 37858528 DOI: 10.1016/bs.mie.2023.08.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
A common mantra in drug discovery is that "You get what you screen for." This is not a promise that you will always get an effective drug candidate, but rather a warning that inaccuracies in your protocol for screening will more likely produce a compound that fails to be an effective candidate because it matches the properties of your screen, not the desired features of an ideal lead compound. It is with this in mind that we examine the current protocols for evaluating drug candidates and highlight some deficiencies while pointing the way to better methods. Many of the errors in data fitting can be rectified by abandoning the traditional equation-based data fitting methods and adopting the more rigorous mechanism-based fitting afforded by computer simulation based on numerical integration of rate equations. Using these methods bypasses the errors in judgement in choosing the appropriate equation for data fitting and the approximations required to derive those equations. In this chapter we outline the limitations and systematic errors in conventional methods of data fitting and illustrate the advantages of computer simulation and introduce the methods of analysis.
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Affiliation(s)
- Kenneth A Johnson
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, United States.
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6
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Johnson KA. History of advances in enzyme kinetic methods: From minutes to milliseconds. Enzymes 2023; 54:107-134. [PMID: 37945168 DOI: 10.1016/bs.enz.2023.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
The last review on transient-state kinetic methods in The Enzymes was published three decades ago (Johnson, K.A., 1992. The Enzymes, XX, 1-61). In that review the foundations were laid out for the logic behind the design and interpretation of experiments. In the intervening years the instrumentation has improved mainly in providing better sample economy and shorter dead times. More significantly, in 1992 we were just introducing methods for fitting data based on numerical integration of rate equations, but the software was slow and difficult to use. Today, advances in numerical integration methods for data fitting have led to fast and dynamic software, making it easy to fit data without simplifying approximations. This approach overcomes multiple disadvantages of traditional data fitting based on equations derived by analytical integration of rate equations, requiring simplifying approximations. Mechanism-based fitting using computer simulation resolves mechanisms by accounting for the concentration dependence of the rates and amplitudes of the reaction to find a set of intrinsic rate constants that reproduce the experimental data, including details about how the experiment was performed in modeling the data. Rather than discuss how to design and interpret rapid-quench and stopped-flow experiments individually, we now focus on how to fit them simultaneously so that the quench-flow data anchor the interpretation of fluorescence signals. Computer simulation streamlines the fitting of multiple experiments globally to yield a single unifying model to account for all available data.
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Affiliation(s)
- Kenneth A Johnson
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, United States.
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7
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Irvin EM, Wang H. Single-molecule imaging of genome maintenance proteins encountering specific DNA sequences and structures. DNA Repair (Amst) 2023; 128:103528. [PMID: 37392578 PMCID: PMC10989508 DOI: 10.1016/j.dnarep.2023.103528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Revised: 06/08/2023] [Accepted: 06/21/2023] [Indexed: 07/03/2023]
Abstract
DNA repair pathways are tightly regulated processes that recognize specific hallmarks of DNA damage and coordinate lesion repair through discrete mechanisms, all within the context of a three-dimensional chromatin landscape. Dysregulation or malfunction of any one of the protein constituents in these pathways can contribute to aging and a variety of diseases. While the collective action of these many proteins is what drives DNA repair on the organismal scale, it is the interactions between individual proteins and DNA that facilitate each step of these pathways. In much the same way that ensemble biochemical techniques have characterized the various steps of DNA repair pathways, single-molecule imaging (SMI) approaches zoom in further, characterizing the individual protein-DNA interactions that compose each pathway step. SMI techniques offer the high resolving power needed to characterize the molecular structure and functional dynamics of individual biological interactions on the nanoscale. In this review, we highlight how our lab has used SMI techniques - traditional atomic force microscopy (AFM) imaging in air, high-speed AFM (HS-AFM) in liquids, and the DNA tightrope assay - over the past decade to study protein-nucleic acid interactions involved in DNA repair, mitochondrial DNA replication, and telomere maintenance. We discuss how DNA substrates containing specific DNA sequences or structures that emulate DNA repair intermediates or telomeres were generated and validated. For each highlighted project, we discuss novel findings made possible by the spatial and temporal resolution offered by these SMI techniques and unique DNA substrates.
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Affiliation(s)
| | - Hong Wang
- Toxicology Program, North Carolina State University, Raleigh, NC, USA; Physics Department, North Carolina State University, Raleigh, NC, USA; Center for Human Health and the Environment, North Carolina State University, Raleigh, NC, USA.
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8
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Plaza-G A I, Lemishko KM, Crespo R, Truong TQ, Kaguni LS, Cao-García FJ, Ciesielski GL, Ibarra B. Mechanism of strand displacement DNA synthesis by the coordinated activities of human mitochondrial DNA polymerase and SSB. Nucleic Acids Res 2023; 51:1750-1765. [PMID: 36744436 PMCID: PMC9976888 DOI: 10.1093/nar/gkad037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 12/16/2022] [Accepted: 01/12/2023] [Indexed: 02/07/2023] Open
Abstract
Many replicative DNA polymerases couple DNA replication and unwinding activities to perform strand displacement DNA synthesis, a critical ability for DNA metabolism. Strand displacement is tightly regulated by partner proteins, such as single-stranded DNA (ssDNA) binding proteins (SSBs) by a poorly understood mechanism. Here, we use single-molecule optical tweezers and biochemical assays to elucidate the molecular mechanism of strand displacement DNA synthesis by the human mitochondrial DNA polymerase, Polγ, and its modulation by cognate and noncognate SSBs. We show that Polγ exhibits a robust DNA unwinding mechanism, which entails lowering the energy barrier for unwinding of the first base pair of the DNA fork junction, by ∼55%. However, the polymerase cannot prevent the reannealing of the parental strands efficiently, which limits by ∼30-fold its strand displacement activity. We demonstrate that SSBs stimulate the Polγ strand displacement activity through several mechanisms. SSB binding energy to ssDNA additionally increases the destabilization energy at the DNA junction, by ∼25%. Furthermore, SSB interactions with the displaced ssDNA reduce the DNA fork reannealing pressure on Polγ, in turn promoting the productive polymerization state by ∼3-fold. These stimulatory effects are enhanced by species-specific functional interactions and have significant implications in the replication of the human mitochondrial DNA.
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Affiliation(s)
- Ismael Plaza-G A
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia, Faraday 9, 28049 Madrid, Spain
| | - Kateryna M Lemishko
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia, Faraday 9, 28049 Madrid, Spain
| | - Rodrigo Crespo
- Departamento de Estructura de la Materia, Física Térmica y Electrónica, Universidad Complutense de Madrid, Pza. de Ciencias, 1, 28040 Madrid, Spain
| | - Thinh Q Truong
- Department of Chemistry, Auburn University at Montgomery, Montgomery, AL 36117, USA
| | - Laurie S Kaguni
- Department of Biochemistry and Molecular Biology and Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, MI 48823, USA
| | - Francisco J Cao-García
- Departamento de Estructura de la Materia, Física Térmica y Electrónica, Universidad Complutense de Madrid, Pza. de Ciencias, 1, 28040 Madrid, Spain
| | - Grzegorz L Ciesielski
- Department of Chemistry, Auburn University at Montgomery, Montgomery, AL 36117, USA.,Department of Biochemistry and Molecular Biology and Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, MI 48823, USA
| | - Borja Ibarra
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia, Faraday 9, 28049 Madrid, Spain.,Nanobiotecnología (IMDEA-Nanociencia), Unidad Asociada al Centro Nacional de Biotecnología (CSIC), 28049 Madrid, Spain
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9
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Lu D, Chatterjee S, Xiao K, Riedel I, Huang CK, Costa A, Cushman S, Neufeldt D, Rode L, Schmidt A, Juchem M, Leonardy J, Büchler G, Blume J, Gern OL, Kalinke U, Wen Tan WL, Foo R, Vink A, van Laake LW, van der Meer P, Bär C, Thum T. A circular RNA derived from the insulin receptor locus protects against doxorubicin-induced cardiotoxicity. Eur Heart J 2022; 43:4496-4511. [PMID: 35758064 PMCID: PMC9637424 DOI: 10.1093/eurheartj/ehac337] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 03/30/2022] [Accepted: 06/09/2022] [Indexed: 12/14/2022] Open
Abstract
AIMS Cardiotoxicity leading to heart failure (HF) is a growing problem in many cancer survivors. As specific treatment strategies are not available, RNA discovery pipelines were employed and a new and powerful circular RNA (circRNA)-based therapy was developed for the treatment of doxorubicin-induced HF. METHODS AND RESULTS The circRNA sequencing was applied and the highly species-conserved circRNA insulin receptor (Circ-INSR) was identified, which participates in HF processes, including those provoked by cardiotoxic anti-cancer treatments. Chemotherapy-provoked cardiotoxicity leads to the down-regulation of Circ-INSR in rodents and patients, which mechanistically contributes to cardiomyocyte cell death, cardiac dysfunction, and mitochondrial damage. In contrast, Circ-INSR overexpression prevented doxorubicin-mediated cardiotoxicity in both rodent and human cardiomyocytes in vitro and in a mouse model of chronic doxorubicin cardiotoxicity. Breast cancer type 1 susceptibility protein (Brca1) was identified as a regulator of Circ-INSR expression. Detailed transcriptomic and proteomic analyses revealed that Circ-INSR regulates apoptotic and metabolic pathways in cardiomyocytes. Circ-INSR physically interacts with the single-stranded DNA-binding protein (SSBP1) mediating its cardioprotective effects under doxorubicin stress. Importantly, in vitro transcribed and circularized Circ-INSR mimics also protected against doxorubicin-induced cardiotoxicity. CONCLUSION Circ-INSR is a highly conserved non-coding RNA which is down-regulated during cardiotoxicity and cardiac remodelling. Adeno-associated virus and circRNA mimics-based Circ-INSR overexpression prevent and reverse doxorubicin-mediated cardiomyocyte death and improve cardiac function. The results of this study highlight a novel and translationally important Circ-INSR-based therapeutic approach for doxorubicin-induced cardiac dysfunction.
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Affiliation(s)
| | | | | | - Isabelle Riedel
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Cheng-Kai Huang
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Alessia Costa
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany,REBIRTH Center for Translational Regenerative Medicine, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Sarah Cushman
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Dimyana Neufeldt
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Laura Rode
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Arne Schmidt
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Malte Juchem
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Julia Leonardy
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Gwen Büchler
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Jonas Blume
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Olivia-Luise Gern
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, Feodor-Lynen-Straße 7, Hannover 30625, Germany,Department of Pathology, University of Veterinary Medicine Hannover, Foundation, Bünteweg 2, Hannover 30559, Germany
| | - Ulrich Kalinke
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, Feodor-Lynen-Straße 7, Hannover 30625, Germany,Cluster of Excellence—Resolving Infection Susceptibility (RESIST), Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Wilson Lek Wen Tan
- Cardiovascular Disease Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Centre for Translational Medicine, 14 Medical Drive, Level 8, Singapore 117599, Republic of Singapore
| | - Roger Foo
- Cardiovascular Disease Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Centre for Translational Medicine, 14 Medical Drive, Level 8, Singapore 117599, Republic of Singapore
| | - Aryan Vink
- Department of Pathology, University Medical Center Utrecht, Heidelberglaan 100, Utrecht 3584, The Netherlands
| | - Linda W van Laake
- Department of Cardiology and Regenerative Medicine Center, University Medical Centre Utrecht, Heidelberglaan 100, Utrecht 3584, The Netherlands
| | - Peter van der Meer
- Department of Cardiology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Groningen 9713, The Netherlands
| | - Christian Bär
- Corresponding authors. Tel: +49 511 532 5272, (T.T.); Tel: +49 511 532 2883, (C.B.)
| | - Thomas Thum
- Corresponding authors. Tel: +49 511 532 5272, (T.T.); Tel: +49 511 532 2883, (C.B.)
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Liu C, Fu Z, Wu S, Wang X, Zhang S, Chu C, Hong Y, Wu W, Chen S, Jiang Y, Wu Y, Song Y, Liu Y, Guo X. Mitochondrial HSF1 triggers mitochondrial dysfunction and neurodegeneration in Huntington's disease. EMBO Mol Med 2022; 14:e15851. [PMID: 35670111 PMCID: PMC9260212 DOI: 10.15252/emmm.202215851] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 05/10/2022] [Accepted: 05/10/2022] [Indexed: 12/18/2022] Open
Affiliation(s)
- Chunyue Liu
- State Key Laboratory of Reproductive Medicine Key Laboratory of Human Functional Genomics of Jiangsu Province Department of Neurobiology Interdisciplinary InnoCenter for Organoids School of Basic Medical Sciences Nanjing Medical University Nanjing China
- State Key Laboratory of Reproductive Medicine Interdisciplinary InnoCenter for Organoids Institute for Stem Cell and Neural Regeneration School of Pharmacy Nanjing Medical University Nanjing China
| | - Zixing Fu
- State Key Laboratory of Reproductive Medicine Key Laboratory of Human Functional Genomics of Jiangsu Province Department of Neurobiology Interdisciplinary InnoCenter for Organoids School of Basic Medical Sciences Nanjing Medical University Nanjing China
| | - Shanshan Wu
- State Key Laboratory of Reproductive Medicine Interdisciplinary InnoCenter for Organoids Institute for Stem Cell and Neural Regeneration School of Pharmacy Nanjing Medical University Nanjing China
| | - Xiaosong Wang
- State Key Laboratory of Reproductive Medicine Key Laboratory of Human Functional Genomics of Jiangsu Province Department of Neurobiology Interdisciplinary InnoCenter for Organoids School of Basic Medical Sciences Nanjing Medical University Nanjing China
| | - Shengrong Zhang
- State Key Laboratory of Reproductive Medicine Key Laboratory of Human Functional Genomics of Jiangsu Province Department of Neurobiology Interdisciplinary InnoCenter for Organoids School of Basic Medical Sciences Nanjing Medical University Nanjing China
| | - Chu Chu
- State Key Laboratory of Reproductive Medicine Interdisciplinary InnoCenter for Organoids Institute for Stem Cell and Neural Regeneration School of Pharmacy Nanjing Medical University Nanjing China
| | - Yuan Hong
- State Key Laboratory of Reproductive Medicine Interdisciplinary InnoCenter for Organoids Institute for Stem Cell and Neural Regeneration School of Pharmacy Nanjing Medical University Nanjing China
| | - Wenbo Wu
- State Key Laboratory of Reproductive Medicine Key Laboratory of Human Functional Genomics of Jiangsu Province Department of Neurobiology Interdisciplinary InnoCenter for Organoids School of Basic Medical Sciences Nanjing Medical University Nanjing China
| | - Shengqi Chen
- State Key Laboratory of Reproductive Medicine Key Laboratory of Human Functional Genomics of Jiangsu Province Department of Neurobiology Interdisciplinary InnoCenter for Organoids School of Basic Medical Sciences Nanjing Medical University Nanjing China
| | - Yueqing Jiang
- State Key Laboratory of Reproductive Medicine Key Laboratory of Human Functional Genomics of Jiangsu Province Department of Neurobiology Interdisciplinary InnoCenter for Organoids School of Basic Medical Sciences Nanjing Medical University Nanjing China
| | - Yang Wu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Key Laboratory of Magnetic Resonance in Biological Systems Wuhan Center for Magnetic Resonance, Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences Wuhan China
| | - Yongbo Song
- Department of Pharmacology Shenyang Pharmaceutical University Shenyang China
| | - Yan Liu
- State Key Laboratory of Reproductive Medicine Interdisciplinary InnoCenter for Organoids Institute for Stem Cell and Neural Regeneration School of Pharmacy Nanjing Medical University Nanjing China
| | - Xing Guo
- State Key Laboratory of Reproductive Medicine Key Laboratory of Human Functional Genomics of Jiangsu Province Department of Neurobiology Interdisciplinary InnoCenter for Organoids School of Basic Medical Sciences Nanjing Medical University Nanjing China
- Department of Endocrinology Sir Run Run Hospital Nanjing Medical University Nanjing Jiangsu China
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11
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Review on the applications of atomic force microscopy imaging in proteins. Micron 2022; 159:103293. [DOI: 10.1016/j.micron.2022.103293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 04/22/2022] [Accepted: 05/06/2022] [Indexed: 11/19/2022]
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12
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Kaur P, Barnes R, Pan H, Detwiler AC, Liu M, Mahn C, Hall J, Messenger Z, You C, Piehler J, Smart R, Riehn R, Opresko PL, Wang H. TIN2 is an architectural protein that facilitates TRF2-mediated trans- and cis-interactions on telomeric DNA. Nucleic Acids Res 2021; 49:13000-13018. [PMID: 34883513 PMCID: PMC8682769 DOI: 10.1093/nar/gkab1142] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 12/08/2021] [Indexed: 12/23/2022] Open
Abstract
The telomere specific shelterin complex, which includes TRF1, TRF2, RAP1, TIN2, TPP1 and POT1, prevents spurious recognition of telomeres as double-strand DNA breaks and regulates telomerase and DNA repair activities at telomeres. TIN2 is a key component of the shelterin complex that directly interacts with TRF1, TRF2 and TPP1. In vivo, the large majority of TRF1 and TRF2 are in complex with TIN2 but without TPP1 and POT1. Since knockdown of TIN2 also removes TRF1 and TRF2 from telomeres, previous cell-based assays only provide information on downstream effects after the loss of TRF1/TRF2 and TIN2. Here, we investigated DNA structures promoted by TRF2-TIN2 using single-molecule imaging platforms, including tracking of compaction of long mouse telomeric DNA using fluorescence imaging, atomic force microscopy (AFM) imaging of protein-DNA structures, and monitoring of DNA-DNA and DNA-RNA bridging using the DNA tightrope assay. These techniques enabled us to uncover previously unknown unique activities of TIN2. TIN2S and TIN2L isoforms facilitate TRF2-mediated telomeric DNA compaction (cis-interactions), dsDNA-dsDNA, dsDNA-ssDNA and dsDNA-ssRNA bridging (trans-interactions). Furthermore, TIN2 facilitates TRF2-mediated T-loop formation. We propose a molecular model in which TIN2 functions as an architectural protein to promote TRF2-mediated trans and cis higher-order nucleic acid structures at telomeres.
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Affiliation(s)
- Parminder Kaur
- Physics Department, North Carolina State University, Raleigh, NC27695, USA
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC 27695, USA
| | - Ryan Barnes
- Department of Environmental and Occupational Health, University of Pittsburgh, UPMC Hillman Cancer Center, PA 15213, USA
| | - Hai Pan
- Physics Department, North Carolina State University, Raleigh, NC27695, USA
| | - Ariana C Detwiler
- Department of Environmental and Occupational Health, University of Pittsburgh, UPMC Hillman Cancer Center, PA 15213, USA
| | - Ming Liu
- Physics Department, North Carolina State University, Raleigh, NC27695, USA
| | - Chelsea Mahn
- Physics Department, North Carolina State University, Raleigh, NC27695, USA
| | - Jonathan Hall
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC 27695, USA
- Toxicology Program, North Carolina State University, Raleigh, NC27695, USA
| | - Zach Messenger
- Toxicology Program, North Carolina State University, Raleigh, NC27695, USA
| | - Changjiang You
- Department of Biology/Chemistry, Universität Osnabrück, Osnabrück 49076, Germany
| | - Jacob Piehler
- Department of Biology/Chemistry, Universität Osnabrück, Osnabrück 49076, Germany
| | - Robert C Smart
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC 27695, USA
- Toxicology Program, North Carolina State University, Raleigh, NC27695, USA
| | - Robert Riehn
- Physics Department, North Carolina State University, Raleigh, NC27695, USA
| | - Patricia L Opresko
- Department of Environmental and Occupational Health, University of Pittsburgh, UPMC Hillman Cancer Center, PA 15213, USA
| | - Hong Wang
- Physics Department, North Carolina State University, Raleigh, NC27695, USA
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC 27695, USA
- Toxicology Program, North Carolina State University, Raleigh, NC27695, USA
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13
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Kosar M, Piccini D, Foiani M, Giannattasio M. A rapid method to visualize human mitochondrial DNA replication through rotary shadowing and transmission electron microscopy. Nucleic Acids Res 2021; 49:e121. [PMID: 34500456 PMCID: PMC8643652 DOI: 10.1093/nar/gkab770] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 08/15/2021] [Accepted: 08/26/2021] [Indexed: 11/21/2022] Open
Abstract
We report a rapid experimental procedure based on high-density in vivo psoralen inter-strand DNA cross-linking coupled to spreading of naked purified DNA, positive staining, low-angle rotary shadowing, and transmission electron microscopy (TEM) that allows quick visualization of the dynamic of heavy strand (HS) and light strand (LS) human mitochondrial DNA replication. Replication maps built on linearized mitochondrial genomes and optimized rotary shadowing conditions enable clear visualization of the progression of the mitochondrial DNA synthesis and visualization of replication intermediates carrying long single-strand DNA stretches. One variant of this technique, called denaturing spreading, allowed the inspection of the fine chromatin structure of the mitochondrial genome and was applied to visualize the in vivo three-strand DNA structure of the human mitochondrial D-loop intermediate with unprecedented clarity.
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Affiliation(s)
- Martin Kosar
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milano, Italy
| | - Daniele Piccini
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milano, Italy
| | - Marco Foiani
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milano, Italy.,Dipartimento di Oncologia & Emato-Oncologia, Università degli Studi di Milano, Milano, Italy
| | - Michele Giannattasio
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milano, Italy.,Dipartimento di Oncologia & Emato-Oncologia, Università degli Studi di Milano, Milano, Italy
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14
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Jurkute N, D'Esposito F, Robson AG, Pitceathly RDS, Cordeiro F, Raymond FL, Moore AT, Michaelides M, Yu-Wai-Man P, Webster AR, Arno G. SSBP1-Disease Update: Expanding the Genetic and Clinical Spectrum, Reporting Variable Penetrance and Confirming Recessive Inheritance. Invest Ophthalmol Vis Sci 2021; 62:12. [PMID: 34905022 PMCID: PMC8684315 DOI: 10.1167/iovs.62.15.12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 11/19/2021] [Indexed: 11/24/2022] Open
Abstract
Purpose To report novel genotypes and expand the phenotype spectrum of SSBP1-disease and explore potential disease mechanism. Methods Five families with previously unsolved optic atrophy and retinal dystrophy underwent whole genome sequencing as part of the National Institute for Health Research BioResource Rare-Diseases and the UK's 100,000 Genomes Project. In silico analysis and protein modelling was performed on the identified variants. Deep phenotyping including retinal imaging and International Society for Clinical Electrophysiology of Vision standard visual electrophysiology was performed. Results Seven individuals from five unrelated families with bilateral optic atrophy and/or retinal dystrophy with extraocular signs and symptoms in some are described. In total, 6 SSBP1 variants were identified including the previously unreported variants: c.151A>G, p.(Lys51Glu), c.335G>A p.(Gly112Glu), and c.380G>A, p.(Arg127Gln). One individual was found to carry biallelic variants (c.380G>A p.(Arg127Gln); c.394A>G p.(Ile132Val)) associated with likely autosomal recessive SSBP1-disease. In silico analysis predicted all variants to be pathogenic and Three-dimensional protein modelling suggested possible disease mechanisms via decreased single-stranded DNA binding affinity or impaired higher structure formation. Conclusions SSBP1 is essential for mitochondrial DNA replication and maintenance, with defects leading to a spectrum of disease that includes optic atrophy and/or retinal dystrophy, occurring with or without extraocular features. This study provides evidence of intrafamilial variability and confirms the existence of an autosomal recessive inheritance in SSBP1-disease consequent upon a previously unreported genotype.
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Affiliation(s)
- Neringa Jurkute
- Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
- Institute of Ophthalmology, University College London, London, United Kingdom
| | - Fabiana D'Esposito
- Imperial College Ophthalmic Research Unit, Western Eye Hospital, Imperial College Healthcare NHS Trust, London, United Kingdom
- Eye Clinic, Department of Neurosciences, Reproductive Sciences and Dentistry, Federico II University, Naples, Italy
| | - Anthony G. Robson
- Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
- Institute of Ophthalmology, University College London, London, United Kingdom
| | - Robert D. S. Pitceathly
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, United Kingdom
| | - Francesca Cordeiro
- Imperial College Ophthalmic Research Unit, Western Eye Hospital, Imperial College Healthcare NHS Trust, London, United Kingdom
| | - F. Lucy Raymond
- NIHR BioResource - Rare Diseases, Cambridge University Hospitals NHS Foundation Trust, Cambridge Biomedical Campus, Cambridge, United Kingdom
- Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Anthony T. Moore
- Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
- Institute of Ophthalmology, University College London, London, United Kingdom
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California, United States
| | - Michel Michaelides
- Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
- Institute of Ophthalmology, University College London, London, United Kingdom
| | - Patrick Yu-Wai-Man
- Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
- Institute of Ophthalmology, University College London, London, United Kingdom
- Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, United Kingdom
- John van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Andrew R. Webster
- Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
- Institute of Ophthalmology, University College London, London, United Kingdom
| | - Gavin Arno
- Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
- Institute of Ophthalmology, University College London, London, United Kingdom
- North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - for the Genomics England Research Consortium
- Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
- Institute of Ophthalmology, University College London, London, United Kingdom
- Imperial College Ophthalmic Research Unit, Western Eye Hospital, Imperial College Healthcare NHS Trust, London, United Kingdom
- Eye Clinic, Department of Neurosciences, Reproductive Sciences and Dentistry, Federico II University, Naples, Italy
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, United Kingdom
- NIHR BioResource - Rare Diseases, Cambridge University Hospitals NHS Foundation Trust, Cambridge Biomedical Campus, Cambridge, United Kingdom
- Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California, United States
- Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, United Kingdom
- John van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
- North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
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15
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Gustafson MA, Perera L, Shi M, Copeland WC. Mechanisms of SSBP1 variants in mitochondrial disease: Molecular dynamics simulations reveal stable tetramers with altered DNA binding surfaces. DNA Repair (Amst) 2021; 107:103212. [PMID: 34464898 PMCID: PMC8526412 DOI: 10.1016/j.dnarep.2021.103212] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 08/13/2021] [Indexed: 11/18/2022]
Abstract
Several mutations in the gene for the mitochondrial single stranded DNA binding protein (SSBP1) have recently been implicated in human disease, but initial reports are insufficient to explain the molecular mechanism of disease, including the possible role of SSBP1 heterotetramers in heterozygous patients. Here we employed molecular simulations to model the dynamics of wild type and 31 variant SSBP1 tetramer systems, including 7 variant homotetramer and 24 representative heterotetramer systems. Our simulations indicate that all variants are stable and most have stronger intermonomer interactions, reduced solvent accessible surface areas, and a net loss of positive surface charge. We then used structural alignments and phosphate binding simulations to predict DNA binding surfaces on SSBP1. Our models suggest that nearly the entire surface of SSBP1, excluding flexible loops and protruding helices, is available for DNA binding, and we observed several potential DNA binding hotspots. Changes to the protein surface in variant SSBP1 tetramers potentially alter anchor points or wrapping paths, rather than abolishing binding altogether. Overall, our findings disqualify tetramer destabilization or gross disruption of DNA binding as mechanisms of disease. Instead, they are consistent with subtle changes to DNA binding, wrapping, or release that cause rare but consequential failures of mtDNA maintenance, which, in turn, are consistent with the late onset of disease in most of the reported SSBP1 cases.
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Affiliation(s)
- Margaret A Gustafson
- Mitochondrial DNA Replication Group, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC, 27709, USA
| | - Lalith Perera
- Computational Chemistry and Molecular Modeling Support Group, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC, 27709, USA
| | - Min Shi
- Biostatistics and Computational Biology Branch, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC, 27709, USA
| | - William C Copeland
- Mitochondrial DNA Replication Group, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC, 27709, USA.
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16
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Kaur P, Pan H, Longley MJ, Copeland WC, Wang H. Using Atomic Force Microscopy to Study the Real Time Dynamics of DNA Unwinding by Mitochondrial Twinkle Helicase. Bio Protoc 2021; 11:e4139. [PMID: 34604445 DOI: 10.21769/bioprotoc.4139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 05/23/2021] [Accepted: 06/29/2021] [Indexed: 12/06/2022] Open
Abstract
Understanding the structure and dynamics of DNA-protein interactions during DNA replication is crucial for elucidating the origins of disorders arising from its dysfunction. In this study, we employed Atomic Force Microscopy as a single-molecule imaging tool to examine the mitochondrial DNA helicase Twinkle and its interactions with DNA. We used imaging in air and time-lapse imaging in liquids to observe the DNA binding and unwinding activities of Twinkle hexamers at the single-molecule level. These procedures helped us visualize Twinkle loading onto and unloading from the DNA in the open-ring conformation. Using traditional methods, it has been shown that Twinkle is capable of unwinding dsDNA up to 20-55 bps. We found that the addition of mitochondrial single-stranded DNA binding protein (mtSSB) facilitates a 5-fold increase in the DNA unwinding rate for the Twinkle helicase. The protocols developed in this study provide new platforms to examine DNA replication and to explore the mechanism driving DNA deletion and human diseases. Graphic abstract: Mitochondrial Twinkle Helicase Dynamics.
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Affiliation(s)
- Parminder Kaur
- Physics Department, North Carolina State University, Raleigh, North Carolina, USA.,Center for Human Health and the Environment, North Carolina State University, Raleigh, North Carolina, USA
| | - Hai Pan
- Physics Department, North Carolina State University, Raleigh, North Carolina, USA
| | - Matthew J Longley
- Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - William C Copeland
- Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - Hong Wang
- Physics Department, North Carolina State University, Raleigh, North Carolina, USA.,Center for Human Health and the Environment, North Carolina State University, Raleigh, North Carolina, USA.,Toxicology Program, North Carolina State University, Raleigh, North Carolina, USA
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17
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Sullivan ED, Longley MJ, Copeland WC. Polymerase γ efficiently replicates through many natural template barriers but stalls at the HSP1 quadruplex. J Biol Chem 2021; 295:17802-17815. [PMID: 33454015 DOI: 10.1074/jbc.ra120.015390] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 10/05/2020] [Indexed: 12/27/2022] Open
Abstract
Faithful replication of the mitochondrial genome is carried out by a set of key nuclear-encoded proteins. DNA polymerase γ is a core component of the mtDNA replisome and the only replicative DNA polymerase localized to mitochondria. The asynchronous mechanism of mtDNA replication predicts that the replication machinery encounters dsDNA and unique physical barriers such as structured genes, G-quadruplexes, and other obstacles. In vitro experiments here provide evidence that the polymerase γ heterotrimer is well-adapted to efficiently synthesize DNA, despite the presence of many naturally occurring roadblocks. However, we identified a specific G-quadruplex-forming sequence at the heavy-strand promoter (HSP1) that has the potential to cause significant stalling of mtDNA replication. Furthermore, this structured region of DNA corresponds to the break site for a large (3,895 bp) deletion observed in mitochondrial disease patients. The presence of this deletion in humans correlates with UV exposure, and we have found that efficiency of polymerase γ DNA synthesis is reduced after this quadruplex is exposed to UV in vitro.
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Affiliation(s)
- Eric D Sullivan
- Mitochondrial DNA Replication Group, Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - Matthew J Longley
- Mitochondrial DNA Replication Group, Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - William C Copeland
- Mitochondrial DNA Replication Group, Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina, USA.
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18
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Oliveira MT, Ciesielski GL. The Essential, Ubiquitous Single-Stranded DNA-Binding Proteins. Methods Mol Biol 2021; 2281:1-21. [PMID: 33847949 DOI: 10.1007/978-1-0716-1290-3_1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Maintenance of genomes is fundamental for all living organisms. The diverse processes related to genome maintenance entail the management of various intermediate structures, which may be deleterious if unresolved. The most frequent intermediate structures that result from the melting of the DNA duplex are single-stranded (ss) DNA stretches. These are thermodynamically less stable and can spontaneously fold into secondary structures, which may obstruct a variety of genome processes. In addition, ssDNA is more prone to breaking, which may lead to the formation of deletions or DNA degradation. Single-stranded DNA-binding proteins (SSBs) bind and stabilize ssDNA, preventing the abovementioned deleterious consequences and recruiting the appropriate machinery to resolve that intermediate molecule. They are present in all forms of life and are essential for their viability, with very few exceptions. Here we present an introductory chapter to a volume of the Methods in Molecular Biology dedicated to SSBs, in which we provide a general description of SSBs from various taxa.
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Affiliation(s)
- Marcos T Oliveira
- Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista "Júlio de Mesquita Filho", Jaboticabal, SP, Brazil
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19
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Falkenberg M, Gustafsson CM. Mammalian mitochondrial DNA replication and mechanisms of deletion formation. Crit Rev Biochem Mol Biol 2020; 55:509-524. [DOI: 10.1080/10409238.2020.1818684] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Claes M. Gustafsson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
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20
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Dynamic human MutSα-MutLα complexes compact mismatched DNA. Proc Natl Acad Sci U S A 2020; 117:16302-16312. [PMID: 32586954 DOI: 10.1073/pnas.1918519117] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
DNA mismatch repair (MMR) corrects errors that occur during DNA replication. In humans, mutations in the proteins MutSα and MutLα that initiate MMR cause Lynch syndrome, the most common hereditary cancer. MutSα surveilles the DNA, and upon recognition of a replication error it undergoes adenosine triphosphate-dependent conformational changes and recruits MutLα. Subsequently, proliferating cell nuclear antigen (PCNA) activates MutLα to nick the error-containing strand to allow excision and resynthesis. The structure-function properties of these obligate MutSα-MutLα complexes remain mostly unexplored in higher eukaryotes, and models are predominately based on studies of prokaryotic proteins. Here, we utilize atomic force microscopy (AFM) coupled with other methods to reveal time- and concentration-dependent stoichiometries and conformations of assembling human MutSα-MutLα-DNA complexes. We find that they assemble into multimeric complexes comprising three to eight proteins around a mismatch on DNA. On the timescale of a few minutes, these complexes rearrange, folding and compacting the DNA. These observations contrast with dominant models of MMR initiation that envision diffusive MutS-MutL complexes that move away from the mismatch. Our results suggest MutSα localizes MutLα near the mismatch and promotes DNA configurations that could enhance MMR efficiency by facilitating MutLα nicking the DNA at multiple sites around the mismatch. In addition, such complexes may also protect the mismatch region from nucleosome reassembly until repair occurs, and they could potentially remodel adjacent nucleosomes.
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21
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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.
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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.
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22
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Cerrón F, de Lorenzo S, Lemishko KM, Ciesielski GL, Kaguni LS, Cao FJ, Ibarra B. Replicative DNA polymerases promote active displacement of SSB proteins during lagging strand synthesis. Nucleic Acids Res 2019; 47:5723-5734. [PMID: 30968132 PMCID: PMC6582349 DOI: 10.1093/nar/gkz249] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 03/22/2019] [Accepted: 03/29/2019] [Indexed: 11/23/2022] Open
Abstract
Genome replication induces the generation of large stretches of single-stranded DNA (ssDNA) intermediates that are rapidly protected by single-stranded DNA-binding (SSB) proteins. To date, the mechanism by which tightly bound SSBs are removed from ssDNA by the lagging strand DNA polymerase without compromising the advance of the replication fork remains unresolved. Here, we aimed to address this question by measuring, with optical tweezers, the real-time replication kinetics of the human mitochondrial and bacteriophage T7 DNA polymerases on free-ssDNA, in comparison with ssDNA covered with homologous and non-homologous SSBs under mechanical tension. We find important differences between the force dependencies of the instantaneous replication rates of each polymerase on different substrates. Modeling of the data supports a mechanism in which strong, specific polymerase-SSB interactions, up to ∼12 kBT, are required for the polymerase to dislodge SSB from the template without compromising its instantaneous replication rate, even under stress conditions that may affect SSB–DNA organization and/or polymerase–SSB communication. Upon interaction, the elimination of template secondary structure by SSB binding facilitates the maximum replication rate of the lagging strand polymerase. In contrast, in the absence of polymerase–SSB interactions, SSB poses an effective barrier for the advance of the polymerase, slowing down DNA synthesis.
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Affiliation(s)
- Fernando Cerrón
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia. 28049 Madrid, Spain.,Departamento Estructura de la Materia, Física Térmica y Electrónica. Universidad Complutense. 28040 Madrid, Spain
| | - Sara de Lorenzo
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia. 28049 Madrid, Spain
| | - Kateryna M Lemishko
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia. 28049 Madrid, Spain.,Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia) & CNB-CSIC-IMDEA Nanociencia Associated Unit "Unidad de Nanobiotecnología". 28049 Madrid, Spain
| | - Grzegorz L Ciesielski
- Department of Biochemistry and Molecular Biology and Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, MI 48823, USA
| | - Laurie S Kaguni
- Department of Biochemistry and Molecular Biology and Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, MI 48823, USA
| | - Francisco J Cao
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia. 28049 Madrid, Spain.,Departamento Estructura de la Materia, Física Térmica y Electrónica. Universidad Complutense. 28040 Madrid, Spain
| | - Borja Ibarra
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia. 28049 Madrid, Spain.,Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia) & CNB-CSIC-IMDEA Nanociencia Associated Unit "Unidad de Nanobiotecnología". 28049 Madrid, Spain
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Holt IJ. The mitochondrial R-loop. Nucleic Acids Res 2019; 47:5480-5489. [PMID: 31045202 PMCID: PMC6582354 DOI: 10.1093/nar/gkz277] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 03/11/2019] [Accepted: 04/29/2019] [Indexed: 12/18/2022] Open
Abstract
The DNA in mitochondria contributes essential components of the organelle’s energy producing machinery that is essential for life. In 1971, many mitochondrial DNA molecules were found to have a third strand of DNA that maps to a region containing critical regulatory elements for transcription and replication. Forty-five years later, a third strand of RNA in the same region has been reported. This mitochondrial R-loop is present on thousands of copies of mitochondrial DNA per cell making it potentially the most abundant R-loop in nature. Here, I assess the discovery of the mitochondrial R-loop, discuss why it remained unrecognized for almost half a century and propose for it central roles in the replication, organization and expression of mitochondrial DNA, which if compromised can lead to disease states.
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Affiliation(s)
- Ian J Holt
- Biodonostia Health Research Institute, 20014 San Sebastián, Spain & IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain.,Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Royal Free Campus, London, NW3 2PF, UK.,CIBERNED (Center for Networked Biomedical Research on Neurodegenerative Diseases, Ministry of Economy and Competitiveness, Institute Carlos III), Madrid, Spain
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Gustafson MA, McCormick EM, Perera L, Longley MJ, Bai R, Kong J, Dulik M, Shen L, Goldstein AC, McCormack SE, Laskin BL, Leroy BP, Ortiz-Gonzalez XR, Ellington MG, Copeland WC, Falk MJ. Mitochondrial single-stranded DNA binding protein novel de novo SSBP1 mutation in a child with single large-scale mtDNA deletion (SLSMD) clinically manifesting as Pearson, Kearns-Sayre, and Leigh syndromes. PLoS One 2019; 14:e0221829. [PMID: 31479473 PMCID: PMC6719858 DOI: 10.1371/journal.pone.0221829] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 08/15/2019] [Indexed: 12/04/2022] Open
Abstract
Mitochondrial DNA (mtDNA) genome integrity is essential for proper mitochondrial respiratory chain function to generate cellular energy. Nuclear genes encode several proteins that function at the mtDNA replication fork, including mitochondrial single-stranded DNA-binding protein (SSBP1), which is a tetrameric protein that binds and protects single-stranded mtDNA (ssDNA). Recently, two studies have reported pathogenic variants in SSBP1 associated with hearing loss, optic atrophy, and retinal degeneration. Here, we report a 14-year-old Chinese boy with severe and progressive mitochondrial disease manifestations across the full Pearson, Kearns-Sayre, and Leigh syndromes spectrum, including infantile anemia and bone marrow failure, growth failure, ptosis, ophthalmoplegia, ataxia, severe retinal dystrophy of the rod-cone type, sensorineural hearing loss, chronic kidney disease, multiple endocrine deficiencies, and metabolic strokes. mtDNA genome sequencing identified a single large-scale 5 kilobase mtDNA deletion (m.8629_14068del5440), present at 68% and 16% heteroplasmy in the proband's fibroblast cell line and blood, respectively, suggestive of a mtDNA maintenance defect. On trio whole exome blood sequencing, the proband was found to harbor a novel de novo heterozygous mutation c.79G>A (p.E27K) in SSBP1. Size exclusion chromatography of p.E27K SSBP1 revealed it remains a stable tetramer. However, differential scanning fluorimetry demonstrated p.E27K SSBP1 relative to wild type had modestly decreased thermostability. Functional assays also revealed p.E27K SSBP1 had altered DNA binding. Molecular modeling of SSBP1 tetramers with varying combinations of mutant subunits predicted general changes in surface accessible charges, strength of inter-subunit interactions, and protein dynamics. Overall, the observed changes in protein dynamics and DNA binding behavior suggest that p.E27K SSBP1 can interfere with DNA replication and precipitate the introduction of large-scale mtDNA deletions. Thus, a single large-scale mtDNA deletion (SLSMD) with manifestations across the clinical spectrum of Pearson, Kearns-Sayre, and Leigh syndromes may result from a nuclear gene disorder disrupting mitochondrial DNA replication.
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Affiliation(s)
- Margaret A. Gustafson
- Genome Integrity and Structural Biology Laboratory, NIEHS, NIH, Research Triangle Park, NC, United States of America
| | - Elizabeth M. McCormick
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Lalith Perera
- Genome Integrity and Structural Biology Laboratory, NIEHS, NIH, Research Triangle Park, NC, United States of America
| | - Matthew J. Longley
- Genome Integrity and Structural Biology Laboratory, NIEHS, NIH, Research Triangle Park, NC, United States of America
| | - Renkui Bai
- GeneDx, Gaithersburg, MD, United States of America
| | - Jianping Kong
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Matthew Dulik
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
- Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Lishuang Shen
- Center for Personalized Medicine, Department of Pathology & Laboratory Medicine, Children’s Hospital Los Angeles, Los Angeles, CA, United States of America
| | - Amy C. Goldstein
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
- Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States of America
| | - Shana E. McCormack
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
- Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States of America
- Division of Endocrinology and Diabetes, Children's Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Benjamin L. Laskin
- Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States of America
- Division of Nephrology, Children's Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Bart P. Leroy
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium
- Department of Ophthalmology, Ghent University Hospital, Ghent, Belgium
- Division of Ophthalmology, Children's Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Xilma R. Ortiz-Gonzalez
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Meredith G. Ellington
- Genome Integrity and Structural Biology Laboratory, NIEHS, NIH, Research Triangle Park, NC, United States of America
| | - William C. Copeland
- Genome Integrity and Structural Biology Laboratory, NIEHS, NIH, Research Triangle Park, NC, United States of America
| | - Marni J. Falk
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
- Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States of America
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