Cited by 173Mitochondrial Function and PathologyDNA Repair MechanismsMetabolism and Genetic Disorders

TWINKLE is an essential mitochondrial helicase required for synthesis of nascent D-loop strands and complete mtDNA replication

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Milenkovic, D., Matic, S., Kuhl, I., Ruzzenente, B., Freyer, C., Jemt, E., Park, C. B., Falkenberg, M. +1 more·2013·Human Molecular Genetics

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.

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Authors
Milenkovic, D., Matic, S., Kuhl, I., Ruzzenente, B., Freyer, C., Jemt, E., Park, C. B., Falkenberg, M., & Larsson, N.-G.
Affiliations
  • Max Planck Institute for Biology of Ageing (DE)
  • Karolinska Institutet (SE)
  • University of Gothenburg (SE)
Corresponding author
Larsson, N.-G.
Venue
Human Molecular Genetics
Published
2013-02-07
Volume
22
Issue
10
Pages
1983-1993
ISSN
  • 0964-6906 (ISSN-L)
  • 1460-2083
OpenAlex
W2167764669
Cited by
173
References
52
Citations by year
2026: 11 · 2025: 18 · 2024: 11 · 2023: 1 · 2022: 19 · 2021: 10 · 2020: 13 · 2019: 17 · 2018: 15 · 2017: 12 · 2016: 19 · 2015: 11 · 2014: 9 · 2013: 7
FWCI
6.86
Type
journal article
Language
en
Open access
Licence
cc-by-nc
Locations
  • Human Molecular Genetics (publishedVersion, cc-by-nc)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by-nc)
  • PubMed Central (publishedVersion, cc-by-nc)
  • PubMed (publishedVersion)
  • AJOU Open Repository (Ajou University) (submittedVersion, cc-by-nc)
  • MPG.PuRe (Max Planck Society) (submittedVersion)
Funders
  • Swedish Cancer Foundation
  • Vetenskapsrådet
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Mitochondrial Function and Pathology
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › DNA Repair Mechanisms
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Clinical Biochemistry › Metabolism and Genetic Disorders
Keywords
Twinkle, mitochondrial DNA replication, DNA helicase, D-loop, mtDNA depletion, conditional knockout, mouse embryo development, DNA polymerase gamma, mitochondrial DNA control region, mitochondrial disease
MeSH terms
Animals, DNA Replication, DNA Helicases, DNA, Mitochondrial, Humans, Mutation, Neuromuscular Diseases, Mice, Knockout, Mitochondrial Proteins, Genetic Diseases, Inborn, Mice

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