Cited by 148Mitochondrial Function and PathologyDNA Repair MechanismsDNA and Nucleic Acid Chemistry

Expression of catalytic mutants of the mtDNA helicase twinkle and polymerase POLG causes distinct replication stalling phenotypes

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Wanrooij, Sjoerd, Goffart, Steffi, Pohjoismäki, Jaakko L.O., Yasukawa, Takehiro, Spelbrink, Johannes N.·2007·Nucleic Acids Research

Abstract

The mechanism of mitochondrial DNA replication is a subject of intense debate. One model proposes a strand-asynchronous replication in which both strands of the circular genome are replicated semi-independently while the other model proposes both a bidirectional coupled leading- and lagging-strand synthesis mode and a unidirectional mode in which the lagging-strand is initially laid-down as RNA by an unknown mechanism (RITOLS mode). Both the strand-asynchronous and RITOLS model have in common a delayed synthesis of the DNA-lagging strand. Mitochondrial DNA is replicated by a limited set of proteins including DNA polymerase gamma (POLG) and the helicase Twinkle. Here, we report the effects of expression of various catalytically deficient mutants of POLG1 and Twinkle in human cell culture. Both groups of mutants reduced mitochondrial DNA copy number by severe replication stalling. However, the analysis showed that while induction of POLG1 mutants still displayed delayed lagging-strand synthesis, Twinkle-induced stalling resulted in maturated, essentially fully double-stranded DNA intermediates. In the latter case, limited inhibition of POLG with dideoxycytidine restored the delay between leading- and lagging-strand synthesis. The observed cause-effect relationship suggests that Twinkle-induced stalling increases lagging-strand initiation events and/or maturation mimicking conventional strand-coupled replication.

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Authors
Wanrooij, S., Goffart, S., Pohjoismäki, J. L. O., Yasukawa, T., & Spelbrink, J. N.
Affiliations
Tampere University Hospital (FI)
Corresponding author
Spelbrink, Johannes N.
Venue
Nucleic Acids Research
Published
2007-04-22
Volume
35
Issue
10
Pages
3238-3251
ISSN
  • 0305-1048 (ISSN-L)
  • 1362-4962
OpenAlex
W2091937165
Cited by
148
References
52
Citations by year
2026: 3 · 2025: 7 · 2024: 6 · 2023: 2 · 2022: 5 · 2021: 3 · 2020: 4 · 2019: 3 · 2018: 10 · 2017: 10 · 2016: 7 · 2015: 11 · 2014: 6 · 2013: 9 · 2012: 11
FWCI
5.16
Type
journal article
Language
en
Open access
Licence
cc-by-nc
Locations
  • Nucleic Acids Research (publishedVersion, cc-by-nc)
  • PubMed Central (publishedVersion, cc-by-nc)
  • PubMed (publishedVersion)
  • UCL Discovery (University College London) (submittedVersion)
Funders
  • Academy of Finland
  • Tampereen Yliopisto
  • Muscular Dystrophy UK
  • Tays
  • Medical Research Council
  • Japan Society for the Promotion of Science
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 › Molecular Biology › DNA and Nucleic Acid Chemistry
Keywords
mitochondrial DNA replication, Twinkle helicase, POLG1, DNA polymerase gamma, catalytic mutant, replication fork stalling, lagging strand synthesis, mitochondrial DNA copy number, zalcitabine
MeSH terms
DNA Polymerase gamma, Cell Line, DNA-Directed DNA Polymerase, DNA Replication, DNA Helicases, DNA, Mitochondrial, Humans, Mutation, Phenotype, Electrophoresis, Gel, Two-Dimensional, Catalytic Domain, Mitochondrial Proteins

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