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Mitochondrial genetic variation is enriched in G-quadruplex regions that stall DNA synthesis in vitro
journal contribution
posted on 2023-06-10, 00:43 authored by Thomas J Butler, Katrina N Estep, Joshua A Sommers, Robert W Maul, Ann Zenobia Moore, Stefania Bandinelli, Francesco Cucca, Marcus A Tuke, Andrew R Wood, Sanjay Kumar Bharti, Daniel F Bogenhagen, Elena Yakubovskaya, Miguel Garcia-Diaz, Thomas A Guilliam, Alicia K Byrd, Kevin D Raney, Aidan DohertyAidan Doherty, Luigi Ferrucci, David Schlessinger, Jun Ding, Robert M Brosh, JrAs the powerhouses of the eukaryotic cell, mitochondria must maintain their genomes which encode proteins essential for energy production. Mitochondria are characterized by guanine-rich DNA sequences that spontaneously form unusual three-dimensional structures known as G-quadruplexes (G4). G4 structures can be problematic for the essential processes of DNA replication and transcription because they deter normal progression of the enzymatic-driven processes. In this study, we addressed the hypothesis that mitochondrial G4 is a source of mutagenesis leading to base-pair substitutions. Our computational analysis of 2757 individual genomes from two Italian population cohorts (SardiNIA and InCHIANTI) revealed a statistically significant enrichment of mitochondrial mutations within sequences corresponding to stable G4 DNA structures. Guided by the computational analysis results, we designed biochemical reconstitution experiments and demonstrated that DNA synthesis by two known mitochondrial DNA polymerases (Pol ?, PrimPol) in vitro was strongly blocked by representative stable G4 mitochondrial DNA structures, which could be overcome in a specific manner by the ATP-dependent G4-resolving helicase Pif1. However, error-prone DNA synthesis by PrimPol using the G4 template sequence persisted even in the presence of Pif1. Altogether, our results suggest that genetic variation is enriched in G-quadruplex regions that impede mitochondrial DNA replication.
History
Publication status
- Published
File Version
- Published version
Journal
Human Molecular GeneticsISSN
0964-6906Publisher
Oxford University PressExternal DOI
Issue
8Volume
29Page range
1292-1309Event location
EnglandDepartment affiliated with
- Sussex Centre for Genome Damage Stability Publications
Full text available
- No
Peer reviewed?
- Yes
Legacy Posted Date
2021-08-25First Compliant Deposit (FCD) Date
2021-08-24Usage metrics
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