University of Sussex
Browse

File(s) under permanent embargo

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, Jr
As 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 Genetics

ISSN

0964-6906

Publisher

Oxford University Press

Issue

8

Volume

29

Page range

1292-1309

Event location

England

Department affiliated with

  • Sussex Centre for Genome Damage Stability Publications

Full text available

  • No

Peer reviewed?

  • Yes

Legacy Posted Date

2021-08-25

First Compliant Deposit (FCD) Date

2021-08-24