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Published on: May 5, 2023
Base Excision Repair in the Mitochondria
Aishwarya Prakash1, Sylvie Doublié1
1Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Stafford Hall, 95 Carrigan Drive, Burlington, Vermont.
Abstract:
The 16.5 kb human mitochondrial genome encodes for 13 polypeptides, 22 tRNAs and 2 rRNAs involved in oxidative phosphorylation. Mitochondrial DNA (mtDNA), unlike its nuclear counterpart, is not packaged into nucleosomes and is more prone to the adverse effects of reactive oxygen species (ROS) generated during oxidative phosphorylation. The past few decades have witnessed an increase in the number of proteins observed to translocate to the mitochondria for the purposes of mitochondrial genome maintenance. The mtDNA damage produced by ROS, if not properly repaired, leads to instability and can ultimately manifest in mitochondrial dysfunction and disease. The base excision repair (BER) pathway is employed for the removal and consequently the repair of deaminated, oxidized, and alkylated DNA bases. Specialized enzymes called DNA glycosylases, which locate and cleave the damaged base, catalyze the first step of this highly coordinated repair pathway. This review focuses on members of the four human BER DNA glycosylase superfamilies and their subcellular localization in the mitochondria and/or the nucleus, as well as summarizes their structural features, biochemical properties, and functional role in the excision of damaged bases.
Insights
Human mitochondrial DNA (mtDNA) is vulnerable to damage from reactive oxygen species (ROS). This review examines DNA glycosylases involved in base excision repair (BER) to maintain mtDNA integrity and prevent mitochondrial dysfunction.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- The human mitochondrial genome (16.5 kb) encodes essential proteins for oxidative phosphorylation.
- Mitochondrial DNA (mtDNA) is susceptible to reactive oxygen species (ROS) damage due to its lack of nucleosomal packaging.
- Accumulated mtDNA damage can lead to mitochondrial dysfunction and disease.
Purpose of the Study:
- To review human base excision repair (BER) DNA glycosylases.
- To detail their subcellular localization (mitochondria and/or nucleus).
- To summarize their structural, biochemical, and functional roles in DNA repair.
Main Methods:
- Literature review of BER DNA glycosylase superfamilies.
- Analysis of subcellular localization data.
- Compilation of structural and biochemical properties.
Main Results:
- Identified four human BER DNA glycosylase superfamilies.
- Detailed their presence in mitochondria and/or nucleus.
- Summarized their roles in excising damaged DNA bases.
Conclusions:
- DNA glycosylases are crucial for repairing ROS-induced mtDNA damage.
- Understanding their localization and function is key to addressing mitochondrial diseases.
- Targeting BER pathways may offer therapeutic strategies for mitochondrial dysfunction.
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