Deciphering the Foundations of Mitochondrial Mutational Spectra: Replication-Driven and Damage-Induced Signatures...

Area of Science:

• Evolutionary Biology
• Genetics
• Molecular Biology

Background:

• Mitochondrial DNA (mtDNA) mutagenesis is critical for understanding disease, aging, and evolution.
• The precise mechanisms driving mtDNA mutations are not fully elucidated.

Purpose of the Study:

• To reconstruct a comprehensive mtDNA mutational spectrum for chordates.
• To identify the key forces and repair pathway deficiencies influencing mtDNA mutagenesis.

Main Methods:

• Analysis of 118,397 synonymous mutations in the CytB gene across 1,697 chordate species.
• Deconvolution of mutational spectra into distinct mutational signatures.

Main Results:

• Identified three primary forces: replication errors (POLG), damage-driven C>T, and oxidative damage-sensitive A>G mutations.
• Uncovered deficiencies in base excision repair (BER) and mismatch repair (MMR) pathways.
• Single-stranded DNA damage, uncorrected by BER/MMR, contributes substantially to mtDNA mutations.

Conclusions:

• mtDNA mutagenesis is influenced by both replication fidelity and DNA damage.
• The oxidative damage-sensitive component of mtDNA mutagenesis may serve as a marker for metabolic processes.
• Deficiencies in DNA repair pathways exacerbate mutation accumulation.