Recurrent erosion of COA1/MITRAC15 exemplifies conditional gene dispensability in oxidative phosphorylation

Area of Science:

• Evolutionary biology
• Molecular genetics
• Comparative genomics

Background:

• Skeletal muscle fibers utilize either oxidative phosphorylation (OXPHOS) or glycolysis for energy.
• Species with high energy demands often rely more on glycolytic fibers, which have reduced OXPHOS activity and lower mitochondrial content.
• This suggests a potential link between glycolytic fiber dominance and reduced reliance on OXPHOS-related genes.

Purpose of the Study:

• To investigate the hypothesis that gene loss within the OXPHOS pathway occurs in lineages heavily dependent on glycolytic muscle fibers.
• To examine the evolutionary history of the COA1/MITRAC15 gene, which is vital for mitochondrial translation.

Main Methods:

• Comparative genomic analysis of the COA1 gene across various species, including cheetahs, birds, rodents, primates, and marsupials.
• Inspection of genome assemblies to identify gene loss events and chromosomal rearrangements.
• Analysis of COA1 exon structure changes in different mammalian lineages.

Main Results:

• Gene-disrupting mutations and loss of the COA1 gene were observed in cheetahs, galliform birds, and rodents.
• Two independent COA1 gene loss events were identified in rodents and marsupials, coinciding with chromosomal rearrangements.
• Changes in COA1 exon structure were documented in primates and felids.
• The genomic region of COA1 is an evolutionary breakpoint region in mammals.

Conclusions:

• The study reveals recurrent COA1 gene loss and structural changes across diverse species.
• These evolutionary events are linked to skeletal muscle fiber composition and energy demands.
• The findings highlight the dispensability of the COA1 gene's chaperone-like function in certain evolutionary contexts.