Alternative start codon selection shapes mitochondrial function during evolution, homeostasis, and disease.

Area of Science:

• Evolutionary biology
• Cell biology
• Genetics

Background:

• Mitochondrial endosymbiosis was a key event in eukaryotic evolution.
• Core proteins needed to adapt for dual function in host cells and mitochondria.
• Alternate start codon selection generates protein isoforms with varied localization.

Purpose of the Study:

• To systematically profile the localization of protein isoforms produced by alternate start codon selection.
• To investigate the evolutionary and pathological significance of dual-localized mitochondrial protein isoforms.
• To understand the mechanisms maintaining dual-localized isoform production and their role in rare diseases.

Main Methods:

• Systematic profiling of protein isoform localization using alternate start codon selection.
• Analysis of evolutionary emergence of dual-localized isoforms.
• Investigation of mechanisms like leaky ribosome scanning and alternative transcription.
• Identification of isoform dysregulation in rare disease patient mutations.

Main Results:

• Hundreds of differentially-localized protein isoforms identified, impacting mitochondrial targeting and function.
• Emergence of dual-localized mitochondrial isoforms linked to early eukaryotic evolution.
• Diverse mechanisms identified for maintaining dual-localized isoform production.
• Specific isoforms found to be dysregulated by rare disease mutations, explaining clinical presentations.

Conclusions:

• Alternative translation initiation and dual-localized protein isoforms are evolutionarily conserved and vital for mitochondrial function.
• Mechanisms for producing dual-localized isoforms are diverse across eukaryotes.
• Mutations affecting these isoforms offer insights into rare disease pathogenesis and clinical variability.
• This study provides a deeper understanding of mitochondrial biology and the role of alternative translation in evolution and disease.