Mitochondrial complexome reveals quality-control pathways of protein import

Area of Science:

• Cell Biology
• Biochemistry
• Molecular Biology

Background:

• Mitochondria are vital for cellular energy, metabolism, and quality control, containing approximately 1,000 proteins.
• While the mitochondrial proteome is known, the organization of these proteins into functional assemblies remains poorly understood.
• Understanding protein organization is key to deciphering mitochondrial function and dysfunction.

Purpose of the Study:

• To quantitatively map mitochondrial protein assemblies in yeast.
• To characterize the complexity and organization of the mitochondrial proteome.
• To identify novel interactions and quality control pathways within mitochondria.

Main Methods:

• High-resolution complexome profiling was employed to analyze over 90% of the yeast mitochondrial proteome.
• The resulting dataset, termed MitCOM, allowed for the resolution of over 5,200 protein peaks.
• Bioinformatic analysis identified protein interactions and functional clusters.

Main Results:

• MitCOM revealed a complex organization of mitochondrial protein assemblies, with distinct patterns for respiration, metabolism, biogenesis, dynamics, regulation, and redox processes.
• Over 5,200 protein peaks were resolved, averaging six peaks per protein, highlighting intricate assembly structures.
• Interactions with key mitochondrial components like cytosolic ribosome receptors, prohibitin scaffolds, and respiratory complexes were identified.
• Quality control pathways at the mitochondrial entry gate, including preprotein ubiquitylation and degradation, were elucidated, with a specific pathway for preprotein removal involving Pth2 identified.

Conclusions:

• The MitCOM dataset provides a comprehensive resource for understanding mitochondrial protein organization and function.
• This study significantly advances our knowledge of mitochondrial machineries, pathways, and quality control mechanisms.
• The interactive profile viewer facilitates further research into mitochondrial protein interactions and cellular processes.