Cox17 is functional when tethered to the mitochondrial inner membrane

Area of Science:

• Mitochondrial biology
• Protein biochemistry
• Cellular respiration

Background:

• Cytochrome c oxidase is crucial for cellular respiration.
• Cox17 protein is essential for assembling cytochrome c oxidase by providing copper ions.
• The precise localization and function of Cox17 within the mitochondrion require further investigation.

Purpose of the Study:

• To determine if Cox17 is functional in shuttling copper ions to the mitochondrion.
• To investigate the role of Cox17's carboxyl-terminal segment in its function.
• To map the functional domains of Cox17 within the mitochondrial intermembrane space.

Main Methods:

• Constructing a Sco2/Cox17 fusion protein to localize Cox17 to the mitochondrial inner membrane.
• Assessing respiratory growth and cytochrome oxidase activity in engineered yeast cells.
• Domain mapping of yeast Cox17 to identify essential functional regions.

Main Results:

• The Sco2/Cox17 fusion protein localized exclusively to the mitochondrion.
• This fusion protein restored respiratory growth and cytochrome oxidase activity in cox17Delta cells.
• A carboxyl-terminal segment of Cox17 was found to be essential for function within the intermembrane space, independent of copper binding.

Conclusions:

• Cox17's function is confined to the mitochondrial intermembrane space.
• The C-terminal amphipathic helix of Cox17 plays a critical role in mitochondrial uptake and retention.
• This C-terminal motif can function independently of the N-terminal copper-binding domain, suggesting distinct functional roles.