A two-step mitochondrial import pathway couples the disulfide relay with matrix complex I biogenesis

Area of Science:

• Mitochondrial biology
• Protein import and biogenesis
• Cellular respiration

Background:

• Mitochondria require precise protein import for function.
• Complex I assembly is crucial for cellular respiration.
• Regulation of mitochondrial protein import is complex.

Purpose of the Study:

• To elucidate the import pathway of NDUFAF8, a complex I assembly factor.
• To understand the role of oxidative modifications in mitochondrial protein import.
• To investigate the coordination between mitochondrial import systems.

Main Methods:

• Mitochondrial import assays
• Protease sensitivity assays
• Disulfide bond analysis
• Genetic manipulation of import factors and proteases

Main Results:

• NDUFAF8 utilizes a two-step import mechanism involving TIM23.
• NDUFAF8 undergoes oxidation in the intermembrane space (IMS) via the disulfide relay.
• Proteases YME1L and CLPP regulate NDUFAF8 levels in IMS and matrix, respectively.
• Efficient import and oxidation are essential for NDUFAF8 function in Complex I biogenesis.

Conclusions:

• The two-step import pathway for NDUFAF8 integrates IMS and matrix import systems.
• This pathway allows coordination between Complex I biogenesis and the mitochondrial disulfide relay.
• Similar two-step import pathways may exist for other mitochondrial proteins.