Mitochondria function in cytoplasmic FeS protein biogenesis.

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Iron-sulfur (FeS) clusters are essential cofactors for numerous proteins involved in critical cellular processes.
• The biogenesis of FeS clusters involves complex, conserved machinery, with distinct mitochondrial (ISC) and cytoplasmic (CIA) pathways in eukaryotes.
• A unique mitochondrial intermediate (X-S) is proposed to link the ISC and CIA pathways.

Purpose of the Study:

• To present genetic and biochemical evidence supporting the role of a mitochondrial FeS intermediate (X-S) exported by Atm1.
• To review structural insights into the Atm1 transporter and its role in FeS cluster biogenesis.
• To elucidate the compartmental roles of glutathione in cellular FeS cluster assembly.

Main Methods:

• Genetic analysis of FeS cluster biogenesis pathways.
• Biochemical assays to characterize FeS cluster assembly and intermediates.
• Review of structural data for the mitochondrial ABC transporter Atm1.
• Analysis of cellular phenotypes resulting from mutations or depletion of ISC machinery components and Atm1.

Main Results:

• Evidence presented supports the existence and function of the X-S intermediate in FeS cluster biogenesis.
• Structural reviews highlight the transport mechanism of Atm1.
• Glutathione's critical role in compartmentalized FeS cluster assembly is emphasized.
• Deficiency in mitochondrial ISC machinery or Atm1 leads to both mitochondrial and cytoplasmic FeS cluster deficits, confirming epistasis.

Conclusions:

• The mitochondrial ISC machinery produces an intermediate (X-S) exported by Atm1, which is crucial for cytoplasmic FeS protein assembly.
• This mechanism explains the observed epistasis between mitochondrial and cytoplasmic FeS biogenesis pathways.
• The findings provide a comprehensive view of eukaryotic FeS cluster biogenesis, highlighting inter-compartmental coordination.