Shared structural features of Miro binding control mitochondrial homeostasis.

Area of Science:

• Mitochondrial biology
• Molecular cell biology
• Protein-protein interactions

Background:

• Miro proteins are conserved mitochondrial GTPases regulating key cellular functions.
• The precise molecular mechanisms and significance of Miro's client interactions for mitochondrial health are largely unknown.

Purpose of the Study:

• To elucidate the molecular basis of Miro protein interactions.
• To identify novel Miro client proteins and assess their role in mitochondrial health.

Main Methods:

• Analysis of known Miro interactors (CENPF, Trak, MYO19) to identify conserved binding motifs.
• Structure-based analysis of Miro's calcium-binding domain to pinpoint interaction sites.
• De novo identification of novel interactors using the discovered Miro-binding motif.

Main Results:

• Identified a conserved hydrophobic pocket in Miro's first calcium-binding domain as the shared binding site.
• Demonstrated that known Miro interactors utilize a similar short motif to bind this pocket.
• Discovered novel Miro interactors, including MTFR1/2/1L, VPS13D, Mdm34, and Parkin, through motif-based screening.

Conclusions:

• Miro acts as a universal mitochondrial adaptor protein through a conserved binding mechanism.
• This mechanism coordinates diverse mitochondrial functions, including lipid transport and protein clearance, essential for mitochondrial health.
• The findings provide a molecular framework for understanding Miro's central role in maintaining mitochondrial homeostasis.