Structure and function of the human mitochondrial MRS2 channel.

Area of Science:

• Mitochondrial biology
• Ion channel biophysics
• Structural biology

Background:

• The Mitochondrial RNA Splicing 2 protein (MRS2) is vital for mitochondrial Mg²⁺ homeostasis and function.
• The precise channel properties and regulatory mechanisms of MRS2 remain largely unknown.

Approach:

• Cryo-electron microscopy was used to determine the structure of MRS2 under various ionic conditions.
• Electrophysiological analyses were performed to characterize MRS2 channel activity and ion selectivity.

Key Points:

• MRS2 forms a pentameric channel structure, revealing the molecular basis of ion permeation.
• MRS2 functions as a Ca²⁺-regulated, non-selective channel permeable to Mg²⁺, Ca²⁺, Na⁺, and K⁺.
• A conserved arginine ring in the MRS2 pore restricts cation flow, preserving mitochondrial proton motive force.

Conclusions:

• This study provides a detailed molecular framework for MRS2 channel function and regulation.
• Understanding MRS2 is critical for insights into mitochondrial integrity and associated diseases.