Insertases scramble lipids: Molecular simulations of MTCH2

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Scramblases facilitate bidirectional lipid transport, crucial for membrane homeostasis, lipid metabolism, and cellular signaling.
• MTCH2 is a mitochondrial outer membrane protein insertase with structural features suggestive of scramblase activity.

Purpose of the Study:

• To investigate the potential scramblase function of MTCH2.
• To elucidate the mechanism by which MTCH2 facilitates lipid transport.
• To compare the activity of MTCH2 with known scramblases.

Main Methods:

• Coarse-grained molecular dynamics simulations.
• Atomistic molecular dynamics simulations.
• Free energy barrier analysis for lipid movement.

Main Results:

• MTCH2 significantly reduces the free energy barrier for lipid movement through its hydrophilic groove.
• MTCH2 demonstrates scramblase activity in silico.
• The in silico scrambling rate of MTCH2 is comparable to that of voltage-dependent anion channel (VDAC).

Conclusions:

• MTCH2 functions as a scramblase, contributing to lipid transport across the mitochondrial outer membrane.
• MTCH2 may have a complementary physiological role to VDAC in mitochondrial lipid dynamics.
• Hydrophilic path-containing insertases, like MTCH2, represent a potential class of scramblases.