Missense mutations on SynGAP C2 domain impair membrane diffusion.

Area of Science:

• Neuroscience
• Molecular Biology
• Biophysics

Background:

• SynGAP is a postsynaptic protein regulating synaptic plasticity and Ras/ERK signaling.
• Its C2 domain may interact with membranes, affecting localization and function.
• The precise membrane interaction mechanism and impact of mutations are unclear.

Purpose of the Study:

• To elucidate how the SynGAP C2 domain associates with lipid bilayers.
• To investigate the effects of disease-associated mutations on this membrane interaction.

Main Methods:

• Extensive molecular dynamics simulations.
• Structural analysis of SynGAP C2 domain-membrane interactions.

Main Results:

• The SynGAP C2 domain binds lipid bilayers in two distinct orientations: top and side.
• These binding modes exhibit different dynamics: faster diffusion (top) vs. stable contacts (side).
• Pathogenic mutations disrupt these dynamics, reducing diffusivity and altering membrane avidity.

Conclusions:

• SynGAP C2 domain employs a dual binding mechanism for membrane interaction.
• Mutations perturb SynGAP's membrane association, potentially explaining its role in neuropathology and cancer.
• This provides a framework for understanding how mutations impact SynGAP's diverse functions.