Structural mechanisms for VMAT2 inhibition by tetrabenazine

Area of Science:

• Neuroscience
• Structural Biology
• Pharmacology

Background:

• Vesicular monoamine transporter 2 (VMAT2) is crucial for neurotransmitter packaging and implicated in neuropsychiatric disorders.
• Understanding VMAT2's mechanism is vital for developing treatments for conditions like Parkinson's disease and for understanding drug actions.

Purpose of the Study:

• To determine the high-resolution structure of VMAT2.
• To elucidate the mechanism of VMAT2 inhibition by tetrabenazine (TBZ).
• To provide insights into VMAT2 transport and conformational dynamics.

Main Methods:

• Cryo-electron microscopy (cryo-EM) at 3.1 Å resolution.
• Structural analysis of the VMAT2-tetrabenzine complex.

Main Results:

• The structure reveals tetrabenazine binding in a central site, inducing an occluded VMAT2 conformation.
• Key residues for cytosolic and lumenal gating, including hydrophobic residues for lumenal gating, were identified.
• Three polar networks potentially involved in proton transduction and conformational dynamics were highlighted.

Conclusions:

• The structure provides a mechanistic basis for non-competitive VMAT2 inhibition by tetrabenazine.
• Insights into VMAT2 architecture, function, and gating mechanisms were gained.
• The findings facilitate the rational design of novel VMAT2-targeting therapeutics.