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Ion channels formed by HIV-1 Vpu: a modelling and simulation study
A L Grice1, I D Kerr, M S Sansom
1Laboratory of Molecular Biophysics, University of Oxford, UK.
FEBS Letters
|April 1, 1997
Summary
The Vpu protein from HIV-1 forms ion channels. Molecular dynamics simulations suggest a five-helix bundle model best explains the channel's conductance and weak cation selectivity.
Area of Science:
- Structural biology
- Biophysics
- Virology
Background:
- The Vpu protein is an integral membrane protein encoded by HIV-1.
- Vpu forms oligomeric ion channels, with each subunit containing a single transmembrane helix.
Purpose of the Study:
- To model the structure of Vpu ion channels.
- To determine the predominant conductance level of Vpu channels.
- To investigate the ion selectivity of Vpu channels.
Main Methods:
- Restrained molecular dynamics simulations were used to model Vpu channels.
- Simulations included bundles of 4, 5, or 6 transmembrane helices.
- Pore radius profiles, conductance predictions, and ion translation energy profiles were analyzed.
Main Results:
- A model of Vpu channels formed by five transmembrane helices (N=5) best matched the predominant channel conductance.
- Pore radius profiles and conductance predictions supported the N=5 model.
- Energy profiles for Na+ and Cl- ion translation indicated weak cation selectivity.
Conclusions:
- The five-helix bundle model accurately represents the Vpu ion channel structure.
- The Vpu channel exhibits weak cation selectivity, consistent with experimental observations.