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Structure and dynamics of K channel pore-lining helices: a comparative simulation study
I H Shrivastava1, C E Capener, L R Forrest
1Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom.
Biophysical Journal
|January 5, 2000
Summary
Molecular dynamics simulations reveal inner pore-lining helices in potassium channels are more flexible. These K-channel dynamics and interactions with lipids may influence protein folding and gating mechanisms.
Area of Science:
- Biophysics
- Structural Biology
- Computational Biology
Background:
- Potassium channels are crucial for cellular function.
- Understanding K-channel helix dynamics is key to their gating mechanisms.
- X-ray structures are unavailable for Kv and Kir channels.
Purpose of the Study:
- To analyze structural and dynamic features of isolated pore-lining helices from K-channels.
- To investigate helix behavior within a lipid bilayer using molecular dynamics.
- To determine optimal helix lengths for Kv and Kir channel models.
Main Methods:
- Nanosecond molecular dynamics (MD) simulations.
- Modeling of KcsA, Shaker (Kv), and Kir6.2 (Kir) channel helices.
- Incorporation of helices into a palmitoyloleoylphosphatidylcholine lipid bilayer with water solvation.
Main Results:
- Inner pore-lining helices (M2, S6) exhibit greater flexibility than outer helices.
- The Pro-Val-Pro motif in Shaker S6 induces flexibility, potentially related to gating.
- H-bonding interactions with water and lipids stabilize helices in the bilayer.
- Aromatic residues at helix extremities show complex motions on various timescales.
Conclusions:
- Helix flexibility and interfacial interactions play roles in K-channel structure and function.
- MD simulations provide insights into membrane protein folding and dynamics.
- Findings contribute to understanding potassium channel gating and stability.