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The glycophorin helix dimer is a paradigm for the exploration of helix-helix interactions in integral membrane proteins. Two NMR structures of the dimer are known, one in a detergent micelle and one in a lipid bilayer. Multiple (4 x 50 ns) molecular dynamics simulations starting from each of the two NMR structures, with each structure in either a dodecyl phosphocholine (DPC) micelle or a dimyristoyl phosphatidylcholine (DMPC) bilayer, have been used to explore the conformational dynamics of the helix dimer. Analysis of the helix-helix interaction, mediated by the GxxxG sequence motif, suggests convergence of the simulations to a common model. This is closer to the NMR structure determined in a bilayer than to micelle structure. The stable dimer interface in the final simulation model is characterized by (i) Gly/Gly packing and (ii) Thr/Thr interhelix H-bonds. These results demonstrate the ability of extended molecular dynamics simulations in a lipid bilayer environment to refine membrane protein structures or models derived from experimental data obtained in protein/detergent micelles.

Original publication

DOI

10.1021/bi0610911

Type

Journal article

Journal

Biochemistry

Publication Date

05/12/2006

Volume

45

Pages

14298 - 14310

Keywords

Cell Membrane, Computer Simulation, Dimerization, Glycophorin, Hydrogen Bonding, Magnetic Resonance Spectroscopy, Micelles, Models, Molecular, Pliability, Protein Binding, Protein Structure, Quaternary, Protein Structure, Secondary, Protein Structure, Tertiary