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Initial structural and dynamic characterization of the M2 protein transmembrane and amphipathic helices in lipid bilayers
Author(s) -
Tian Changlin,
Gao Philip Fei,
Pinto Lawrence H.,
Lamb Robert A.,
Cross Timothy A.
Publication year - 2003
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.03168503
Subject(s) - chemistry , lipid bilayer , helix (gastropod) , transmembrane protein , bilayer , crystallography , transmembrane domain , amphiphile , tetramer , protein secondary structure , lipid bilayer phase behavior , membrane protein , biophysics , membrane , biochemistry , organic chemistry , ecology , receptor , snail , copolymer , biology , enzyme , polymer
Amphipathic helices in membrane proteins that interact with the hydrophobic/hydrophilic interface of the lipid bilayer have been difficult to structurally characterize. Here, the backbone structure and orientation of an amphipathic helix in the full‐length M2 protein from influenza A virus has been characterized. The protein has been studied in hydrated DMPC/DMPG lipid bilayers above the gel to liquid‐crystalline phase transition temperature by solid‐state NMR spectroscopy. Characteristic PISA (Polar Index Slant Angle) wheels reflecting helical wheels have been observed in uniformly aligned bilayer preparations of both uniformly 15 N labeled and amino acid specific labeled M2 samples. Hydrogen/deuterium exchange studies have shown the very slow exchange of some residues in the amphipathic helix and more rapid exchange for the transmembrane helix. These latter results clearly suggest the presence of an aqueous pore. A variation in exchange rate about the transmembrane helical axis provides additional support for this claim and suggests that motions occur about the helical axes in this tetramer to expose the entire backbone to the pore.