Solid-state ~(15)N-NMR Investigations on the pH dependent Conformation of Trp-41 of the M2 Proton Channel of Influenza A Virus;

摘要

The M2 proton-conductive channel of influenza A virus is a tetrameric bundle which forms an integral membrane protein that is activated after endocytosis in the endosome at low pH. For proton gating the side chains His-37 and Trp-41 are identified to play an important role. Here, we investigated these side chain conformations of a synthetic 25-residue peptide containing the M2 trans-membrane domain (M2TMD) by solid state nuclear magnetic resonance (NMR) experiments and quantum mechanics/molecular mechanics (QM/MM) simulations. The trans-membrane peptide was reconstituted as an a-helical tetrameric bundle in liquid crystalline lipid membranes in the form of multilamellar vesicles and/or oriented model membranes. The M2TMD was labelled with ~(15)N-（ε1) at Trp-41. We applied different static ~(15)N-NMR experiments and investigated the motionally narrowed ~(15)N chemical shift tensors of Trp-41 for closed and opened states. The following side chain torsion angles for Trp-41 were obtained: (x1=-110°±30°, X2=+130°±30°) and (x1=-55°±30°, X2=+130°±30°) in the closed and open state.