Magic-Angle-Spinning NMR of the Drug Resistant S31N M2 Proton Transporter from Influenza A

Abstract

We report chemical shift assignments of the drug-resistant S31N mutant of M2[subscript 18–60] determined using 3D magic-angle-spinning (MAS) NMR spectra acquired with a [superscript 15]N–[superscript 13]C ZF-TEDOR transfer followed by [superscript 13]C–[superscript 13]C mixing by RFDR. The MAS spectra reveal two sets of resonances, indicating that the tetramer assembles as a dimer of dimers, similar to the wild-type channel. Helicies from the two sets of chemical shifts are shown to be in close proximity at residue H37, and the assignments reveal a difference in the helix torsion angles, as predicted by TALOS+, for the key resistance residue N31. In contrast to wild-type M2[subscript 18–60], chemical shift changes are minimal upon addition of the inhibitor rimantadine, suggesting that the drug does not bind to S31N M2.