2n70

Publication Abstract from PubMed

We report a magic angle spinning (MAS) NMR structure of the drug-resistant S31N mutation of M218-60 from Influenza A. The protein was dispersed in diphytanoyl-sn-glycero-3-phosphocholine lipid bilayers, and the spectra and an extensive set of constraints indicate that M218-60 consists of a dimer of dimers. In particular, approximately 280 structural constraints were obtained using dipole recoupling experiments that yielded well-resolved (13)C-(15)N, (13)C-(13)C, and (1)H-(15)N 2D, 3D, and 4D MAS spectra, all of which show cross-peak doubling. Interhelical distances were measured using mixed (15)N/(13)C labeling and with deuterated protein, MAS at omegar/2pi = 60 kHz, omega0H/2pi = 1000 MHz, and (1)H detection of methyl-methyl contacts. The experiments reveal a compact structure consisting of a tetramer composed of four transmembrane helices, in which two opposing helices are displaced and rotated in the direction of the membrane normal relative to a four-fold symmetric arrangement, yielding a two-fold symmetric structure. Side chain conformations of the important gating and pH-sensing residues W41 and H37 are found to differ markedly from four-fold symmetry. The rmsd of the structure is 0.7 A for backbone heavy atoms and 1.1 A for all heavy atoms. This two-fold symmetric structure is different from all of the previous structures of M2, many of which were determined in detergent and/or with shorter constructs that are not fully active. The structure has implications for the mechanism of H(+) transport since the distance between His and Trp residues on different helices is found to be short. The structure also exhibits two-fold symmetry in the vicinity of the binding site of adamantyl inhibitors, and steric constraints may explain the mechanism of the drug-resistant S31N mutation.

Structure and Mechanism of the Influenza A M218-60 Dimer of Dimers.,Andreas LB, Reese M, Eddy MT, Gelev V, Ni QZ, Miller EA, Emsley L, Pintacuda G, Chou JJ, Griffin RG J Am Chem Soc. 2015 Dec 2;137(47):14877-86. doi: 10.1021/jacs.5b04802. Epub 2015 , Aug 31. PMID:26218479^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.