Proton-based structural analysis of a heptahelical transmembrane protein in lipid bilayers

The structures and properties of membrane proteins in lipid bilayers are expected to closely resemble those in native cell-membrane environments, although they have been difficult to elucidate. By performing solid-state NMR measurements at very fast (100 kHz) magic-angle spinning rates and at high (23.5 T) magnetic field, severe sensitivity and resolution challenges are overcome, enabling the atomic-level characterization of membrane proteins in lipid environments. This is demonstrated by extensive 1H-based resonance assignments of the fully protonated heptahelical membrane protein proteorhodopsin, and the efficient identification of numerous1H–1H dipolar interactions, which provide distance constraints, inter-residue proximities, relative orientations of secondary structural elements, and protein–cofactor interactions in the hydrophobic transmembrane regions. These results establish a general approach for high-resolution structural studies of membrane proteins in lipid environments via solid-state NMR.

Lalli, D., Idso, M.N., Andreas, L.B., Baxter, N., Han, S., Chmelka, B.F. and Pintacuda, G.
Journal of the American Chemical Society
Volume: 139
Number: 37
Pages: 13006–13012
Date: July, 2017
ICB Affiliated Authors: Bradley F Chmelka, Songi Han