Membrane proteins, site-directed solid-state

Site-directed solid state NMR spectra of [3- C]Ala- and [l- C]Val-labelled bacteriorhodopsin as a typical membrane protein in lipid bilayers, have been reported. Well-resolved NMR signals were observed for monomeric [3- C]Ala- bacteriorhodopsin in egg phosphatidylcholine bilayer at ambient temperature, although several NMR signals from the loops and transmembrane a-helices were still suppressed. The NMR results were used to elucidate the effect of 2D array formation on the backbone dynamics of membrane proteins in lipid bilayers. 

SITE-DIRECTED SOLID-STATE NMR ON MEMBRANE PROTEINS 101... 

So far, we were concerned with site-directed solid-state NMR studies on fully hydrated integral membrane proteins in which anisotropic spin interactions leading to broadened line widths are not averaged as they are in solution NMR but a variety of motions with various timescale from millisecond to microsecond are persistent because of integration into the lipid bilayer. It is still difficult to obtain structural information for peripheral membrane proteins which are not integrated but bound to a membrane surface, because the persistent anisotropic interaction with the membrane surface still hampers the utilization of the solution NMR approach. 

It is therefore concluded that site-directed solid-state NMR provides an excellent means to probe the conformational features of membrane-binding proteins which cannot be examined by any other spectroscopic means. 

H. Saito, J. Mikami, S. Yamaguchi, M. Tanio, A. Kira, T. Arakawa, K. Yamamoto, S. Tuzi, Site-directed solid-state NMR studies on membrane proteins strategy and goals toward revealing conformation and dynamics as illustrated for C-labeled bacteriorhodopsin, Magn. Reson. Chem. 42 (2004) 218—230. 

H. Saito, Site-directed solid-state NMR on membrane proteins, Annu. Rep. NMR Spectrosc. 57 (2006) 100-171. 

H. Saito, K. Yamamoto, S. Tuzi, S. Yamaguchi, Backbone dynamics of membrane proteins in lipid bHayers the effect of two dimensional array formationas revealed by site-directed solid-state C NMR studies on [3- C]Ala- and [l- C]Val-labeled bacterorhodopsin, Biochim. Biophys. Acta 1616 (2003) 127-136. 

Fig. 14. Plot of the g values g,g ) and of the average g value g vs rhombicity (UJ of (a) wild type (open symbol) and variant forms (closed symbols) of the Rieske protein in yeast bci complex where the residues Ser 183 and Tyr 185 forming hydrogen bonds into the cluster have been replaced by site-directed mutagenesis [Denke et al. (35) Merbitz-Zahradnik, T. Link, T. A., manuscript in preparation] and of (b) the Rieske cluster in membranes of Rhodobacter capsulatus in different redox states of the quinone pool and with inhibitors added [data from Ding et al. (79)]. The solid lines represent linear fits to the data points the dashed lines reproduce the fits to the g values of all Rieske and Rieske-type proteins shown in Fig. 13.

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