Dynamic structure, signal recognition and material transport of membrane protein

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Two-dimensional array formation and dynamicsThe NMR spectra of Bacteriorhodopsin mutant W12L, W80L that cannot make two-dimensional crystal shows that the protein-protein interaction and protein-lipid interaction change. The dynamics of transmembrane a-helix changes a frequency 10^2 to 10^4 and in 2D crystal, membrane surface has relatively slow mobility (less than 50 μs).The effect of Glu residue for Bacteriorhodopsin stabilityIt was elucidated that Glu^9,Glu^<74>,Glu^<194> and Glu^<204>, which are located at extracellular side, contribute to protein stability. Since Glu^<194> and Glu^<204> are proton release residues, this result implies a relationship between pump function and dynamics.Structure and dynamics of pharaonis phoborhodopsin (ppR) and transducer pHtrII(1-159)A dynamic structure of ppR reconstituted into lipid bilayer agree well with monomeric bacteriorhodopsin. When ppR bind to transducer pHtrII( 1-159), a NMR signal which is assigned loop vanishes because of the interference between dynamics and proton deccooupling frequency (10^5Hz). On the other hand, from NMR spectra, pHtrII(1-159) has α-helix not only transmembranr region but also cytoplasmic side protruding from membrane surface. When ppR-pHtrII(1-159) complex is formed, it become clear that fluctuation of this protruding helix increase and the contribution to signal transduction was suggested.