Structural and functional divergence of rhodopsin super-family

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(1) Crystallization of retinal proteins by the membrane fusion method:(1) The chloride ion pump from Natoronomonas pharaonis, pharaonis halorhodopsin(pHR), was crystallized, and its structure was determined at 2. 0 Aresolution.(2) Deltarhodopsin(dR3), a light-driven proton pomp found in the cell membrane of Haloterrigena thermotolerans, was crystallized, and its structure was determined at 2. 7 A resolution.(2) Structural analyses of the photoreaction intermediates of bacteriorhodopsin:(1) The structure of the M intermediate was determined at various pH levels. It was shown that the formation of M intermediate at neutral pH is accompanied by a complete destruction of the paired structure of two glutamates in the proton release channel, while this destruction is incomplete at a weakly acidic pH.(2) Using the Leu93-to-Ala mutant(BR_L93A) of bacteriorhodopsin, the structure of the O intermediate was determined at 2. 3 A resolution(3) Structural analyses of the light-driven chloride ion pu … More mp(pHR):(1) The crystal structures of the O-like blue form and the yellow anion-depleted form of pHR were determined at 1. 8 ? 2. 0 A resolutions. The result allowed us to elucidate the mechanism by which the chloride ion is removed from the active site near the protonated Schiff base of retinal.(2) The crystal structure of an M-like intermediate of the pHR-azide complex was determined at 2. 3 A resolution. It is shown that the cytoplasmic half of helix F undergoes a large structural change during the proton pumping cycle(3) A mutant of pHR(pHR_ΔBC) in which a long loop between transmembrane helices B and C was partially deleted was expressed in E. coli. It was shown that the photocycle of pHR_ΔBC is not influenced by the membrane potential, while the uptake process of chloride ion is much faster than observed in the wild-type pHR.(4) Structural analyses of squid rhodopsin(1) The primary photochemical reaction intermediate(Baso) of squid rhodopsin was determined at 2. 7 A resolution.(2) Light-induced structural changes in octopus rhodopsin(oRh) were investigated by small-angle X-ray scattering method. Less