1vgo

Crystal Structure of Archaerhodopsin-2

spinqualitylabelsall models 1vgo, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1vgo is a 2 chain structure with sequence from Halobacterium sp. AUS-2. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.5Å Ligands: BNG, RET, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function BACR2_HALS2 Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Archaerhodopsin-1 and -2 (aR-1 and aR-2) are light-driven proton pumps found in Halorubrum sp. aus-1 and -2, which share 55-58% sequence identity with bacteriorhodopsin (bR), a proton pump found in Halobacterium salinarum. In this study, aR-1 and aR-2 were crystallized into 3D crystals belonging to P4(3)2(1)2 (a = b = 128.1 A, c = 117.6 A) and C222(1) (a = 122.9 A, b = 139.5 A, c = 108.1 A), respectively. In both the crystals, the asymmetric unit contains two protein molecules with slightly different conformations. Each subunit is composed of seven helical segments as seen in bR but, unlike bR, aR-1 as well as aR-2 has a unique omega loop near the N terminus. It is found that the proton pathway in the extracellular half (i.e. the proton release channel) is more opened in aR-2 than in aR-1 or bR. This structural difference accounts for a large variation in the pKa of the acid purple-to-blue transition among the three proton pumps. All the aromatic residues surrounding the retinal polyene chain are conserved among the three proton pumps, confirming a previous argument that these residues are required for the stereo-specificity of the retinal isomerization. In the cytoplasmic half, the region surrounded by helices B, C and G is highly conserved, while the structural conservation is very low for residues extruded from helices E and F. Structural conservation of the hydrophobic residues located on the proton uptake pathway suggests that their precise arrangement is necessary to prevent a backward flow of proton in the presence of a large pH gradient and membrane potential. An empty cavity is commonly seen in the vicinity of Leu93 contacting the retinal C13 methyl. Existence of such a cavity is required to allow a large rotation of the side-chain of Leu93 at the early stage of the photocycle, which has been shown to accompany water translocation across the Schiff base. Crystal structures of archaerhodopsin-1 and -2: Common structural motif in archaeal light-driven proton pumps.,Enami N, Yoshimura K, Murakami M, Okumura H, Ihara K, Kouyama T J Mol Biol. 2006 May 5;358(3):675-85. Epub 2006 Mar 3. PMID:16540121 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Bacteriorhodopsin 3D structures Rhodopsin 3D structures

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