3vi0

Crystal structure of the O intermediate of the L93A mutant of bacteriorhodopsin

spinqualitylabelsall models 3vi0, resolution 2.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3vi0 is a 1 chain structure with sequence from Halobacterium salinarum NRC-1. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.3Å Ligands: GLC, L2P, MAN, RET, SGA, SOG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function BACR_HALSA Light-driven proton pump. Publication Abstract from PubMed The lifetime of the O intermediate of bacteriorhodopsin (BR) is extended by a factor of approximately 250 in the Leu93-to-Ala mutant (BR_L93A). To clarify the structural changes occurring in the last stage of the proton pumping cycle of BR, we crystallized BR_L93A into a hexagonal P622 crystal. Diffraction data from the unphotolyzed state showed that the deletion of three carbon atoms from Leu93 is compensated by the insertion of four water molecules in the cytoplasmic vicinity of retinal. This insertion of water is suggested to be responsible for the blue-shifted lambda(max) (540 nm) of the mutant. A long-lived sub-state of O with a red-shifted lambda(max) ( approximately 565 nm) was trapped when the crystal of BR_L93A was flash-cooled after illumination with green light. This sub-state (O(slow) ) bears considerable similarity to the M intermediate of native BR; that is, it commonly shows deformation of helix C and the FG loop, downward orientation of the side chain of Arg82 and disruption of the Glu194/Glu204 pair. In O(slow) , however, the main chain of Lys216 is less distorted and retinal takes on the 13-cis/15-syn configuration. Another significant difference is seen in the pH dependence of the structure of the proton release group, the pK(a) value of which is suggested to be much lower in O(slow) than in M. Proteins 2012. (c) 2012 Wiley Periodicals, Inc. Crystal structure of the O intermediate of the Leu93-->Ala mutant of bacteriorhodopsin.,Zhang J, Yamazaki Y, Hikake M, Murakami M, Ihara K, Kouyama T Proteins. 2012 May 29. doi: 10.1002/prot.24124. PMID:22641602 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Bacteriorhodopsin 3D structures

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