2ntu

Bacteriorhodopsin, wild type, before illumination

spinqualitylabelsall models 2ntu, resolution 1.53Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2ntu is a 1 chain structure with sequence from Halobacterium salinarum. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.53Å Ligands: RET Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function BACR_HALSA Light-driven proton pump. 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 The L to M reaction of the bacteriorhodopsin photocycle includes the crucial proton transfer from the retinal Schiff base to Asp85. In spite of the importance of the L state in deciding central issues of the transport mechanism in this pump, the serious disagreements among the three published crystallographic structures of L have remained unresolved. Here, we report on the X-ray diffraction structure of the L state, to 1.53-1.73 A resolutions, from replicate data sets collected from six independent crystals. Unlike earlier studies, the partial occupancy refinement uses diffraction intensities from the same crystals before and after the illumination to produce the trapped L state. The high reproducibility of inter-atomic distances, and bond angles and torsions of the retinal, lends credibility to the structural model. The photoisomerized 13-cis retinal in L is twisted at the C(13)=C(14) and C(15)=NZ double-bonds, and the Schiff base does not lose its connection to Wat402 and, therefore, to the proton acceptor Asp85. The protonation of Asp85 by the Schiff base in the L-->M reaction is likely to occur, therefore, via Wat402. It is evident from the structure of the L state that various conformational changes involving hydrogen-bonding residues and bound water molecules begin to propagate from the retinal to the protein at this stage already, and in both extracellular and cytoplasmic directions. Their rationales in the transport can be deduced from the way their amplitudes increase in the intermediates that follow L in the reaction cycle, and from the proton transfer reactions with which they are associated. Structural changes in the L photointermediate of bacteriorhodopsin.,Lanyi JK, Schobert B J Mol Biol. 2007 Feb 2;365(5):1379-92. Epub 2006 Nov 10. PMID:17141271 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Bacteriorhodopsin 3D structures

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