1r84
NMR structure of the 13-cis-15-syn retinal in dark_adapted bacteriorhodopsin
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OverviewOverview
The two forms of bacteriorhodopsin present in the dark-adapted state, containing either all-trans or 13-cis,15-syn retinal, were examined by, using solution state NMR, and their structures were determined. Comparison, of the all-trans and the 13-cis,15-syn forms shows a shift in position of, about 0.25 A within the pocket of the protein. Comparing this to the, 13-cis,15-anti chromophore of the catalytic cycle M-intermediate, structure, the 13-cis,15-syn form demonstrates a less pronounced up-tilt, of the retinal C12[bond]C14 region, while leaving W182 and T178, essentially unchanged. The N[bond]H dipole of the Schiff base orients, toward the extracellular side in both forms, however, it reorients toward, the intracellular side in the 13-cis,15-anti configuration to form the, catalytic M-intermediate. Thus, the change of the N[bond]H dipole is, considered primarily responsible for energy storage, conformation changes, of the protein, and the deprotonation of the Schiff base. The structural, similarity of the all-trans and 13-cis,15-syn forms is taken as strong, evidence for the ion dipole dragging model by which proton (hydroxide ion), translocation follows the change of the dipole.
About this StructureAbout this Structure
1R84 is a Single protein structure of sequence from Halobacterium salinarum with RET as ligand. Full crystallographic information is available from OCA.
ReferenceReference
The structures of the active center in dark-adapted bacteriorhodopsin by solution-state NMR spectroscopy., Patzelt H, Simon B, terLaak A, Kessler B, Kuhne R, Schmieder P, Oesterhelt D, Oschkinat H, Proc Natl Acad Sci U S A. 2002 Jul 23;99(15):9765-70. Epub 2002 Jul 15. PMID:12119389
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