2arl

The 2.0 angstroms crystal structure of a pocilloporin at pH 3.5: the structural basis for the linkage between color transition and halide binding

spinqualitylabelsall models 2arl, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2arl is a 1 chain structure with sequence from Montipora efflorescens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ACY, CL, IOD NonStd Res: CRQ Resources: FirstGlance, OCA, RCSB, PDBsum Function [NFCP_MONEF] Thought to play a role in photoprotection of the coral's resident symbiont microalgae's photosystems from photoinhibition caused by high light levels found near the surface of coral reefs. 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 pocilloporin Rtms5 and an engineered variant Rtms5H146S undergo distinct color transitions (from blue to red to yellow to colorless) in a pH-dependent manner. pK(a) values of 4.1 and 3.2 were determined for the blue (absorption lambda(max), 590 nm) to yellow (absorption lambda(max), approximately 453 nm) transitions of Rtms5 and Rtms5H146. The pK(a) for the blue-yellow transition of Rtms5H146S increased by 1.4 U in the presence of 0.1 M KI, whereas the pK(a) for the same transition of Rtms5 was relatively insensitive to added halides. To understand the structural basis for these observations, we have determined to 2.0 angstroms resolution the crystal structure of a yellow form of Rtms5H146S at pH 3.5 in the presence of iodide. Iodide was found occupying a pocket in the structure with a pH of 3.5, forming van der Waals contacts with the tyrosyl moiety of the chromophore. Elsewhere, it was determined that this pocket is occupied by a water molecule in the Rtms5H146S structure (pH 8.0) and by the side chain of histidine 146 in the wild-type Rtms5 structure. Collectively, our data provide an explanation for the observed linkage between color transitions for Rtms5H146S and binding to halides. The 2.0 angstroms crystal structure of a pocilloporin at pH 3.5: the structural basis for the linkage between color transition and halide binding.,Wilmann PG, Battad J, Beddoe T, Olsen S, Smith SC, Dove S, Devenish RJ, Rossjohn J, Prescott M Photochem Photobiol. 2006 Mar-Apr;82(2):359-66. PMID:16613486 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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