1gka

The molecular basis of the coloration mechanism in lobster shell. beta-crustacyanin at 3.2 A resolution

spinqualitylabelsall models 1gka, resolution 3.23Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1gka is a 2 chain structure with sequence from Homarus gammarus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 3.23Å Ligands: AXT, D12, EPE, TRS Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function CRA1_HOMGA Binds the carotenoid astaxanthin (AXT) which provides the blue coloration to the carapace of the lobster. 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 binding of the carotenoid astaxanthin (AXT) in the protein multimacromolecular complex crustacyanin (CR) is responsible for the blue coloration of lobster shell. The structural basis of the bathochromic shift mechanism has long been elusive. A change in color occurs from the orange red of the unbound dilute AXT (lambda(max) 472 nm in hexane), the well-known color of cooked lobster, to slate blue in the protein-bound live lobster state (lambda(max) 632 nm in CR). Intriguingly, extracted CR becomes red on dehydration and on rehydration goes back to blue. Recently, the innovative use of softer x-rays and xenon derivatization yielded the three-dimensional structure of the A(1) apoprotein subunit of CR, confirming it as a member of the lipocalin superfamily. That work provided the molecular replacement search model for a crystal form of the beta-CR holo complex, that is an A(1) with A(3) subunit assembly including two bound AXT molecules. We have thereby determined the structure of the A(3) molecule de novo. Lobster has clearly evolved an intricate structural mechanism for the coloration of its shell using AXT and a bathochromic shift. Blue/purple AXT proteins are ubiquitous among invertebrate marine animals, particularly the Crustacea. The three-dimensional structure of beta-CR has identified the protein contacts and structural alterations needed for the AXT color regulation mechanism. The molecular basis of the coloration mechanism in lobster shell: beta-crustacyanin at 3.2-A resolution.,Cianci M, Rizkallah PJ, Olczak A, Raftery J, Chayen NE, Zagalsky PF, Helliwell JR Proc Natl Acad Sci U S A. 2002 Jul 23;99(15):9795-800. Epub 2002 Jul 15. PMID:12119396 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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