3ale

A type III polyketide synthase that produces diarylheptanoid

spinqualitylabelsall models 3ale, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3ale is a 4 chain structure with sequence from Oryza sativa Japonica Group. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.5Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function CUS_ORYSJ Plant-specific type III polyketide synthase (PKS) that catalyzes the one-pot formation of the C6-C7-C6 diarylheptanoid scaffold of bisdemethoxycurcumin by the condensation of two molecules of 4-coumaroyl-CoA and one molecule of malonyl-CoA. Publication Abstract from PubMed Curcuminoid synthase (CUS) from Oryza sativa is a plant-specific type III polyketide synthase (PKS) that catalyzes the remarkable one-pot formation of the C(6)-C(7)-C(6) diarylheptanoid scaffold of bisdemethoxycurcumin, by the condensation of two molecules of 4-coumaroyl-CoA and one molecule of malonyl-CoA. The crystal structure of O. sativa CUS was solved at 2.5-A resolution, which revealed a unique, downward expanding active-site architecture, previously unidentified in the known type III PKSs. The large active-site cavity is long enough to accommodate the two C(6)-C(3) coumaroyl units and one malonyl unit. Furthermore, the crystal structure indicated the presence of a putative nucleophilic water molecule, which forms hydrogen bond networks with Ser351-Asn142-H(2)O-Tyr207-Glu202, neighboring the catalytic Cys174 at the active-site center. These observations suggest that CUS employs unique catalytic machinery for the one-pot formation of the C(6)-C(7)-C(6) scaffold. Thus, CUS utilizes the nucleophilic water to terminate the initial polyketide chain elongation at the diketide stage. Thioester bond cleavage of the enzyme-bound intermediate generates 4-coumaroyldiketide acid, which is then kept within the downward expanding pocket for subsequent decarboxylative condensation with the second 4-coumaroyl-CoA starter, to produce bisdemethoxycurcumin. The structure-based site-directed mutants, M265L and G274F, altered the substrate and product specificities to accept 4-hydroxyphenylpropionyl-CoA as the starter to produce tetrahydrobisdemethoxycurcumin. These findings not only provide a structural basis for the catalytic machinery of CUS but also suggest further strategies toward expanding the biosynthetic repertoire of the type III PKS enzymes. Structural basis for the one-pot formation of the diarylheptanoid scaffold by curcuminoid synthase from Oryza sativa.,Morita H, Wanibuchi K, Nii H, Kato R, Sugio S, Abe I Proc Natl Acad Sci U S A. 2010 Nov 16;107(46):19778-83. Epub 2010 Nov 1. PMID:21041675 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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