6cxu

Structure of the S167H mutant of human indoleamine 2,3 dioxygenase in complex with tryptophan and cyanide

spinqualitylabelsall models 6cxu, resolution 2.49Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6cxu is a 2 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.49Å Ligands: CYN, HEM, TRP Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function I23O1_HUMAN Catalyzes the cleavage of the pyrrol ring of tryptophan and incorporates both atoms of a molecule of oxygen. Publication Abstract from PubMed Human indoleamine 2,3-dioxygenase 1 (hIDO1) and tryptophan dioxygenase (hTDO) catalyze the same dioxygenation reaction of Trp to generate N-formyl kynurenine (NFK). They share high structural similarity, especially in the active site. However, hIDO1 possesses a unique inhibitory substrate binding site (Si) that is absent in hTDO. In addition, in hIDO1, the indoleamine group of the substrate Trp is H-bonded to S167 through a bridging water, while that in hTDO is directly H-bonded to H76. Here we show that Trp binding to the Si site or the mutation of S167 to histidine in hIDO1 retards its turnover activity, and that the inhibited activity can be rescued by an effector, 3-indole ethanol (IDE). Kinetic studies reveal that the inhibited activity introduced by Trp binding to the Si site is a result of retarded recombination of the ferryl moiety with Trp epoxide to form NFK, and that IDE reverses the effect by preventing Trp from binding to the Si site. In contrast, the abolished activity induced by the S167H mutation is primarily a result of ~5000-fold reduction in the O2 binding rate constant, possibly due to the blockage of a ligand delivery tunnel, and that IDE binding to the Si site reverses the effect by reopening the tunnel. The data offer new insights into structure-based design of hIDO1-selective inhibitors. Inhibition Mechanisms of Human Indoleamine 2,3 Dioxygenase 1.,Lewis-Ballester A, Karkashon S, Batabyal D, Poulos TL, Yeh SR J Am Chem Soc. 2018 Jun 13. doi: 10.1021/jacs.8b03691. PMID:29897749 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Dioxygenase 3D structures

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