3tf5 | pdb_00003tf5

Structure of UDP-glucose dehydrogenase V132 deletion

spinqualitylabelsall models 3tf5, resolution 2.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3tf5 is a 3 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Related: 3prj, 3ptz, 2q3e, 2qg4 Gene: NM_003359, UGDH (Homo sapiens) Activity: UDP-glucose 6-dehydrogenase, with EC number 1.1.1.22 Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed UDP-alpha-D-xylose (UDX) acts as a feedback inhibitor of human UDP-alpha-D-glucose 6-dehydrogenase (hUGDH) by activating an unusual allosteric switch, the Thr131 loop. UDX binding induces the Thr131 loop to translate ~5 A through the protein core, changing packing interactions and rotating a helix (alpha6(136-144)) to favor the formation of an inactive hexameric complex. But how does to conformational change occur given the steric packing constraints of the protein core? To answer this question, we deleted Val132 from the Thr131 loop to approximate an intermediate state in the allosteric transition. The 2.3 A resolution crystal structure of the deletion construct (Delta132) reveals an open conformation that relaxes steric constraints and facilitates repacking of the protein core. Sedimentation velocity studies show that the open conformation stabilizes the Delta132 construct as a hexamer with point group symmetry 32, similar to that of the active complex. In contrast, the UDX-inhibited enzyme forms a lower-symmetry, horseshoe-shaped hexameric complex. We show that the Delta132 and UDX-inhibited structures have similar hexamer-building interfaces, suggesting that the hinge-bending motion represents a path for the allosteric transition between the different hexameric states. On the basis of (i) main chain flexibility and (ii) a model of the conformational change, we propose that hinge bending can occur as a concerted motion between adjacent subunits in the high-symmetry hexamer. We combine these results in a structurally detailed model for allosteric feedback inhibition and substrate--product exchange during the catalytic cycle. Conformational flexibility in the allosteric regulation of human UDP-alpha-D-glucose 6-dehydrogenase.,Sennett NC, Kadirvelraj R, Wood ZA Biochemistry. 2011 Nov 8;50(44):9651-63. Epub 2011 Oct 13. PMID:21961565 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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