2vuy

Crystal structure of Glycogen Debranching exzyme TreX from Sulfolobus solfatarius

spinqualitylabelsall models 2vuy, resolution 3.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2vuy is a 2 chain structure with sequence from Saccharolobus solfataricus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 3Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function P95868_SACSO 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 TreX is an archaeal glycogen-debranching enzyme that exists in two oligomeric states in solution, as a dimer and tetramer. Unlike its homologs, TreX from Sulfolobus solfataricus shows dual activities for alpha-1,4-transferase and alpha-1,6-glucosidase. To understand this bifunctional mechanism, we determined the crystal structure of TreX in complex with an acarbose ligand. The acarbose intermediate was covalently bound to Asp363, occupying subsites -1 to -3. Although generally similar to the monomeric structure of isoamylase, TreX exhibits two different active-site configurations depending on its oligomeric state. The N terminus of one subunit is located at the active site of the other molecule, resulting in a reshaping of the active site in the tetramer. This is accompanied by a large shift in the "flexible loop" (amino acids 399-416), creating connected holes inside the tetramer. Mutations in the N-terminal region result in a sharp increase in alpha-1,4-transferase activity and a reduced level of alpha-1,6-glucosidase activity. On the basis of geometrical analysis of the active site and mutational study, we suggest that the structural lid (acids 99-97) at the active site generated by the tetramerization is closely associated with the bifunctionality and in particular with the alpha-1,4-transferase activity. These results provide a structural basis for the modulation of activities upon TreX oligomerization that may represent a common mode of action for other glycogen-debranching enzymes in higher organisms. Structural insight into the bifunctional mechanism of the glycogen-debranching enzyme TreX from the archaeon Sulfolobus solfataricus.,Woo EJ, Lee S, Cha H, Park JT, Yoon SM, Song HN, Park KH J Biol Chem. 2008 Oct 17;283(42):28641-8. Epub 2008 Aug 14. PMID:18703518 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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