3frk | pdb_00003frk

X-ray structure of QdtB from T. thermosaccharolyticum in complex with a PLP:TDP-3-aminoquinovose aldimine

spinqualitylabelsall models 3frk, resolution 2.15Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3frk is a 2 chain structure with sequence from Thermoanaerobacterium thermosaccharolyticum. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.15Å Ligands: TQP Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function Q6TFC4_THETR 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 3-Acetamido-3,6-dideoxy-alpha-d-glucose or Quip3NAc is an unusual deoxyamino sugar found in the O-antigens of some Gram-negative bacteria and in the S-layers of Gram-positive bacteria. It is synthesized in these organisms as a dTDP-linked sugar via the action of five enzymes. The focus of this investigation is on QdtB from Thermoanaerobacterium thermosaccharolyticum E207-71, a PLP-dependent aminotransferase that catalyzes the penultimate step in the production of dTDP-Quip3NAc. For this analysis, the enzyme was crystallized in the presence of its product, dTDP-Quip3N, and the structure was solved and refined to 2.15 A resolution. QdtB is a dimer, and its overall fold places it into the well-characterized aspartate aminotransferase superfamily. Electron density corresponding to the bound product reveals the presence of a Schiff base between C-4' of the PLP cofactor and the amino nitrogen of the sugar. Those amino acid side chains involved in binding the dTDP-sugar into the active site include Tyr 183, His 309, and Tyr 310 from subunit 1 and Lys 219 from subunit 2. Notably there is a decided lack of interactions between the pyranosyl C-4' hydroxyl of the dTDP-sugar and the protein. In keeping with this observation, we show that QdtB can also turn over dTDP-3-acetamido-3,6-dideoxy-alpha-d-galactose. This investigation represents the first structural analysis of a sugar-modifying aminotransferase with a bound product in its active site that functions at the C-3' rather than the C-4' position of the hexose. Structural analysis of QdtB, an aminotransferase required for the biosynthesis of dTDP-3-acetamido-3,6-dideoxy-alpha-D-glucose.,Thoden JB, Schaffer C, Messner P, Holden HM Biochemistry. 2009 Feb 24;48(7):1553-61. PMID:19178182 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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