2dtx | pdb_00002dtx

Structure of Thermoplasma acidophilum aldohexose dehydrogenase (AldT) in complex with D-mannose

spinqualitylabelsall models 2dtx, resolution 1.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2dtx is a 2 chain structure with sequence from "thermoplasma_acidophila"_(sic)_darland_et_al._1970 "thermoplasma acidophila" (sic) darland et al. 1970. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: BMA, SO4 Related: 2dtd, 2dte Gene: Ta0754 ("Thermoplasma acidophila" (sic) Darland et al. 1970) Activity: Glucose 1-dehydrogenase (NAD(+)), with EC number 1.1.1.118 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum 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 The D-aldohexose dehydrogenase from the thermoacidophilic archaea Thermoplasma acidophilum (AldT) belongs to the short-chain dehydrogenase/reductase (SDR) superfamily and catalyzes the oxidation of several monosaccharides with a preference for NAD(+) rather than NADP(+) as a cofactor. It has been found that AldT is a unique enzyme that exhibits the highest dehydrogenase activity against D-mannose. Here, we describe the crystal structures of AldT in ligand-free form, in complex with NADH, and in complex with the substrate D-mannose, at 2.1 A, 1.65 A, and 1.6 A resolution, respectively. The AldT subunit forms a typical SDR fold with an unexpectedly long C-terminal tail and assembles into an intertwined tetramer. The D-mannose complex structure reveals that Glu84 interacts with the axial C2 hydroxyl group of the bound D-mannose. Structural comparison with Bacillus megaterium glucose dehydrogenase (BmGlcDH) suggests that the conformation of the glutamate side-chain is crucial for discrimination between D-mannose and its C2 epimer D-glucose, and the conformation of the glutamate side-chain depends on the spatial arrangement of nearby hydrophobic residues that do not directly interact with the substrate. Elucidation of the D-mannose recognition mechanism of AldT further provides structural insights into the unique substrate selectivity of AldT. Finally, we show that the extended C-terminal tail completely shuts the substrate-binding pocket of the neighboring subunit both in the presence and absence of substrate. The elaborate inter-subunit interactions between the C-terminal tail and the entrance of the substrate-binding pocket imply that the tail may play a pivotal role in the enzyme activity. Structural insights into unique substrate selectivity of Thermoplasma acidophilum D-aldohexose dehydrogenase.,Yasutake Y, Nishiya Y, Tamura N, Tamura T J Mol Biol. 2007 Apr 6;367(4):1034-46. Epub 2007 Jan 16. PMID:17300803 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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