3kl3

Crystal structure of Ligand bound XynC

spinqualitylabelsall models 3kl3, resolution 2.33Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3kl3 is a 4 chain structure with sequence from Bacsu. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: BDP, DHI, GCU, PG4 Related: 3gtn, 3kl0, 3kl5 Gene: BSU18150, xynC, ynfF (BACSU) Activity: Glucuronoarabinoxylan endo-1,4-beta-xylanase, with EC number 3.2.1.136 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [XYNC_BACSU] Catalyzes the depolymerization of methylglucuronoxylan (MeGAXn) from different sources. It cleaves the beta-1,4-xylosidic bond penultimate to that linking carbon one of the xylose residue substituted with alpha-1,2-linked 4-O-methyl-D-glucuronate (MeGA). Publication Abstract from PubMed Xylanases of glycosyl hydrolase family 30 (GH30) have been shown to cleave beta-1,4 linkages of 4-O-methylglucuronoxylan (MeGX(n)) as directed by the position along the xylan chain of an alpha-1,2-linked 4-O-methylglucuronate (MeGA) moiety. Complete hydrolysis of MeGX(n) by these enzymes results in singly substituted aldouronates having a 4-O-methylglucuronate moiety linked to a xylose penultimate from the reducing terminal xylose and some number of xylose residues toward the nonreducing terminus. This novel mode of action distinguishes GH30 xylanases from the more common xylanase families that cleave MeGX(n) in accessible regions. To help understand this unique biochemical function, we have determined the structure of XynC in its native and ligand-bound forms. XynC structure models derived from diffraction data of XynC crystal soaks with the simple sugar glucuronate (GA) and the tetrameric sugar 4-O-methyl-aldotetrauronate resulted in models containing GA and 4-O-methyl-aldotriuronate, respectively. Each is observed in two locations within XynC surface openings. Ligand coordination occurs within the XynC catalytic substrate binding cleft and on the structurally fused side beta-domain demonstrating a substrate targeting role for this putative carbohydrate binding module. Structural data reveal that GA acts as a primary functional appendage for recognition and hydrolysis of the MeGX(n) polymer by the protein. This work compares the structure of XynC with a previously reported homologous enzyme, XynA, from Erwinia chrysanthemi and analyzes the ligand binding sites. Our results identify the molecular interactions that define the unique function of XynC and homologous GH30 enzymes. Ligand-Bound Structures of a Glycosyl Hydrolase Family 30 Glucuronoxylan Xylanohydrolase.,St John FJ, Hurlbert JC, Rice JD, Preston JF, Pozharski E J Mol Biol. 2011 Jan 19. PMID:21256135 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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