4fnv

Crystal Structure of Heparinase III

spinqualitylabelsall models 4fnv, resolution 1.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4fnv is a 1 chain structure with sequence from Bacteroides thetaiotaomicron VPI-5482. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function HEPC_BACTN Specifically cleaves heparan sulfate-rich regions of acidic polysaccharides. Does not act on N,O-desulfated glucosamine or N-acetyl-O-sulfated glucosamine linkages. Functions in cleaving metazoan heparan sulfate and providing carbon, nitrogen and sulfate sources for microorganisms. Publication Abstract from PubMed Heparinase III (HepIII) is a 73-kDa polysaccharide lyase (PL) that degrades the heparan sulfate (HS) polysaccharides at sulfate-rare regions, which are important co-factors for a vast array of functional distinct proteins including the well-characterized antithrombin and the FGF/FGFR signal transduction system. It functions in cleaving metazoan heparan sulfate (HS) and providing carbon, nitrogen and sulfate sources for host microorganisms. It has long been used to deduce the structure of HS and heparin motifs; however, the structure of its own is unknown. Here we report the crystal structure of the HepIII from Bacteroides thetaiotaomicron at a resolution of 1.6 A. The overall architecture of HepIII belongs to the (alpha/alpha)5 toroid subclass with an N-terminal toroid-like domain and a C-terminal beta-sandwich domain. Analysis of this high-resolution structure allows us to identify a potential HS substrate binding site in a tunnel between the two domains. A tetrasaccharide substrate bound model suggests an elimination mechanism in the HS degradation. Asn260 and His464 neutralize the carboxylic group, whereas Tyr314 serves both as a general base in C-5 proton abstraction, and a general acid in a proton donation to reconstitute the terminal hydroxyl group, respectively. The structure of HepIII and the proposed reaction model provide a molecular basis for its potential practical utilization and the mechanism of its eliminative degradation for HS polysaccarides. Structural basis of heparan sulfate-specific degradation by heparinase III.,Dong W, Lu W, McKeehan WL, Luo Y, Ye S Protein Cell. 2012 Jul 21. PMID:23011846 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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