5ac4 | pdb_00005ac4

GH20C, Beta-hexosaminidase from Streptococcus pneumoniae in complex with GalNAc

spinqualitylabelsall models 5ac4, resolution 2.08Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5ac4 is a 2 chain structure with sequence from Streptococcus pneumoniae TIGR4. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: NGA Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function A0A0H2US73_STRPN Publication Abstract from PubMed An important facet of the interaction between the pathogen Streptococcus pneumoniae (pneumococcus) and its human host is the ability of this bacterium to process host glycans. To achieve cleavage of the glycosidic bonds in host glycans, S. pneumoniae deploys a wide array of glycoside hydrolases. Here, we identify and characterize a new family 20 glycoside hydrolase, GH20C, from S. pneumoniae. Recombinant GH20C possessed the ability to hydrolyze the beta-linkages joining either N-acetylglucosamine or N-acetylgalactosamine to a wide variety of aglycon residues, thus revealing this enzyme to be a generalist N-acetylhexosaminidase in vitro. X-ray crystal structures were determined for GH20C in a ligand-free form, in complex with the N-acetylglucosamine and N-acetylgalactosamine products of catalysis and in complex with both gluco- and galacto-configured inhibitors O-(2-acetamido-2-deoxy-D-glucopyranosylidene)amino N-phenyl carbamate (PUGNAc), O-(2-acetamido-2-deoxy-D-galactopyranosylidene)amino N-phenyl carbamate (GalPUGNAc), N-acetyl-D-glucosamine-thiazoline (NGT), and N-acetyl-D-galactosamine-thiazoline (GalNGT) at resolutions from 1.84 to 2.7 A. These structures showed N-acetylglucosamine and N-acetylgalactosamine to be recognized via identical sets of molecular interactions. Although the same sets of interaction were maintained with the gluco- and galacto-configured inhibitors, the inhibition constants suggested preferred recognition of the axial O4 when an aglycon moiety was present (Ki for PUGNAc > GalPUGNAc) but preferred recognition of an equatorial O4 when the aglycon was absent (Ki for GalNGT > NGT). Overall, this study reveals GH20C to be another tool that is unique in the arsenal of S. pneumoniae and that it may implement the effort of the bacterium to utilize and/or destroy the wide array of host glycans that it may encounter. A Second beta-Hexosaminidase Encoded in the Streptococcus pneumoniae Genome Provides an Expanded Biochemical Ability to Degrade Host Glycans.,Robb M, Robb CS, Higgins MA, Hobbs JK, Paton JC, Boraston AB J Biol Chem. 2015 Dec 25;290(52):30888-900. doi: 10.1074/jbc.M115.688630. Epub, 2015 Oct 21. PMID:26491009 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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