View source for 5a55


==The native structure of GH101 from Streptococcus pneumoniae TIGR4==
<StructureSection load='5a55' size='340' side='right'caption='[[5a55]], [[Resolution|resolution]] 1.85&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[5a55]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Streptococcus_pneumoniae_TIGR4 Streptococcus pneumoniae TIGR4]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5A55 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5A55 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.85&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=EDO:1,2-ETHANEDIOL'>EDO</scene>, <scene name='pdbligand=MN:MANGANESE+(II)+ION'>MN</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=5a55 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5a55 OCA], [https://pdbe.org/5a55 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5a55 RCSB], [https://www.ebi.ac.uk/pdbsum/5a55 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5a55 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/GH101_STRPN GH101_STRPN] Is involved in the breakdown of mucin-type O-linked glycans. Specifically removes the T-antigen disaccharide (Gal-beta-1,3-GalNAc-alpha) from extracellular host glycoproteins. Is representative of a broadly important class of virulence factors (By similarity).
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== Publication Abstract from PubMed ==
O-linked glycosylation is one of the most abundant post-translational modifications of proteins. Within the secretory pathway of higher eukaryotes, the core of these glycans is frequently an N-acetylgalactosamine residue that is alpha-linked to serine or threonine residues. Glycoside hydrolases in family 101 are presently the only known enzymes to be able to hydrolyze this glycosidic linkage. Here we determine the high-resolution structures of the catalytic domain comprising a fragment of GH101 from Streptococcus pneumoniae TIGR4, SpGH101, in the absence of carbohydrate, and in complex with reaction products, inhibitor, and substrate analogues. Upon substrate binding, a tryptophan lid (residues 724-WNW-726) closes on the substrate. The closing of this lid fully engages the substrate in the active site with D764 positioned directly beneath C1 of the sugar residue bound within the -1 subsite, consistent with its proposed role as the catalytic nucleophile. In all of the bound forms of the enzyme, however, the proposed catalytic acid/base residue was found to be too distant from the glycosidic oxygen (&gt;4.3 A) to serve directly as a general catalytic acid/base residue and thereby facilitate cleavage of the glycosidic bond. These same complexes, however, revealed a structurally conserved water molecule positioned between the catalytic acid/base and the glycosidic oxygen. On the basis of these structural observations we propose a new variation of the retaining glycoside hydrolase mechanism wherein the intervening water molecule enables a Grotthuss proton shuttle between E796 and the glycosidic oxygen, permitting this residue to serve as the general acid/base catalytic residue.

Structural analysis of a family 101 glycoside hydrolase in complex with carbohydrates reveals insights into its mechanism.,Gregg KJ, Suits MD, Deng L, Vocadlo DJ, Boraston AB J Biol Chem. 2015 Aug 24. pii: jbc.M115.680470. PMID:26304114<ref>PMID:26304114</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 5a55" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Streptococcus pneumoniae TIGR4]]
[[Category: Boraston AB]]
[[Category: Deng L]]
[[Category: Gregg KJ]]
[[Category: Suits MDL]]
[[Category: Vocadlo DJ]]