View source for 5hqa


==A Glycoside Hydrolase Family 97 enzyme in complex with Acarbose from Pseudoalteromonas sp. strain K8==
<StructureSection load='5hqa' size='340' side='right'caption='[[5hqa]], [[Resolution|resolution]] 1.75&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[5hqa]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Pseudoalteromonas_sp._K8 Pseudoalteromonas sp. K8]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5HQA OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5HQA 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]] 1.747&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=AC1:6-METHYL-5-(4,5,6-TRIHYDROXY-3-HYDROXYMETHYL-CYCLOHEX-2-ENYLAMINO)-TETRAHYDRO-PYRAN-2,3,4-TRIOL'>AC1</scene>, <scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=FMT:FORMIC+ACID'>FMT</scene>, <scene name='pdbligand=GLC:ALPHA-D-GLUCOSE'>GLC</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=PRD_900007:alpha-acarbose'>PRD_900007</scene>, <scene name='pdbligand=UNX:UNKNOWN+ATOM+OR+ION'>UNX</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=5hqa FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5hqa OCA], [https://pdbe.org/5hqa PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5hqa RCSB], [https://www.ebi.ac.uk/pdbsum/5hqa PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5hqa ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/A0A0Y0DFX2_9GAMM A0A0Y0DFX2_9GAMM] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Here we report the first crystal structure of a secretory alpha-glucoside hydrolase isolated from Pseudoalteromonas sp. K8, PspAG97A, which belongs to glycoside hydrolase family 97 and exhibits halophilic property. PspAG97A lacks an acidic surface, that is considered essential for protein stability at high salinity. Interestingly, PspAG97A unusually contains a chloride ion coordinated by the guanidinium group of Arg171 and the main chain amide groups of Tyr172 and Glu173 at the active site. The structures of PspAG97A complexed with acarbose and panose demonstrate that residues Glu173, Arg171 and Asn170 for subsite +1 decide the substrate specificity of the enzyme for the alpha-1,6-glucosidic linkage. Structural alterations observed in the R171K variant and enzyme kinetic experiments focusing on chloride assisted activation suggest that the active site chloride serves to properly orient Glu173, Arg171 and Asn170 to facilitate substrate recognition. Furthermore, the chloride assists the binding of Glu173 to the conserved calcium ion and plays an essential role in properly positioning the base catalyst Glu456. In sum, our results provide valuable insight into the structural basis of protein halophilicity.

Structures of PspAG97A alpha-glucoside hydrolase reveal a novel mechanism for chloride induced activation.,He C, Li J, Li W, Xue Y, Fang Z, Fang W, Zhang X, Wang X, Xiao Y J Struct Biol. 2016 Dec;196(3):426-436. doi: 10.1016/j.jsb.2016.09.009. Epub 2016, Sep 16. PMID:27645700<ref>PMID:27645700</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 5hqa" style="background-color:#fffaf0;"></div>

==See Also==
*[[Alpha-glucosidase 3D structures|Alpha-glucosidase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Pseudoalteromonas sp. K8]]
[[Category: He C]]
[[Category: Li J]]
[[Category: Xiao Y]]