View source for 6xrk


==GH5-4 broad specificity endoglucanase from an uncultured bovine rumen ciliate==
<StructureSection load='6xrk' size='340' side='right'caption='[[6xrk]], [[Resolution|resolution]] 1.42&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6xrk]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Uncultured_bovine_rumen_ciliate Uncultured bovine rumen ciliate]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6XRK OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6XRK 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]] 1.419&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=BTB:2-[BIS-(2-HYDROXY-ETHYL)-AMINO]-2-HYDROXYMETHYL-PROPANE-1,3-DIOL'>BTB</scene>, <scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=PEG:DI(HYDROXYETHYL)ETHER'>PEG</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=6xrk FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6xrk OCA], [https://pdbe.org/6xrk PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6xrk RCSB], [https://www.ebi.ac.uk/pdbsum/6xrk PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6xrk ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/G5DDB8_9CILI G5DDB8_9CILI] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Broad-specificity glycoside hydrolases (GHs) contribute to plant biomass hydrolysis by degrading a diverse range of polysaccharides, making them useful catalysts for renewable energy and biocommodity production. Discovery of new GHs with improved kinetic parameters or more tolerant substrate-binding sites could increase the efficiency of renewable bioenergy production even further. GH5 has over 50 subfamilies exhibiting selectivities for reaction with beta-(1,4)-linked oligo- and polysaccharides. Among these, subfamily 4 (GH5_4) contains numerous broad-selectivity endoglucanases that hydrolyze cellulose, xyloglucan, and mixed-linkage glucans. We previously surveyed the whole subfamily and found over 100 new broad-specificity endoglucanases, although the structural origins of broad specificity remained unclear. A mechanistic understanding of GH5_4 substrate specificity would help inform the best protein design strategies and the most appropriate industrial application of broad-specificity endoglucanases. Here we report structures of 10 new GH5_4 enzymes from cellulolytic microbes and characterize their substrate selectivity using normalized reducing sugar assays and MS. We found that GH5_4 enzymes have the highest catalytic efficiency for hydrolysis of xyloglucan, glucomannan, and soluble beta-glucans, with opportunistic secondary reactions on cellulose, mannan, and xylan. The positions of key aromatic residues determine the overall reaction rate and breadth of substrate tolerance, and they contribute to differences in oligosaccharide cleavage patterns. Our new composite model identifies several critical structural features that confer broad specificity and may be readily engineered into existing industrial enzymes. We demonstrate that GH5_4 endoglucanases can have broad specificity without sacrificing high activity, making them a valuable addition to the biomass deconstruction toolset.

A structural and kinetic survey of GH5_4 endoglucanases reveals determinants of broad substrate specificity and opportunities for biomass hydrolysis.,Glasgow EM, Kemna EI, Bingman CA, Ing N, Deng K, Bianchetti CM, Takasuka TE, Northen TR, Fox BG J Biol Chem. 2020 Dec 18;295(51):17752-17769. doi: 10.1074/jbc.RA120.015328. PMID:33454012<ref>PMID:33454012</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6xrk" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Uncultured bovine rumen ciliate]]
[[Category: Bingman CA]]
[[Category: Fox BG]]
[[Category: Glasgow EM]]
[[Category: Smith RW]]