5z3c: Difference between revisions
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<StructureSection load='5z3c' size='340' side='right'caption='[[5z3c]], [[Resolution|resolution]] 1.60Å' scene=''> | <StructureSection load='5z3c' size='340' side='right'caption='[[5z3c]], [[Resolution|resolution]] 1.60Å' scene=''> | ||
== Structural highlights == | == Structural highlights == | ||
<table><tr><td colspan='2'>[[5z3c]] is a 1 chain structure with sequence from [ | <table><tr><td colspan='2'>[[5z3c]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Krifd Krifd]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5Z3C OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5Z3C FirstGlance]. <br> | ||
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=GOL:GLYCEROL'>GOL</scene></td></tr> | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=GOL:GLYCEROL'>GOL</scene></td></tr> | ||
<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">Kfla_1896 ([ | <tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">Kfla_1896 ([https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=479435 KRIFD])</td></tr> | ||
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[ | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=5z3c FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5z3c OCA], [https://pdbe.org/5z3c PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5z3c RCSB], [https://www.ebi.ac.uk/pdbsum/5z3c PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5z3c ProSAT]</span></td></tr> | ||
</table> | </table> | ||
== Function == | == Function == | ||
[[ | [[https://www.uniprot.org/uniprot/IMGH_KRIFD IMGH_KRIFD]] Involved in the intracellular degradation of the cyclic tetrasaccharide cyclobis-(1-6)-alpha-nigerosyl (CNN) formed extracellularly from starch. Catalyzes the hydrolysis of alpha-1,6-glucosidic linkage from the non-reducing end of isomaltose to yield beta-D-glucose and D-glucose. Can also act on panose and isomaltotriose at a lower rate. It displays low or no activity toward CNN and the general GH15 enzyme substrates such as maltose, soluble starch or dextran.<ref>PMID:27302067</ref> | ||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
Glycoside hydrolase family 15 (GH15) inverting enzymes contain two glutamate residues functioning as a general acid catalyst and a general base catalyst, for isomaltose glucohydrolase (IGHase), Glu178 and Glu335, respectively. Generally, a two-catalytic residue-mediated reaction exhibits a typical bell-shaped pH-activity curve. However, IGHase is found to display atypical non-bell-shaped pH-kcat and pH-kcat /Km profiles, theoretically better-fitted to a three-catalytic residue-associated pH-activity curve. We determined the crystal structure of IGHase by the single-wavelength anomalous dispersion method using sulfur atoms and the cocrystal structure of a catalytic base mutant E335A with isomaltose. Although the activity of E335A was undetectable, the electron density observed in its active site pocket did not correspond to an isomaltose but a glycerol and a beta-glucose, cryoprotectant, and hydrolysis product. Our structural and biochemical analyses of several mutant enzymes suggest that Tyr48 acts as a second catalytic base catalyst. Y48F mutant displayed almost equivalent specific activity to a catalytic acid mutant E178A. Tyr48, highly conserved in all GH15 members, is fixed by another Tyr residue in many GH15 enzymes; the latter Tyr is replaced by Phe290 in IGHase. The pH profile of F290Y mutant changed to a bell-shaped curve, suggesting that Phe290 is a key residue distinguishing Tyr48 of IGHase from other GH15 members. Furthermore, F290Y is found to accelerate the condensation of isomaltose from glucose by modifying a hydrogen-bonding network between Tyr290-Tyr48-Glu335. The present study indicates that the atypical Phe290 makes Tyr48 of IGHase unique among GH15 enzymes. | |||
Structural insights reveal the second base catalyst of isomaltose glucohydrolase.,Tagami T, Chen M, Furunaga Y, Kikuchi A, Sadahiro J, Lang W, Okuyama M, Tanaka Y, Iwasaki T, Yao M, Kimura A FEBS J. 2022 Feb;289(4):1118-1134. doi: 10.1111/febs.16237. Epub 2021 Oct 30. PMID:34665923<ref>PMID:34665923</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
<div class="pdbe-citations 5z3c" style="background-color:#fffaf0;"></div> | |||
== References == | == References == | ||
<references/> | <references/> | ||