View source for 4cel


==ACTIVE-SITE MUTANT D214N DETERMINED AT PH 6.0 WITH NO LIGAND BOUND IN THE ACTIVE SITE==
<StructureSection load='4cel' size='340' side='right'caption='[[4cel]], [[Resolution|resolution]] 2.20&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4cel]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Trichoderma_reesei Trichoderma reesei]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4CEL OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4CEL 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]] 2.2&#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=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene>, <scene name='pdbligand=PCA:PYROGLUTAMIC+ACID'>PCA</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=4cel FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4cel OCA], [https://pdbe.org/4cel PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4cel RCSB], [https://www.ebi.ac.uk/pdbsum/4cel PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4cel ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/GUX1_HYPJE GUX1_HYPJE] The biological conversion of cellulose to glucose generally requires three types of hydrolytic enzymes: (1) Endoglucanases which cut internal beta-1,4-glucosidic bonds; (2) Exocellobiohydrolases that cut the dissaccharide cellobiose from the non-reducing end of the cellulose polymer chain; (3) Beta-1,4-glucosidases which hydrolyze the cellobiose and other short cello-oligosaccharides to glucose.
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/ce/4cel_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=4cel ConSurf].
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== Publication Abstract from PubMed ==
The roles of the residues in the catalytic trio Glu212-Asp214-Glu217 in cellobiohydrolase I (CBHI) from Trichoderma reesei have been investigated by changing these residues to their isosteric amide counterparts. Three mutants, E212Q, D214N and E217Q, were constructed and expressed in T. reesei. All three point mutations significantly impair the catalytic activity of the enzyme, although all retain some residual activity. On the small chromophoric substrate CNP-Lac, the kcat values were reduced to 1/2000, 1/85 and 1/370 of the wild-type activity, respectively, whereas the KM values remained essentially unchanged. On insoluble crystalline cellulose, BMCC, no significant activity was detected for the E212Q and E217Q mutants, whereas the D214N mutant retained residual activity. The consequences of the individual mutations on the active-site structure were assessed for two of the mutants, E212Q and D214N, by X-ray crystallography at 2.0 A and 2.2 A resolution, respectively. In addition, the structure of E212Q CBHI in complex with the natural product, cellobiose, was determined at 2.0 A resolution. The active-site structure of each mutant is very similar to that of the wild-type enzyme. In the absence of ligand, the active site of the D214N mutant contains a calcium ion firmly bound to Glu212, whereas that of E212Q does not. This supports our hypothesis that Glu212 is the charged species during catalysis. As in the complex of wild-type CBHI with bound o-iodobenzyl-1-thio-beta-D-glucoside, cellobiose is bound to the two product sites in the complex with E212Q. However, the binding of cellobiose differs from that of the glucoside in that the cellobiose is shifted away from the trio of catalytic residues to interact more intimately with a loop that is part of the outer wall of the active site.

Activity studies and crystal structures of catalytically deficient mutants of cellobiohydrolase I from Trichoderma reesei.,Stahlberg J, Divne C, Koivula A, Piens K, Claeyssens M, Teeri TT, Jones TA J Mol Biol. 1996 Nov 29;264(2):337-49. PMID:8951380<ref>PMID:8951380</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 4cel" style="background-color:#fffaf0;"></div>

==See Also==
*[[Cellobiohydrolase 3D structures|Cellobiohydrolase 3D structures]]
*[[Glucanase 3D structures|Glucanase 3D structures]]
== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Trichoderma reesei]]
[[Category: Divne C]]
[[Category: Jones TA]]
[[Category: Stahlberg J]]