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1q2b

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[[Image:1q2b.jpg|left|200px]]<br /><applet load="1q2b" size="350" color="white" frame="true" align="right" spinBox="true"
 
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caption="1q2b, resolution 1.60&Aring;" />
 
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'''CELLOBIOHYDROLASE CEL7A WITH DISULPHIDE BRIDGE ADDED ACROSS EXO-LOOP BY MUTATIONS D241C AND D249C'''<br />
 
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==Overview==
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==CELLOBIOHYDROLASE CEL7A WITH DISULPHIDE BRIDGE ADDED ACROSS EXO-LOOP BY MUTATIONS D241C AND D249C==
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The exo-loop of Trichoderma reesei cellobiohydrolase Cel7A forms the roof of the active site tunnel at the catalytic centre. Mutants were designed to study the role of this loop in crystalline cellulose degradation. A hydrogen bond to substrate made by a tyrosine at the tip of the loop was removed by the Y247F mutation. The mobility of the loop was reduced by introducing a new disulphide bridge in the mutant D241C/D249C. The tip of the loop was deleted in mutant Delta(G245-Y252). No major structural disturbances were observed in the mutant enzymes, nor was the thermostability of the enzyme affected by the mutations.The Y247F mutation caused a slight k(cat) reduction on 4-nitrophenyl lactoside, but only a small effect on cellulose hydrolysis. Deletion of the tip of the loop increased both k(cat) and K(M) and gave reduced product inhibition. Increased activity was observed on amorphous cellulose, while only half the original activity remained on crystalline cellulose. Stabilisation of the exo-loop by the disulphide bridge enhanced the activity on both amorphous and crystalline cellulose. The ratio Glc(2)/(Glc(3)+Glc(1)) released from cellulose, which is indicative of processive action, was highest with Tr Cel7A wild-type enzyme and smallest with the deletion mutant on both substrates. Based on these data it seems that the exo-loop of Tr Cel7A has evolved to facilitate processive crystalline cellulose degradation, which does not require significant conformational changes of this loop.
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<StructureSection load='1q2b' size='340' side='right'caption='[[1q2b]], [[Resolution|resolution]] 1.60&Aring;' scene=''>
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== Structural highlights ==
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<table><tr><td colspan='2'>[[1q2b]] is a 1 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=1Q2B OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1Q2B FirstGlance]. <br>
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</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.6&#8491;</td></tr>
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<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CO:COBALT+(II)+ION'>CO</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene>, <scene name='pdbligand=PCA:PYROGLUTAMIC+ACID'>PCA</scene></td></tr>
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1q2b FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1q2b OCA], [https://pdbe.org/1q2b PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1q2b RCSB], [https://www.ebi.ac.uk/pdbsum/1q2b PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1q2b ProSAT]</span></td></tr>
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</table>
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== Function ==
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[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.
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== Evolutionary Conservation ==
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[[Image:Consurf_key_small.gif|200px|right]]
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Check<jmol>
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<jmolCheckbox>
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<scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/q2/1q2b_consurf.spt"</scriptWhenChecked>
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<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
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<text>to colour the structure by Evolutionary Conservation</text>
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</jmolCheckbox>
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</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=1q2b ConSurf].
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<div style="clear:both"></div>
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==About this Structure==
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==See Also==
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1Q2B is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Hypocrea_jecorina Hypocrea jecorina] with <scene name='pdbligand=NAG:'>NAG</scene> and <scene name='pdbligand=CO:'>CO</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Cellulose_1,4-beta-cellobiosidase Cellulose 1,4-beta-cellobiosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.91 3.2.1.91] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1Q2B OCA].
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*[[Cellobiohydrolase 3D structures|Cellobiohydrolase 3D structures]]
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*[[Glucanase 3D structures|Glucanase 3D structures]]
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==Reference==
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__TOC__
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Engineering the exo-loop of Trichoderma reesei cellobiohydrolase, Cel7A. A comparison with Phanerochaete chrysosporium Cel7D., von Ossowski I, Stahlberg J, Koivula A, Piens K, Becker D, Boer H, Harle R, Harris M, Divne C, Mahdi S, Zhao Y, Driguez H, Claeyssens M, Sinnott ML, Teeri TT, J Mol Biol. 2003 Oct 31;333(4):817-29. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=14568538 14568538]
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</StructureSection>
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[[Category: Cellulose 1,4-beta-cellobiosidase]]
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[[Category: Large Structures]]
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[[Category: Hypocrea jecorina]]
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[[Category: Trichoderma reesei]]
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[[Category: Single protein]]
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[[Category: Harris M]]
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[[Category: Harris, M.]]
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[[Category: Jones TA]]
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[[Category: Jones, T A.]]
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[[Category: Stahlberg J]]
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[[Category: Stahlberg, J.]]
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[[Category: CO]]
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[[Category: NAG]]
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[[Category: cellulase]]
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[[Category: cellulose degradation]]
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[[Category: disulphide mutant]]
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[[Category: glycoprotein]]
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[[Category: glycosidase]]
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[[Category: glycosylated protein]]
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[[Category: hydrolase]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:35:08 2008''
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Current revision

CELLOBIOHYDROLASE CEL7A WITH DISULPHIDE BRIDGE ADDED ACROSS EXO-LOOP BY MUTATIONS D241C AND D249C

PDB ID 1q2b

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