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| | ==Crystal structure of the GH2 exo-beta-mannanase from Xanthomonas axonopodis pv. citri in complex with mannose== | | ==Crystal structure of the GH2 exo-beta-mannanase from Xanthomonas axonopodis pv. citri in complex with mannose== |
| - | <StructureSection load='6bye' size='340' side='right' caption='[[6bye]], [[Resolution|resolution]] 2.13Å' scene=''> | + | <StructureSection load='6bye' size='340' side='right'caption='[[6bye]], [[Resolution|resolution]] 2.13Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[6bye]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Xanac Xanac]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6BYE OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6BYE FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[6bye]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Xanthomonas_citri_pv._citri_str._306 Xanthomonas citri pv. citri str. 306]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6BYE OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6BYE FirstGlance]. <br> |
| - | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=ACT:ACETATE+ION'>ACT</scene>, <scene name='pdbligand=BMA:BETA-D-MANNOSE'>BMA</scene></td></tr> | + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.126Å</td></tr> |
| - | <tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">XAC3075 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=190486 XANAC])</td></tr> | + | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ACT:ACETATE+ION'>ACT</scene>, <scene name='pdbligand=BMA:BETA-D-MANNOSE'>BMA</scene></td></tr> |
| - | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6bye FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6bye OCA], [http://pdbe.org/6bye PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6bye RCSB], [http://www.ebi.ac.uk/pdbsum/6bye PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6bye ProSAT]</span></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=6bye FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6bye OCA], [https://pdbe.org/6bye PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6bye RCSB], [https://www.ebi.ac.uk/pdbsum/6bye PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6bye ProSAT]</span></td></tr> |
| | </table> | | </table> |
| - | <div style="background-color:#fffaf0;">
| + | == Function == |
| - | == Publication Abstract from PubMed == | + | [https://www.uniprot.org/uniprot/Q8PI23_XANAC Q8PI23_XANAC] |
| - | The classical microbial strategy for depolymerization of beta-mannan polysaccharides involves the synergistic action of at least two enzymes, endo-1,4-beta-mannanases and beta-mannosidases. In this work, we describe the first exo-beta-mannanase from the GH2 family, isolated from Xanthomonas axonopodis pv. citri (XacMan2A), which can efficiently hydrolyze both manno-oligosaccharides and beta-mannan into mannose. It represents a valuable process simplification in the microbial carbon uptake that could be of potential industrial interest. Biochemical assays revealed a progressive increase in the hydrolysis rates from mannobiose to mannohexaose, which distinguishes XacMan2A from the known GH2 beta-mannosidases. Crystallographic analysis indicates that the active-site topology of XacMan2A underwent profound structural changes at the positive-subsite region, by the removal of the physical barrier canonically observed in GH2 beta-mannosidases, generating a more open and accessible active site with additional productive positive subsites. Besides that, XacMan2A contains two residue substitutions in relation to typical GH2 beta-mannosidases, Gly(439) and Gly(556), which alter the active site volume and are essential to its mode of action. Interestingly, the only other mechanistically characterized mannose-releasing exo-beta-mannanase so far is from the GH5 family, and its mode of action was attributed to the emergence of a blocking loop at the negative-subsite region of a cleft-like active site, whereas in XacMan2A, the same activity can be explained by the removal of steric barriers at the positive-subsite region in an originally pocket-like active site. Therefore, the GH2 exo-beta-mannanase represents a distinct molecular route to this rare activity, expanding our knowledge about functional convergence mechanisms in carbohydrate-active enzymes.
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| - | Structural basis of exo-beta-mannanase activity in the GH2 family.,Domingues MN, Souza FHM, Vieira PS, de Morais MAB, Zanphorlin LM, Dos Santos CR, Pirolla RAS, Honorato RV, de Oliveira PSL, Gozzo FC, Murakami MT J Biol Chem. 2018 Aug 31;293(35):13636-13649. doi: 10.1074/jbc.RA118.002374. Epub, 2018 Jul 11. PMID:29997257<ref>PMID:29997257</ref>
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| - | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>
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| - | </div>
| + | |
| - | <div class="pdbe-citations 6bye" style="background-color:#fffaf0;"></div>
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| | | | |
| | ==See Also== | | ==See Also== |
| - | *[[Mannosidase|Mannosidase]] | + | *[[Mannosidase 3D structures|Mannosidase 3D structures]] |
| - | == References ==
| + | |
| - | <references/>
| + | |
| | __TOC__ | | __TOC__ |
| | </StructureSection> | | </StructureSection> |
| - | [[Category: Xanac]] | + | [[Category: Large Structures]] |
| - | [[Category: Domingues, M N]] | + | [[Category: Xanthomonas citri pv. citri str. 306]] |
| - | [[Category: Morais, M A.B]]
| + | [[Category: Domingues MN]] |
| - | [[Category: Murakami, M T]] | + | [[Category: Morais MAB]] |
| - | [[Category: Vieira, P S]] | + | [[Category: Murakami MT]] |
| - | [[Category: Carbohydrate]] | + | [[Category: Vieira PS]] |
| - | [[Category: Hydrolase-carbohydrate complex]] | + | |
