View source for 4pmx


==Crystal structure of GH10 endo-b-1,4-xylanase (XynB) from Xanthomonas axonopodis pv citri in the native form==
<StructureSection load='4pmx' size='340' side='right'caption='[[4pmx]], [[Resolution|resolution]] 1.30&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4pmx]] is a 1 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=4PMX OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4PMX FirstGlance]. <br>
</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></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=4pmx FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4pmx OCA], [https://pdbe.org/4pmx PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4pmx RCSB], [https://www.ebi.ac.uk/pdbsum/4pmx PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4pmx ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/Q8PET6_XANAC Q8PET6_XANAC] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Xanthomonas pathogens attack a variety of economically-relevant plants and their xylan CUT system (Carbohydrate Utilization with TonB-dependent outer membrane transporter system) contains two major xylanase-related genes, XynA and XynB, which influence biofilm formation and virulence by molecular mechanisms still elusive. Herein, we demonstrated that XynA is a rare reducing-end xylose-releasing exo-oligoxylanase and not an endo-beta-1,4-xylanase as predicted. Structural analysis revealed that an insertion in the beta7-alpha7 loop induces dimerization and promotes a physical barrier at the +2 subsite conferring this unique mode of action within the GH10 family. A single mutation that impaired dimerization became XynA active against xylan and high endolytic activity was achieved when this loop was tailored to match a canonical sequence of endo-beta-1,4-xylanases, supporting our mechanistic model. On the other hand, the divergent XynB showed to be a classical endo-beta-1,4-xylanase, despite the low sequence similarity to characterized GH10 xylanases. Interestingly, this enzyme contains a calcium ion bound nearby to the glycone-binding region, which is required for catalytic activity and structural stability. These results shed light on the molecular basis for xylan degradation by Xanthomonas and suggest how these enzymes synergistically assist infection and pathogenesis. Our findings indicate that XynB contributes to breach the plant cell-wall barrier providing nutrients and facilitating the translocation of effector molecules, whereas the exo-oligoxylanase XynA possibly participates in the suppression of oligosaccharide-induced immune responses.

Molecular mechanisms associated with xylan degradation by Xanthomonas plant pathogens.,Santos CR, Hoffmam ZB, Martins VP, Zanphorlin LM, Assis LH, Honorato RV, Oliveira PS, Ruller R, Murakami MT J Biol Chem. 2014 Sep 29. pii: jbc.M114.605105. PMID:25266726<ref>PMID:25266726</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4pmx" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Xanthomonas citri pv. citri str. 306]]
[[Category: Martins VPM]]
[[Category: Murakami MT]]
[[Category: Ruller R]]
[[Category: Santos CR]]
[[Category: Zanphorlin LM]]