View source for 10qi


==Crystal Structure of Treponema denticola Sialidase (TDE_0471) D165A mutant bound to 3'-sialyllactose (only Neu5Ac visible)==
<StructureSection load='10qi' size='340' side='right'caption='[[10qi]], [[Resolution|resolution]] 1.81&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[10qi]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Treponema_denticola Treponema denticola]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=10QI OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=10QI 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]] 1.81&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CD:CADMIUM+ION'>CD</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene>, <scene name='pdbligand=PEG:DI(HYDROXYETHYL)ETHER'>PEG</scene>, <scene name='pdbligand=SIA:O-SIALIC+ACID'>SIA</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=10qi FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=10qi OCA], [https://pdbe.org/10qi PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=10qi RCSB], [https://www.ebi.ac.uk/pdbsum/10qi PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=10qi ProSAT]</span></td></tr>
</table>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The complement system is a central pillar of innate immunity, yet how bacterial glycan-modifying enzymes subvert complement function remains poorly understood. Bacterial sialidases remove terminal sialic acids from host sialoglycans, but their direct impact on complement immunity is unclear. Here, we investigate the impact of six sialidases from five human pathogens on complement immunity using an integrated approach combining genetics, biochemistry, glycobiology, mass spectrometry, and structural biology. We demonstrate that major complement components (IgG, C1q, C4, and C5) and regulators (Factor I, Factor H, and C4bp) are sialylated, and that bacterial sialidase-mediated desialylation suppresses complement activation and surface deposition, thereby enabling complement evasion. Despite extensive sequence diversity, biochemical and structural analyses reveal that all examined sialidases share a conserved six-bladed beta-propeller catalytic domain and cleave both N-acetylneuraminic and N-glycolylneuraminic acids, the predominant mammalian sialic acids. Together, these findings uncover a conserved mechanism by which diverse bacterial pathogens disable complement immunity through desialylation.

Bacterial exo-alpha-sialidases subvert the complement system through desialylation.,Kurniyati K, Clark ND, Fu Q, Zhang S, Qiu W, Malkowski MG, Li C bioRxiv [Preprint]. 2026 Feb 5:2026.02.05.703967. doi: , 10.64898/2026.02.05.703967. PMID:41676663<ref>PMID:41676663</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 10qi" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Treponema denticola]]
[[Category: Clark ND]]
[[Category: Malkowski MG]]