View source for 2vkh


==CRYSTAL STRUCTURE OF THE CATALYTIC DOMAIN OF LETHAL TOXIN FROM CLOSTRIDIUM SORDELLII IN COMPLEX WITH UDP-GLC AND CALCIUM ION==
<StructureSection load='2vkh' size='340' side='right'caption='[[2vkh]], [[Resolution|resolution]] 2.30&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2vkh]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Paeniclostridium_sordellii Paeniclostridium sordellii]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2VKH OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2VKH 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]] 2.3&#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=UPG:URIDINE-5-DIPHOSPHATE-GLUCOSE'>UPG</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=2vkh FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2vkh OCA], [https://pdbe.org/2vkh PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2vkh RCSB], [https://www.ebi.ac.uk/pdbsum/2vkh PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2vkh ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/TCSL1_PAESO TCSL1_PAESO] Precursor of a cytotoxin that targets the vascular endothelium, inducing an anti-inflammatory effect and resulting in lethal toxic shock syndrome (PubMed:19527792, PubMed:24919149, PubMed:29146177). TcsL constitutes the main toxin that mediates the pathology of P.sordellii infection, an anaerobic Gram-positive bacterium found in soil and in the gastrointestinal and vaginal tracts of animals and humans; although the majority of carriers are asymptomatic, pathogenic P.sordellii infections arise rapidly and are highly lethal (PubMed:29146177). This form constitutes the precursor of the toxin: it enters into host cells and mediates autoprocessing to release the active toxin (Glucosyltransferase TcsL) into the host cytosol (PubMed:32302524, PubMed:17334356, PubMed:27303685). Targets vascular endothelium by binding to the semaphorin proteins SEMA6A and SEMA6B, and enters host cells via clathrin-mediated endocytosis (PubMed:32302524). Once entered into host cells, acidification in the endosome promotes the membrane insertion of the translocation region and formation of a pore, leading to translocation of the GT44 and peptidase C80 domains across the endosomal membrane (By similarity). This activates the peptidase C80 domain and autocatalytic processing, releasing the N-terminal part (Glucosyltransferase TcsL), which constitutes the active part of the toxin, in the cytosol (PubMed:17334356, PubMed:27303685).[UniProtKB:P18177]<ref>PMID:17334356</ref> <ref>PMID:19527792</ref> <ref>PMID:24919149</ref> <ref>PMID:27303685</ref> <ref>PMID:32302524</ref> <ref>PMID:29146177</ref>   Active form of the toxin, which is released into the host cytosol following autoprocessing and inactivates small GTPases (PubMed:8626575, PubMed:8626586, PubMed:9632667, PubMed:17901056, PubMed:19744486, PubMed:24905543, PubMed:24919149, PubMed:27303685, PubMed:27023605, PubMed:30622517). Acts by mediating monoglucosylation of small GTPases of the Ras (H-Ras/HRAS, K-Ras/KRAS, N-Ras/NRAS and Ral/RALA) family in host cells at the conserved threonine residue located in the switch I region ('Thr-37/35'), using UDP-alpha-D-glucose as the sugar donor (PubMed:8858106, PubMed:8626575, PubMed:8626586, PubMed:9632667, PubMed:17901056, PubMed:19744486, PubMed:24905543, PubMed:24919149, PubMed:27023605, PubMed:30622517). Also able to catalyze monoglucosylation of some members of the Rho family (Rac1 and Rap2A), but with less efficiency than with Ras proteins (PubMed:8626586, PubMed:9632667, PubMed:19744486, PubMed:24905543). Monoglucosylation of host small GTPases completely prevents the recognition of the downstream effector, blocking the GTPases in their inactive form and leading to apoptosis (PubMed:8626586, PubMed:9632667, PubMed:17910886). Induces an anti-inflammatory effect, mainly by inactivating Ras proteins which results in blockage of the cell cycle and killing of immune cells (PubMed:17910886, PubMed:24919149). The absence or moderate local inflammatory response allows C.sordellii spreading in deep tissues, production of toxin which is released in the general circulation and causes a toxic shock syndrome (PubMed:24919149, PubMed:29146177).<ref>PMID:17901056</ref> <ref>PMID:17910886</ref> <ref>PMID:19744486</ref> <ref>PMID:24905543</ref> <ref>PMID:24919149</ref> <ref>PMID:27023605</ref> <ref>PMID:27303685</ref> <ref>PMID:30622517</ref> <ref>PMID:8626575</ref> <ref>PMID:8626586</ref> <ref>PMID:8858106</ref> <ref>PMID:9632667</ref> <ref>PMID:29146177</ref> 
== 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/vk/2vkh_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.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=2vkh ConSurf].
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== Publication Abstract from PubMed ==
The crystal structures of the catalytic fragments of 'lethal toxin' from Clostridium sordellii and of 'alpha-toxin' from Clostridium novyi have been established. Almost half of the residues follow the chain fold of the glycosyl-transferase type A family of enzymes; the other half forms large alpha-helical protrusions that are likely to confer specificity for the respective targeted subgroup of Rho proteins in the cell. In the crystal, the active center of alpha-toxin contained no substrates and was disassembled, whereas that of lethal toxin, which was ligated with the donor substrate UDP-glucose and cofactor Mn2+, was catalytically competent. Surprisingly, the structure of lethal toxin with Ca2+ (instead of Mn2+) at the cofactor position showed a bound donor substrate with a disassembled active center, indicating that the strictly octahedral coordination sphere of Mn2+ is indispensable to the integrity of the enzyme. The homologous structures of alpha-toxin without substrate, distorted lethal toxin with Ca2+ plus donor, active lethal toxin with Mn2+ plus donor and the homologous Clostridium difficile toxin B with a hydrolyzed donor have been lined up to show the geometry of several reaction steps. Interestingly, the structural refinement of one of the three crystallographically independent molecules of Ca2+-ligated lethal toxin resulted in the glucosyl half-chair conformation expected for glycosyl-transferases that retain the anomeric configuration at the C1'' atom. A superposition of six acceptor substrates bound to homologous enzymes yielded the position of the nucleophilic acceptor atom with a deviation of &lt;1 A. The resulting donor-acceptor geometry suggests that the reaction runs as a circular electron transfer in a six-membered ring, which involves the deprotonation of the nucleophile by the beta-phosphoryl group of the donor substrate UDP-glucose.

Conformational changes and reaction of clostridial glycosylating toxins.,Ziegler MO, Jank T, Aktories K, Schulz GE J Mol Biol. 2008 Apr 11;377(5):1346-56. Epub 2008 Jan 5. PMID:18325534<ref>PMID:18325534</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Paeniclostridium sordellii]]
[[Category: Aktories K]]
[[Category: Jank T]]
[[Category: Schulz GE]]
[[Category: Ziegler MOP]]