View source for 1e1h


==Crystal Structure of recombinant Botulinum Neurotoxin Type A Light Chain, self-inhibiting Zn endopeptidase.==
<StructureSection load='1e1h' size='340' side='right'caption='[[1e1h]], [[Resolution|resolution]] 1.80&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1e1h]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Clostridium_botulinum Clostridium botulinum]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1E1H OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1E1H 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]] 1.8&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ZN:ZINC+ION'>ZN</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=1e1h FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1e1h OCA], [https://pdbe.org/1e1h PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1e1h RCSB], [https://www.ebi.ac.uk/pdbsum/1e1h PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1e1h ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/BXA2_CLOBJ BXA2_CLOBJ] Botulinum toxin causes flaccid paralysis by inhibiting neurotransmitter (acetylcholine) release from the presynaptic membranes of nerve terminals of eukaryotic host skeletal and autonomic nervous system, with frequent heart or respiratory failure. Precursor of botulinum neurotoxin A2 which has 2 coreceptors; complex polysialylated gangliosides found on neural tissue and specific membrane-anchored proteins found in synaptic vesicles. Receptor proteins are exposed on host presynaptic cell membrane during neurotransmitter release, when the toxin heavy chain (HC) binds to them. Upon synaptic vesicle recycling the toxin is taken up via the endocytic pathway. When the pH of the toxin-containing endosome drops a structural rearrangement occurs so that the N-terminus of the HC forms pores that allows the light chain (LC) to translocate into the cytosol. Once in the cytosol the disulfide bond linking the 2 subunits is reduced and LC cleaves its target protein on synaptic vesicles, preventing their fusion with the cytoplasmic membrane and thus neurotransmitter release (By similarity).[UniProtKB:P0DPI0]  Has proteolytic activity. After translocation into the eukaryotic host cytosol, LC hydrolyzes the 197-Gln-|-Arg-198 bond in SNAP25, blocking neurotransmitter release (PubMed:16846233).<ref>PMID:16846233</ref>   Responsible for host epithelial cell transcytosis, host nerve cell targeting and translocation of light chain (LC) into host cytosol. Composed of 3 subdomains; the translocation domain (TD), and N-terminus and C-terminus of the receptor-binding domain (RBD). The RBD is responsible for the adherence of the toxin to the cell surface. It simultaneously recognizes 2 coreceptors; polysialated gangliosides and the receptor protein SV2 in close proximity on host synaptic vesicles (PubMed:28252640, PubMed:29649119). The N-terminus of the TD wraps an extended belt around the perimeter of the LC, protecting Zn(2+) in the active site; it may also prevent premature LC dissociation from the translocation channel and to protect toxin prior to translocation (By similarity). The TD inserts into synaptic vesicle membrane to allow translocation into the host cytosol (By similarity).[UniProtKB:P0DPI0]<ref>PMID:28252640</ref> <ref>PMID:29649119</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/e1/1e1h_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=1e1h ConSurf].
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== Publication Abstract from PubMed ==
Clostridium botulinum neurotoxins (BoNTs), the most potent toxins known, disrupt neurotransmission through proteolysis of proteins involved in neuroexocytosis. The light chains of BoNTs are unique zinc proteases that have stringent substrate specificity and require exceptionally long substrates. We have determined the crystal structure of the protease domain from BoNT serotype A (BoNT/A). The structure reveals a homodimer in a product-bound state, with loop F242-V257 from each monomer deeply buried in its partner's catalytic site. The loop, which acts as a substrate, is oriented in reverse of the canonical direction for other zinc proteases. The Y249-Y250 peptide bond of the substrate loop is hydrolyzed, leaving the Y249 product carboxylate coordinated to the catalytic zinc. From the crystal structure of the BoNT/A protease, detailed models of noncanonical binding and proteolysis can be derived which we propose are also consistent with BoNT/A binding and proteolysis of natural substrate synaptosome-associated protein of 25 kDa (SNAP-25). The proposed BoNT/A substrate-binding mode and catalytic mechanism are markedly different from those previously proposed for the BoNT serotype B.

Crystal structure of Clostridium botulinum neurotoxin protease in a product-bound state: Evidence for noncanonical zinc protease activity.,Segelke B, Knapp M, Kadkhodayan S, Balhorn R, Rupp B Proc Natl Acad Sci U S A. 2004 May 4;101(18):6888-93. Epub 2004 Apr 23. PMID:15107500<ref>PMID:15107500</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 1e1h" style="background-color:#fffaf0;"></div>

==See Also==
*[[Botulinum neurotoxin 3D structures|Botulinum neurotoxin 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Clostridium botulinum]]
[[Category: Large Structures]]
[[Category: Knapp M]]
[[Category: Rupp B]]