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| | <StructureSection load='6cwg' size='340' side='right'caption='[[6cwg]], [[Resolution|resolution]] 2.60Å' scene=''> | | <StructureSection load='6cwg' size='340' side='right'caption='[[6cwg]], [[Resolution|resolution]] 2.60Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[6cwg]] is a 4 chain structure with sequence from [http://en.wikipedia.org/wiki/Alpaca Alpaca] and [http://en.wikipedia.org/wiki/Castor_bean Castor bean]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6CWG OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6CWG FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[6cwg]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Ricinus_communis Ricinus communis] and [https://en.wikipedia.org/wiki/Vicugna_pacos Vicugna pacos]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6CWG OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6CWG FirstGlance]. <br> |
| - | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</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]] 2.6Å</td></tr> |
| - | <tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/rRNA_N-glycosylase rRNA N-glycosylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.2.22 3.2.2.22] </span></td></tr> | + | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</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=6cwg FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6cwg OCA], [http://pdbe.org/6cwg PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6cwg RCSB], [http://www.ebi.ac.uk/pdbsum/6cwg PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6cwg 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=6cwg FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6cwg OCA], [https://pdbe.org/6cwg PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6cwg RCSB], [https://www.ebi.ac.uk/pdbsum/6cwg PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6cwg ProSAT]</span></td></tr> |
| | </table> | | </table> |
| | == Function == | | == Function == |
| - | [[http://www.uniprot.org/uniprot/RICI_RICCO RICI_RICCO]] Ricin is highly toxic to animal cells and to a lesser extent to plant cells. The A chain acts as a glycosidase that removes a specific adenine residue from an exposed loop of the 28S rRNA (A4324 in mammals), leading to rRNA breakage. As this loop is involved in elongation factor binding, modified ribosomes are catalytically inactive and unable to support protein synthesis. The A chain can inactivate a few thousand ribosomes per minute, faster than the cell can make new ones. Therefore a single A chain molecule can kill an animal cell. The B chain binds to beta-D-galactopyranoside moieties on cell surface glycoproteins and glycolipids and facilitates the entry into the cell of the A chain; B chains are also responsible for cell agglutination (Lectin activity). | + | [https://www.uniprot.org/uniprot/RICI_RICCO RICI_RICCO] Ricin is highly toxic to animal cells and to a lesser extent to plant cells. The A chain acts as a glycosidase that removes a specific adenine residue from an exposed loop of the 28S rRNA (A4324 in mammals), leading to rRNA breakage. As this loop is involved in elongation factor binding, modified ribosomes are catalytically inactive and unable to support protein synthesis. The A chain can inactivate a few thousand ribosomes per minute, faster than the cell can make new ones. Therefore a single A chain molecule can kill an animal cell. The B chain binds to beta-D-galactopyranoside moieties on cell surface glycoproteins and glycolipids and facilitates the entry into the cell of the A chain; B chains are also responsible for cell agglutination (Lectin activity). |
| | <div style="background-color:#fffaf0;"> | | <div style="background-color:#fffaf0;"> |
| | == Publication Abstract from PubMed == | | == Publication Abstract from PubMed == |
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| | ==See Also== | | ==See Also== |
| | *[[Antibody 3D structures|Antibody 3D structures]] | | *[[Antibody 3D structures|Antibody 3D structures]] |
| | + | *[[Ricin 3D structures|Ricin 3D structures]] |
| | + | *[[3D structures of non-human antibody|3D structures of non-human antibody]] |
| | == References == | | == References == |
| | <references/> | | <references/> |
| | __TOC__ | | __TOC__ |
| | </StructureSection> | | </StructureSection> |
| - | [[Category: Alpaca]] | |
| - | [[Category: Castor bean]] | |
| | [[Category: Large Structures]] | | [[Category: Large Structures]] |
| - | [[Category: RRNA N-glycosylase]] | + | [[Category: Ricinus communis]] |
| - | [[Category: Mantis, N]] | + | [[Category: Vicugna pacos]] |
| - | [[Category: Rudolph, M J]] | + | [[Category: Mantis N]] |
| - | [[Category: Immune system]] | + | [[Category: Rudolph MJ]] |
| - | [[Category: Ricin catalytic subunit]]
| + | |
| - | [[Category: Vhh antibody]]
| + | |
| Structural highlights
Function
RICI_RICCO Ricin is highly toxic to animal cells and to a lesser extent to plant cells. The A chain acts as a glycosidase that removes a specific adenine residue from an exposed loop of the 28S rRNA (A4324 in mammals), leading to rRNA breakage. As this loop is involved in elongation factor binding, modified ribosomes are catalytically inactive and unable to support protein synthesis. The A chain can inactivate a few thousand ribosomes per minute, faster than the cell can make new ones. Therefore a single A chain molecule can kill an animal cell. The B chain binds to beta-D-galactopyranoside moieties on cell surface glycoproteins and glycolipids and facilitates the entry into the cell of the A chain; B chains are also responsible for cell agglutination (Lectin activity).
Publication Abstract from PubMed
Ricin toxin's enzymatic subunit (RTA) has been subjected to intensive B cell epitope mapping studies using a combination of competition ELISAs, hydrogen exchange-mass spectrometry and X-ray crystallography. Those studies identified four spatially distinct clusters (I-IV) of toxin-neutralizing epitopes on the surface of RTA. Here we describe A9, a new single domain camelid antibody (VHH) that was proposed to recognize a novel epitope on RTA that straddles clusters I and III. The X-ray crystal structure of A9 bound to RTA (2.6 A resolution) revealed extensive antibody contact with RTA's beta-strand h (732 A2 buried surface area; BSA), along with limited engagement with alpha-helix D (90 A2) and alpha-helix C (138 A2). Collectively, these contacts explain the overlap between epitope clusters I and III, as identified by competition ELISA. However, considerable binding affinity, and, consequently, toxin-neutralizing activity of A9 is mediated by an unusual CDR2 containing five consecutive Gly residues that interact with alpha-helix B (82 A2), a known neutralizing hotspot on RTA. Removal of a single Gly residue from the penta-glycine stretch in CDR2 reduced A9's binding affinity by 10-fold and eliminated toxin-neutralizing activity. Computational modeling indicates that removal of a Gly from CDR2 does not perturb contact with RTA per se, but results in the loss of an intramolecular hydrogen bond network involved in stabilizing CDR2 in the unbound state. These results reveal a novel configuration of a CDR2 element involved in neutralizing ricin toxin.
Contribution of an unusual CDR2 element of a single domain antibody in ricin toxin binding affinity and neutralizing activity.,Rudolph MJ, Vance DJ, Kelow S, Angalakurthi SK, Nguyen S, Davis SA, Rong Y, Middaugh CR, Weis DD, Dunbrack R Jr, Karanicolas J, Mantis NJ Protein Eng Des Sel. 2018 Jul 1;31(7-8):277-287. doi: 10.1093/protein/gzy022. PMID:30265352[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Rudolph MJ, Vance DJ, Kelow S, Angalakurthi SK, Nguyen S, Davis SA, Rong Y, Middaugh CR, Weis DD, Dunbrack R Jr, Karanicolas J, Mantis NJ. Contribution of an unusual CDR2 element of a single domain antibody in ricin toxin binding affinity and neutralizing activity. Protein Eng Des Sel. 2018 Jul 1;31(7-8):277-287. doi: 10.1093/protein/gzy022. PMID:30265352 doi:http://dx.doi.org/10.1093/protein/gzy022
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