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| | ==Ala6 Variant of ImI Conotoxin== | | ==Ala6 Variant of ImI Conotoxin== |
| - | <StructureSection load='2ifi' size='340' side='right'caption='[[2ifi]], [[NMR_Ensembles_of_Models | 15 NMR models]]' scene=''> | + | <StructureSection load='2ifi' size='340' side='right'caption='[[2ifi]]' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[2ifi]] is a 1 chain structure. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2IFI OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2IFI FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[2ifi]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Synthetic_construct Synthetic construct]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2IFI OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2IFI FirstGlance]. <br> |
| - | </td></tr><tr id='NonStdRes'><td class="sblockLbl"><b>[[Non-Standard_Residue|NonStd Res:]]</b></td><td class="sblockDat"><scene name='pdbligand=NH2:AMINO+GROUP'>NH2</scene></td></tr> | + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Solution NMR</td></tr> |
| - | <tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat"><div style='overflow: auto; max-height: 3em;'>[[2ifj|2ifj]], [[2ifz|2ifz]], [[2igu|2igu]], [[2ih6|2ih6]], [[2ih7|2ih7]]</div></td></tr> | + | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=NH2:AMINO+GROUP'>NH2</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=2ifi FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2ifi OCA], [https://pdbe.org/2ifi PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2ifi RCSB], [https://www.ebi.ac.uk/pdbsum/2ifi PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2ifi 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=2ifi FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2ifi OCA], [https://pdbe.org/2ifi PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2ifi RCSB], [https://www.ebi.ac.uk/pdbsum/2ifi PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2ifi ProSAT]</span></td></tr> |
| | </table> | | </table> |
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| | </StructureSection> | | </StructureSection> |
| | [[Category: Large Structures]] | | [[Category: Large Structures]] |
| - | [[Category: Kang, T S]] | + | [[Category: Synthetic construct]] |
| - | [[Category: Kini, R M]] | + | [[Category: Kang TS]] |
| - | [[Category: Conotoxin]] | + | [[Category: Kini RM]] |
| - | [[Category: Disulfide linkage]]
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| - | [[Category: Ribbon conformation]]
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| - | [[Category: Toxin]]
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| Structural highlights
Publication Abstract from PubMed
Alpha-conotoxins isolated from Conus venoms contain 11-19 residues and preferentially fold into the globular conformation that possesses a specific disulfide pairing pattern (C1-3, C2-4). We and others isolated a new family of chi-conotoxins (also called lambda conotoxins) with the conserved cysteine framework of alpha-conotoxins but with alternative disulfide pairing (C1-4, C2-3) resulting in the ribbon conformation. In both families, disulfide pairing and hence folding are important for their biological potency. By comparing the structural differences, we identified potential structural determinants responsible for the folding tendencies of these conotoxins. We examined the role of conserved proline in the first intercysteine loop and the conserved C-terminal amide on folding patterns of synthetic analogues of ImI conotoxin by comparing the isoforms with the regiospecifically synthesized conformers. Deamidation at the C-terminus and substitution of proline in the first intercysteine loop switch the folding pattern from the globular form of alpha-conotoxins to the ribbon form of chi/lambda-conotoxins. The findings are corroborated by reciprocal folding of CMrVIA chi/lambda-conotoxins. Substitution of Lys-6 from the first intercysteine loop of CMrVIA conotoxin with proline, as well as the inclusion of an amidated C-terminal shifted the folding preference of CMrVIA conotoxin from its native ribbon conformation toward the globular conformation. Binding assays of ImI conotoxin analogues with Aplysia and Bulinus acetylcholine binding protein indicate that both these substitutions and their consequent conformational change substantially impact the binding affinity of ImI conotoxin. These results strongly indicate that the first intercysteine loop proline and C-terminal amidation act as conformational switches in alpha- and chi/lambda-conotoxins.
Protein folding determinants: structural features determining alternative disulfide pairing in alpha- and chi/lambda-conotoxins.,Kang TS, Radic Z, Talley TT, Jois SD, Taylor P, Kini RM Biochemistry. 2007 Mar 20;46(11):3338-55. Epub 2007 Feb 22. PMID:17315952[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Kang TS, Radic Z, Talley TT, Jois SD, Taylor P, Kini RM. Protein folding determinants: structural features determining alternative disulfide pairing in alpha- and chi/lambda-conotoxins. Biochemistry. 2007 Mar 20;46(11):3338-55. Epub 2007 Feb 22. PMID:17315952 doi:10.1021/bi061969o
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