The synthesis, structural characterization, and receptor specificity of the alpha-conotoxin Vc1.1.
The alpha-conotoxin Vc1.1 is a small disulfide-bonded peptide currently in development as a treatment for neuropathic pain. This study describes the synthesis, determination of the disulfide connectivity, and the determination of the three-dimensional structure of Vc1.1 using NMR spectroscopy. Vc1.1 was shown to inhibit nicotine-evoked membrane currents in isolated bovine chromaffin cells in a concentration-dependent manner and preferentially targets peripheral nicotinic acetylcholine receptor (nAChR) subtypes over central subtypes. Specifically, Vc1.1 is selective for alpha3-containing nAChR subtypes. The three-dimensional structure of Vc1.1 comprises a small alpha-helix spanning residues Pro6 to Asp11 and is braced by the I-III, II-IV disulfide connectivity seen in other alpha-conotoxins. A comparison of the structure of Vc1.1 with other alpha-conotoxins, taken together with nAChR selectivity data, suggests that the conserved proline at position 6 is important for binding, whereas a number of residues in the C-terminal portion of the peptide contribute toward the selectivity. The structure reported here should open new opportunities for further development of Vc1.1 or analogues as analgesic agents.
Clark
Richard J
RJ
Institute for Molecular Bioscience and School of Biomedical Sciences, University of Queensland, Brisbane, Queensland 4072, Australia.
Fischer
Harald
H
Nevin
Simon T
ST
Adams
David J
DJ
Craik
David J
DJ
D000311:Adrenal Glands / Q000166:cytology; D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D019439:Chromaffin Cells / Q000166:cytology / Q000378:metabolism; D020916:Conotoxins / Q000737:chemistry* / Q000378:metabolism; D004220:Disulfides / Q000737:chemistry; D004594:Electrophysiology; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009538:Nicotine / Q000494:pharmacology; D009865:Oocytes / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D011392:Proline / Q000737:chemistry; D011485:Protein Binding; D017510:Protein Folding; D014981:Xenopus
D020916:Conotoxins; D004220:Disulfides; D010455:Peptides; C507383:alpha-conotoxin Vc1.1; D009538:Nicotine; D011392:Proline; D010100:Oxygen