A synthetic combinatorial strategy for developing α-conotoxin analogs as potent α7 nicotinic acetylcholine receptor antagonists Article

Armishaw, CJ, Singh, N, Medina-Franco, JL et al. (2010). A synthetic combinatorial strategy for developing α-conotoxin analogs as potent α7 nicotinic acetylcholine receptor antagonists . JOURNAL OF BIOLOGICAL CHEMISTRY, 285(3), 1809-1821. 10.1074/jbc.M109.071183

cited authors

  • Armishaw, CJ; Singh, N; Medina-Franco, JL; Clark, RJ; Scott, KCM; Houghten, RA; Jensen, AA

abstract

  • α-Conotoxins are peptide neurotoxins isolated from venomous cone snails that display exquisite selectivity for different subtypes of nicotinic acetylcholine receptors (nAChR). They are valuable research tools that have profound implications in the discovery of new drugs for a myriad of neuropharmacological conditions. They are characterized by a conserved two-disulfide bond framework, which gives rise to two intervening loops of extensively mutated amino acids that determine their selectivity for different nAChR subtypes. We have used a multistep synthetic combinatorial approach using α-conotoxin ImI to develop potent and selective α7 nAChR antagonists. A positional scan synthetic combinatorial library was constructed based on the three residues of the n-loop of α-conotoxin ImI to give a total of 10,648 possible combinations that were screened for functional activity in anα7 nAChR Fluo-4/Ca2+ assay, allowing amino acids that confer antagonistic activity for this receptor to be identified. A second series of individual α-conotoxin analogs based on the combinations of defined active amino acid residues from positional scan synthetic combinatorial library screening data were synthesized. Several analogs exhibited significantly improved antagonist activity for the α7 nAChR compared with WT-ImI. Binding interactions between the analogs and the α7 nAChR were explored using a homology model of the amino-terminal domain based on a crystal structure of an acetylcholine-binding protein. Finally, a third series of refined analogs was synthesized based on modeling studies, which led to several analogs with refined pharmacological properties. Of the 96 individual α-conotoxin analogs synthesized, three displayed ≥10-fold increases in antagonist potency compared with WT-ImI. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.

publication date

  • January 15, 2010

published in

Digital Object Identifier (DOI)

start page

  • 1809

end page

  • 1821

volume

  • 285

issue

  • 3