A synthetic combinatorial strategy for developing a-conotoxin analogs as potent a7 nicotinic acetylcholine receptor antagonists

Christopher J Armishaw; Narender Singh; Jose L Medina-Franco; Richard J Clark; Krystle C M Scott; Richard A Houghten; Anders Asbjørn Jensen

doi:10.1074/jbc.M109.071183

A synthetic combinatorial strategy for developing a-conotoxin analogs as potent a₇ nicotinic acetylcholine receptor antagonists

Christopher J Armishaw, Narender Singh, Jose L Medina-Franco, Richard J Clark, Krystle C M Scott, Richard A Houghten, Anders Asbjørn Jensen

31 Citations (Scopus)

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.

Original language	English
Journal	Journal of Biological Chemistry
Volume	285
Issue number	3
Pages (from-to)	1809-1821
ISSN	0021-9258
DOIs	https://doi.org/10.1074/jbc.M109.071183
Publication status	Published - 15 Jan 2010

Keywords

Former Faculty of Pharmaceutical Sciences

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10.1074/jbc.M109.071183

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A synthetic combinatorial strategy for developing a-conotoxin analogs as potent a₇ nicotinic acetylcholine receptor antagonists. / Armishaw, Christopher J; Singh, Narender; Medina-Franco, Jose L et al.

In: Journal of Biological Chemistry, Vol. 285, No. 3, 15.01.2010, p. 1809-1821.

Research output: Contribution to journal › Journal article › Research › peer-review

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