Rational design of a-conotoxin analogues targeting a7 nicotinic acetylcholine receptors: Improved antagonistic activity by incorporation of proline derivatives

Christopher Armishaw; Anders Asbjørn Jensen; Thomas Balle; Richard J Clark; Kasper Harpsøe; Christian Skonberg; Tommy Liljefors; Kristian Strømgaard

doi:10.1074/jbc.M806136200

Rational design of a-conotoxin analogues targeting a7 nicotinic acetylcholine receptors: Improved antagonistic activity by incorporation of proline derivatives

Christopher Armishaw, Anders Asbjørn Jensen, Thomas Balle, Richard J Clark, Kasper Harpsøe, Christian Skonberg, Tommy Liljefors, Kristian Strømgaard

43 Citations (Scopus)

Abstract

Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels and belong to the superfamily of Cys-loop receptors. Valuable insight into the orthosteric ligand binding to nAChRs in recent years has been obtained from the crystal structures of acetylcholine binding proteins (AChBPs) that share significant sequence homology with the amino-terminal domains of the nAChRs. alpha-Conotoxins which are isolated from the venom of carnivorous marine snails selectively inhibit the signalling of neuronal nAChR subtypes. Co-crystal structures of alpha-conotoxins in complex with AChBP show that the side chain of a highly conserved proline residue in these toxins is oriented towards the hydrophobic binding pocket in the AChBP, but does not have direct interactions with this pocket. In the present study, we have designed and synthesized analogues of alpha-conotoxins ImI and PnIA[A10L], by introducing a range of substituents on the Pro6 residue in these toxins to probe the importance of this residue for their binding to the nAChRs. Pharmacological characterization of the toxin analogues at the alpha(7) nAChR show that while polar and charged groups on Pro6 result in analogues with significantly reduced antagonistic activities, analogues with aromatic and hydrophobic substituents in the Pro6 position exhibit moderate activity at the receptor. Interestingly, introduction of a 5-(R)-Phenyl substituent at Pro6 in alpha-conotoxin ImI gives rise to a conotoxin analogue with a significantly higher binding affinity and antagonistic activity at the alpha(7) nAChR than those exhibited by the native conotoxin.

Original language	English
Journal	Journal of Biological Chemistry
Volume	284
Issue number	14
Pages (from-to)	9498-9512
ISSN	0021-9258
DOIs	https://doi.org/10.1074/jbc.M806136200
Publication status	Published - 2009

Keywords

Former Faculty of Pharmaceutical Sciences

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10.1074/jbc.M806136200

Cite this

Armishaw, C., Jensen, A. A., Balle, T., Clark, R. J., Harpsøe, K., Skonberg, C., Liljefors, T., & Strømgaard, K. (2009). Rational design of a-conotoxin analogues targeting a7 nicotinic acetylcholine receptors: Improved antagonistic activity by incorporation of proline derivatives. Journal of Biological Chemistry, 284(14), 9498-9512. https://doi.org/10.1074/jbc.M806136200

Rational design of a-conotoxin analogues targeting a7 nicotinic acetylcholine receptors : Improved antagonistic activity by incorporation of proline derivatives. / Armishaw, Christopher; Jensen, Anders Asbjørn; Balle, Thomas et al.

In: Journal of Biological Chemistry, Vol. 284, No. 14, 2009, p. 9498-9512.

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

Armishaw, C, Jensen, AA, Balle, T, Clark, RJ, Harpsøe, K, Skonberg, C, Liljefors, T & Strømgaard, K 2009, 'Rational design of a-conotoxin analogues targeting a7 nicotinic acetylcholine receptors: Improved antagonistic activity by incorporation of proline derivatives', Journal of Biological Chemistry, vol. 284, no. 14, pp. 9498-9512. https://doi.org/10.1074/jbc.M806136200

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abstract = "Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels and belong to the superfamily of Cys-loop receptors. Valuable insight into the orthosteric ligand binding to nAChRs in recent years has been obtained from the crystal structures of acetylcholine binding proteins (AChBPs) that share significant sequence homology with the amino-terminal domains of the nAChRs. alpha-Conotoxins which are isolated from the venom of carnivorous marine snails selectively inhibit the signalling of neuronal nAChR subtypes. Co-crystal structures of alpha-conotoxins in complex with AChBP show that the side chain of a highly conserved proline residue in these toxins is oriented towards the hydrophobic binding pocket in the AChBP, but does not have direct interactions with this pocket. In the present study, we have designed and synthesized analogues of alpha-conotoxins ImI and PnIA[A10L], by introducing a range of substituents on the Pro6 residue in these toxins to probe the importance of this residue for their binding to the nAChRs. Pharmacological characterization of the toxin analogues at the alpha(7) nAChR show that while polar and charged groups on Pro6 result in analogues with significantly reduced antagonistic activities, analogues with aromatic and hydrophobic substituents in the Pro6 position exhibit moderate activity at the receptor. Interestingly, introduction of a 5-(R)-Phenyl substituent at Pro6 in alpha-conotoxin ImI gives rise to a conotoxin analogue with a significantly higher binding affinity and antagonistic activity at the alpha(7) nAChR than those exhibited by the native conotoxin.",

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