TY - JOUR

T1 - Rational design of a-conotoxin analogues targeting a7 nicotinic acetylcholine receptors

T2 - Improved antagonistic activity by incorporation of proline derivatives

AU - Armishaw, Christopher

AU - Jensen, Anders Asbjørn

AU - Balle, Thomas

AU - Clark, Richard J

AU - Harpsøe, Kasper

AU - Skonberg, Christian

AU - Liljefors, Tommy

AU - Strømgaard, Kristian

PY - 2009

Y1 - 2009

N2 - 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.

AB - 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.

KW - Former Faculty of Pharmaceutical Sciences

U2 - 10.1074/jbc.M806136200

DO - 10.1074/jbc.M806136200

M3 - Journal article

C2 - 19131337

VL - 284

SP - 9498

EP - 9512

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 14

ER -