Research

Binding of long-chain α-neurotoxin would stabilize the resting state of nAChR: A comparative study with α-conotoxin

Adak Nasiripourdori , Bijan Ranjbar and Hossein Naderi-Manesh

Department of Biophysics, Faculty of Science, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran

author email corresponding author email

Theoretical Biology and Medical Modelling 2009, 6:3doi:10.1186/1742-4682-6-3

Published:	11 February 2009

Abstract

Background

The details of interaction in a complex between potent antagonists such as long chain α-neurotoxins and α-conotoxins with nicotinic acetylcholine receptor (nAChR), and conformational changes induced by these antagonists, are not yet clear.

Modeling

In order to uncover some of these critical structural features, we conducted a docking simulation and a molecular dynamics simulation (MD) of a model of the ligand binding domain of nAChR in complex with a long-chain α-neurotoxin and an α-conotoxin.

Results

Our docking results confirm the claim that T.nAChR is in the basal or resting state, which favors binding to the alpha-neurotoxins. Moreover, more correct "hits" for the α/γ interface upon docking for conotoxin-nAChR confirm the preference of conotoxin GI for the α/γ interface. More importantly, upon binding of α-neurotoxin, ligand-bonded nAChR is less dynamic in certain domains than the apo form of the conotoxin-AChR complex. Some critical interactions in the binding site such as the salt bridge formed between K145/D200 in the neurotoxin-nAChR complex is further stabilized during the MD simulation, while it is obviously more labile in the apo form.

Conclusion

These observations could support the claim that alpha neurotoxins stabilize the nAChR resting state.