Binding of long-chain alpha-neurotoxin would stabilize the resting state of nAChR: a comparative study with alpha-conotoxin.
BACKGROUND
The details of interaction in a complex between potent antagonists such as long chain alpha-neurotoxins and alpha-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 alpha-neurotoxin and an alpha-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 alpha/gamma interface upon docking for conotoxin-nAChR confirm the preference of conotoxin GI for the alpha/gamma interface. More importantly, upon binding of alpha-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.


CONCLUSIONS
These observations could support the claim that alpha neurotoxins stabilize the nAChR resting state.
Nasiripourdori
Adak
A
Department of Biophysics, Faculty of Science, Tarbiat Modares University, P,O, Box 14115-175, Tehran, Iran. nasiripour@modares.ac.ir
Ranjbar
Bijan
B
Naderi-Manesh
Hossein
H
D000818:Animals; D020916:Conotoxins / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D009498:Neurotoxins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011978:Receptors, Nicotinic / Q000737:chemistry / Q000378:metabolism*; D014101:Torpedo
D020916:Conotoxins; D009498:Neurotoxins; D011978:Receptors, Nicotinic