Computational And Functional Mapping Of Human And Rat Alpha 6 Beta 4 Nicotinic Acetylcholine Receptors Reveals Species-Specific Ligand-Binding Motifs

Nicotinic acetylcholine receptors (nAChRs) are pharmacological targets for the treatment of neuropathic pain, and the a6 beta 4 subtype has been identified as particularly promising. Rat a6 beta 4 nAChRs are less sensitive to some ligands than the human homologue potentially complicating the use of rodent a6 beta 4 receptors for screening therapeutic compounds. We used molecular dynamics simulations coupled with functional assays to study the interaction between alpha-conotoxin PeIA and a6 beta 4 nAChRs and to identify key ligand-receptor interactions that contribute to species differences in alpha-conotoxin potency. Our results show that human and rat a6 beta 4 nAChRs have distinct ligand-binding motifs and show markedly different sensitivities to alpha-conotoxins. These studies facilitated the creation of PeIA-5667, a peptide that shows 270-fold higher potency for rat a6 beta 4 nAChRs over native PeIA and similar potency for the human homologue. Our results may inform the design of therapeutic ligands that target a6 beta 4 nAChRs for the treatment of neuropathic pain.