Creating an α7 Nicotinic Acetylcholine Recognition Domain from the Acetylcholine-binding Protein

Abstract

Background:The homo-pentameric ␣7 nicotinic acetylcholine receptor is an important target in design of selective drugs for disorders involving this prevalent receptor family. Results: ␣7/Ac-AChBP structured chimeric protein resembles binding characteristics of native receptor. Conclusion: Soluble mutant templates can be used in the design of novel ␣7-selective drugs. Significance: Crystallographic structures of surrogates can guide therapeutic development for nicotinic acetylcholine receptor ligands.

Acetylcholine-Binding Protein Engineered to Mimic the α4-α4 Binding Pocket in α4β2 Nicotinic Acetylcholine Receptors Reveals Interface Specific Interactions Important for Binding and Activity

“…To accommodate such ligands a more comprehensive mutational approach could be adopted. This has been successfully done for the nAChR a7 in a chimeric construct with Ac-AChBP that was shown to accommodate both agonists and antagonists (Li et al, 2011;Nemecz and Taylor, 2011). The interpretation of binding and function in a structural context requires a unique well defined response.…”

Crystal structure of a human neuronal nAChR extracellular domain in pentameric assembly: Ligand-bound α2 homopentamer

“…Both provided invaluable information about the structure of a nAChR ECD, but because of their monomeric state, only the principal face of the ligand binding site was associated with a ligand. Nevertheless, there have been successful efforts to design and crystallize α7-AChBP chimeras where the binding site was composed mainly of α7 residues and the overall sequence identity to α7 approached 70% (18,19). The latter is an ingenious strategy to reveal the structures of the binding sites of a plethora of nAChR subunits because the AChBP scaffold provides considerably useful information about the structural features involved in the agonist binding.…”

“…Because of their considerable homology, especially in their binding sites, designing a novel drug specific for one type of nAChR can be a challenging procedure and requires the addition of more structural information. Following this need, structural studies of the nAChR have been the focus of numerous laboratories, leading to the achievement of many breakthroughs, such as the cryo-electron microscopy structure of the Torpedo nAChR (10) and the X-ray crystal structures of acetylcholine binding proteins (AChBPs; homologs of the ECD of nAChR) (11)(12)(13), mouse muscle-type α1 and human neuronal α9 nAChR ECDs (14,15), GLIC and ELIC (two prokaryotic homologs of pLGICs) (16,17), and two α7 nAChR ECD-AChBP chimeras (18,19). In addition, the structures of other members of the superfamily have recently become available, including that of an invertebrate anionic glutamate receptor (20), the human GABA A β3 (21), the mouse 5-HT 3 receptor (22), the human α3 glycine receptor (23), and the zebrafish α1 glycine receptor (24).…”

Therapeutic Potential ofα7 Nicotinic Acetylcholine Receptors

“…Sharing a high degree of sequence homology with the N-terminal domain of nAChRs, this protein was amenable to crystallization and provided the first atomic resolution image of the LBD (Brejc et al, 2001). Since this initial work, crystallization of AChBP from several invertebrates, including Aplysia californica and Capitella Therapeutic Potential of a7 nAChRs teleta, with different ligands, has been used as a tool to direct more efficient drug development (Hansen et al, 2005;Smit et al, 2006;Gao et al, 2006;Rucktooa et al, 2009;Sander et al, 2010;Nemecz and Taylor, 2011;Kombo et al, 2012;Billen et al, 2012). Despite these interesting results, important differences remained between a ligand bound to AChBP versus to a7 nAChRs, as shown in studies that attempted to link the development of new a7 nAChR ligands based on predictions from AChBP binding (Ulens et al, 2009;Akdemir et al, 2011).…”