Neuronal nicotinic acetylcholine receptors (nAChRs) belong to the superfamily of pentameric ligand-gated ion channels (pLGICs) that mediate fast neurotransmission and are therapeutic targets for various neurological diseases and disorders. However, no single high-resolution structure has yet been determined for any full-length nAChRs that contains the extracellular (ECD), transmembrane (TMD), and intracellular (ICD) domains. Neither X-ray crystallography nor cryo-EM is suitable for resolving structures of the flexible ICD. Lines of evidence suggest direct interactions between nAChRs and intracellular proteins implicated in synaptic plasticity and cell signaling pathways, but few molecular details have been revealed due to the lack of high-resolution structures of the ICD. Here, we propose to determine structures of ?7nAChR, which is one of the most abundant nAChR subtypes in the brain. We have successfully produced functional human full-length ?7nAChR and the TMD+ICD of ?7nAChR along with substantial preliminary structural and functional results, which built a solid foundation for carrying out structural investigations of ?7nAChR. Using nuclear magnetic resonance spectroscopy (NMR) and electron paramagnetic resonance (EPR), we will determine atomic-resolution structures of the ICD. The ICD structures will be integrated with available structures of the ECD and TMD, as well as with our newly collected structure restraints to generate structures for full-length ?7nAChR in the resting state. We will elucidate conformational changes underlying ?7nAChR desensitization, which is known to play a significant role in the synaptic control of action-potential transmission. Finally, we will determine binding modes of ?7nAChR networked with intracellular scaffold proteins that affect the distribution of ?7nAChR on the cell surface. The generated structures will provide useful information for developing treatment strategies for diseases related to ?7nAChR.
The ?7 nicotinic acetylcholine receptor (?7nAChR) is one of the most abundant nAChRs in the brain and plays a critical role in regulating cognition and memory. ?7nAChR is a key target for treating various neurodegenerative diseases and disorders. The proposed studies will determine structures of ?7nAChR in different functional states, elucidate the structural basis of ?7nAChR interaction with intracellular proteins involved in neurological disorders, and provide valuable information for the development of ?7nAChR-specific modulators with therapeutic potential.
