Project Grant F32GM169165

MOLECULAR GATING OF THE HUMAN MUSCLE NACHR - PROJECT SUMMARY NICOTINIC ACETYLCHOLINE RECEPTORS (NACHR) ARE NON-SELECTIVE LIGAND GATED CATION CHANNELS THAT BELONG TO THE CYS-LOOP SUPERFAMILY OF NEUROTRANSMITTER RECEPTORS. CYS-LOOP RECEPTORS PLAY DIVERSE ROLES IN HUMAN PHYSIOLOGY, MEDIATING BOTH EXCITATORY AND INHIBITORY NEURONAL SIGNALING. DUE TO THEIR DIVERSE PHYSIOLOGICAL ROLES, THEY ARE INVOLVED IN MANY HEALTH CONDITIONS INCLUDING ADDICTION, NEUROLOGICAL DISORDERS, CARDIOVASCULAR DISEASE, AND CANCER. CYS-LOOP RECEPTORS ALL SHARE A COMMON GATING CYCLE IN WHICH, UPON AGONIST BINDING, ACTIVATE AND TRANSITION FROM A NON-CONDUCTING RESTING STATE TO AN OPEN-CHANNEL AND ACTIVATED STATE. AFTER ACTIVATION, IN SUSTAINED PRESENCE OF NEUROTRANSMITTER OR OTHER AGONISTS, THE RECEPTOR TRANSITIONS TO A NON-CONDUCTING DESENSITIZED STATE. DECREASING AGONIST CONCENTRATIONS AND AGONIST UNBINDING ALLOW THE RECEPTOR TO RETURN TO THE RESTING, ACTIVATABLE STATE. GIVEN THEIR IMPORTANCE, THERE HAVE BEEN EXTENSIVE EFFORTS TO UNDERSTAND THE MOLECULAR BASIS OF CYS-LOOP RECEPTOR GATING. TO DATE, MANY STRUCTURES OF THE NACHR AND OTHER CYS-LOOP RECEPTORS HAVE BEEN DETERMINED, BUT CRITICAL COMPONENTS OF THE CONFORMATIONAL CYCLE REMAIN OBSCURE. KEY QUESTIONS REMAIN ABOUT HOW THESE CHANNELS TRANSITION TO AN OPEN STATE, AND THE MOLECULAR ARCHITECTURE OF THE OPEN STATE ITSELF. THIS IS LARGELY DRIVEN BY AN ABUNDANCE OF RESTING AND DESENSITIZED STRUCTURES, THE RESULT OF TRADITIONAL EXPERIMENTAL CONDITIONS. TO BETTER UNDERSTAND RECEPTOR GATING, THESE PROTEINS NEED TO BE STUDIED IN THE PROCESS OF ACTIVATION RATHER THAN UNDER STEADY-STATE CONDITIONS. HERE, I WILL USE A COMBINATION OF TIME RESOLVED CRYO-EM, ELECTROPHYSIOLOGY EXPERIMENTS, AND MOLECULAR DYNAMICS SIMULATIONS TO PROBE THE MOLECULAR MECHANISM OF HUMAN ADULT MUSCLE NACHR GATING. THESE STUDIES WILL PROVIDE AN UNPRECEDENTED LOOK INTO THE FUNCTION OF LIGAND GATED ION CHANNELS, AND WILL INFORM OUR UNDERSTANDING OF THE MOLECULAR BASIS OF DISEASE. SUCH INSIGHT WILL BE IMMENSELY VALUABLE, IN REVEALING BOTH SHARED AND RECEPTOR-SPECIFIC MECHANISMS OF ACTIVATION, ALLOWING FOR RAPID DEVELOPMENT OF SELECTIVE, STATE SPECIFIC THERAPEUTICS FOR A RANGE NERVOUS SYSTEM CONDITIONS.