A fundamental principle of biomedicine is that small molecules can bind to specific receptors to trigger physiological responses. We seek to understand the energetic nature of the molecular events that occur at the neurotransmitter binding sites of the neuromuscular acetylcholine receptor when this channel 'gates'between non-conducting and ion-conducting conformations. This knowledge will help us understand the biophysical mechanisms of ligand-protein complexes, and will advance our ability to design new drugs for nicotinic (and other) receptors. Structure-based drug discovery should incorporate the fact that drug action depends on the differential binding of ligands to inactive vs. active conformations of a receptor. To address this point we will use single-channel electrophysiology and kinetic analysis to study unliganded gating, which will allow us to measure all of the salient activation equilibrium constants and to ascertain the energetic contributions of the side chains at each of the two transmitter binding sites. We will also estimate differential binding energies for small ligand probes, in both wild type and mutant receptors. Eventually, this knowledge will be used to engineer acetylcholine receptors that respond predictably to arbitrary ligands.

Public Health Relevance

The experiments outlined in this project establish the fundamental principles for engineering a protein to respond in predictable ways to specific drugs. These principles can be applied to the development of new pharmaceuticals, and to understanding the mechanism by which a drug causes a protein to change shape.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
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Biophysics of Neural Systems Study Section (BPNS)
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Silberberg, Shai D
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State University of New York at Buffalo
Schools of Medicine
United States
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Auerbach, Anthony (2015) Agonist activation of a nicotinic acetylcholine receptor. Neuropharmacology 96:150-6
Purohit, Prasad; Bruhova, Iva; Gupta, Shaweta et al. (2014) Catch-and-hold activation of muscle acetylcholine receptors having transmitter binding site mutations. Biophys J 107:88-99
Poulin, Hugo; Bruhova, Iva; Timour, Quadiri et al. (2014) Fluoxetine blocks Nav1.5 channels via a mechanism similar to that of class 1 antiarrhythmics. Mol Pharmacol 86:378-89
Purohit, Prasad; Auerbach, Anthony (2013) Loop C and the mechanism of acetylcholine receptor-channel gating. J Gen Physiol 141:467-78
Gupta, Shaweta; Purohit, Prasad; Auerbach, Anthony (2013) Function of interfacial prolines at the transmitter-binding sites of the neuromuscular acetylcholine receptor. J Biol Chem 288:12667-79
Jadey, Snehal; Purohit, Prasad; Auerbach, Anthony (2013) Action of nicotine and analogs on acetylcholine receptors having mutations of transmitter-binding site residue ýýG153. J Gen Physiol 141:95-104
Auerbach, Anthony (2013) The energy and work of a ligand-gated ion channel. J Mol Biol 425:1461-75
Nayak, Tapan K; Auerbach, Anthony (2013) Asymmetric transmitter binding sites of fetal muscle acetylcholine receptors shape their synaptic response. Proc Natl Acad Sci U S A 110:13654-9
Bruhova, Iva; Gregg, Timothy; Auerbach, Anthony (2013) Energy for wild-type acetylcholine receptor channel gating from different choline derivatives. Biophys J 104:565-74
Auerbach, Anthony (2012) Thinking in cycles: MWC is a good model for acetylcholine receptor-channels. J Physiol 590:93-8

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