- The broad, long-term aim of our research is to understand how neurotransmitters activate receptor-coupled ion channels of the Cys-loop superfamily. Focusing on the acetylcholine receptor (AChR) at the motor synapse, we address the central question of how ACh binding triggers opening of an ion channel intrinsic to the AChR. Toward understanding the binding-triggering process, we propose to (i) determine how residues at the junction of binding and pore domains link agonist binding to channel gating, (ii) delineate a comprehensive reaction mechanism underlying AChR activation, (iii) identify structures at subunit interfaces that mediate inter-subunit global coupling, and (iv) develop a water-soluble AChR ligand binding domain for studies of structure and ligand recognition. The approach combines site-directed mutagenesis, naturally-occurring mutations, single channel kinetic analysis, structural modeling, computational methods and protein biochemical and structural methods. Completion of the proposal will advance understanding of synaptic transmission and drug action at motor endplates, facilitate treatment of inherited disorders of synaptic receptors, while the general principles will provide insight into how structure gives rise to mechanism for other members of the Cys-loop receptor superfamily. Project narrative- Throughout the nervous system, moment-to-moment communication relies on post-synaptic receptors to detect nerve-released neurotransmitter and change the membrane potential. The change in membrane potential elicits a response in the receptive cell, such as muscle contraction, neuro-secretion or a change in excitability and thus altered communication with other cells. In many neurological diseases and drug addiction the interaction between neurotransmitter and post- synaptic receptor is altered, which if understood, could provide bases for rational therapy. Furthermore, many clinically useful drugs act on post-synaptic receptors, but often have unwanted side effects. Understanding both structures and molecular mechanisms of post-synaptic receptors would enable design of more specific drugs.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS031744-21
Application #
8228119
Study Section
Biophysics of Neural Systems Study Section (BPNS)
Program Officer
Silberberg, Shai D
Project Start
1992-09-01
Project End
2015-02-28
Budget Start
2012-03-01
Budget End
2015-02-28
Support Year
21
Fiscal Year
2012
Total Cost
$610,843
Indirect Cost
$206,579
Name
Mayo Clinic, Rochester
Department
Type
DUNS #
006471700
City
Rochester
State
MN
Country
United States
Zip Code
55905
Sine, Steven M; Huang, Sun; Li, Shu-Xing et al. (2013) Inter-residue coupling contributes to high-affinity subtype-selective binding of *-bungarotoxin to nicotinic receptors. Biochem J 454:311-21
Huang, Sun; Li, Shu-Xing; Bren, Nina et al. (2013) Complex between *-bungarotoxin and an *7 nicotinic receptor ligand-binding domain chimaera. Biochem J 454:303-10
Mukhtasimova, Nuriya; Sine, Steven M (2013) Nicotinic receptor transduction zone: invariant arginine couples to multiple electron-rich residues. Biophys J 104:355-67
daCosta, Corrie J B; Sine, Steven M (2013) Stoichiometry for drug potentiation of a pentameric ion channel. Proc Natl Acad Sci U S A 110:6595-600
Wang, Hai-Long; Cheng, Xiaolin; Sine, Steven M (2012) Intramembrane proton binding site linked to activation of bacterial pentameric ion channel. J Biol Chem 287:6482-9
daCosta, Corrie J B; Free, Chris R; Corradi, Jeremías et al. (2011) Single-channel and structural foundations of neuronal ?7 acetylcholine receptor potentiation. J Neurosci 31:13870-9
Li, Shu-Xing; Huang, Sun; Bren, Nina et al. (2011) Ligand-binding domain of an ?7-nicotinic receptor chimera and its complex with agonist. Nat Neurosci 14:1253-9
Sine, Steven M; Wang, Hai-Long; Hansen, Scott et al. (2010) On the origin of ion selectivity in the Cys-loop receptor family. J Mol Neurosci 40:70-6
Engel, Andrew G; Shen, Xin-Ming; Selcen, Duygu et al. (2010) What have we learned from the congenital myasthenic syndromes. J Mol Neurosci 40:143-53
Mukhtasimova, Nuriya; Lee, Won Yong; Wang, Hai-Long et al. (2009) Detection and trapping of intermediate states priming nicotinic receptor channel opening. Nature 459:451-4

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