Allosteric Coupling in Homomeric Cys-loop Receptors

Summary

Principal Investigator: STEVEN SINE
Abstract: Neurotransmitter receptors of the Cys-loop superfamily mediate fast synaptic transmission throughout the central and peripheral nervous systems. Their essential task is to transduce binding of neurotransmitter into opening of an intrinsic ion channel, yet the mechanism by which this transduction is achieved remains unknown. This proposal aims to delineate two fundamental facets of the transduction mechanism in homomeric Cys-loop receptors: (1) the number of agonist binding sites and binding-pore coupling regions required for activation by the agonist and (2) the structural basis for coupling agonist binding to channel gating. The proposed studies take advantage of the relative structural simplicity of homomeric receptors, employ a novel method for generating receptors with prescribed numbers of intact binding sites and coupling regions, and build on our recent demonstration that a network of interdependent loops functionally couples ligand binding and pore domains. The experiments combine expression of chimeric and non-chimeric receptors in mammalian cells, measurements of single channel current amplitudes and dwell times, measurements of ionic currents following rapid application of agonist, site-directed mutagenesis, and structural modeling of receptors. The approaches developed will allow the transduction mechanism to be addressed in all types of Cys-loop receptors, while the overall insights will advance our understanding of how post-synaptic receptors function in health, disease and in the presence of therapeutic drugs. Lay description: Cys-loop receptors relay signals from cell to cell throughout the nervous system, and are implicated in a wide variety of diseases, such as myasthenia, hyperekplexia, epilepsy, and nicotine addiction. They are also targets for drugs used clinically, such as muscle relaxants, anxiolytics, and anticonvulsants. Knowledge of how Cys-loop receptors operate at the molecular level is essential to developing therapeutic strategies and drugs with fewer side effects.
Funding Period: 2006-07-15 - 2010-06-30
more information: NIH RePORT

Top Publications

  1. pmc Functional relationships between agonist binding sites and coupling regions of homomeric Cys-loop receptors
    Natalia Andersen
    Instituto de Investigaciones Bioquimicas, Universidad Nacional del Sur Consejo Nacional de Investigaciones Científicas y Técnicas, Bahia Blanca 8000, Argentina
    J Neurosci 31:3662-9. 2011
  2. pmc Experimental protocols alter phototransduction: the implications for retinal processing at visual threshold
    Anthony W Azevedo
    Department of Physiology and Biophysics and Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA
    J Neurosci 31:3670-82. 2011
  3. pmc Single-channel and structural foundations of neuronal α7 acetylcholine receptor potentiation
    Corrie J B daCosta
    Receptor Biology Laboratory, Departments of Physiology and Biomedical Engineering and Neurology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
    J Neurosci 31:13870-9. 2011
  4. pmc The interface between extracellular and transmembrane domains of homomeric Cys-loop receptors governs open-channel lifetime and rate of desensitization
    Cecilia Bouzat
    Instituto de Investigaciones Bioquimicas, Universidad Nacional del Sur Consejo Nacional de Investigaciones Científicas y Técnicas, Bahia Blanca 8000, Argentina
    J Neurosci 28:7808-19. 2008
  5. pmc Number and locations of agonist binding sites required to activate homomeric Cys-loop receptors
    Diego Rayes
    Instituto de Investigaciones Bioquimicas, Universidad Nacional del Sur Consejo Nacional de Investigaciones Científicas y Técnicas, 8000 Bahia Blanca, Argentina
    J Neurosci 29:6022-32. 2009
  6. pmc Single-channel kinetic analysis for activation and desensitization of homomeric 5-HT(3)A receptors
    Jeremías Corradi
    Instituto de Investigaciones Bioquimicas de Bahia Blanca, Universidad Nacional del Sur Consejo Nacional de Investigaciones Científicas y Técnicas, Bahia Blanca, Argentina
    Biophys J 97:1335-45. 2009

Scientific Experts

  • C Bouzat
  • Jeremías Corradi
  • Steven M Sine
  • Corrie J B daCosta
  • Natalia Andersen
  • Anthony W Azevedo
  • Diego Rayes
  • Mariana Bartos
  • Fred Rieke
  • Chris R Free
  • Fernanda Gumilar
  • María José De Rosa

Detail Information

Publications6

  1. pmc Functional relationships between agonist binding sites and coupling regions of homomeric Cys-loop receptors
    Natalia Andersen
    Instituto de Investigaciones Bioquimicas, Universidad Nacional del Sur Consejo Nacional de Investigaciones Científicas y Técnicas, Bahia Blanca 8000, Argentina
    J Neurosci 31:3662-9. 2011
    ..The overall findings show that, whereas the agonist binding sites contribute interdependently and asymmetrically to open-channel stability, the coupling regions contribute independently and symmetrically...
  2. pmc Experimental protocols alter phototransduction: the implications for retinal processing at visual threshold
    Anthony W Azevedo
    Department of Physiology and Biophysics and Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA
    J Neurosci 31:3670-82. 2011
    ....
  3. pmc Single-channel and structural foundations of neuronal α7 acetylcholine receptor potentiation
    Corrie J B daCosta
    Receptor Biology Laboratory, Departments of Physiology and Biomedical Engineering and Neurology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
    J Neurosci 31:13870-9. 2011
    ..However mutation of five residues lining a cavity within each subunit's transmembrane domain abolishes PNU potentiation, defining minimal structural determinants of PNU potentiation...
  4. pmc The interface between extracellular and transmembrane domains of homomeric Cys-loop receptors governs open-channel lifetime and rate of desensitization
    Cecilia Bouzat
    Instituto de Investigaciones Bioquimicas, Universidad Nacional del Sur Consejo Nacional de Investigaciones Científicas y Técnicas, Bahia Blanca 8000, Argentina
    J Neurosci 28:7808-19. 2008
    ....
  5. pmc Number and locations of agonist binding sites required to activate homomeric Cys-loop receptors
    Diego Rayes
    Instituto de Investigaciones Bioquimicas, Universidad Nacional del Sur Consejo Nacional de Investigaciones Científicas y Técnicas, 8000 Bahia Blanca, Argentina
    J Neurosci 29:6022-32. 2009
    ..The overall results provide a framework for defining mechanisms of activation and drug modulation for homo-pentameric Cys-loop receptors...
  6. pmc Single-channel kinetic analysis for activation and desensitization of homomeric 5-HT(3)A receptors
    Jeremías Corradi
    Instituto de Investigaciones Bioquimicas de Bahia Blanca, Universidad Nacional del Sur Consejo Nacional de Investigaciones Científicas y Técnicas, Bahia Blanca, Argentina
    Biophys J 97:1335-45. 2009
    ..The application of the model to M4 mutant receptors shows that position 10' contributes to channel opening and closing rates. Thus, our kinetic model provides a foundation for understanding structural bases of activation and drug action...