Dynorphin Neuropeptides Decrease Apparent Proton Affinity of ASIC1a by Occluding the Acidic Pocket

Journal of Medicinal Chemistry, vol. 64, pp. 13299–13311

Abstract

Prolonged acidosis, as it occurs during ischemic stroke, induces neuronal death via acid-sensing ion channel 1a (ASIC1a). Concomitantly, it desensitizes ASIC1a, highlighting the pathophysiological significance of modulators of ASIC1a acid sensitivity. One such modulator is the opioid neuropeptide big dynorphin (Big Dyn) which binds to ASIC1a and enhances its activity during prolonged acidosis. The molecular determinants and dynamics of this interaction remain unclear, however. Here, we present a molecular interaction model showing a dynorphin peptide inserting deep into the acidic pocket of ASIC1a. We confirmed experimentally that the interaction is predominantly driven by electrostatic forces, and using noncanonical amino acids as photo-cross-linkers, we identified 16 residues in ASIC1a contributing to Big Dyn binding. Covalently tethering Big Dyn to its ASIC1a binding site dramatically decreased the proton sensitivity of channel activation, suggesting that Big Dyn stabilizes a resting conformation of ASIC1a and dissociates from its binding site during channel opening.

Authors 7

1. Lilia Leisle corresponding Aachen Institute of Physiology

   RWTH Aachen University

   Affiliation as printed

   Institute of Physiology, RWTH Aachen University, 52074 Aachen, Germany

2. Michael A. Margreiter Aachen Institute of Organic Chemistry

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Computational Biomedicine−Institute for Advanced Simulation/Institute of Neuroscience and Medicine, Forschungszentrum Jülich, 52425 Jülich, Germany

   Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany

3. Audrey Ortega-Ramírez Aachen Institute of Physiology

   RWTH Aachen University

   Affiliation as printed

   Institute of Physiology, RWTH Aachen University, 52074 Aachen, Germany

4. Elinor Cleuvers Aachen Institute of Physiology

   RWTH Aachen University

   Affiliation as printed

   Institute of Physiology, RWTH Aachen University, 52074 Aachen, Germany

5. Michèle Bachmann Aachen Institute of Physiology

   RWTH Aachen University

   Affiliation as printed

   Institute of Physiology, RWTH Aachen University, 52074 Aachen, Germany

6. Giulia Rossetti Aachen Department of Neurology

   Forschungszentrum Jülich · Jülich Supercomputing Centre · RWTH Aachen University

   Affiliation as printed

   Computational Biomedicine−Institute for Advanced Simulation/Institute of Neuroscience and Medicine, Forschungszentrum Jülich, 52425 Jülich, Germany

   Department of Neurology, RWTH Aachen University, 52074 Aachen, Germany

   Jülich Supercomputing Center (JSC), Forschungszentrum Jülich, 52425 Jülich, Germany

7. Stefan Gründer corresponding Aachen Institute of Physiology

   RWTH Aachen University

   Affiliation as printed

   Institute of Physiology, RWTH Aachen University, 52074 Aachen, Germany