title: Interaction of extracellular loop II of κ-opioid receptor (196-228) with opioid peptide dynorphin in membrane environments as revealed by solid state nuclear magnetic resonance, quartz crystal microbalance and molecular dynamics simulation.
abstract: κ-Opioid receptor is a member of the opioid receptor family and selectively interacts with the opioid peptide dynorphin. Extracellular loop II (ECL-II) of the κ-opioid receptor displays an amphiphilic helix in membrane environments and the N-terminal α-helix of dynorphin A(1-17) (hereafter DynA17) is inserted into the membrane with the tilt angle of 21° to the bilayer normal. ECL-II peptides (1-33), corresponding to 196-228 of κ-opioid receptor with [1-(13)C]- or [3-(13)C]-labeled amino acids were incorporated into large [dimyristoylphosphatidyl choline (DMPC)/ dihexanoylphosphatidyl choline (DHPC) = 3, q = 3] and small bicelle (q = 1) systems. (13)C direct detection with dipolar decoupling and magic angle spinning (DD-MAS) nuclear magnetic resonance (NMR) spectra were recorded, and the (13)C chemical shift perturbation clearly indicated that DynA17 interacts with ECL-II at the location of Val10-Ala15. Quartz crystal microbalance measurements were performed to determine the binding constant of ECL-II with DynA17 and indicated that the binding constant between DynA17 and ECL-II embedded in the lipid layer was 72 times larger than that between DynA17 and the lipid. The result of the molecular dynamics simulation clearly indicates that the C-terminus of DynA17 interact with the amino acid residues of the region between Val10-Gln14 of ECL-II. These results suggest that DynA17 interacts with the ECL-II of the κ-opioid receptor through a hydrophobic and short-lived electrostatic interaction with high affinity in the outer surface of the membrane.
authors: Graduate School of Engineering, Yokohama National University , 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
authors: Atsushi
authors: A
authors: Kira
authors: Namsrai
authors: N
authors: Javkhlantugs
authors: Takenori
authors: T
authors: Miyamori
authors: Yoshiyuki
authors: Y
authors: Sasaki
authors: Masayuki
authors: M
authors: Eguchi
authors: Izuru
authors: I
authors: Kawamura
authors: Kazuyoshi
authors: K
authors: Ueda
authors: Akira
authors: A
authors: Naito
mesh_terms: D002462:Cell Membrane / Q000737:chemistry*; D004399:Dynorphins / Q000737:chemistry*; D006801:Humans; D056004:Molecular Dynamics Simulation; D019906:Nuclear Magnetic Resonance, Biomolecular; D058525:Quartz Crystal Microbalance Techniques; D017473:Receptors, Opioid, kappa / Q000737:chemistry*
chemical_list: D017473:Receptors, Opioid, kappa; D004399:Dynorphins