Rebuilding a macromolecular membrane complex at the atomic scale: case of the Kir6.2 potassium channel coupled to the muscarinic acetylcholine receptor M2.
Ion channel-coupled receptors (ICCR) are artificial proteins built from a G protein-coupled receptor and an ion channel. Their use as molecular biosensors is promising in diagnosis and high-throughput drug screening. The concept of ICCR was initially validated with the combination of the muscarinic receptor M2 with the inwardly rectifying potassium channel Kir6.2. A long protein engineering phase has led to the biochemical characterization of the M2-Kir6.2 construct. However, its molecular mechanism remains to be elucidated. In particular, it is important to determine how the activation of M2 by its agonist acetylcholine triggers the modulation of the Kir6.2 channel via the M2-Kir6.2 linkage. In the present study, we have developed and validated a computational approach to rebuild models of the M2-Kir6.2 chimera from the molecular structure of M2 and Kir6.2. The protocol was first validated on the known protein complexes of the μ-opioid Receptor, the CXCR4 receptor and the Kv1.2 potassium channel. When applied to M2-Kir6.2, our protocol produced two possible models corresponding to two different orientations of M2. Both models highlights the role of the M2 helices I and VIII in the interaction with Kir6.2, as well as the role of the Kir6.2 N-terminus in the channel opening. Those two hypotheses will be explored in a future experimental study of the M2-Kir6.2 construct.
Laboratoire de Chimie et Biologie des Métaux, Institut de Recherche en Technologie et Sciences pour le Vivant, CEA iRTSV/LCBM/GMCT, CNRS UMR 5249, Université Grenoble Alpes, F-38054, Grenoble Cedex 9, France.
Nicolas
N
Sapay
Argel
A
Estrada-Mondragon
Christophe
C
Moreau
Michel
M
Vivaudou
Serge
S
Crouzy
D015374:Biosensing Techniques; D015640:Ion Channel Gating; D062105:Molecular Docking Simulation; D046912:Multiprotein Complexes / Q000378:metabolism* / Q000648:ultrastructure; D018408:Patch-Clamp Techniques; D024661:Potassium Channels, Inwardly Rectifying / Q000378:metabolism* / Q000648:ultrastructure; D015202:Protein Engineering; D043585:Receptor, Muscarinic M2 / Q000378:metabolism* / Q000648:ultrastructure; D019718:Receptors, CXCR4 / Q000378:metabolism; D017450:Receptors, Opioid, mu / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism* / Q000648:ultrastructure; D000099161:Kcnj11 Channel
D046912:Multiprotein Complexes; D024661:Potassium Channels, Inwardly Rectifying; D043585:Receptor, Muscarinic M2; D019718:Receptors, CXCR4; D017450:Receptors, Opioid, mu; D011993:Recombinant Fusion Proteins; D000099161:Kcnj11 Channel
G-protein coupled receptor; ion channel; membrane protein; protein-protein docking