A Usual G‐Protein‐Coupled Receptor in Unusual Membranes

Abstract

G-protein-coupled receptors (GPCRs) are the largest family of membrane-bound receptors and constitute ~50% of all known drug targets. They offer great potential for membrane protein nanotechnologies. We report here a charge-interaction-directed reconstitution mechanism that induces spontaneous insertion of bovine rhodopsin, the eukaryotic GPCR, into both lipid- and polymer-based artificial membranes. We reveal a new allosteric mode of rhodopsin activation incurred by the non-biological membranes: the cationic membrane drives a transition from inactive MI to activated MII state in the absence of high [H+] or negative spontaneous curvature. We attribute this activation to the attractive charge interaction between the membrane surface and the deprotonated Glu134 residue of the rhodopsin-conserved ERY sequence motif that helps break the cytoplasmic “ionic lock”. This study unveils a novel design concept of non-biological membranes to reconstitute and harness GPCR functions in synthetic systems.

Real time monitoring of membrane GPCR reconstitution by plasmon waveguide resonance: on the role of lipids

“…30 for a review). A more recent method based on charge-interaction directed reconstitution mechanism has been reported for the spontaneous insertion of bovine rhodopsin in both lipid- and polymer-based artificial membranes31. A preferential contact between a membrane protein hydrophilic domain and the membrane by charge attraction triggers membrane protein insertion and decortications of detergent micelles associated with the membrane protein hydrophobic domain.…”

Quasi-elastic Neutron Scattering Reveals Ligand-Induced Protein Dynamics of a G-Protein-Coupled Receptor

“…The chromophore 11- cis -retinal locks the rhodopsin in the inactive dark state, and it acts as an inverse-agonist by preventing interaction with its cognate G-protein (transducin). Upon photon absorption, the 11- cis -retinal isomerizes to all- trans , yielding rearrangement of the protein conformation by two protonation switches. , The photoisomerization of retinal occurs within 200 fs, causing rhodopsin to undergo a series of multiscale transitions. , Currently, X-ray crystal structures are available for rhodopsin in the dark state, , as well as several freeze-trapped photointermediates, , including the ligand-free opsin apoprotein. Both solid-state NMR methods , and site-directed spin labeling (SDSL) have been extensively applied to study rhodopsin .…”

“…Upon photon absorption, the 11-cis-retinal isomerizes to alltrans, yielding rearrangement of the protein conformation by two protonation switches. 11,12 The photoisomerization of retinal occurs within 200 fs, causing rhodopsin to undergo a series of multiscale transitions. 13,14 Currently, X-ray crystal structures are available for rhodopsin in the dark state, 15,16 as well as several freeze-trapped photointermediates, 7,17 including the ligand-free opsin apoprotein.…”

Powdered G-Protein-Coupled Receptors

“…Upon photon absorption, the 11-cis-retinal isomerizes to all-trans, yielding rearrangement of the protein conformation by two protonation switches. 28,29 Photoisomerization of retinal occurs within less than 200 fs, 30 causing rhodopsin to undergo a series of multiscale conformational transitions, 31,32 where dynamics of the protein play a crucial role in its biological signaling function. Solid-state NMR methods, 21,33 X-ray diffraction, 34 solution X-ray scattering, 35 and site-directed spin labeling (SDSL) 36 have all been extensively applied to study the functional reaction cycle of rhodopsin.…”