title: Kinetic, energetic, and mechanical differences between dark-state rhodopsin and opsin.
abstract: Rhodopsin, the photoreceptor pigment of the retina, initiates vision upon photon capture by its covalently linked chromophore 11-cis-retinal. In the absence of light, the chromophore serves as an inverse agonist locking the receptor in the inactive dark state. In the absence of chromophore, the apoprotein opsin shows low-level constitutive activity. Toward revealing insight into receptor properties controlled by the chromophore, we applied dynamic single-molecule force spectroscopy to quantify the kinetic, energetic, and mechanical differences between dark-state rhodopsin and opsin in native membranes from the retina of mice. Both rhodopsin and opsin are stabilized by ten structural segments. Compared to dark-state rhodopsin, the structural segments stabilizing opsin showed higher interaction strengths and mechanical rigidities and lower conformational variabilities, lifetimes, and free energies. These changes outline a common mechanism toward activating G-protein-coupled receptors. Additionally, we detected that opsin was more pliable and frequently stabilized alternate structural intermediates.
authors: Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland.
authors: Shiho
authors: S
authors: Kawamura
authors: Moritz
authors: M
authors: Gerstung
authors: Alejandro T
authors: AT
authors: Colozo
authors: Jonne
authors: J
authors: Helenius
authors: Akiko
authors: A
authors: Maeda
authors: Niko
authors: N
authors: Beerenwinkel
authors: Paul S-H
authors: PS
authors: Park
authors: Daniel J
authors: DJ
authors: Müller
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism; D003624:Darkness; D007700:Kinetics; D051379:Mice; D018345:Mice, Knockout; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D055355:Opsins / Q000737:chemistry* / Q000378:metabolism; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012172:Retinaldehyde / Q000737:chemistry* / Q000378:metabolism; D012243:Rhodopsin / Q000737:chemistry* / Q000378:metabolism; D012374:Rod Cell Outer Segment / Q000737:chemistry* / Q000378:metabolism; D013816:Thermodynamics; D019745:cis-trans-Isomerases / Q000172:deficiency / Q000235:genetics; D000099178:Retinoid Isomerohydrolase
chemical_list: D055355:Opsins; D012172:Retinaldehyde; D012243:Rhodopsin; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase