From the structure of vertebrate and invertebrate rhodopsins to new applications in optogenetics

Professor for Structural Biology ETH Zürich D-BIOL and Head of Biology and Chemistry Division, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland

In this project, we explore the use of light-sensitive G protein-coupled receptors (GPCRs) ¬–opsins– for the development of new optogenetic tools to control cellular signalling processes using light: opto-GPCRs. In a first stage we identified several new opsins capable of GPCR pathways. We extensively characterized the most promising candidate opsins biochemically in cellular assays and finally in vivo. We developed the basis for engineering bistable opsins towards more effective optogenetic tools. For this, we determined the first structure of a recombinant invertebrate rhodopsin, carried out a detailed study of the chromophore binding site with advanced biophysical methods. We were able to compare in detail monostable and bistable visual pigments. The bistable pigments in several aspects are closer to the ligand binding pharmacologically relevant family A GPCRs. In a successful engineering attempt, we were able to identify mutations that shift the wavelengths of an invertebrate rhodopsin towards the infrared. This is important for the penetration of the light into tissues. The engineered opto-GPCRs are an important alternative to the channel opsins related optogenetic tools and they have a wide range of applications that is not restricted to neurons.
C. Tsai, J. Marino, R. Adaixo, F. Pamula, J. Muehle, S. Maeda, T. Flock, N. Taylor, I. Mohammed, H. Matile, R. Dawson, X. Deupi, H. Stahlberg, G. Schertler: Cryo-EM structure of the rhodopsin-Gαi-βγ complex reveals binding of the rhodopsin C-terminal tail to the gβ subunit. eLife 8 (2019)
T. Nagata, M. Koyanagi, R. Lucas and A. Terakita: An all-trans-retinal-binding opsin peropsin as a potential dark-active and light-inactivated G protein-coupled receptor. Sci. Rep. 8, 3535 (2018)
E. Gerrard, E. Mutt, T. Nagata, M. Koyanagi, T. Flock, E. Lesca, G. F. X. Schertler, A. Terakita, X. Deupi, R. Lucas: Convergent evolution of tertiary structure in rhodopsin visual proteins from vertebrates and box jellyfish. Proceedings of the National Academy of Sciences (USA) 115(24):6201-6206 (2018)
T. Nagata, M. Koyanagi, H. Tsukamoto, E. Mutt, G. F. X. Schertler, X. Deupi, A. Terakita: The counterion–retinylidene Schiff base interaction of an invertebrate rhodopsin rearranges upon light activation. Communications biology 2 (1), 180 (2019)
D. Ehrenberg, N. Varma, X. Deupi, M. Koyanagi, A. Terakita, G.F.X. Schertler, J. Heberle, E. Lesca: The two-photon reversible reaction of the bistable jumping spider rhodopsin-1. Biophysical journal 116 (7), 1248-1258 (2019)
N. Varma, E. Mutt, 1, J. Mühle, V. Panneels, A. Terakita, X. Deupi, P. Nogly, G.F.X. Schertler, E. Lesca: Crystal structure of a light-sensitive bistable class A GPCR. Proceedings of the National Academy of Sciences, 201902192 (2019)