Characterization of biomodal light-switchable rhodopsins and tailoring for optogentic application

• Applicant: Professor Dr. Peter Hegemann
• Subject Area: Biophysics
• Term: from 2013 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 119438981

Melanopsins are Photoreceptors that are in mamals responsible for non-viual photoreception and control processes like pupil constriction and circadian rhythm. The so far known Melanopsins of mamals (mouse) and some of the zebrafish melanopsins are photochromic and bimodal switchable between the dark state and the signaling state, a property that is of highest interest for optogenetic application. In this project we will express several melanopsins in HEK-cells, COPS cells and in Pichia pastoris and carry out studies in the UV/Vis and vibrational spectroscopy on time scales ranging from fs to seconds (with Tilo Mathes in Amsterdam). For optogenetic applications we will produce hybrids of photochromic melanopsins and GPCR-type hormone receptors with the intention to activate hormone receptor signalling with light. We will validate this concept in collaboration with Soojin Ryu targeting corticotrophin releasing hormone (CRH). For this approach we will purify and characterise Parapinopsin of lamprey and opn4 of zebrafish. We exchange the intracellular loops against the complementary loops of the hormone receptor and test the function in fish larvae with Soojin Ryu.

• DFG Programme: Research Units
• Subproject of: FOR 1279: “Protein-based Photoswitches” as Optogenetic Tools
• Major Instrumentation: FPLC-Anlage
• Instrumentation Group: 1350 Flüssigkeits-Chromatographen (außer Aminosäureanalysatoren 317), Ionenaustauscher