Humboldt-Universität zu Berlin - Experimentelle Biophysik

Dr. Katja Stehfest



Room:  404


Tel:    (030) 2093 8646



My research interest is centered on structure-function relationships of light-gated ion channels (Channelrhodopsins) and light-activated Rhodopsin-coupled enzymes. The overall goal of my research is to characterize the structure and mechanism of (enzyme) rhodopsin activation by a combination of mutational studies on heterologously expressed protein, functional assays, time-resolved spectroscopy and structural techniques like X-ray crystallography. Currently, I focus on understanding of the chimera C1C2 that acts as a proton and sodium channel but that also provided the basis for engineering a chloride-selective channel. Although the crystal structure of C1C2 in its closed state is known (Kato et al 2012), structural information of the different photocycle states, in particular the conducting state, remain elusive. The aim of my project is to expand our knowledge about light-induced overall structural changes in the holoprotein by characterizing interesting functional variants of C1C2 and by applying them to x-ray crystallographic approaches. Another focus of my research lies on the spectroscopic and enzymatic characterization of recently identified Rhodopsin-guanylyl cyclases from zoospores of aquatic fungi like Blastocladiella emersonii or Catenaria augillulale. This new class of rhodopsin-enzyme produces the second messenger cyclic GMP by activation with green light and has the potential to become a new tool for optogenetic manipulation of cellular signaling pathways. The aim of this project is to understand the mechanism of signal transduction between the photoreceptor and cyclase domains by applying a spectrum of biochemical and structural means.


Also involved in this projekt: Christina Schnick