Project B5

Spectroscopic investigations of proton transfer processes and hydrogen-bonded networks in bacterial phytochromes and channelrhodopsins

Principal Investigator: Prof. Dr. Franz Bartl (Charité)

The B5-project approaches an improved mechanistic understanding of the photocycle and the associated protonation dynamics of both channelrhodopsins and bacterial phytochromes. Difference spectroscopy in the infrared and the UV-visible range is directly combined in advanced static and time-resolved experiments with millisecond resolution at room and low temperatures. In wild-type and genetically modified proteins, the role of specific side chains for proton transfer processes occurring during the photocycle is investigated. In a collaborative effort, an understanding of the interplay between proton transfer processes and structural changes of the photoreceptors which are crucial for protein function is approached.


2017 - 2019

Fudim, R., Szczepek, M., Vierock, J., Vogt, A., Schmidt, A., Kleinau, G., Fischer, P., Bartl, F., Scheerer, P., Hegemann, P. (2019). Design of a light-gated proton channel based on the crystal structure of Coccomyxa rhodopsin. Sci Signal. 2019 Mar 19;12(573). pii: eaav4203. doi: 10.1126/scisignal.aav4203

Kaufmann, J.C.D., Krause, B.S., Grimm, C., Ritter, E., Hegemann, P., Bartl, F.J. (2017). Proton transfer reactions in the red light-activatable channelrhodopsin variant ReaChR and their relevance for its function. J Biol Chem. 2017 Aug 25;292(34):14205-14216. doi: 10.1074/jbc.M117.779629.

Krause, B.S., Grimm, C., Kaufmann, J.C.D., Schneider, F., Sakmar, T.P., Bartl, F.J., and Hegemann, P. (2017). Complex Photochemistry within the Green-Absorbing Channelrhodopsin ReaChR. Biophysical Journal 112, 1166-1175.

Krause, B. S., Kaufmann, J. C. D., Kuhne,, J., Vierock, J. T. T., Huber, T., Sakmar, T. P., Gerwert, K., Bartl,, F. J., and Hegemann, P. (2019). Tracking pore hydration in channelrhodopsin by site-directed infrared-active azido probes. Biochemistry. Feb 19. doi: 10.1021/acs.biochem.8b01211.

Takiden, A., Velazquez-Escobar, F., Dragelj, J., Woelke, A.L., Knapp E.-W., Piwowarski, P., Bartl, F., Hildebrandt, P., and Mroginski, M.A. (2017). Structural and Vibrational Characterization of the Chromophore Binding Site of Bacterial Phytochrome Agp1. Photochemistry and Photobiology 93, 713-723.

2013 - 2016

Kuhne, J., Eisenhauer, K., Ritter, E., Hegemann, P., Gerwert, K., and Bartl, F. (2015). Early Formation of the Ion-Conducting Pore in Channelrhodopsin-2. Angewandte Chemie International Edition 54, 4953-4957.

Pyta, K., Przybylski, P., and Bartl, F. (2015). Regioselective Long-Range Proton Transfer in New Rifamycin Antibiotics: A Process in which Crown Ethers Act as Stronger Br circle divide nsted Bases than Amines. ChemPhysChem 16, 938-942.

Ritter, E., Piwowarski, P., Hegemann, P., and Bartl, F.J. (2013). Light-dark Adaptation of Channelrhodopsin C128T Mutant. Journal of Biological Chemistry 288, 10451-10458.

Salewski, J., Escobar, F.V., Kaminski, S., von Stetten, D., Keidel, A., Rippers, Y., Michael, N., Scheerer, P., Piwowarski, P., Bartl, F., Frankenberg-Dinkel, N., Ringsdorf, S., Gaertner, W., Lamparter, T., Mroginski, M.A., and Hildebrandt, P. (2013). Structure of the Biliverdin Cofactor in the Pfr State of Bathy and Prototypical Phytochromes. Journal of Biological Chemistry 288, 16800-16814.

Velazquez Escobar, F., Piwowarski, P., Salewski, J., Michael, N., Fernandez Lopez, M., Rupp, A., Muhammad Qureshi, B., Scheerer, P., Bartl, F., Frankenberg-Dinkel, N., Siebert, F., Mroginski, M.A., and Hildebrandt, P. (2015). A protonation-coupled feedback mechanism controls the signalling process in bathy phytochromes. Nature Chemistry 7, 423-430. [Link to news section.]