Project B7 aims to elucidate cause-effect relations in the coupling of proton dynamics to conformational changes in phytochromes, light-gated channels and light driven pumps. Femtosecond (fs) polarization resolved Vis-pump IR-probe spectroscopy (upvi) represents an excellent tool to investigate local structural changes of the chromophore, the protein backbone, amino acid side chains, and water clusters. Hydrogen bonds can be monitored by spectral changes of specific vibrational bands and their orientations. Ground state heterogeneity can be resolved into species with distinct quantum yields. Rate-determining proton-transfer steps will be identified by measurements at different pH and temperature. A new ns pump – upvi setup is going to be developed to investigate selected intermediate states of the photoreaction and determine structural changes during keto-enol transition involved in the phytochrome photocycle. Comparison of structural dynamics of various ground state conformations between different phytochromes (Cph1, Agp1, Agp2, plant phytochromes) will reveal general principles of the cause-effect relation.
Stensitzki, T., Yang, Y., Wölke, A.L., Knapp, E.-W., Hughes, J., Mroginski, M. A., and Heyne, K. (2017). Influence of Heterogeneity on the Ultrafast Photoisomerization Dynamics of Pfr in Cph1 Phytochrome. Photochemistry and Photobiology 93, 703-712.
Linke, M., Yang, Y., Zienicke, B., Hammam, M.A.S., von Haimberger, T., Zacarias, A., Inomata, K., Lamparter, T., and Heyne, K. (2013). Electronic transitions and heterogeneity of the bacteriophytochrome Pr absorption band: An angle balanced polarization resolved femtosecond VIS pump-IR probe study. Biophysical Journal 105, 1756-1766.
Stensitzki, T., Muders, V., Schlesinger, R., Heberle, J., and Heyne, K. (2015). The primary photoreaction of channelrhodopsin-1: Wavelength dependent photoreactions induced by ground-state heterogeneity. Frontiers in Molecular Biosciences 2, 41.
Stensitzki, T., Yang, Y., Berg, A., Mahammed, A., Gross, Z., and Heyne, K. (2016). Ultrafast electronic and vibrational dynamics in brominated aluminum corroles: Energy relaxation and triplet formation. Structural Dynamics 3, 043210.
Stensitzki, T., Yang, Y., Muders, V., Schlesinger, R., Heberle, J., and Heyne, K. (2016). Femtosecond infrared spectroscopy of channelrhodopsin-1 chromophore isomerization. Structural Dynamics 3, 043208.
Velazquez Escobar, F., von Stetten, D., Günther-Lütkens, M., Keidel, A., Michael, N., Lamparter, T., Essen, L.-O., Hughes, J., Gärtner, W., Yang, Y., Heyne, K., Mroginski, M.A., and Hildebrandt, P. (2015). Conformational heterogeneity of the Pfr chromophore in plant and cyanobacterial phytochromes. Frontiers in Molecular Biosciences 2, 37.
Yang, Y., Heyne, K., Mathies, R.A., and Dasgupta, J. (2016). Non-Bonded Interactions Drive the Sub-Picosecond Bilin Photoisomerization in the Pfr State of Phytochrome Cph1. ChemPhysChem 17, 369-374.
Yang, Y., Linke, M., von Haimberger, T., Matute, R., González, L., Schmieder, P., and Heyne, K. (2014). Active and silent chromophore isoforms for phytochrome Pr photoisomerization: An alternative evolutionary strategy to optimize photoreaction quantum yields. Structural Dynamics 1, 014701.