In the present paper Maria Andrea Mroginski, Peter Hildebrand, Patrick Scheerer (projects B6, C2, C3) and coworkers investigate the molecular mechanism underlying photoinduced reaction sequences within cells of plants, bacteria and fungi. Many fundamental physiological processes are regulated by modular photorecptors, i.e. phytochromes. Thus, light serves as initiator of processes such as photosynthesis, seed germination, flowering and shade avoidance. The present study tries to satisfy the need for structural data of functionally relevant intermediate states, namely the Meta-F intermediate state of an Agp2 variant from Agrobacterium fabrum in order to fully understand the underlying molecular mechanisms. The study verifies the identity of an intermediate by Raman spectroscopy that displays significant reorientations of almost all amino acids surrounding the chromophore. The results allow identifying structural motifs that might serve as switch for initiating the functional structure change that is linked to the activation and deactivation of these photoreceptors.

Publication: Schmidt, A., Sauthof, L., Szczepek, M., Lopez, M., Velázquez, F., Qureshi, B. M., Michael, N., Buhrke, D., Stevens, T., Kwiatkowski, D., von Stetten, D., Mroginski, M. A., Krauß, N., Lamparter, T. , Hildebrandt, P., and Scheerer, P. (2018). Structural snapshot of a bacterial phytochrome in its functional intermediate state. Nature Commun 9, 4912, doi: 10.1038/s41467-018-07392-7.