Structure of the month - November 2018
Structural snapshot of a bacterial phytochrome in its functional intermediate state
Andrea Schmidt1, Luisa Sauthof1, Michal Szczepek1, Maria Fernandez Lopez2, Francisco Velazquez Escobar2, Bilal M. Qureshi1,5, Norbert Michael2, David Buhrke2, Tammo Stevens1, Dennis Kwiatkowski1,David von Stetten3,6, Maria Andrea Mroginski2, Norbert Krauß4, Tilman Lamparter4, Peter Hildebrandt2 & Patrick Scheerer1
Phytochromes are modular photoreceptors of plants, bacteria and fungi that use light as a source of information to regulate fundamental physiological processes. Interconversion between the active and inactive states is accomplished by a photoinduced reaction sequence which couples the sensor with the output module. However, the underlying molecular mechanism is yet not fully understood due to the lack of structural data of functionally relevant intermediate states. Here we report the crystal structure of a Meta-F intermediate state of an Agp2 variant from Agrobacterium fabrum. This intermediate, the identity of which was verified by resonance Raman spectroscopy, was formed by irradiation of the parent Pfr state and displays significant reorientations of almost all amino acids surrounding the chromophore. Structural comparisons allow identifying structural motifs that might serve as conformational switch for initiating the functional secondary structure change that is linked to the (de-)activation of these photoreceptors.
1 Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charitéplatz 1, Berlin, D-10117, Germany.
2 Technische Universität Berlin, Institut für Chemie, Sekr. PC 14, Straße des 17. Juni 135, Berlin, D-10623, Germany.
3 Structural Biology Group, European Synchrotron Radiation Facility, CS 40220 F-38043 Grenoble Cedex 9, France.
4 Karlsruhe Institute of Technology (KIT), Botanical Institute, Fritz-Haber-Weg 4, Karlsruhe, D-76131, Germany.
5 Present address: Division of Biological & Environmental Sciences & Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955–6900, Saudi Arabia.
6 Present address: European Molecular Biology Laboratory (EMBL), Hamburg Outstation c/o DESY, Notkestrasse 85, Hamburg, D-22607, Germany.
These authors contributed equally: Andrea Schmidt, Luisa Sauthof, Michal Szczepek, Maria Fernandez Lopez.
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