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.
|Original language||English (US)|
|State||Published - Nov 21 2018|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We thank Anja Koch and Brian Bauer for assistance in purifying reagents. We are grateful to Manfred Weiss and the scientific staff of the BESSY-MX/Helmholtz Zentrum Berlin für Materialien und Energie at beamlines BL14.1, BL14.2 and BL14.3 operated by the Joint Berlin MX-Laboratory at the BESSY II electron storage ring (Berlin-Adlershof, Germany) and the scientific staff of the European Synchrotron Radiation Facility (ESRF, Grenoble) at beamlines ID23-1, ID23-2, ID29, ID30A-1, ID30A-3 and ID30B for continuous support. This work was supported by grants from the Deutsche Forschungsgemeinschaft (SFB1078-B6 to P.H. and P.S.; SFB1078-C3 to M.A.M.; SFB740-B6 to P.S.), Integrated Graduate School fellowship of SFB1078 to L.S., European Synchrotron Radiation Facility (ESRF beamtime BAG to N.K., D.v.S. and P.S.), DFG Cluster of Excellence ‘Unifying Concepts in Catalysis’ (Research Field E4 to M.A.M., P.H. and P.S.) and the Einstein Center of Catalysis EC2 Berlin (to P.H., F.V.E., M.A.M. and P.S.).