How plants see

Plants need light to live, yet photosynthesis is only a part of the story. They also have phytochromes, photoreceptor proteins which provide information about the light environment and thereby control the biochemistry of the cell and thence the development of the plant. To achieve this, phytochromes control thousands of genes, perhaps a quarter of the entire genome – but how exactly that is brought about is in many respects unclear. How is the photon energy used to activate the protein? What structural changes occur and how are they brought about? What new characteristics of the protein are responsible for transferring the light signal to the cell and its genome?  
Jon Hughes (project B8) and coworkers employed X-ray crystallographic measurements at the BESSY II synchrotron to solve the 3D structures of different phytochromes at near atomic resolution, revealing much about the molecular functionality in the Pr state. Together with Peter Hildebrandt (project B6), they also used spectroscopic methods to analyse the photoactivation process, in particular changes in chromophore geometry, hydrogen bonding networks and protonation dynamics. These new insights represent an important step forward in understanding phytochrome function. The next step will be to solve the structure of the photoactivated Pfr state: this will be absolutely critical in understanding the system as a whole.

Paper published in the 04 May 2020 issue of Nature Plants:

Nagano, S., Guan, K., Shenkutie, S., Feiler, C., Weiss, M. S., Kraskov, A., Buhrke, D., Hildebrandt, P., Hughes, J. (2020). Structural insights into photoactivation and signalling in plant phytochromes. Nat Plants 6, 581-588. doi: 10.1038/s41477-020-0638-y