Structural photoactivation of a full-length bacterial phytochrome

Alexander Bjorling, Oskar Berntsson, Heli Lehtivuori, Heikki Takala, Ashley J. Hughes, Matthijs Panman, Maria Hoernke, Stephan Niebling, Leocadie Henry, Robert Henning, Irina Kosheleva, Vladimir Chukharev, Nikolai V. Tkachenko, Andreas Menzel, Gemma Newby, Dmitry Khakhulin, Michael Wulff, Janne A. Ihalainen, Sebastian Westenhoff

Research output: Contribution to JournalArticleAcademicpeer-review


Phytochromes are light sensor proteins found in plants, bacteria, and fungi. They function by converting a photon absorption event into a conformational signal that propagates from the chromophore through the entire protein. However, the structure of the photoactivated state and the conformational changes that lead to it are not known. We report time-resolved x-ray scattering of the full-length phytochrome from Deinococcus radiodurans on micro-and millisecond time scales. We identify a twist of the histidine kinase output domains with respect to the chromophore-binding domains as the dominant change between the photoactivated and resting states. The time-resolved data further show that the structural changes up to the microsecond time scales are small and localized in the chromophore-binding domains. The global structural change occurs within a few milliseconds, coinciding with the formation of the spectroscopic meta-Rc state. Our findings establish key elements of the signaling mechanism of full-length bacterial phytochromes.
Original languageEnglish
JournalScience advances
Issue number8
Publication statusPublished - Aug 2016


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