Signal amplification and transduction in phytochrome photosensors

Heikki Takala, Alexander Björling, Oskar Berntsson, Heli Lehtivuori, Stephan Niebling, Maria Hoernke, Irina Kosheleva, Robert Henning, Andreas Menzel, Janne A. Ihalainen*, Sebastian Westenhoff

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


Sensory proteins must relay structural signals from the sensory site over large distances to regulatory output domains. Phytochromes are a major family of red-light-sensing kinases that control diverse cellular functions in plants, bacteria and fungi(1-9). Bacterial phytochromes consist of a photosensory core and a carboxy-terminal regulatory domain(10,11). Structures of photosensory cores are reported in the resting state(12-18) and conformational responses to light activation have been proposed in the vicinity of the chromophore(19-23). However, the structure of the signalling state and the mechanism of downstream signal relay through the photosensory core remain elusive. Here we report crystal and solution structures of the resting and activated states of the photosensory core of the bacteriophytochrome from Deinococcus radiodurans. The structures show an open and closed form of the dimeric protein for the activated and resting states, respectively. This nanometre-scale rearrangement is controlled by refolding of an evolutionarily conserved 'tongue', which is in contact with the chromophore. The findings reveal an unusual mechanism in which atomic-scale conformational changes around the chromophore are first amplified into ana angstrom-scale distance change in the tongue, and further grow into a nanometre-scale conformational signal. The structural mechanism is a blueprint for understanding how phytochromes connect to the cellular signalling network.
Original languageEnglish
Pages (from-to)245-248
Number of pages4
Issue number7499
Publication statusPublished - 8 May 2014


Dive into the research topics of 'Signal amplification and transduction in phytochrome photosensors'. Together they form a unique fingerprint.

Cite this