Light-induced structural changes in a monomeric bacteriophytochrome

Heikki Takala, Stephan Niebling, Oskar Berntsson, Alexander Björling, Heli Lehtivuori, Heikki Häkkänen, Matthijs Panman, Emil Gustavsson, Maria Hoernke, Gemma Newby, Federico Zontone, Michael Wulff, Andreas Menzel, Janne A. Ihalainen, Sebastian Westenhoff

Research output: Contribution to journalArticleScientificpeer-review

20 Citations (Scopus)


Phytochromes sense red light in plants and various microorganism. Light absorption causes structural changes within the protein, which alter its biochemical activity. Bacterial phytochromes are dimeric proteins, but the functional relevance of this arrangement remains unclear. Here, we use time-resolved X-ray scattering to reveal the solution structural change of a monomeric variant of the photosensory core module of the phytochrome from Deinococcus radiodurans. The data reveal two motions, a bend and a twist of the PHY domain with respect to the chromophore-binding domains. Infrared spectroscopy shows the refolding of the PHY tongue. We conclude that a monomer of the phytochrome photosensory core is sufficient to perform the light-induced structural changes. This implies that allosteric cooperation with the other monomer is not needed for structural activation. The dimeric arrangement may instead be intrinsic to the biochemical output domains of bacterial phytochromes.

Original languageEnglish
Article number054701
JournalStructural Dynamics
Issue number5
Publication statusPublished - 1 Sept 2016
Externally publishedYes
Publication typeA1 Journal article-refereed

ASJC Scopus subject areas

  • Radiation
  • Instrumentation
  • Condensed Matter Physics
  • Spectroscopy


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