Ubiquitous Structural Signaling in Bacterial Phytochromes

Alexander Björling, Oskar Berntsson, Heikki Takala, Kevin D. Gallagher, Hardik Patel, Emil Gustavsson, Rachael St. Peter, Phu Duong, Angela Nugent, Fan Zhang, Peter Berntsen, Roberto Appio, Ivan Rajkovic, Heli Lehtivuori, Matthijs R. Panman, Maria Hoernke, Stephan Niebling, Rajiv Harimoorthy, Tilman Lamparter, Emina A. StojkovićJanne A. Ihalainen*, Sebastian Westenhoff

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


The phytochrome family of light-switchable proteins has long been studied by biochemical, spectroscopic and crystallographic means, while a direct probe for global conformational signal propagation has been lacking. Using solution X-ray scattering, we find that the photosensory cores of several bacterial phytochromes undergo similar large-scale structural changes upon red-light excitation. The data establish that phytochromes with ordinary and inverted photocycles share a structural signaling mechanism and that a particular conserved histidine, previously proposed to be involved in signal propagation, in fact tunes photoresponse.

Original languageEnglish
Pages (from-to)3379-3383
Number of pages5
JournalJournal of Physical Chemistry Letters
Issue number17
Publication statusPublished - 3 Sept 2015


  • phytochromes
  • protein dynamics
  • signal transduction
  • X-ray scattering


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