High-resolution crystal structures of transient intermediates in the phytochrome photocycle

Melissa Carrillo, Suraj Pandey, Juan Sanchez, Moraima Noda, Ishwor Poudyal, Luis Aldama, Tek Narsingh Malla, Elin Claesson, Weixiao Yuan Wahlgren, Denisse Feliz, Vukica Šrajer, Michał Maj, Leticia Castillon, So Iwata, Eriko Nango, Rie Tanaka, Tomoyuki Tanaka, Luo Fangjia, Kensuke Tono, Shigeki OwadaSebastian Westenhoff, Emina A. Stojković, Marius Schmidt

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


Phytochromes are red/far-red light photoreceptors in bacteria to plants, which elicit a variety of important physiological responses. They display a reversible photocycle between the resting Pr state and the light-activated Pfr state. Light signals are transduced as structural change through the entire protein to modulate its activity. It is unknown how the Pr-to-Pfr interconversion occurs, as the structure of intermediates remains notoriously elusive. Here, we present short-lived crystal structures of the photosensory core modules of the bacteriophytochrome from myxobacterium Stigmatella aurantiaca captured by an X-ray free electron laser 5 ns and 33 ms after light illumination of the Pr state. We observe large structural displacements of the covalently bound bilin chromophore, which trigger a bifurcated signaling pathway that extends through the entire protein. The snapshots show with atomic precision how the signal progresses from the chromophore, explaining how plants, bacteria, and fungi sense red light.

Original languageEnglish
Pages (from-to)743-754.e4
Issue number7
Publication statusPublished - 2021 Jul 1


  • Lumi-R
  • Pfr
  • Pr
  • X-ray free electron lasers
  • bacteriophytochrome
  • infrared fluorescent protein tissue markers
  • photoconversion
  • photocycle
  • photosensory core module
  • time-resolved serial femtosecond crystallography


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