Modulation of Structural Heterogeneity Controls Phytochrome Photoswitching

Biophys J. 2020 Jan 21;118(2):415-421. doi: 10.1016/j.bpj.2019.11.025. Epub 2019 Nov 26.


Phytochromes sense red/far-red light and control many biological processes in plants, fungi, and bacteria. Although the crystal structures of dark- and light-adapted states have been determined, the molecular mechanisms underlying photoactivation remain elusive. Here, we demonstrate that the conserved tongue region of the PHY domain of a 57-kDa photosensory module of Deinococcus radiodurans phytochrome changes from a structurally heterogeneous dark state to an ordered, light-activated state. The results were obtained in solution by utilizing a laser-triggered activation approach detected on the atomic level with high-resolution protein NMR spectroscopy. The data suggest that photosignaling of phytochromes relies on careful modulation of structural heterogeneity of the PHY tongue.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Darkness
  • Deinococcus
  • Light*
  • Models, Molecular
  • Nuclear Magnetic Resonance, Biomolecular
  • Phytochrome / chemistry*
  • Phytochrome / metabolism
  • Protein Domains


  • Phytochrome