Modulation of Structural Heterogeneity Controls Phytochrome Photoswitching
Emil Gustavsson1, Linnéa Isaksson1, Cecilia Persson2
1Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden.
Biophysical Journal
|December 17, 2019
Summary
Phytochromes use a structured tongue region in their PHY domain to activate upon light exposure. This structural change in Deinococcus radiodurans phytochrome is key to its photosignaling mechanism.
Area of Science:
- Biochemistry
- Molecular Biology
- Spectroscopy
Background:
- Phytochromes are photoreceptors crucial for regulating biological processes in plants, fungi, and bacteria.
- While crystal structures exist, the molecular mechanisms of phytochrome photoactivation remain unclear.
Purpose of the Study:
- To elucidate the molecular mechanisms of phytochrome photoactivation.
- To investigate the structural dynamics of the PHY domain's tongue region during light adaptation.
Main Methods:
- Utilized laser-triggered activation of Deinococcus radiodurans phytochrome.
- Employed high-resolution protein Nuclear Magnetic Resonance (NMR) spectroscopy in solution.
- Analyzed atomic-level structural changes in the PHY domain's tongue region.
Main Results:
- The conserved tongue region of the PHY domain transitions from a heterogeneous dark state to an ordered, light-activated state.
- Demonstrated dynamic structural changes at the atomic level.
- Provided insights into the solution-state behavior of phytochrome.
Conclusions:
- Phytochrome photosignaling depends on the precise modulation of structural heterogeneity within the PHY tongue region.
- The study reveals a novel mechanism for light-induced structural transitions in phytochromes.
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