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Updated: Jul 12, 2025
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Published on: November 20, 2017
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Long-Time Oxygen and Superoxide Localization in Arabidopsis thaliana Cryptochrome
K Michael Salerno1, Janna Domenico1, Nam Q Le1
1Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, Maryland 20723, United States.
Journal of Chemical Information and Modeling
|October 24, 2023
Summary
Cryptochromes bind oxygen, potentially forming superoxide. Molecular dynamics simulations show oxygen and superoxide can bind within cryptochrome proteins for extended periods, suggesting a role in biological redox reactions.
Area of Science:
- Biochemistry
- Structural Biology
- Computational Biology
Background:
- Cryptochromes are conserved proteins binding flavin adenine dinucleotide (FAD) in their photolyase-homology region (PHR).
- FAD's redox states and light absorption are crucial for cryptochrome functions.
- Reactive oxygen species (ROS), like superoxide, are biologically significant but their formation in cryptochromes is unclear.
Purpose of the Study:
- To investigate oxygen interaction with the *Arabidopsis thaliana* cryptochrome 1 (AtCRY1) PHR domain.
- To determine if cryptochromes can facilitate the formation of superoxide via electron transfer from FAD.
Main Methods:
- Molecular dynamics (MD) simulations of oxygen interacting with the AtCRY1 PHR domain.
- Analysis of oxygen binding locations and unbinding times using MD trajectories and replica simulations.
- Estimation of electron-transfer rates using Marcus theory for identified binding sites.
Main Results:
- Oxygen molecules were observed to localize within the AtCRY1 PHR domain for tens of nanoseconds.
- Superoxide molecules demonstrated significantly longer localization times within the protein.
- Identified binding sites suggest potential for electron transfer from FAD to oxygen.
Conclusions:
- Long-duration binding of oxygen and superoxide within cryptochromes supports their potential role in redox reactions.
- These findings suggest a possible mechanism for superoxide formation catalyzed by cryptochromes.
- Comparison with electron-transfer flavoprotein (ETF) highlights conserved FAD-binding protein mechanisms.
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