Observation of conformational dynamics in single light-harvesting proteins from cryptophyte algae
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5.0095763.pdf
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Published version
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5.57 MB
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Author(s)
Moya, Raymundo
Norris, Audrey C
Spangler, Leah C
Scholes, Gregory D
Schlau-Cohen, Gabriela S
Date Issued
July 21, 2022
Journal
The Journal of Chemical Physics
Publisher
AIP Publishing
Citation
Moya, Raymundo, Norris, Audrey C, Spangler, Leah C, Scholes, Gregory D and Schlau-Cohen, Gabriela S. 2022. "Observation of conformational dynamics in single light-harvesting proteins from cryptophyte algae." The Journal of Chemical Physics, 157 (3).
Version
Final published version
Abstract
Photosynthetic organisms use pigment–protein complexes to capture the sunlight that powers most life on earth. Within these complexes, the position of the embedded pigments is all optimized for light harvesting. At the same time, the protein scaffold undergoes thermal fluctuations that vary the structure, and, thus, photophysics, of the complexes. While these variations are averaged out in ensemble measurements, single-molecule spectroscopy provides the ability to probe these conformational changes. We used single-molecule fluorescence spectroscopy to identify the photophysical substates reflective of distinct conformations and the associated conformational dynamics in phycoerythrin 545 (PE545), a pigment–protein complex from cryptophyte algae. Rapid switching between photophysical states was observed, indicating that ensemble measurements average over a conformational equilibrium. A highly quenched conformation was also identified, and its population increased under high light. This discovery establishes that PE545 has the characteristics to serve as a photoprotective site. Finally, unlike homologous proteins from the evolutionarily related cyanobacteria and red algae, quenching was not observed upon photobleaching, which may allow for robust photophysics without the need for rapid repair or replacement machinery. Collectively, these observations establish the presence of a rich and robust set of conformational states of PE545. Cryptophytes exhibit particularly diverse energetics owing to the variety of microenvironments in which they survive, and the conformational states and dynamics reported here may provide photophysical flexibility that contributes to their remarkable ability to flourish under diverse conditions.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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Creative Commons Attribution 4.0 International license
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DOI of Published Version
https://doi.org/10.1063/5.0095763
