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Article

Photo-Switching of Protein Dynamical Collectivity

1
Department of Physics, University at Buffalo, Buffalo, NY 14260, USA
2
JILA, 440 UCB, University of Colorado, Boulder, CO 80309, USA
3
Department of Chemistry, 215 UCB, University of Colorado, Boulder, CO 80309, USA
*
Author to whom correspondence should be addressed.
Photonics 2021, 8(8), 302; https://doi.org/10.3390/photonics8080302
Received: 16 June 2021 / Revised: 23 July 2021 / Accepted: 25 July 2021 / Published: 29 July 2021
We examine changes in the picosecond structural dynamics with irreversible photobleaching of red fluorescent proteins (RFP) mCherry, mOrange2 and TagRFP-T. Measurements of the protein dynamical transition using terahertz time-domain spectroscopy show in all cases an increase in the turn-on temperature in the bleached state. The result is surprising given that there is little change in the protein surface, and thus, the solvent dynamics held responsible for the transition should not change. A spectral analysis of the measurements guided by quasiharmonic calculations of the protein absorbance reveals that indeed the solvent dynamical turn-on temperature is independent of the thermal stability/photostate however the protein dynamical turn-on temperature shifts to higher temperatures. This is the first demonstration of switching the protein dynamical turn-on temperature with protein functional state. The observed shift in protein dynamical turn-on temperature relative to the solvent indicates an increase in the required mobile waters necessary for the protein picosecond motions, that is, these motions are more collective. Melting-point measurements reveal that the photobleached state is more thermally stable, and structural analysis of related RFP’s shows that there is an increase in internal water channels as well as a more uniform atomic root mean squared displacement. These observations are consistent with previous suggestions that water channels form with extended light excitation providing O2 access to the chromophore and subsequent fluorescence loss. We report that these same channels increase internal coupling enhancing thermal stability and collectivity of the picosecond protein motions. The terahertz spectroscopic characterization of the protein and solvent dynamical onsets can be applied generally to measure changes in collectivity of protein motions. View Full-Text
Keywords: protein collectivity; terahertz; thermal stability; fluorescent proteins; photobleaching protein collectivity; terahertz; thermal stability; fluorescent proteins; photobleaching
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MDPI and ACS Style

Xu, M.; George, D.; Jimenez, R.; Markelz, A. Photo-Switching of Protein Dynamical Collectivity. Photonics 2021, 8, 302. https://doi.org/10.3390/photonics8080302

AMA Style

Xu M, George D, Jimenez R, Markelz A. Photo-Switching of Protein Dynamical Collectivity. Photonics. 2021; 8(8):302. https://doi.org/10.3390/photonics8080302

Chicago/Turabian Style

Xu, Mengyang, Deepu George, Ralph Jimenez, and Andrea Markelz. 2021. "Photo-Switching of Protein Dynamical Collectivity" Photonics 8, no. 8: 302. https://doi.org/10.3390/photonics8080302

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