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Nanosecond protein dynamics in a red/green cyanobacteriochrome revealed by transient IR spectroscopy


Buhrke, David; Oppelt, Kerstin T; Heckmeier, Philipp J; Fernandez-Teran, Ricardo; Hamm, Peter (2020). Nanosecond protein dynamics in a red/green cyanobacteriochrome revealed by transient IR spectroscopy. Journal of Chemical Physics, 153(24):245101.

Abstract

Over the last decades, photoreceptive proteins were extensively studied with biophysical methods to gain a fundamental understanding of their working mechanisms and further guide the development of optogenetic tools. Time-resolved infrared (IR) spectroscopy is one of the key methods to access their functional non-equilibrium processes with high temporal resolution but has the major drawback that experimental data are usually highly complex. Linking the spectral response to specific molecular events is a major obstacle. Here, we investigate a cyanobacteriochrome photoreceptor with a combined approach of transient absorption spectroscopy in the visible and IR spectral regions. We obtain kinetic information in both spectral regions by analysis with two different fitting methods: global multiexponential fitting and lifetime analysis. We investigate the ground state dynamics that follow photoexcitation in both directions of the bi-stable photocycle (Pr* and Pg*) in the nanosecond and microsecond time regimes. We find two ground state intermediates associated with the decay of Pr* and four with Pg* and report the macroscopic time constants of their interconversions. One of these processes is assigned to a structural change in the protein backbone.

Abstract

Over the last decades, photoreceptive proteins were extensively studied with biophysical methods to gain a fundamental understanding of their working mechanisms and further guide the development of optogenetic tools. Time-resolved infrared (IR) spectroscopy is one of the key methods to access their functional non-equilibrium processes with high temporal resolution but has the major drawback that experimental data are usually highly complex. Linking the spectral response to specific molecular events is a major obstacle. Here, we investigate a cyanobacteriochrome photoreceptor with a combined approach of transient absorption spectroscopy in the visible and IR spectral regions. We obtain kinetic information in both spectral regions by analysis with two different fitting methods: global multiexponential fitting and lifetime analysis. We investigate the ground state dynamics that follow photoexcitation in both directions of the bi-stable photocycle (Pr* and Pg*) in the nanosecond and microsecond time regimes. We find two ground state intermediates associated with the decay of Pr* and four with Pg* and report the macroscopic time constants of their interconversions. One of these processes is assigned to a structural change in the protein backbone.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Scopus Subject Areas:Physical Sciences > General Physics and Astronomy
Physical Sciences > Physical and Theoretical Chemistry
Uncontrolled Keywords:Physical and Theoretical Chemistry, General Physics and Astronomy
Language:English
Date:28 December 2020
Deposited On:02 Feb 2021 11:57
Last Modified:03 Feb 2021 21:02
Publisher:American Institute of Physics
ISSN:0021-9606
OA Status:Green
Publisher DOI:https://doi.org/10.1063/5.0033107

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