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  Molecular mechanisms of spectral tuning and excited-state decay in phytochrome photoreceptors

Maximowitsch, E. (2020). Molecular mechanisms of spectral tuning and excited-state decay in phytochrome photoreceptors. PhD Thesis, Universität Heidelberg, Heidelberg.

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Item Permalink: http://hdl.handle.net/21.11116/0000-0003-6E90-F Version Permalink: http://hdl.handle.net/21.11116/0000-0005-8083-5
Genre: Thesis

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Maximowitsch_Diss_2019.pdf (Any fulltext), 17MB
 
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 Creators:
Maximowitsch, Eglé1, 2, Author              
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1Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Max Planck Society, ou_1497700              
2Cytochrome P450, Max Planck Institute for Medical Research, Max Planck Society, ou_1497697              

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Free keywords: phytochrome, charge transfer, electron transfer, spectral tuning, spectral shift
 Abstract: Most organisms on earth are able to sense light, to which they adapt their behavior by using photoreceptor proteins containing light-absorbing chromophores. Phytochrome photoreceptors contain a covalently-attached tetrapyrrole chromophore and switch between two thermally stable forms, a red-absorbing (Pr) and a far-red-absorbing (Pfr) state. Although phytochromes have been studied for more than fifty years, the molecular mechanisms defining their photoinduced properties are not fully understood, hampering the efficient engineering of phytochrome-based molecular tools. The computational study presented in this thesis combines quantum chemical calculations and molecular dynamics simulations in order to elucidate the molecular mechanisms of spectral tuning and excited-state decay in phytochromes. The calculations have demonstrated that the spectral red shift of the Pfr state is induced by the hydrogen bond formation between the chromophore and a highly conserved aspartate. Here it is also shown how the formation of this hydrogen bond is coupled to dynamics of other active-site interactions. In addition, the chromophore deprotonation by a protein residue is proposed to contribute to the absorption at the Q-band blue shoulder in the Pr-state spectrum. For the first time, the photoinduced electron transfer coupled to proton transfer was characterized in phytochromes. These charge transfer pathways may contribute to the excited-state decay by quenching fluorescence and influencing photoproduct formation. The discoveries provided in this thesis will facilitate further phytochrome investigations and the rational design of phytochrome-based fluorescent markers and optogenetic tools.

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Language(s): eng - English
 Dates: 2019-04-012019-05-232020
 Publication Status: Published in print
 Pages: 193
 Publishing info: Heidelberg : Universität Heidelberg
 Table of Contents: -
 Rev. Type: -
 Degree: PhD

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