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Effect of the PHY Domain on the Photoisomerization Step of the Forward P r →P fr Conversion of a Knotless Phytochrome
Author(s) -
Fischer Tobias,
Xu Qianzhao,
Zhao KaiHong,
Gärtner Wolfgang,
Slavov Chavdar,
Wachtveitl Josef
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202003138
Subject(s) - photoisomerization , chromophore , phytochrome , phy , isomerization , biophysics , chemistry , domain (mathematical analysis) , pas domain , photochemistry , computer science , biochemistry , biology , catalysis , botany , mathematics , physical layer , telecommunications , red light , mathematical analysis , transcription factor , wireless , gene
Phytochrome photoreceptors operate via photoisomerization of a bound bilin chromophore. Their typical architecture consists of GAF, PAS and PHY domains. Knotless phytochromes lack the PAS domain, while retaining photoconversion abilities, with some being able to photoconvert with just the GAF domain. Therefore, we investigated the ultrafast photoisomerization of the P r state of a knotless phytochrome to reveal the effect of the PHY domain and its “tongue” region on the transduction of the light signal. We show that the PHY domain does not affect the initial conformational dynamics of the chromophore. However, it significantly accelerates the consecutively induced reorganizational dynamics of the protein, necessary for the progression of the photoisomerization. Consequently, the PHY domain keeps the bilin and its binding pocket in a more reactive conformation, which decreases the extent of protein reorganization required for the chromophore isomerization. Thereby, less energy is lost along nonproductive reaction pathways, resulting in increased efficiency.