Effect of the PHY domain on the photoisomerization step of the forward Pr→Pfr conversion of a knotless phytochrome

  • 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 Pr 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.
Author:Tobias Fischer, Qianzhao Xu, Kai-Hong Zhao, Wolfgang Gärtner, Chavdar Slavov, Josef WachtveitlORCiDGND
Parent Title (English):Chemistry
Place of publication:Weinheim
Document Type:Article
Date of Publication (online):2020/08/19
Date of first Publication:2020/08/19
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2022/03/09
Tag:bilin-binding photoreceptors; photochemistry; photoisomerization; time-resolved spectroscopy
Page Number:6
First Page:17261
Last Page:17266
C.S. and J.W. acknowledge Deutsche Forschungsgemeinschaft (WA 1850/4-2 and WA 1850/4-3). W.G. is grateful for the continuous support from the University of Leipzig. K.-H.Z. acknowledges the National Natural Science Foundation of China (NSFC: 31861143029; 31770822). Q.X. is recipient of a research-exchange grant from the Chinese Scholar Council (CSC). The authors thank Dr. Chen Song for providing the homology model of the All2699g1g2 construct. Open access funding enabled and organized by Projekt DEAL.
Institutes:Biochemie, Chemie und Pharmazie
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften
Licence (German):License LogoCreative Commons - Namensnennung 4.0