Influence of the PHY domain on the ms-photoconversion dynamics of a knotless phytochrome

  • The ability of some knotless phytochromes to photoconvert without the PHY domain allows evaluation of the distinct effect of the PHY domain on their photodynamics. Here, we compare the ms dynamics of the single GAF domain (g1) and the GAF-PHY (g1g2) construct of the knotless phytochrome All2699 from cyanobacterium Nostoc punctiforme. While the spectral signatures and occurrence of the intermediates are mostly unchanged by the domain composition, the presence of the PHY domain slows down the early forward and reverse dynamics involving chromophore and protein binding pocket relaxation. We assign this effect to a more restricted binding pocket imprinted by the PHY domain. The photoproduct formation is also slowed down by the presence of the PHY domain but to a lesser extent than the early dynamics. This indicates a rate limiting step within the GAF and not the PHY domain. We further identify a pH dependence of the biphasic photoproduct formation hinting towards a pKa dependent tuning mechanism. Our findings add to the understanding of the role of the individual domains in the photocycle dynamics and provide a basis for engineering of phytochromes towards biotechnological applications.

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Author:Tobias FischerORCiDGND, Lisa KöhlerORCiD, Tanja OttORCiD, Chen SongORCiD, Josef WachtveitlORCiDGND, Chavdar SlavovORCiDGND
Parent Title (English):Photochemical & photobiological sciences
Place of publication:Heidelberg
Document Type:Article
Date of Publication (online):2022/06/10
Date of first Publication:0222/06/10
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2023/04/27
Tag:Flash photolysis; Knotless phytochrome; Photochemistry; Time-resolved spectroscopy
Page Number:10
First Page:1627
Last Page:1636
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 - CC BY - Namensnennung 4.0 International