Interactions Between phyB and PIF Proteins Alter Thermal Reversion Reactions in vitro

Robert W. Smith*, Britta Helwig, Adrie H. Westphal, Eran Pel, Jan Willem Borst, Christian Fleck

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

8 Citations (Scopus)

Abstract

The dynamic behavior of the plant red/far-red light photoreceptor phytochrome B (phyB) has been elucidated in natural and synthetic systems. Red light switches phyB from the inactive Pr state to the active Pfr state, a process that is reversed by far-red light. Alongside light signals, phyB activity is constrained by thermal reversion (that is prominent in the dark) and protein–protein interactions between phyB, other phytochrome molecules, and, among others, PHYTOCHROME INTERACTING FACTORs (PIFs). Requirements for phyB-PIF association have been well studied and are central to light-regulated synthetic tools. However, it is unknown whether PIF interactions influence transitions of phyB between different conformers. Here, we show that the in vitro thermal reversion of phyB involves multiple reactions. Thermal reversion of phyB in vitro is inhibited by PIF6, and this effect is observed at all temperatures tested. We analyzed our experimental data using a mathematical model containing multiple Pfr conformers, in accordance with previous findings. Remarkably, each Pfr conformer is differentially regulated by PIF6 and temperature. As a result, we speculate that in vivo phytochrome signaling networks may require similar levels of complexity to fine-tune responses to the external environment.
Original languageEnglish
Pages (from-to)1525-1531
JournalPhotochemistry and Photobiology
Volume93
Issue number6
DOIs
Publication statusPublished - 1 Nov 2017

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