Asymmetric activation mechanism of a homodimeric red light regulated photoreceptor

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Abstract

Organisms adapt to environmental cues using diverse signaling networks. In order to sense and integrate light for regulating various biological functions, photoreceptor proteins have evolved in a modular way. This modularity is targeted in the development of optogenetic tools enabling the control of cellular events with high spatiotemporal precision. However, the limited understanding of signaling mechanisms impedes the rational design of innovative photoreceptor-effector couples. Here we reveal molecular details of signal transduction in phytochrome-regulated diguanylyl-cyclases. Asymmetric structural changes of the full-length homodimer result in a functional heterodimer featuring two different photoactivation states. Structural changes around the cofactors result in a quasi-translational rearrangement of the distant coiled-coil sensor-effector linker. Eventually, this regulates enzymatic activity by modulating the dimer interface of the output domains. Considering the importance of phytochrome heterodimerization in plant signaling, our mechanistic details of asymmetric photoactivation in a bacterial system reveal novel aspects of the evolutionary adaptation of phytochromes.

Data availability

Diffraction data have been deposited in the PDB under the accession code 6ET7.

The following data sets were generated

1. Gourinchas G
2. Winkler A
(2017) Activated heterodimer of the bacteriophytochrome regulated diguanylyl cyclase variant - S505V A526V - from Idiomarina species A28L
PDB 6ET7.

https://www.rcsb.org/structure/6et7

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Author details

Geoffrey Gourinchas

Institute of Biochemistry, Graz University of Technology, Graz, Austria

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-2543-3518
Udo Heintz

Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg, Germany

Competing interests
The authors declare that no competing interests exist.
Andreas Winkler

Institute of Biochemistry, Graz University of Technology, Graz, Austria

For correspondence
andreas.winkler@tugraz.at

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0001-6221-9671

Funding

Austrian Science Fund (P27124)

Andreas Winkler

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.