A1 Journal article (refereed)
The interconnecting hairpin extension "arm" : An essential allosteric element of phytochrome activity (2023)

Kurttila, M., Rumfeldt, J., Takala, H., & Ihalainen, J. A. (2023). The interconnecting hairpin extension "arm" : An essential allosteric element of phytochrome activity. Structure, 31(9), 1100-1108, e1-e4. https://doi.org/10.1016/j.str.2023.06.007

JYU authors or editors

Kurttila, Moona
Rumfeldt, Jessica
Takala, Heikki
Ihalainen, Janne

Publication details

All authors or editors: Kurttila, Moona; Rumfeldt, Jessica; Takala, Heikki; Ihalainen, Janne A.

Journal or series: Structure

ISSN: 0969-2126

eISSN: 1878-4186

Publication year: 2023

Publication date: 30/06/2023

Volume: 31

Issue number: 9

Pages range: 1100-1108, e1-e4

Publisher: Elsevier

Publication country: United Kingdom

Publication language: English

DOI: https://doi.org/10.1016/j.str.2023.06.007

Publication open access: Openly available

Publication channel open access: Partially open access channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/88305

Abstract

In red-light sensing phytochromes, isomerization of the bilin chromophore triggers structural and dynamic changes across multiple domains, ultimately leading to control of the output module (OPM) activity. In between, a hairpin structure, "arm", extends from an interconnecting domain to the chromophore region. Here, by removing this protein segment in a bacteriophytochrome from Deinococcus radiodurans (DrBphP), we show that the arm is crucial for signal transduction. Crystallographic, spectroscopic, and biochemical data indicate that this variant maintains the properties of DrBphP in the resting state. Spectroscopic data also reveal that the armless systems maintain the ability to respond to light. However, there is no subsequent regulation of OPM activity without the arms. Thermal denaturation reveals that the arms stabilize the DrBphP structure. Our results underline the importance of the structurally flexible interconnecting hairpin extensions and describe their central role in the allosteric coupling of phytochromes.

Keywords: proteins; receptors (biochemistry); cell signaling; photochemistry

Free keywords: phytochrome; photosensor; signal transduction; thermal stability; allostery; PACS; 87.15; 87.14 2000 MSC; 92-05; 92-11; histidine kinanase; photoreceptor; structure and function; protein structure

Fields of science: