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Published on: October 24, 2014
Bacterial phytochromes: more than meets the light.
Michele E Auldridge1, Katrina T Forest
1Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA.
Critical Reviews in Biochemistry and Molecular Biology
|January 22, 2011
Summary
Phytochromes, initially known as plant red/far-red light sensors, are now recognized as versatile microbial sensors across the light spectrum and even as redox sensors. Their modular structures enable diverse signaling pathways.
Area of Science:
- Structural biology
- Microbial sensory systems
- Photochemistry
Background:
- Phytochromes are photoreceptors historically studied in plants, sensing red/far-red light via a tetrapyrrole chromophore.
- Their conserved PAS-GAF-PHY architecture facilitates light-dependent conformational changes and signal transduction.
- Key structural features include a figure-of-eight knot and an α-helix crucial for intramolecular signaling.
Purpose of the Study:
- To review the structures of bacterial phytochromes and their implications for signal transmission.
- To discuss the expanding known sensory capabilities and physiological functions of bacterial phytochromes.
- To highlight the modularity and evolutionary diversity of phytochrome sensory receptors.
Main Methods:
- Analysis of existing three-dimensional structural data of bacterial phytochromes.
- Review of literature on identified microbial phytochromes and their functions.
- Comparative analysis of phytochrome architectures and signaling mechanisms.
Main Results:
- Bacterial phytochromes exhibit diverse structures beyond the canonical PAS-GAF-PHY, sensing a broader spectrum of light (yellow, green, blue, violet).
- Phytochromes function not only as photoreceptors but also as redox sensors, demonstrating expanded sensory roles.
- Structural insights reveal mechanisms of signal transmission from chromophore to output domains in bacterial systems.
Conclusions:
- Bacterial phytochromes represent a highly adaptable class of sensory receptors with diverse architectures and functions.
- Structural studies are crucial for understanding the mechanisms underlying phytochrome-mediated signaling in microbes.
- The growing body of research on bacterial phytochromes reveals their significant roles in microbial environmental responses.
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