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Bacterial bilin- and flavin-binding photoreceptors
Summary
About a quarter of bacteria possess red and blue light sensing photoreceptors, including phytochromes and cryptochromes. These modular systems, switchable by light, integrate various signaling domains for diverse cellular responses.
Area of Science:
- Microbiology
- Biochemistry
- Genomics
Background:
- Prokaryotic genomes reveal widespread open reading frames (ORFs) encoding red and blue light sensing photoreceptors.
- These include bilin-binding phytochromes and flavin-binding cryptochromes, LOV, and BLUF proteins.
- Approximately 25% of bacteria possess at least one of these photosensory proteins.
Purpose of the Study:
- To investigate the distribution of red- and blue-light sensors across prokaryotic phyla and classes.
- To understand their functional activity as light-switched systems.
- To assign photochemical/physiological functions to heterologously expressed gene products.
Main Methods:
- Genome-based approaches and database searches.
- Heterologous expression of gene products.
- Characterization of photochemistry and physiological functions.
Main Results:
- Widespread distribution of red and blue light sensing photoreceptors in bacteria.
- Presence of multiple photoreceptor types and combinations within single prokaryotes.
- Photoreceptors equipped with signaling domains for cellular responses, integrating light-sensing with other stimuli detection (e.g., osmo-regulation, pH).
Conclusions:
- Bacterial photoreceptors form modular, light-switchable systems.
- These systems integrate diverse signaling domains, previously associated with other stimuli.
- Physiological functions are increasingly being assigned to these bacterial photoreceptors following photochemical characterization.
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