Study reveals autoinducer-2 functions as both quorum sensing signal and metabolic nutrient in bacteria
Researchers found that autoinducer-2 (AI-2), a bacterial signaling molecule, also functions as a metabolic nutrient that bacteria can consume for energy, blurring the line between communication and metabolism. The study shows that AI-2 production is controlled by carbon availability rather than just cell density, and that some bacteria can use AI-2 as their sole carbon source. This discovery suggests that AI-2's signaling role may have evolved from an earlier function as a nutrient, revealing an underappreciated metabolic dimension to bacterial communication.
A new study published on bioRxiv demonstrates that autoinducer-2 (AI-2), a molecule bacteria use for quorum sensing (coordinating behavior based on population density), also serves as a metabolic substrate that cells can utilize for energy. The research shows that in E. coli, the expression of genes involved in AI-2 sensing is controlled not only by AI-2 concentration but also by the availability of carbon sources, meaning bacteria prioritize other nutrients over AI-2 signaling. Using a FRET-based biosensor, the researchers demonstrated that AI-2 uptake affects intracellular signaling molecules in ways similar to nutrient transport. The team found that this dual metabolic-signaling function is conserved across Enterobacteriaceae species and isolated soil and plant-associated bacteria that can use AI-2 as their sole carbon source. These findings suggest an evolutionary model where AI-2 originally functioned as a nutrient, with its quorum sensing role emerging later or co-evolving with its metabolic function.
What's missing
The study's own limitations and open questions are not detailed in the abstract provided. The evolutionary hypothesis about AI-2's origins, while supported by the genomic and functional data presented, remains speculative and would benefit from additional paleogenomic or experimental validation.
What different sources said
- bioRxivCenter
Autoinducer-2 functions as both a quorum sensing and metabolic signal in Escherichia coli
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