Autoinducer-2 functions as both a quorum-sensing and metabolic signal in Escherichia coli.

AI-2 functions as both a quorum-sensing and metabolic signal in Escherichia coli, with nutrient availability overriding cell density in controlling its signaling pathways.

• Why it matters: Understanding how bacteria coordinate behavior through signaling and metabolism is crucial for insights into microbial ecology and evolution, yet the connection between nutrient sensing and quorum sensing remains unclear.
• What they did: The study examined AI-2 regulation in E. coli using genomic analysis, a FRET-based biosensor, and bacterial isolates capable of utilizing AI-2 as a sole carbon source, revealing conserved metabolic regulation mechanisms.
• The result: Findings show that nutrient sources influence AI-2 signaling independently of cell density, and some bacteria can metabolize AI-2 as a nutrient, suggesting that AI-2 evolved from ancestral nutrient-sensing pathways to serve as a signaling molecule.