Branched-chain amino acid availability as a metabolic cue regulating virulence in foodborne bacterial pathogens.

Virulence of foodborne pathogens, the ability to cause disease upon ingestion of contaminated food, depends on toxin production, host colonization, and gastrointestinal stress survival. Branched-chain amino acids (BCAAs), including leucine, isoleucine, and valine, function as key metabolic signals that coordinate virulence regulation. Fluctuations in BCAA availability reshape intracellular metabolic states and regulatory networks, influencing pathogenic behavior. This review summarizes current knowledge on how foodborne pathogens sense, acquire, and utilize BCAAs, covering transport systems, biosynthetic pathways and RNA-based mechanisms (T-box riboswitches and sRNAs) that regulate BCAAs utilization, alongside CodY-dependent circuits. We emphasize how these processes collectively modulate toxin production, stress adaptation, and biofilm formation. By integrating advances in BCAA-mediated metabolic signaling, this review highlights how metabolic cues shape virulence and explores targeting BCAA pathways for foodborne pathogen control.