SCARA3 and infection: Moreover, several iron uptake systems and proteins controlling iron homeostasis have been identified in transcriptome analysis as part of the CsrA regulon in other pathogens26,52,53 Our study now provides metabolomic evidence that the Csr system exerts a link between carbon metabolism and iron uptake to optimize fitness and virulence during infection by its influence on the aromatic amino acid biosynthesis pathway, which includes the biosynthesis of one of the most potent bacterial iron chelators.