Phenylalanine- and tyrosine-dependent production of enterobactin in Escherichia coli.

Under low-iron conditions, Escherichia coli synthesizes the siderophore enterobactin. When compared to wild-type cells grown in iron sufficient medium, cells grown under iron limitation, in the absence of tyrosine and phenylalanine or the presence of both, increased catechol production (a measure of enterobactin and its degradation product 2,3-dihydroxybenzoic acid) 5- to 9-fold while cells supplemented with tyrosine alone produced a 10- to 20-fold increase. Mutations in fur, tyrA, pheA, or pheU generally resulted in increased enterobactin production, while a tyrR mutant was unaffected by combinations of tyrosine and phenylalanine.