In microorganisms and plants the first step in the aromatic acid biosynthetic pathway is the condensation of PEP and E4P, with the release of the phosphate of PEP and the formation of DAHP. This reaction is catalyzed by DAHP synthase, which in microorganisms is also the target for negative-feedback regulation of the pathway mediated either by the pathway intermediate chorismate, or by endproducts phenylalanine, tyrosine and tryptophan. In Escherichia coli, aroG gene encodes phenylalanine-sensitiv...