Members of the 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthetase family (EC: 2.5.1.54) catalyse the first step in aromatic amino acid biosynthesis from chorismate. Class I (see INTERPRO: IPR006218) includes bacterial and yeast enzymes; class II includes higher plants and various microorganisms [PMID:8760910].

The first step in the common pathway leading to the biosynthesis of aromatic compounds is the stereospecific condensation of phosphoenolpyruvate (PEP) and D-erythrose-4-phosphate (E4P) giving rise to 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP). This reaction is catalyzed by DAHP synthase, a metal-activated enzyme, which in microorganisms is the target for negative-feedback regulation by pathway intermediates or by end products.