May be involved in the synthesis of secondary metabolites derived from intermediates of the pre-chorismate pathway up to shikimate. D-erythrose 4-phosphate + H2O + phosphoenolpyruvate = 7-phospho-2-dehydro-3-deoxy-D-arabino-heptonate + phosphate Metabolic intermediate biosynthesis; chorismate biosynthesis; chorismate from D-erythrose 4-phosphate and phosphoenolpyruvate: step 1/7. Higher levels seen in the cotyledons than in the leaves and flowers. Lower levels seen in the roots and stems. Belongs to the class-II DAHP synthase family.