Involved in pristinamycin I biosynthesis (PubMed:9044253). Probably catalyzes the formation of 3-(4-aminophenyl)pyruvate from 4-amino-4-deoxyprephenate (Probable). 4-amino-4-deoxyprephenate + NAD(+) = 3-(4-aminophenyl)pyruvate + CO2 + H(+) + NADH Antibiotic biosynthesis. Belongs to the prephenate/arogenate dehydrogenase family.