Involved in chloramphenicol biosynthesis (PubMed:11577160). 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. Disruption of the gene causes severe decrease in chloramphenicol production. Belongs to the prephenate/arogenate dehydrogenase family.