Involved in the biosynthesis of the antibiotics tetracycline and oxytetracycline. Catalyzes the C(5) reduction of 5a,11a-dehydrooxytetracycline to yield oxytetracycline as a major product. Also catalyzes the C(12) reduction of 5a,11a-dehydrotetracycline (12-dehydrotetracycline) to produce tetracycline as a minor product. H(+) + oxidized coenzyme F420-(gamma-L-Glu)(n) + tetracycline = 5a,11a-dehydrotetracycline + reduced coenzyme F420-(gamma-L-Glu)(n) H(+) + oxidized coenzyme F420-(gamma-L-Glu)(n) + oxytetracycline = 5a,11a-dehydrooxytetracycline + reduced coenzyme F420-(gamma-L-Glu)(n) Antibiotic biosynthesis; oxytetracycline biosynthesis. Cells lacking this gene are unable to produce oxytetracycline. Belongs to the pyridoxamine 5'-phosphate oxidase family.