Biosynthetic conclusions from the functional dissection of oxygenases for biosynthesis of actinorhodin and related Streptomyces antibiotics.

Actinorhodin (ACT) produced by Streptomyces coelicolor A3(2) belongs to the benzoisochromanequinone (BIQ) class of antibiotics. ActVA-ORF5, a flavin-dependent monooxygenase (FMO) essential for ACT biosynthesis, forms a two-component enzyme system in combination with a flavin:NADH oxidoreductase, ActVB. The genes for homologous two-component FMOs are found in the biosynthetic gene clusters for two other BIQs, granaticin (GRA) and medermycin (MED), and a closely related antibiotic, alnumycin (ALN).