Biosynthesis of the terpene phenalinolactone in Streptomyces sp Tu6071:: Analysis of the gene cluster and generation of derivatives

Phenalinolactones are terpene glycosides with antibacterial activity. A striking structural feature is a highly oxidized gamma-butyrolactone of elusive biosynthetic origin. To investigate the genetic basis of the phenalinolactones biosynthesis, we cloned and sequenced the corresponding gene cluster from the producer strain Streptomyces sp. Tu6071. Spanning a 42 kbp region, 35 candidate genes could be assigned to putatively encode biosynthetic, regulatory, and resistance-conferring functions. Targeted gene inactivations were carried out to specifically manipulate the phenalinolactones pathway. The inactivation of a sugar methyltransferase gene and a cytochrome P450 monoxygenase gene led to the production of modified phenalinolactone derivatives. The inactivation of a Fe(II)/alpha-ketoglutarate-dependent dioxygenase gene disrupted the biosynthetic pathway within gamma-butyrolactone formation. The structure elucidation of the accumulating intermediate indicated that pyruvate is the biosynthetic precursor of the gamma butyrolactone moiety.