Pentalenolactone Biosynthesis.Molecular Cloning and Assignment of Biochemical Function to PtII,a Cytochrome P450 of Streptomyces avermitilis

摘要

Streptomyces are a rich source of bioactive secondary metabolites.The 9.03 Mb linear chromosome of S.avermitilis,the producer of the widely used antiparasitic avermectins,harbors 7575 open reading frames (ORFs) of which 33 encode cytochrome P450 enzymes.One of these CYP genes,ptlI (SAV2999,CYP183A1),is found within the gene cluster for the biosynthesis of the sesquiterpene antibiotic pentalenolactone (1).This cluster lies in a 13.4 kb segment,centered at 3.75 Mb in the S.avermitilis genome,that contains 13 unidirectionally transcribed ORFs (Figure 1).