Cloning and characterization of a regulatory gene of the SARP family and its flanking region from Streptomyces ambofaciens

In a search for activators of secondary metabolism we isolated a 12.6-kb DN A fragment from a genomic library of Streptomyces ambofaciens NRRL 2240 (th e spiramycin producer). Sequencing of 6 kb of the cloned fragment revealed a cluster of four ORFs (ORF1-4) whose deduced products showed similarities to those of other genes involved in polyketide biosynthesis, including a pa thway-specific regulatory gene of the SARP family. The results of insertion al inactivation of some of the cloned genes clearly indicate that the isola ted cluster does not code for spiramycin production, suggesting that some o ther polyketide compound might well be produced by this strain.