Directed transfer of large DNA fragments between Streptomyces species

The biosynthesis of complex natural products in bacteria is invariably enco ded within large gene clusters. Although this facilitates the cloning of su ch gene clusters, their heterologous expression in genetically amenable hos ts remains a challenging problem, principally due to the difficulties assoc iated with manipulating large DNA fragments. Here we describe a new method for the directed transfer of a gene cluster from one Streptomyces species t o another. The method takes advantage of tra gene-mediated conjugal transfe r of chromosomal DNA between actinomycetes. As proof of principle, we demon strate transfer of the entire similar to 22-kb actinorhodin gene cluster, a nd also the high-frequency cotransfer of two loci that are 150 to 200 kb ap art, from Streptomyces coelicolor to an engineered derivative of Streptomyc es lividans.