Genomewide insertional mutagenesis in Streptomyces coelicolor reveals additional genes involved in morphological differentiation

The filamentous soil bacterium Streptomyces coelicolor undergoes a complex cycle of morphological differentiation involving the formation of an aerial mycelium and the production of pigmented antibiotics. We have developed a procedure for generating insertional mutants of S. coelicolor based on in v itro transposition of a plasmid library of cloned 5. coelicolor DNAs. The i nsertionally mutated library was introduced into S. coelicolor, and transpo son insertions were recovered at widely scattered locations around the chro mosome. Many of the insertions revealed previously uncharacterized genes, a nd several caused novel mutant phenotypes, such as altered pigment producti on, enhanced antibiotic sensitivity, delayed or impaired formation of aeria l hyphae, and a block in spore formation. The sporulation mutant harbored a n insertion in one of three adjacent genes that are apparently unique to St reptomyces but are each represented by at least 20 paralogs at dispersed lo cations in the chromosome. individual members of the three families often a re found grouped together in a characteristic arrangement suggesting that t hey have a common function.