The Streptomyces bacteria have an unusual filamentous morphology that sets them apart from other prokaryotes. Their life cycle starts with spore germination and the generation of filamentous “substrate hyphae” that grow to form a vegetative colony. Later, developmental cues trigger the formation of another cell type called the “aerial hyphae”  which grow up from the colony surface and eventually generate a new generation of spores. An unusual feature of two cell types is that  they use fundamental cell biological processes in unusual ways. For example, the cell wall synthesis, cell division and chromosome segregation apparatus are deployed differently in both cell types than in the more familiar rod shaped or coccoid bacteria. Another feature that sets these bacteria apart is their extensive “secondary” or “specialized” metabolism which generates a very large set of biologically active small molecules. These molecules have served as a reservoir of lead compounds for drug discovery.

We have investigated the interactions of streptomycetes bacteria with biologically active small molecules. In this lecture I will discuss how we have used these chemical probes to perturb the regulation of secondary metabolism and the sporulation pathway. In addition to generating novel antibiotic leads this work is providing new insights into the molecular mechanisms that control the life cycle of this remarkable genus.