Purification and structural determination of SCB1, a gamma-butyrolactone that elicits antibiotic production in Streptomyces coelicolor A3(2)

Early stationary phase culture supernatants of Streptomyces coelicolor A3(2 ) contained at least four small diffusible signaling molecules that could e licit precocious antibiotic synthesis in the producing strain. The compound s were not detected in exponentially growing cultures. One of these compoun ds, SCB1, was purified to homogeneity and shown to be a gamma-butyrolactone of structure (2R,3R,1'R)-2-(1'-hydroxy-6-methylheptyl)-3- hydroxymethylbut anolide. Bioassays of chemically synthesized SCB1, and of its purified ster eoisomers, suggest that SCB1 acts in a highly specific manner to elicit the production of both actinorhodin and undecylprodigiosin, the two pigmented antibiotics made by S, coelicolor.