γ-Butyrolactones: Streptomyces signalling molecules regulating antibiotic production and differentiation

Small signalling molecules called γ-butyrolactones are mainly produced by Streptomyces species in which they regulate antibiotic production and morphological differentiation. Their molecular mechanism of action has recently been unravelled in several streptomycetes, revealing a diverse and complex system. γ-Butyrolactones and their receptors also occur in some other Actinobacteria, suggesting that this is a general regulatory system for antibiotic production. The γ-butyrolactones bind to receptors, many of which are involved in regulation of specific antibiotic biosynthesis clusters. The importance of understanding how secondary metabolites are regulated and how environmental and physiological signals are sensed highlights the relevance of studying this system.