Streptomyces A-Factor

A-Factor is a γ-butyrolactone autoregulator that acts as a microbial hormone in Streptomyces griseus. It induces morphological differentiation and secondary metabolite production, such as streptomycin, by binding to and inactivating the repressor protein ArpA, thereby derepressing target genes. This small molecule is a key tool for studying bacterial quorum sensing, antibiotic biosynthesis, and cellular differentiation in both in vivo and in vitro experimental systems.