A Novel AdpA Homologue Negatively Regulates Morphological Differentiation in Streptomyces xiamenensis 318

AdpA is a key regulator of secondary metabolism and morphological differentiation inStreptomyces species. However, AdpA had not been reported to negatively regulate morphological differentiation. Here, we characterized the regulatory role of AdpASx inStreptomyces xiamenensis 318, which has a naturally streamlined genome. In this strain, AdpASx negatively regulated cell growth and morphological differentiation by directly controlling genes associated with these functions. AdpASx also bidirectionally controlled the biosynthesis of xiamenmycin and PTMs by directly regulating their gene clusters rather than through other regulators. Our findings provide additional evidence for the versatility of AdpA in regulating morphological differentiation and secondary metabolism inStreptomyces .