Level of AdpA Directly Affects Expression of Developmental Genes in Streptomyces coelicolor

AdpA is a key regulator of morphological differentiation in STREPTOMYCES: In contrast to Streptomyces griseus, relatively little is known about AdpA protein functions in Streptomyces coelicolor. Here, we report for the first time the translation accumulation profile of the S. coelicolor adpA (adpASc) gene; the level of S. coelicolor AdpA (AdpASc) increased, reaching a maximum in the early stage of aerial mycelium formation (after 36 h), and remained relatively stable for the next several hours (48 to 60 h), and then the signal intensity decreased considerably. AdpASc specifically binds the adpASc promoter region in vitro and in vivo, suggesting that its expression is autoregulated; surprisingly, in contrast to S. griseus, the protein presumably acts as a transcriptional activator. We also demonstrate a direct influence of AdpASc on the expression of several genes whose products play key roles in the differentiation of S. coelicolor: STI, a protease inhibitor; RamR, an atypical response regulator that itself activates expression of the genes for a small modified peptide that is required for aerial growth; and ClpP1, an ATP-dependent protease. The diverse influence of AdpASc protein on the expression of the analyzed genes presumably results mainly from different affinities of AdpASc protein to individual promoters.