Nitric oxide signaling for actinorhodin production in Streptomyces coelicolor A3(2) via the DevS/R two-component system.

Nitric oxide (NO) is an important signaling molecule in eukaryotic and prokaryotic cells. A previous study revealed an NOS-independent NO production metabolic cycle in which the three nitrogen oxides, nitrate (NO3 -), nitrite (NO2 -) and NO were generated in the actinobacterium Streptomyces coelicolor A3(2). NO was suggested to act as a signaling molecule, functioning as a hormone that regulates secondary metabolism. Here, we demonstrate the NO-mediated regulation of the production of the blue pigmented antibiotic, actinorhodin (ACT), via the heme-based DevS/R two-component system (TCS). Intracellular NO controls the stabilization or inactivation of DevS, depending on the NO concentration. An electrophoretic mobility shift assay and chromatin immunoprecipitation-quantitative polymerase chain reaction analysis revealed the direct binding between DevR and the promoter region of actII-ORF4, resulting in gene expression. Our results indicate that NO simultaneously regulates the DevS/R TCS, thereby strictly controlling the secondary metabolism of S. coelicolor A3(2).ImportanceDiverse organisms, such as mammals, plants, and bacteria, utilize NO via well known signal transduction mechanisms. Many useful secondary metabolites producer Streptomyces genus bacteria had been also suggested the metabolisms regulated by endogenously produced NO; however, the regulatory mechanisms remain to be elucidated. In this study, we demonstrated the molecular mechanism by which endogenously produced NO regulates antibiotic production via DevS/R TCS in S. coelicolor A3 (2). NO serves as both a stabilizer and a repressor in the regulation of antibiotic production. This report shows the mechanism by which Streptomyces utilizes endogenously produced NO to modulate their normal life cycle. Moreover, this study implies that studying NO signaling in actinobacteria can help in the development of both clinical strategies against pathogenic actinomycetes and the actinobacterial industries.