The Pleiotropic Regulator AdpA Regulates the Removal of Excessive Sulfane Sulfur in Streptomyces coelicolor

Reactive sulfane sulfur (RSS), including persulfide, polysulfide, and elemental sulfur (S-8), has important physiological functions, such as resisting antibiotics in Pseudomonas aeruginosa and Escherichia coli and regulating secondary metabolites production in Streptomyces spp. However, at excessive levels it is toxic. Streptomyces cells may use known enzymes to remove extra sulfane sulfur, and an unknown regulator is involved in the regulation of these enzymes. AdpA is a multi-functional transcriptional regulator universally present in Streptomyces spp. Herein, we report that AdpA was essential for Streptomyces coelicolor survival when facing external RSS stress. AdpA deletion also resulted in intracellular RSS accumulation. Thioredoxins and thioredoxin reductases were responsible for anti-RSS stress via reducing RSS to gaseous hydrogen sulfide (H2S). AdpA directly activated the expression of these enzymes at the presence of excess RSS. Since AdpA and thioredoxin systems are widely present in Streptomyces, this finding unveiled a new mechanism of anti-RSS stress by these bacteria.

Automated summary

Reactive sulfane sulfur (RSS) has important physiological functions in bacteria, but is toxic at excessive levels. AdpA, a multi-functional transcriptional regulator, is essential for the survival of Streptomyces when facing external RSS stress. This study found that AdpA activates the expression of thioredoxins and thioredoxin reductases, which reduce RSS to gaseous hydrogen sulfide (H2S) in the presence of excess RSS. This discovery unveils a new mechanism of anti-RSS stress in Streptomyces through AdpA and the thioredoxin system.