Metabolism of phosphate-limited cultures of Streptomyces. IV. Protein-phosphorylation of antibiotics-producing cultures.

It has been demonstrated that in the cellular proteins of Streptomyces hygroscopicus JA 6599 and Streptomyces noursei JA 3890 b, the producers of the antibiotics turimycin and nourseothricin, respectively, phosphorylated proteins are present. Numbers and concentrations of phosphorylated proteins decreased during the idiophase as characterized by phosphate limitation, antibiotic biosynthesis and phosphatase formation. Phosphoamino acids of serine, threonine and tyrosine were found in the hydrolysates of proteins. Protein tyrosyl kinase was demonstrated in the cellular extracts. The results supports the hypothesis that protein phosphorylation possesses a function in the regulation of growth and secondary product formation.