A novel tyrosine-phosphorylated protein inhibiting the growth of Streptomyces cells

Very few of the tyrosine-phosphorylated proteins in Streptomyces have been identified. Here, we identify a tyrosine-phosphorylated protein from Streptomyces coelicolor A3(2), designated as SCO5717. The protein possesses Walker motifs and a tyrosine cluster at the C-terminus. When sco5717 harboring its own promoter was introduced into the S. coelicolor cell, the growth was inhibited. An sco5717-disrupted mutant formed aerial mycelium earlier than the wild-type strain, suggesting that SCO5717 controls the cell growth of S. coelicolor. Although the recombinant SCO5717 showed an ATPase activity, it lacked self-phosphorylation ability, suggesting that SCO5717 is a novel tyrosine-phosphorylated protein, which is distinguishable from bacterial protein tyrosine kinases known so far.     

Analysis of <Emphasis Type="Italic">Streptomyces coelicolor</Emphasis> M145 genes <Emphasis Type="Italic">SCO4164</Emphasis> and <Emphasis Type="Italic">SCO5854</Emphasis> encoding putative rhodaneses

Streptomyces coelicolor genome carries two apparently paralogous genes, SCO4164 and SCO5854, that encode putative thiosulfate sulfurtransferases (rhodaneses). These genes (and their presumed translation products) are highly conserved and widely distributed across actinobacterial genomes. The SCO4164 knockout strain was unable to grow on minimal media with either sulfate or sulfite as the sole sulfur source. The SCO5854 mutant had no growth defects in the presence of various sulfur sources; however, it produced significantly less amounts of actinorhodin. Furthermore, we discuss possible links between basic interconversions of inorganic sulfur species and secondary metabolism in S. coelicolor.     

Polyhydroxyalkanoate accumulation in Streptomyces coelicolor affected by SCO7613 gene region

Polyhydroxyalkanoate (PHA) is stored as an important carbon and energy source in bacterial cells. For biomedical applications, gram-positive bacteria can be better sources of PHAs, since they lack outer membrane lipopolysaccharide. Although gram-positive Streptomyces coelicolor A3(2) has been indicated as a high potential PHA producer, pha C gene that encodes the key enzyme PHA synthase in the metabolic pathway is not determined in its genome. BLAST search results of the GenBank database argued that SCO7613 could specify a putative polyhydroxyalkanoate synthase (PhaC) responsible for PHA biosynthesis. Deduced amino acid sequence of SCO7613 showed the presence of conserved lipase box like sequence, ⁵⁵⁵GASAG⁵⁵⁹, in which serine residue was present as the active nucleophile. Present study describes deletion of putative S. coelicolor pha C gene via PCR dependent method. We showed that SCO7613 is not an essential gene in S. coelicolor and its deletion affected PHA accumulation negatively although it is not ceased. Transcomplementation abolished the mutant phenotype, demonstrating that the decrease in PHA resulted from the deletion of SCO7613.