Phosphoproteomic and proteomic profiling of serine/threonine protein kinase PkaE of Streptomyces coelicolor A3(2) and its role in secondary metabolism and morphogenesis.

Abstract

This study aimed to investigate the role of serine/threonine kinase PkaE in Streptomyces coelicolor A3(2). Liquid chromatography tandem mass spectrometry was performed for comparative phosphoproteome and proteome analyses of S. coelicolor A3(2), followed by an in vitro phosphorylation assay. Actinorhodin production in the pkaE deletion mutant was lower than that in wild-type S. coelicolor A3(2), and the spores of the pkaE deletion mutant were damaged. Furthermore, phosphoproteome analysis revealed that 6 proteins were significantly differentially hypophosphorylated in pkaE deletion mutant (p <0.05, fold-change ≤ 0.66), including BldG and FtsZ. In addition, the in vitro phosphorylation assay revealed that PkaE phosphorylated FtsZ. Comparative proteome analysis revealed 362 differentially expressed proteins (p <0.05) and six downregulated proteins in the pkaE deletion mutant involved in actinorhodin biosynthesis. Gene ontology enrichment analysis revealed that PkaE participates in various biological and cellular processes. Hence, S. coelicolor PkaE participates in actinorhodin biosynthesis and morphogenesis.