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

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