The acetyltransferase SCO0988 controls positively specialized metabolism and morphological differentiation in the model strains and .

Streptomycetes are well-known antibiotic producers possessing in their genomes numerous silent biosynthetic pathways that might direct the biosynthesis of novel bio-active specialized metabolites. It is thus of great interest to find ways to enhance the expression of these pathways to discover most needed novel antibiotics. In this study, we demonstrated that the over-expression of acetyltransferase SCO0988 up-regulated the production of specialized metabolites and accelerated sporulation of the weak antibiotic producer, and that the deletion of this gene had opposite effects in the strong antibiotic producer, . The comparative analysis of the acetylome of a strain over-expressing with that of the original strain revealed that SCO0988 acetylates a broad range of proteins of various pathways including BldKB/SCO5113, the extracellular solute-binding protein of an ABC-transporter involved in the up-take of a signal oligopeptide of the quorum sensing pathway. The up-take of this oligopeptide triggers the "bald cascade" that regulates positively specialized metabolism, aerial mycelium formation and sporulation in . Interestingly, BldKB/SCO5113 was over-acetylated on four Lysine residues, including Lys, upon SCO0988 over-expression. The bald phenotype of a mutant could be complemented by native but not by variant of in which the Lys was replaced by arginine, an amino acid that could not be acetylated or by glutamine, an amino acid that is expected to mimic acetylated lysine. Our study demonstrated that Lys was a critical residue for BldKB function but was inconclusive concerning the impact of acetylation of Lys on BldKB function.