Comparative Proteomic Analysis of Streptomyces lividans Wild-Type andppkMutant Strains Reveals the Importance of Storage Lipids for Antibiotic Biosynthesis

Abstract

ABSTRACTStreptomyces lividansTK24 is a strain that naturally produces antibiotics at low levels, but dramatic overproduction of antibiotics occurs upon interruption of theppkgene. However, the role of the Ppk enzyme in relation to the regulation of antibiotic biosynthesis remains poorly understood. In order to gain a better understanding of the phenotype of theppkmutant, the proteomes of the wild-type (wt) andppkmutant strains, grown for 96 h on R2YE medium limited in phosphate, were analyzed. Intracellular proteins were separated on two-dimensional (2D) gels, spots were quantified, and those showing a 3-fold variation or more were identified by mass spectrometry. The expression of 12 proteins increased and that of 29 decreased in theppkmutant strain. Our results suggested that storage lipid degradation rather than hexose catabolism was taking place in the mutant. In order to validate this hypothesis, the triacylglycerol contents of the wt andppkmutant strains ofS. lividansas well as that ofStreptomyces coelicolorM145, a strain that produces antibiotics at high levels and is closely related toS. lividans, were assessed using electron microscopy and thin-layer chromatography. These studies highlighted the large difference in triacylglycerol contents of the three strains and confirmed the hypothetical link between storage lipid metabolism and antibiotic biosynthesis inStreptomyces.