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

Abstract

dStreptomyces lividans TK24 is a strain that naturally produces antibiotics at low levels, but dramatic overproduction of antibiotics occurs upon interruption of the ppk gene. 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 the ppk mutant, the proteomes of the wild-type (wt) and ppk mutant 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 the ppk mutant 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 and ppk mutant strains of S. lividans as well as that of Streptomyces coelicolor M145, a strain that produces antibiotics at high levels and is closely related to S. 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 in Streptomyces.

Structural and biochemical analysis of a phosin fromStreptomyces chartreusisreveals a combined polyphosphate‐ and metal‐binding fold

“…In the model strain Streptomyces lividans , one of the genes strongly upregulated in conditions of P i limitation and found to exert a major negative influence on antibiotic production is ppk . This gene encodes a polyphosphate (polyP) kinase (Ppk), which uses ATP to synthesise polyP .…”

Aromatic Polyketide GTRI‐02 is a Previously Unidentified Product of theactGene Cluster inStreptomyces coelicolor A3(2)

“…Two aldol reactions at C‐2/C‐11 and C‐3/C‐8 then close the bicyclic system to form a 3,4‐dihydronaphthalen‐1(2 H )‐one backbone, whereby the aromatase/cyclase ActVlI might be involved in dehydration. The acetyl substituent in 1 could be generated either by β‐oxidation of the C 2 acetate in tandem with spontaneous release of CO 2 , or by direct cleavage at C‐13/C‐14 to release the C 3 malonate. An alternative possible biosynthetic pathway of 1 is to follow the initial reaction steps of mutactin biosynthesis.…”

Regulation of specialised metabolites in Actinobacteria – expanding the paradigms

“…For example, acetyl‐CoA is a precursor for polyketide biosynthesis, which can be generated via degradation of triacylglycerols. Thus, actinomycete species, which degrade storage lipids at a higher rate, will provide higher levels of acetyl‐CoA and ultimately produce higher levels of specialised polyketide metabolites (Le Maréchal et al ., ) and hence why oil‐based fermentation media are used extensively for industrial polyketide biosynthesis (Hiltner et al ., ). When more than one polyketide is encoded in the genome of the same strain, it is likely that one of these metabolites will be produced preferentially.…”