Identification of glucose kinase‐dependent and ‐independent pathways for carbon control of primary metabolism, development and antibiotic production inStreptomyces coelicolorby quantitative proteomics

Abstract

SummaryMembers of the soil-dwelling prokaryotic genus Streptomyces are indispensable for the recycling of complex polysaccharides, and produce a wide range of natural products. Nutrient availability is a major determinant for the switch to development and antibiotic production in streptomycetes. Carbon catabolite repression (CCR), a main signalling pathway underlying this phenomenon, was so far considered fully dependent on the glycolytic enzyme glucose kinase (Glk). Here we provide evidence of a novel Glkindependent pathway in Streptomyces coelicolor, using advanced proteomics that allowed the comparison of the expression of some 2000 proteins, including virtually all enzymes for central metabolism. While CCR and inducer exclusion of enzymes for primary and secondary metabolism and precursor supply for natural products is mostly mediated via Glk, enzymes for the urea cycle, as well as for biosynthesis of the g-butyrolactone Scb1 and the responsive cryptic polyketide Cpk are subject to Glk-independent CCR. Deletion of glkA led to strong downregulation of biosynthetic proteins for prodigionins and calciumdependent antibiotic (CDA) in mannitol-grown cultures. Repression of bldB, bldN, and its target bldM may explain the poor development of S. coelicolor on solid-grown cultures containing glucose. A new model for carbon catabolite repression in streptomycetes is presented.

Molecular Regulation of Antibiotic Biosynthesis in Streptomyces

“…Significant effects of glucose on carbon source uptake, central carbon and nitrogen metabolic enzymes (and the nitrogen regulator GlnR), some developmental proteins, and proteins closely or directly involved in RED, CDA, and CPK antibiotic production were found, but there was no effect on DasR. Notably, GlkA was involved in the effects on RED and CDA production but did not affect glucose regulation of SCB1 and CPK biosynthetic enzymes, revealing an uncharacterized second mechanism (92). The central enzyme pyruvate phosphate dikinase, which was particularly highly repressed by glucose in a GlkA-independent manner, was suggested as a possible key player in this second mechanism (92).…”

“…Notably, GlkA was involved in the effects on RED and CDA production but did not affect glucose regulation of SCB1 and CPK biosynthetic enzymes, revealing an uncharacterized second mechanism (92). The central enzyme pyruvate phosphate dikinase, which was particularly highly repressed by glucose in a GlkA-independent manner, was suggested as a possible key player in this second mechanism (92). These complex data sets will be difficult to interpret until samples are also examined during the antibiotic production phase, and progress has been made on the molecular basis of glucose kinase effects.…”

“…A thorough review of this topic is included in reference 20. A recent proteomic study examined the effects of added glucose on exponentially growing cultures of S. coelicolor and its glucose kinase (glkA) mutant in minimal medium supplied with mannitol or fructose (92). Significant effects of glucose on carbon source uptake, central carbon and nitrogen metabolic enzymes (and the nitrogen regulator GlnR), some developmental proteins, and proteins closely or directly involved in RED, CDA, and CPK antibiotic production were found, but there was no effect on DasR.…”

Characterization of Polyphosphate Glucokinase SCO5059 fromStreptomyces coelicolorA3(2)

“…The K m values of SCO5059 for glucose and polyphosphate (poly(P) 6 ) were estimated to be 12 and 4 M, respectively, and the k cat value was 0.3 s À1 at pH 7.7 at 28 C. SCO5059 homologs are highly conserved among Streptomyces, and can work as polyphosphate glucokinase as well.…”

“…They are industrially important as producers of antibiotics, antitumor agents, immune-suppressants, and insecticides. For these reasons, the regulation of glk gene expression, [2][3][4][5][6][7][8][9] and the biochemistry studies of Streptomycete Glks, have been extensively investigated.…”