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The differences in phenotype and antibiotic production between a deletion mutant and a wild-type strain (WT) were compared to demonstrate the function of an unknown regulator in Streptomyces. The method which allowed to newly characterize a member of the MarR-like regulator family, SCO5405 (AbsC) to control pyruvate dehydrogenase in Streptomyces coelicolor could also be used as high-throughput approach for the characterization of unknown regulators.

A rapid and effective screening tool based on a cell-free Escherichia coli-based expression system was developed to identify quorum sensing (QS) molecules of Streptomyces involved in diverse cellular functions, such as virulence, biofilm formation, secondary metabolism, and cell differentiation. The assay system could be applied to successfully confirm SCB1, a [gamma]-butyrolactone molecule in Streptomyces coelicolor, binding to its known receptor, ScbR and could also be used to study other strains for which screening tools for QS molecules is not developed.

A successful model system for the identification of SCB1 from Streptomyces coelicolor is reported. Using S. coelicolor as a model system, SCB1 was detected from only 100 ml of the culture broth after solvent extraction.

Members of the ROK family of proteins are mostly transcriptional regulators and kinases that generally relate to the control of primary metabolism, whereby its member glucose kinase acts as the central control protein in carbon control in Streptomyces. Here, we show that deletion of SCO6008 (rok7B7) strongly affects carbon catabolite repression (CCR), growth, and antibiotic production in Streptomyces coelicolor. Deletion of SCO7543 also affected antibiotic production, while no major changes were observed after deletion of the rok family genes SCO0794, SCO1060, SCO2846, SCO6566, or SCO6600. Global expression profiling of the rok7B7 mutant by proteomics and microarray analysis revealed strong upregulation of the xylose transporter operon xylFGH, which lies immediately downstream of rok7B7, consistent with the improved growth and delayed development of the mutant on xylose. The enhanced CCR, which was especially obvious on rich or xylose-containing media, correlated with elevated expression of glucose kinase and of the glucose transporter GlcP. In liquid-grown cultures, expression of the biosynthetic enzymes for production of prodigionines, siderophores, and calcium-dependent antibiotic (CDA) was enhanced in the mutant, and overproduction of prodigionines was corroborated by matrix-assisted laser desorption ionization-time-of-flight analysis. These data present Rok7B7 as a pleiotropic regulator of growth, CCR, and antibiotic production in Streptomyces. [ABSTRACT FROM AUTHOR]