  Feast or famine: the global regulator DasR links nutrient stress to antibiotic production by StreptomycesRigali, Sébastien  ; ; et alin EMBO Reports (2008), 9(7), 670-675 Members of the soil-dwelling prokaryotic genus Streptomyces produce a wealth of secondary metabolites, including antibiotics and anti-tumour agents. Their formation is intimately coupled with the onset of ... [more ▼] Members of the soil-dwelling prokaryotic genus Streptomyces produce a wealth of secondary metabolites, including antibiotics and anti-tumour agents. Their formation is intimately coupled with the onset of development, triggered by the nutrient status of the habitat. We propose the first complete signalling cascade from nutrient sensing to development and antibiotic biosynthesis. We show that a high concentration of N-acetylglucosamine - perhaps mimicking the accumulation of N-acetylglucosamine after autolytic degradation of the vegetative mycelium - is a major checkpoint for the onset of secondary metabolism. The response is transmitted to the antibiotic pathway-specific activators via the pleiotropic transcriptional repressor DasR, whose regulon also includes all N-acetylglucosamine-related catabolic genes. The results have led to a new strategy for activating “cryptic” pathways for secondary metabolite biosynthesis, which are abundant in actinomycete genomes, thereby offering new prospects in the fight against multiply drug resistant pathogens and cancers. [less ▲] Detailed reference viewed: 55 (2 ULg)Psychrophilic microorganisms: challenges for lifeD'Amico, Salvino ; ; et alin EMBO Reports (2006), 7(4), 385-389 The ability of psychrophiles to survive and proliferate at low temperatures implies that they have overcome key barriers inherent to permanently cold environments. These challenges include: reduced enzyme ... [more ▼] The ability of psychrophiles to survive and proliferate at low temperatures implies that they have overcome key barriers inherent to permanently cold environments. These challenges include: reduced enzyme activity; decreased membrane fluidity; altered transport of nutrients and waste products; decreased rates of transcription, translation and cell division; protein cold- denaturation; inappropriate protein folding; and intracellular ice formation. Cold- adapted organisms have successfully evolved features, genotypic and/ or phenotypic, to surmount the negative effects of low temperatures and to enable growth in these extreme environments. In this review, we discuss the current knowledge of these adaptations as gained from extensive biochemical and biophysical studies and also from genomics and proteomics. [less ▲] Detailed reference viewed: 8 (1 ULg) |
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