Nitrogen-dependent regulation of secondary metabolism in Ustilago maydis

点击翻译按钮获取中文摘要

Many microorganisms respond to conditions of nutrient limitation with the secretion of amphipathic secondary metabolites. These substances act as biosurfactants and enhance attachment of microorganisms to hydrophobic surfaces, increase the bioavailability of water-insoluble nutrients and often display antibiotic activity. Here we use the dimorphic phytopathogenic fungus Ustilago maydis to study the nitrogendependent regulation of two glycolipid biosynthetic gene clusters. The large ustilagic acid (UA) gene cluster contains a regulatory gene encoding a potential zinc finger domain protein, which is critical for the production of this secondary metabolite. Expression of this putative transcription factor is both necessary and sufficient for the induction of all UA biosynthetic cluster genes. The mannosylerythritol lipid (MEL) biosynthetic gene cluster is also induced by nitrogen limitation, but does not contain a specific transcription factor. Interestingly, expression of this gene cluster is also affected by transcriptional regulators that control mating and pathogenicity in U. maydis. We will combine molecular and genomic approaches to characterize promoters and transcription factors involved in the nitrogen-dependent regulation of these biosurfactant biosynthetic gene clusters. The longterm goal of this project is the elucidation of the molecular mechanisms operating in the environmental control of secondary metabolism in U. maydis.