Molecular identification of the transcriptional activator of carotenoid biosynthesis in the fungus Fusarium fujikuroi

• Applicant: Dr. Steffen Nordzieke
• Subject Area: Organismic Interactions, Chemical Ecology and Microbiomes of Plant Systems ; Metabolism, Biochemistry and Genetics of Microorganisms ; Cell Biology
• Term: from 2015 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 281458954

Carotenoids include over 600 different chemical compounds, bearing a large variety of different characteristics. Many of them are key elements of secondary metabolism of bacteria, plants, and fungi. Due to their individual abilities, they provide a large subset of molecular tasks in protecting individuals against light induced or oxidative damage, which reflects their importance for all classes of eukaryotic life. Animals and humans are unable to produce carotenoids. Nevertheless, they are prerequisites for the formation of Vitamin A, and for the protection of the macula lutea. According to this, humans have to incorporate a sufficient amount of carotenoids through their diets. An undersupply, which is common in developing countries, leads to severe defects in vision, skin composition, and the immune systemFungal systems provide an excellent source for the industrial production of natural carotenoids, thereby avoiding biological inactive isomers which are typical byproducts of chemical synthesis. Additionally, fungi need few requirements, are easy to cultivate and, due to their fermentability, can produce enormous amounts of secondary metabolites. To optimize the industrial production, detailed knowledge about the composition and regulation of fungal carotenoid biosynthesis is important.The plant pathogen Fusarium fujikuroi serves as a fungal model system to study carotenoid biosynthesis since the 1980´s. Due to the already performed research of the host group, the structural genes for all proteins involved in the synthesis of carotenoids are known, whereas the regulation of these genes remains unclear. The aim of this project is to characterize novel regulatory proteins of the carotenoid pathway, such as the predicted CarC, a yet undescribed positive regulator of carotenoid biosynthesis expected to interact with the already described negative regulator CarS. For this, Co Immunoprecipitation experiments, pull-down assays, and a heterologous expression in S. cerevisiae will be utilized, aiming at specific characteristics attributed to CarC. These experiments will lead to a credible list of potential candidates. Genetic deletions of the corresponding genes, followed by in depth analyses of the resulting phenotypes, will serve as control experiments and, simultaneously, provide detailed insights also into potential secondary roles of CarC.Already having a strong background in the field of protein-protein interaction and fungal protein complexes, the applicant is highly qualified to perform the targeted experiments. As the host group is one of the leading facilities in the research on F. fujikuroi and has already characterized the structural genes needed for the carotenoid biosynthesis, the collaboration will close the last scientific gap left in the investigation of the regulation. The obtained results may contribute to optimize the industrial production of carotenoids in fungi, further preventing a Vitamin A undersupply of the population.

• DFG Programme: Research Fellowships
• International Connection: Spain
• Host: Professor Javier Avalos, Ph.D.