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

• Final Report Year: 2017

Final Report Abstract

Fusarium fujikuroi is a filamentous ascomycete producing a large spectrum of secondary metabolites. Among others it produces the economically interesting carotenoids, required as natural food colorants, food supplements, or as supplements in cosmetic products. Since all structural genes for the carotenoid biosynthesis are known, this offers the excellent opportunity to study the connected regulatory processes directly, allowing the exploration of yield improvement strategies and their transfer to different fungal systems. During his fellowship, the awardee was successful in establishing a new method for the identification of transcriptional regulators, based on Biotin-coupled promoters and subsequent mass spectromic analyses. Based on simple application, this method can be used as a simple and fast alternative for chromatin immunoprecipitation sequencing (ChIP seq). With the help of this method, the awardee was able to identify potential transcriptional activators of the carotenoid synthesis, which are most likely members of the HMG group of transcription factors. Likewise, he discovered a different subset of regulatory proteins influencing the transcription of the opsin gene carO and the structural carotenoid genes carB, carRA, and carX, supporting the high resolution of this method. Besides the technical advances, the awardee provided evidence that the carotenoid regulator CarS is itself subject to many regulatory processes besides the already described proteinprotein interactions, among them alternative splicing, a very rare phenomenon in ascomycetes. Taken together, the awardee was able to identify a whole subset of transcription factors, working together with at least four different isoforms of the central regulator CarS to control the level of carotenoids produced by F. fujikuroi. Determining the single effects of each of these components will be the central points of future studies.

Publications

• (2016) Molecular identification of transcriptional regulators of carotenoid biosynthesis in the fungus Fusarium fujikuroi. 13th European Conference on Fungal Biology (Paris, France)
  Nordzieke S, Ruger-Herreros M , Limón MC, Avalos J
  
• (2017) Carotenoid Production by Filamentous Fungi and Yeasts. In A.A. Sibirny (ed.) (2017) Biotechnology of Yeasts and Filamentous Fungi. Springer
  Avalos J, Nordzieke S, Parra O, Pardo-Medina J, Limón MC
  
• (2017) New insights into the transcriptional regulation of carotenoid genes in Fusarium fujikuroi. 29th Fungal Genetics Conference (Asilomar, USA)
  Nordzieke S, Ruger-Herreros M, Limón MC, Avalos J