Universiteit Leiden

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Research project

Functions of autophagy in the filamentous fungus Aspergillus niger

What are the functions of autophagy in the filamentous fungus Aspergillus niger?

2011 - 2015
Arthur Ram
NCSB-KC AddOn project funded via the Kluyver Centre for Genomics of Industrial Fermentation (KC) NCSB-KC AddOn project funded via the Kluyver Centre for Genomics of Industrial Fermentation (KC)

Studying autophagy could provide valuable tools to improve production yields in the industrial cell factory Aspergillus niger.

The filamentous fungus Aspergillus niger is an industrially important fungus commonly exploited for the production of enzymes and organic acids. In this project we study how autophagy is involved in several cellular processes.

Autophagy is a bulk degradation system, functioning in the delivery of all kinds of cytoplasmic materials to the vacuole for degradation. The process is induced upon starvation, during which it plays an important role in the recycling of nutrients to be reused by the cell.

We used RNA sequencing analysis to study the induction of autophagy-related genes both during carbon and nitrogen starvation. Our results suggest that autophagy promotes survival by recycling of nutrients and metabolic adaptation to starvation stress.

Currently we study the role of autophagy in protein secretion and the degradation of incorrectly folded proteins. For the latter we developed a fusion of the fluorescent GFP with a misfolded protein and expressed it in autophagy mutants. Using confocal microscopy we address the question whether autophagy is involved in the degradation of misfolded proteins.

The presence of efficient degradation systems in Aspergillus niger significantly reduces production yields of heterologous proteins in this fungus. This study will provide a better understanding of the autophagy process in Aspergillus niger, which is valuable for the improvement of this fungus as a production host for homologous and heterologous proteins.

  • Nitsche BM, Burggraaf-van Welzen AM, Lamers G, Meyer V, Ram AF (2013) Autophagy promotes survival in aging submerged cultures of the filamentous fungus Aspergillus niger. Appl Microbiol Biotechnol 97: 8205–8218.
  • van Munster JM*, Burggraaf AM*, Pocsi I, Szilágyi M, Emr Ti and  Ram AF. Post-genomic approaches to dissect carbon starvation responses in Aspergilli. In: Penicillium and Aspergillus in the post-genome era I. Benoit, M. Andersen and R.P. de Vries (Eds). *equal contributions
  • Burggraaf AM, Ram AF. Autophagy is dispensable to overcome ER stress in the filamentous fungus Aspergillus niger. Microbiology open. 2016 Aug;5(4):647-58.
  • Burggraaf AM, Punt PJ, Ram AF. The unconventional secretion of PepN is independent of a functional autophagy machinery in the filamentous fungus Aspergillus niger. FEMS Microbiol Lett. 2016 Aug;363(15)
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