Spatially resolving the secretome within the mycelium of the cell factory Aspergillus niger

Pauline Krijgsheld, A.F. Maarten Altelaar, Harm Post, Jeffrey H. Ringrose, Wally H. Müller, Albert J.R. Heck, Han. A.B. Wösten

Author address: 

Microbiology and Kluyver Centre for Genomics of Industrial Fermentation, Utrecht Universit   Biomolecular Mass Spectrometry and Proteomics, Netherlands Proteomics Centre, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceu

Abstract: 

Fungi secrete enzymes to convert organic matter into small molecules that can serve as nutrients. Hyphae at the periphery of the colony are exposed to unexplored organic material, whereas the center of the colony experiences a utilized substrate. This suggests that the enzymes that are secreted by different zones in the colony are different. Aspergillus niger is an important cell factory for the industrial production of enzymes. Here, we determined with stable isotope dimethyl labeling the secretome of 5 concentric zones of 78208;day8208;old xylose8208;grown colonies of A. niger that had either or not been treated with cycloheximide. As expected, cycloheximide blocked secretion of proteins at the periphery of the colony. Unexpectedly, protein release was increased by cycloheximide in the intermediate and central zones of the mycelium when compared to non8208;treated colonies. Electron microscopy indicated that this is due to partial degradation of the cell wall. A total of 124 and 59 proteins were detected in the medium of xylose grown colonies that had or had not been treated with cycloheximide. Apparently, a major part of the proteins are associated with the cell walls of A. niger. Taken together, cycloheximide can be used to obtain a (near) complete secretome of A. niger. Moreover, the total amount of protein is increased upon treatment with this antibiotic. The composition of the secretome in each of the 5 concentric zones differed. This study thus describes spatial release of proteins in A. niger, which is instrumental in understanding how fungi degrade complex substrates in nature. This project was financed by the Kluyver Centre for Genomics of Industrial Fermentation and the Netherlands Proteomics Centre, which are part of the NGI
2012

abstract No: 

PR8.11

Full conference title: 

11 th European Conference on Fungal Genetics
    • ECFG 11th (2012)