Systems analysis unfolds the relationship between the phosphoketolase pathway and growth in Aspergillus nidulans.
BACKGROUND
Aspergillus nidulans is an important model organism for studies on fundamental eukaryotic cell biology and on industrial processes due to its close relation to A. niger and A. oryzae. Here we identified the gene coding for a novel metabolic pathway in A. nidulans, namely the phosphoketolase pathway, and investigated the role of an increased phosphoketolase activity.


RESULTS
Over-expression of the phosphoketolase gene (phk) improved the specific growth rate on xylose, glycerol and ethanol. Transcriptome analysis showed that a total of 1,222 genes were significantly affected by over-expression of the phk, while more than half of the affected genes were carbon source specific. During growth on glucose medium, the transcriptome analysis showed that the response to phk over-expression is targeted to neutralize the effect of the over-expression by regulating the acetate metabolism and initiate a growth dampening response.


CONCLUSIONS
Metabolic flux analysis using (13)C-labelled glucose, showed that over-expression of phosphoketolase added flexibility to the central metabolism. Our findings further suggests that A. nidulans is not optimized for growth on xylose, glycerol or ethanol as the sole carbon sources.
Panagiotou
Gianni
G
Center for Microbial Biotechnology, Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark.
Andersen
Mikael R
MR
Grotkjaer
Thomas
T
Regueira
Torsten B
TB
Hofmann
Gerald
G
Nielsen
Jens
J
Olsson
Lisbeth
L
D000446:Aldehyde-Lyases / Q000235:genetics / Q000378:metabolism*; D001233:Aspergillus nidulans / Q000201:enzymology* / Q000254:growth & development*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D016681:Genome, Fungal; D053858:Metabolic Networks and Pathways / Q000235:genetics; D008954:Models, Biological; D013597:Systems Analysis
D005656:Fungal Proteins; D000446:Aldehyde-Lyases; C022367:phosphoketolase