title: Systems analysis unfolds the relationship between the phosphoketolase pathway and growth in Aspergillus nidulans.
abstract: 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.
authors.affiliation: Center for Microbial Biotechnology, Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark.
authors.forename: Gianni
authors.initials: G
authors.lastname: Panagiotou
authors.forename: Mikael R
authors.initials: MR
authors.lastname: Andersen
authors.forename: Thomas
authors.initials: T
authors.lastname: Grotkjaer
authors.forename: Torsten B
authors.initials: TB
authors.lastname: Regueira
authors.forename: Gerald
authors.initials: G
authors.lastname: Hofmann
authors.forename: Jens
authors.initials: J
authors.lastname: Nielsen
authors.forename: Lisbeth
authors.initials: L
authors.lastname: Olsson
mesh_terms: 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
chemical_list: D005656:Fungal Proteins; D000446:Aldehyde-Lyases; C022367:phosphoketolase