Generation of a genome scale metabolic model (GEM) of Rhodosporidium toruloides would provide a deeper understanding of oleaginicity and facilitate the design of genetic engineering strategies. We have used the RAVEN toolbox to create a first draft GEM of R. toruloides based on protein homology to Saccharomyces cerevisiae model yeast 7.6 and to Yarrowia lipolitica model iYali4.01. Unlike S. cerevisiae, R. toruloides contains a gene encoding ATP:citrate lyase, which is the main source of acetyl-CoA for lipid synthesis. In addition, a mitochondrial beta-oxidation pathway provides additional source of acetyl-CoA in this yeast. Unlike Y. lipolytica, R. toruloides expresses a cytoplasmic malic enzyme that provides an alternative to NADPH generation through the pentose-phosphate pathway. The model was used to simulate lipid production in R. toruloides on both glucose and xylose substrates. The reaction of phosphorolytic cleavage of xylulose-5-P by phosphoketolase with generation of acetyl phosphate and glyceraldehyde-3-phosphate was shown to enable efficient conversion of xylose into lipids.

Poster presentations:

Tiukova I., Brandenburg J., Nielsen J., Sandgren M., Kerkhoven E. “Genome-scale Metabolic Model of the oleaginous yeast Rhodosporidium toruloides” 33rd International Specialised Symposium on Yeast, 26-29 June 2017, Cork, Ireland

Tiukova I., Sandgren M., Nielsen J., Kerkhoven E. “Using Genome Scale Metabolic Model to Explore the Lipid Producing Machinery of Rhodosporidium toruloides”, 28th International Conference on Yeast Genetics and Molecular Biology (ICYGMB), August 27 – September 1, 2017, Prague, Czech Republic