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. 2018 Mar 9;7:e32110. doi: 10.7554/eLife.32110

Figure 6. Overview of R. toruloides lipid metabolism.

Key metabolic pathways and cellular functions mediating lipid metabolism as identified from fitness scores on fatty acid and enrichment scores from lipid accumulation screens. Fitness and/or enrichment scores for individual genes are depicted graphically by relative size of hexagonal, circular or star icons respectively. Only fitness scores for genes with consistent growth defects on at least one fatty acid (see Supplementary file 2) and enrichment scores from high confidence clusters (see Figure 5 and Supplementary file 2) are shown. Enrichment scores were averaged between buoyancy and FACS experiments, except for genes with confounding enrichment scores in rich media conditions, for which only FACS data were averaged. Positive scores (orange circles) represent genes for which mutants have increased lipid accumulation. Negative fitness scores (blue stars) represent genes for which mutants have decreased lipid accumulation. Genes detected in proteomics of R. toruloides lipid droplets by Zhu et al. (RAC1, GUT2, PLIN1, EGH1, RIP1, MGL2, AAT1, CIR2, MLS1, and RTO4_8963) or found in lipid droplets of many organisms (DGA1 and BSCL2) (see Supplementary file 5) are depicted under ‘Lipid Droplet’ and also their molecular functions, e.g. ‘G Protein Switches’ for RAC1. The following figure supplements are available for Figure 6.

Figure 6.

Figure 6—figure supplement 1. Genes directly effecting TAG biosynthesis in R. toruloides.

Figure 6—figure supplement 1.

Model pathway illustrating genes involved in glycolysis, triacylglyceride (TAG) synthesis, and cytosolic NAD+/NADH balance during TAG synthesis. Genes for which mutants had altered lipid accumulation (enrichment scores in clusters LA1, LA6, LA7, or LA8) are highlighted in orange or blue. Genes with low rates of T-DNA insertion (essential genes and genes for which mutants have a strong growth defect) are highlighted in grey. The primary source of NADPH in R. toruloides remains unclear (see Appendix 1 for detail). Speculative pathways mediating NADPH production are indicated with dashed grey arrows. DAG: diacylglycerol, PA: phosphatidic acid, LPA: lysophosphatidic acid, G3P: glycerol-3-phosphate, DHAP: dihydroxy-acetone-phosphate, GADP: glycerate 3-phosphate, 1,3BPG: 1,3-bisphosphoglycerate, 3 PG: 3-phosphoglycerate, 2 PG: 2-phosphoglycerate, PEP: phosphoenolpyruvate, OAA: oxaloacetate.