title: Quantitative modeling of triacylglycerol homeostasis in yeast--metabolic requirement for lipolysis to promote membrane lipid synthesis and cellular growth.
abstract: Triacylglycerol metabolism in Saccharomyces cerevisiae was analyzed quantitatively using a systems biological approach. Cellular growth, glucose uptake and ethanol secretion were measured as a function of time and used as input for a dynamic flux-balance model. By combining dynamic mass balances for key metabolites with a detailed steady-state analysis, we trained a model network and simulated the time-dependent degradation of cellular triacylglycerol and its interaction with fatty acid and membrane lipid synthesis. This approach described precisely, both qualitatively and quantitatively, the time evolution of various key metabolites in a consistent and self-contained manner, and the predictions were found to be in excellent agreement with experimental data. We showed that, during pre-logarithmic growth, lipolysis of triacylglycerol allows for the rapid synthesis of membrane lipids, whereas de novo fatty acid synthesis plays only a minor role during this growth phase. Progress in triacylglycerol hydrolysis directly correlates with an increase in cell size, demonstrating the importance of lipolysis for supporting efficient growth initiation.
authors.affiliation: Institute of Chemistry, University of Graz, Austria. juergen.zanghellini@uni-graz.at
authors.forename: Jürgen
authors.initials: J
authors.lastname: Zanghellini
authors.forename: Klaus
authors.initials: K
authors.lastname: Natter
authors.forename: Christian
authors.initials: C
authors.lastname: Jungreuthmayer
authors.forename: Armin
authors.initials: A
authors.lastname: Thalhammer
authors.forename: Christoph F
authors.initials: CF
authors.lastname: Kurat
authors.forename: Gabriela
authors.initials: G
authors.lastname: Gogg-Fassolter
authors.forename: Sepp D
authors.initials: SD
authors.lastname: Kohlwein
authors.forename: Hans-Hennig
authors.initials: HH
authors.lastname: von Grünberg
mesh_terms: D048708:Cell Growth Processes; D000431:Ethanol / Q000378:metabolism; D005227:Fatty Acids / Q000096:biosynthesis; D005947:Glucose / Q000378:metabolism; D006706:Homeostasis; D007700:Kinetics; D050356:Lipid Metabolism; D008066:Lipolysis / Q000502:physiology*; D008563:Membrane Lipids / Q000096:biosynthesis*; D008954:Models, Biological; D049490:Systems Biology / Q000379:methods*; D014280:Triglycerides / Q000378:metabolism*; D015003:Yeasts / Q000378:metabolism*
chemical_list: D005227:Fatty Acids; D008563:Membrane Lipids; D014280:Triglycerides; D000431:Ethanol; D005947:Glucose