A kinetic model of catabolic adaptation and protein reprofiling in Saccharomyces cerevisiae during temperature shifts

In this article, we aim to find an explanation for the surprisingly thin line, with regard to temperature, between cell growth, growth arrest and ultimately loss of cell viability. To this end, we used an integrative approach including both experimental and modelling work. We measured the shortand long-term effects of increases in growth temperature from 28°C to 37, 39, 41, 42 or 43°C on the central metabolism of Saccharomyces cerevisiae. Based on the experimental data, we developed a kinetic mathematical model that describes the metabolic and energetic changes in growing bakers' yeast when exposed to a specific temperature upshift. The model includes the temperature dependence of core energy-conserving pathways, trehalose synthesis, protein synthesis and proteolysis. Because our model focuses on protein synthesis and degradation, the net result of which is important in determining the cell's capacity to grow, the model includes growth, i.e. glucose is consumed and biomass and adenosine nucleotide cofactors are produced. The model reproduces both the observed initial metabolic response and the subsequent relaxation into a new steady-state, compatible with the new ambient temperature. In addition, it shows that the energy consumption for proteome reprofiling may be a major determinant of heat-induced growth arrest and subsequent recovery or cell death.