Yeast trehalose-6P tolerance to various stresses relies on the synthase (Tps1) protein, not on trehalose [Microbiology]

May 1st, 2015 by Petitȷean, M., Teste, M.–A., Francois, J. M., Parrou, J.–L.

Trehalose is a stable disaccharide commonly found in nature, from bacteria to fungi and plants. In the model yeast Saccharomyces cerevisiae, claims that trehalose is a stress protectant were based indirectly either on correlation between accumulation of trehalose and high resistance to various stresses, or on stress hypersensitivity of mutants deleted for TPS1, which encodes the first enzyme in trehalose biosynthetic pathway. Our goal was to investigate more directly which one, between trehalose and /or the Tps1 protein per se, may serve yeast cells to withstand exposure to stress. By employing an original strategy that combined the use of mutant strains expressing catalytically inactive variants of Tps1, with MAL+ yeast strains able to accumulate trehalose from an exogenous supply, we bring for the first time unbiased proofs that trehalose does not protect yeast cells from dying and that the stress-protecting role of trehalose in this eukaryotic model was largely overestimated. Conversely, we identified the Tps1 protein per se as a key player for yeast survival in response to temperature, oxidative and desiccation stress. We also showed by robust RT-qPCR and genetic interaction analysis, that the role of Tps1 in thermotolerance is not dependent upon Hsf1-dependent transcription activity. Finally, our results revealed that the Tps1 protein is essential to maintain ATP levels during heat shock. Altogether, these findings supported the idea that Tps1 is endowed with a regulatory function in energy homeostasis, which is essential to withstand adverse conditions and maintain cellular integrity.