Metabolic phenotypes of Saccharomyces cerevisiae mutants with altered trehalose 6-phosphate dynamics
2013
Walther, Thomas | Mtimet, Narjes | Alkim, Ceren | Vax, Amelie | Loret, Marie-Odile | Ullah, Azmat | Gancedo, Carlos | Smits, Gertien J. | François, Jean Marie | Laboratoire d'Ingénierie des Systèmes Biologiques et des Procédés (LISBP) ; Institut National de la Recherche Agronomique (INRA)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse) ; Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS) | Swammerdam Institute for Life Sciences (SILS) ; Universiteit van Amsterdam = University of Amsterdam (UvA) | Inst Invest Biomed Alberto Sols ; Consejo Superior de Investigaciones Cientificas [España] = Spanish National Research Council [Spain] (CSIC) | ANR (Agence Nationale de la Recherche) Blanc [05-2-42128]; Region Midi Pyrenees (France) [09003813]; Spanish Ministry of Science and Innovation (MICINN) [BFU2010-19628-C02-02]; HEC (Higher Education Commission) Pakistan
In Saccharomyces cerevisiae, synthesis of T6P (trehalose 6-phosphate) is essential for growth on most fermentable carbon sources. In the present study, the metabolic response to glucose was analysed in mutants with different capacities to accumulate T6P. A mutant carrying a deletion in the T6P synthase encoding gene, TPS1, which had no measurable T6P, exhibited impaired ethanol production, showed diminished plasma membrane H+-ATPase activation, and became rapidly depleted of nearly all adenine nucleotides which were irreversibly converted into inosine. Deletion of the AMP deaminase encoding gene, AMD1, in the tps1 strain prevented inosine formation, but did not rescue energy balance or growth on glucose. Neither the 90%-reduced T6P content observed in a tps1 mutant expressing the Tps1 protein from Yarrowia lipolytica, nor the hyperaccumulation of T6P in the tps2 mutant had significant effects on fermentation rates, growth on fermentable carbon sources or plasma membrane H+-ATPase activation. However, intracellular metabolite dynamics and pH homoeostasis were strongly affected by changes in T6P concentrations. Hyperaccumulation of T6P in the tps2 mutant caused an increase in cytosolic pH and strongly reduced growth rates on non-fermentable carbon sources, emphasizing the crucial role of the trehalose pathway in the regulation of respiratory and fermentative metabolism.
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