Metabolic regulation of the trehalose content of vegetative yeast

FEBS Letters

Burgert, Markus¹  Wagner, Jean-Claude¹  Winkler, Karl¹  Kienle, Iris¹  Holzer, Helmut¹ 

[1] Biochemisches Institut, Universität Freiburg, Hermann-Herder-Str. 7, D-7800 Freiburg, Germany

关键词: Trehalose assay with acid trehalase;    Neutral trehalase;    Trehalose 6-phosphate synthase;    Heat shock;    Regulation of trehalose concentration;    Metabolic regulation;   

DOI  :  10.1016/0014-5793(91)81299-N

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

We have investigated the mechanism by which heat shock conditions lead to a reversible accumulation of trehalose in growing yeast. When cells of S. cerevisiae MI growing exponentially at 30°C were shifted to 45°C for 20 min, or to 39°C for 40 min, the concentration of trehalose increased by about 25-fold; an effect reversed upon lowering the temperature to 30°C. This was compared to the more than 50-fold rise in trehalose levels obtained upon transition from the exponential to the stationary growth phase. Whereas the latter was paralleled by a 12-fold increase in the activity of trehalose-6-phosphate synthase, no significant change in the activities of trehalose-synthesizing and -degrading enzymes was measured under heat shock conditions. Accordingly, cycloheximide did not prevent the heat-induced accumulation of trehalose. However, the concentrations of the substrates for trehalose-6-phosphate synthase, i.e. glucose-6-phosphate and UDP-glucose, were found to rise during heat shock by about 5–10-fold. Since the elevated levels of both sugars are still well below the K _m-values determined for trehalose-6-phosphate synthase in vitro, they are likely to contribute to the increase in trehalose under heat shock conditions. A similar increase in the steady-state levels was obtained for other intermediates of the glycolytic pathway between glucose and triosephosphate, including ATP. This suggests that temperature-dependent changes in the kinetic parameters of glycolytic enzymes vary in steady-state levels of intermediates of sugar metabolism, including an increase of those that are required for trehalose synthesis. Trehalose, glucose-6-phosphate, UDP-glucose, and ATP, were all found to increase during the 40 min heat treatment at 39°C. Since this also occurs in a mutant lacking the heat shock-induced protein HSP104 (Δhsp104), this protein cannot be involved in the accumulation of trehalose under these heat shock conditions. However, mutant Δhsp104, in contrast to the parental wild-type, was sensitive towards a 20 min incubation at 50°C. Since this mutant also accumulated normal levels of trehalose, we conclude that HSP104 function, and not the accumulation of trehalose, protects S. cerevisiae from the damage caused by a 50°C treatment.

【 授权许可】

Unknown