Nwaka S, Mechler B, Destruelle M, Holzer H
Biochemisches Institut, Universität Freiburg, Germany.
FEBS Lett. 1995 Mar 6;360(3):286-90. doi: 10.1016/0014-5793(95)00105-i.
In the yeast Saccharomyces cerevisiae, some studies have shown that trehalose and its hydrolysis may play an important physiological role during the life cycle of the cell. Recently, other studies demonstrated a close correlation between trehalose levels and tolerance to heat stress, suggesting that trehalose may be a protectant which contributes to thermotolerance. We had reported lack of correlation between trehalose accumulation and increase in thermotolerance under certain conditions, suggesting that trehalose may not mediate thermotolerance [Nwaka, S., et al. (1994) FEBS Lett. 344, 225-228]. Using mutants of the trehalase genes, NTH1 and YBR0106, we have demonstrated the necessity of these genes in recovery of yeast cells after heat shock, suggesting a role of these genes in thermotolerance (Nwaka, S., Kopp, M., and Holzer, H., submitted for publication). In the present paper, we have analysed the expression of the trehalase genes under heat stress conditions and present genetic evidence for the 'poor-heat-shock-recovery' phenotype associated with NTH1 and YBR0106 mutants. Furthermore, we show a growth defect of neutral and acid trehalase-deficient mutants during transition from glucose to glycerol, which is probably related to the 'poor-heat-shock-recovery' phenomenon.
在酿酒酵母中，一些研究表明海藻糖及其水解在细胞生命周期中可能发挥重要的生理作用。最近，其他研究表明海藻糖水平与热应激耐受性之间存在密切关联，这表明海藻糖可能是一种有助于耐热性的保护剂。我们曾报道在某些条件下，海藻糖积累与耐热性增加之间缺乏相关性，这表明海藻糖可能不介导耐热性 [Nwaka, S., 等人 (1994) 《欧洲生物化学学会联合会快报》344, 225 - 228]。利用海藻糖酶基因NTH1和YBR0106的突变体，我们证明了这些基因在热休克后酵母细胞恢复中的必要性，这表明这些基因在耐热性中发挥作用 (Nwaka, S., Kopp, M., 和Holzer, H., 已投稿待发表)。在本文中，我们分析了热应激条件下海藻糖酶基因的表达，并为与NTH1和YBR0106突变体相关的“热休克恢复不良”表型提供了遗传学证据。此外，我们发现中性和酸性海藻糖酶缺陷型突变体在从葡萄糖向甘油转变过程中存在生长缺陷，这可能与“热休克恢复不良”现象有关。
