Zähringer H, Burgert M, Holzer H, Nwaka S
Institut für Biochemie und Molekularbiologie, Universität Freiburg, Germany.
FEBS Lett. 1997 Aug 4;412(3):615-20. doi: 10.1016/s0014-5793(97)00868-5.
We have shown previously that expression of the NTH1 gene is increased at heat stress (40 degrees C) both at the mRNA and enzymatic activity levels. This increased expression was correlated to the requirement of the NTH1 gene for recovery after heat shock at 50 degrees C and the presence of stress responsive elements STRE (CCCCT) 3 times in its promoter region [S. Nwaka et al., FEBS Lett. 360 (1995) 286-290; S. Nwaka et al., J. Biol. Chem. 270 (1995) 10193-10198]. We show here that expression of the NTH1 gene and its product, neutral trehalase (Nthlp), are also induced by other stressors such as H2O2, CuSO4, NaAsO2, and cycloheximide (CHX). Heat-induced expression of the NTH1 gene is shown to be accompanied by accumulation of trehalose. In contrast, the chemical stressors which also induce the expression of NTH1 did not lead to accumulation of trehalose under similar conditions. Our data suggest that: (1) heat- and chemical stress-induced expression of neutral trehalase is largely due to de novo protein synthesis, and (2) different mechanisms may control the heat- and chemical stress-induced expression of NTH1 at the transcriptional level. Participation of neutral trehalase (Nth1p) in multiple stress response dependent and independent on trehalose is discussed.
我们之前已经表明，在热应激（40摄氏度）下，NTH1基因在mRNA和酶活性水平上的表达均会增加。这种表达增加与NTH1基因在50摄氏度热休克后恢复的需求以及其启动子区域中存在3次应激反应元件STRE（CCCCT）相关[S. Nwaka等人，《欧洲生物化学学会联合会快报》360（1995）286 - 290；S. Nwaka等人，《生物化学杂志》270（1995）10193 - 10198]。我们在此表明，NTH1基因及其产物中性海藻糖酶（Nthlp）的表达也会被其他应激源诱导，如H2O2、CuSO4、NaAsO2和环己酰亚胺（CHX）。热诱导的NTH1基因表达伴随着海藻糖的积累。相比之下，同样诱导NTH1表达的化学应激源在类似条件下并未导致海藻糖的积累。我们的数据表明：（1）热应激和化学应激诱导的中性海藻糖酶表达在很大程度上归因于从头合成蛋白质，并且（2）不同的机制可能在转录水平上控制热应激和化学应激诱导的NTH1表达。本文讨论了中性海藻糖酶（Nth1p）在依赖和不依赖海藻糖的多种应激反应中的参与情况。
