Brandau S, Dresel A, Clos J
Leishmaniasis Research Group, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Federal Republic of Germany.
Biochem J. 1995 Aug 15;310 ( Pt 1)(Pt 1):225-32. doi: 10.1042/bj3100225.
We have analysed the transcription of three heat-shock genes, HSP70, HSP83 and ClpB, in the protozoan parasite Leishmania. All three heat-shock genes are transcribed constitutively and not heat-inducibly. However, we find that two major heat-shock proteins, HSP70 and HSP83, are synthesized at elevated rates during heat stress. We conclude that the cellular stress response in Leishmaniae is regulated exclusively on a post-transcriptional level much in contrast with all other eukaryotes examined so far. The induced synthesis of HSP70 and HSP83, however, does not increase the steady-state level of either protein significantly. This is compensated by high constitutive levels of both proteins: HSP70 and HSP83 make up 2.1% and 2.8%, respectively, of the total protein in unstressed Leishmania promastigotes. Also, HSP70 is a strictly cytoplasmic protein in Leishmania and does not relocate into the nucleus during heat stress, as it does in other eukaryotes examined in the past.
我们分析了原生动物寄生虫利什曼原虫中三个热休克基因HSP70、HSP83和ClpB的转录情况。这三个热休克基因都是组成型转录，而非热诱导型转录。然而，我们发现两种主要的热休克蛋白HSP70和HSP83在热应激期间合成速率升高。我们得出结论，利什曼原虫中的细胞应激反应完全在转录后水平受到调控，这与迄今为止研究的所有其他真核生物形成鲜明对比。然而，HSP70和HSP83的诱导合成并未显著提高这两种蛋白的稳态水平。这由两种蛋白的高组成型水平得到补偿：在未受应激的利什曼原虫前鞭毛体中，HSP70和HSP83分别占总蛋白的2.1%和2.8%。此外，HSP70在利什曼原虫中是一种严格的细胞质蛋白，在热应激期间不会像过去研究的其他真核生物那样转移到细胞核中。
