Chemistry Institute, University of Campinas UNICAMP, Campinas, SP, 13083-970, Brazil.
Plant Physiol Biochem. 2010 Feb-Mar;48(2-3):108-16. doi: 10.1016/j.plaphy.2010.01.001. Epub 2010 Jan 15.
Small heat shock proteins (sHsp) constitute an important chaperone family linked to conformational diseases. In plants, sHsps prevent protein aggregation by acting as thermosensors and to enhance cell stress tolerance. SsHsp17.2 and SsHsp17.9 are the most highly expressed class I sHsps in sugarcane. They exist as dodecamers at 20 degrees C and have distinct substrate specificities. Therefore, they are useful models to study how class I SHsps work. Here we present data on the effects of heat on the oligomerization and chaperone activity of SsHsp17.2 and SsHsp17.9. Using several biophysical and biochemical probes, we show that the effects of heat are completely reversible, an important property for proteins that act at heat shock temperatures. SsHsp17.2 and SsHsp17.9 dodecamers dissociated to dimers at temperatures ranging from 40 to 45 degrees C and this dissociation was followed by enhanced chaperone activity. We conclude that high temperature affects the oligomeric state of these chaperones, resulting in enhanced chaperone activity.
小分子热休克蛋白（sHsp）构成了与构象疾病相关的重要伴侣蛋白家族。在植物中，sHsps 通过充当热传感器来防止蛋白质聚集，并增强细胞应激耐受性。SsHsp17.2 和 SsHsp17.9 是甘蔗中表达水平最高的 I 类 sHsps。它们在 20°C 下以十二聚体形式存在，具有不同的底物特异性。因此，它们是研究 I 类 SHsps 工作方式的有用模型。在这里，我们提供了关于热对 SsHsp17.2 和 SsHsp17.9 寡聚化和伴侣活性影响的数据。使用多种生物物理和生化探针，我们表明热的影响是完全可逆的，对于在热激温度下起作用的蛋白质来说，这是一个重要的特性。SsHsp17.2 和 SsHsp17.9 十二聚体在 40 至 45°C 的温度范围内解聚为二聚体，随后伴侣活性增强。我们得出结论，高温会影响这些伴侣蛋白的寡聚状态，从而增强伴侣活性。
