The middle domain of Hsp90 acts as a discriminator between different types of client proteins
The middle domain of Hsp90 acts as a discriminator between different types of client proteins
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DOI：
10.1128/mcb.02188-05
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发表时间：
2006-11-01
影响因子：
5.3
通讯作者：
Obermann, Wolfgang M. J.
中科院分区：
文献类型：
--
作者：
Hawle, Patricija;Siepmann, Martin;Obermann, Wolfgang M. J.
Hsp90激活客户蛋白的机制是个谜，目前还不确定Hsp90是否对所有蛋白质都采用一条共同的途径。用突变分析的方法，我们在体内研究了Hsp90的中间结构域(Hsp90M)对糖皮质激素受体(GR)和激酶v-Src这两种客户蛋白的激活作用。值得注意的是，在W300A突变酵母菌株中，由于细胞蛋白水平增加了10倍，v-Src的整体细胞活性大大提高。相反，GR的细胞活性几乎不受W300A突变的影响，但对S485Y和T525I交换非常敏感。此外，我们发现Hsp90M的S485Y和T525I突变降低了ATP的水解率，这表明Hsp90 ATPase的调控比之前假设的更严格。因此，GR和v-Src的激活对Hsp90的生化有不同的要求，并且依赖于Hsp90M不同的功能区。因此，Hsp90M似乎区分不同的底物类型，并调节分子伴侣以适当地激活底物。
The mechanism of client protein activation by Hsp90 is enigmatic, and it is uncertain whether Hsp90 employs a common route for all proteins. Using a mutational analysis approach, we investigated the activation of two types of client proteins, glucocorticoid receptor (GR) and the kinase v-Src by the middle domain of Hsp90 (Hsp90M) in vivo. Remarkably, the overall cellular activity of v-Src was highly elevated in a W300A mutant yeast strain due to a 10-fold increase in cellular protein levels of the kinase. In contrast, the cellular activity of GR remained almost unaffected by the W300A mutation but was dramatically sensitive to S485Y and T525I exchanges. In addition, we show that mutations S485Y and T525I in Hsp90M reduce the ATP hydrolysis rate, suggesting that Hsp90 ATPase is more tightly regulated than assumed previously. Therefore, the activation of GR and v-Src has various demands on Hsp90 biochemistry and is dependent on separate functional regions of Hsp90M. Thus, Hsp90M seems to discriminate between different substrate types and to adjust the molecular chaperone for proper substrate activation.