Molecular chaperones of the Hsp110 family act as nucleotide exchange factors of Hsp70s
Molecular chaperones of the Hsp110 family act as nucleotide exchange factors of Hsp70s
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DOI：
10.1038/sj.emboj.7601138
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发表时间：
2006-06-07
期刊：
影响因子：
11.4
通讯作者：
Hartl, F. Ulrich
中科院分区：
文献类型：
--
作者：
Dragovic, Zdravko;Broadley, Sarah A.;Hartl, F. Ulrich
Hsp 70分子伴侣在蛋白质折叠中的功能依赖于辅伴侣的调节。Hsp 40 s增加了Hsp 70的低内在ATP酶活性，并且核苷酸交换因子（NEFs）去除ATP水解后的ADP，使Hsp 70与非天然蛋白质底物的新的相互作用循环成为可能。在这里，我们表明，成员的Hsp 70相关的Hsp 110家族与Hsp 70在真核细胞质中的蛋白质折叠合作。哺乳动物Hsp 110和酵母同源物Sse 1 p/2 p分别催化酿酒酵母中Hsp 70及其直向同源物Ssa 1 p上的有效核苷酸交换。此外，Sse 1 p对Ssb 1 p具有相同的作用，Ssb 1 p是酵母中Hsp 70的核糖体相关亚型。突变分析表明，N-末端ATP酶结构域和最终的Sse 1 p的C-末端所需的核苷酸交换活性。热休克蛋白110同源物显着增加热休克蛋白70介导的热变性萤火虫荧光素酶在体外的重折叠的速率和产量。类似地，在体内热应激下，SSE 1的缺失导致酵母细胞中萤火虫荧光素酶折叠缺陷。我们的数据表明，Hsp 110蛋白是真核Hsp 70蛋白折叠机制的重要组成部分。
Hsp70 molecular chaperones function in protein folding in a manner dependent on regulation by co-chaperones. Hsp40s increase the low intrinsic ATPase activity of Hsp70, and nucleotide exchange factors ( NEFs) remove ADP after ATP hydrolysis, enabling a new Hsp70 interaction cycle with non-native protein substrate. Here, we show that members of the Hsp70-related Hsp110 family cooperate with Hsp70 in protein folding in the eukaryotic cytosol. Mammalian Hsp110 and the yeast homologues Sse1p/2p catalyze efficient nucleotide exchange on Hsp70 and its orthologue in Saccharomyces cerevisiae, Ssa1p, respectively. Moreover, Sse1p has the same effect on Ssb1p, a ribosome-associated isoform of Hsp70 in yeast. Mutational analysis revealed that the N-terminal ATPase domain and the ultimate C-terminus of Sse1p are required for nucleotide exchange activity. The Hsp110 homologues significantly increase the rate and yield of Hsp70-mediated re-folding of thermally denatured firefly luciferase in vitro. Similarly, deletion of SSE1 causes a firefly luciferase folding defect in yeast cells under heat stress in vivo. Our data indicate that Hsp110 proteins are important components of the eukaryotic Hsp70 machinery of protein folding.