Hop modulates hsp70/hsp90 interactions in protein folding
Hop modulates hsp70/hsp90 interactions in protein folding
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DOI：
10.1074/jbc.273.6.3679
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发表时间：
1998-02-06
影响因子：
4.8
通讯作者：
Toft, DO
中科院分区：
文献类型：
--
作者：
Johnson, BD;Schumacher, RJ;Toft, DO
Hop 是一种 60 kDa 的蛋白质，其特征在于它能够结合两个伴侣蛋白 hsp70 和 hsp90。我们使用变性萤火虫荧光素酶的重折叠测定法测试了 Hop 的功能。我们发现，Hop 参与兔网织红细胞裂解液中热变性萤火虫荧光素酶的重折叠过程。啤酒花还在纯化的重折叠系统中刺激 hsp70 和 Ydj-1 的重折叠。 Hsp90 还可以刺激重折叠，并且在 Hop 和 hsp90 都存在的情况下观察到最佳的重折叠。当 Hop 被其酵母同源物 Sti1 取代时，观察到类似的刺激。在 Hop 与 hsp70 和 hsp90 结合的测定中，Hop 优先与 ADP 结合的 hsp70 形成复合物，并且该过程不受 hsp90 存在的影响。啤酒花不会改变 hsp70 的 ATP 酶活性或 ADP 解离速率。 Hop 似乎还与 hsp90 的 ADP 结合形式结合，阻止 hsp90 依赖 ATP 转化为能够与 p23 相互作用的形式。相反，一旦 p23 与 hsp90 结合，Hop 结合就会减弱。这些结果证实了 Hop 提供了 hsp70 和 hsp90 之间的物理联系，并且还表明 Hop 调节这两种伴侣蛋白的活性。
Hop is a 60-kDa protein characterized by its ability to bind the two chaperones, hsp70 and hsp90. We have tested the function of Hop using an assay for the refolding of denatured firefly luciferase. We show that Hop is involved in the process of refolding thermally denatured firefly luciferase in rabbit reticulocyte lysate. Hop also stimulates refolding by hsp70 and Ydj-1 in a purified refolding system. Hsp90 can also stimulate refolding, and optimal refolding is observed in the presence of both Hop and hsp90. Similar stimulation was observed when Hop was replaced by its yeast homolog Sti1. In assays of the binding of Hop to hsp70 and hsp90, Hop preferentially forms a complex with ADP-bound hsp70, and this process is unaffected by the presence of hsp90. Hop does not alter the ATPase activity or the rate of ADP dissociation of hsp70. Hop also appears to bind to the ADP-bound form of hsp90, blocking the ATP-dependent conversion of hsp90 to a form capable of interacting with p23. Conversely, once p23 is bound to hsp90, Hop binding is diminished. These results confirm that Hop provides a physical link between hsp70 and hsp90 and also indicate that Hop modulates the activities of both of these chaperone proteins.