Feedback regulation of heat shock factor 1 (Hsf1) activity by Hsp70-mediated trimer unzipping and dissociation from DNA
Feedback regulation of heat shock factor 1 (Hsf1) activity by Hsp70-mediated trimer unzipping and dissociation from DNA
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DOI：
10.15252/embj.2019104096
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发表时间：
2020-06-03
期刊：
影响因子：
11.4
通讯作者：
Mayer, Matthias P.
中科院分区：
文献类型：
--
作者：
Kmiecik, Szymon W.;Le Breton, Laura;Mayer, Matthias P.
热休克反应是由热休克转录因子Hsf1在所有真核细胞中协调的对蛋白毒性应激的普遍转录反应。尽管经过40多年的深入研究，Hsf1活性调节的机制在分子水平上仍然知之甚少。在后生动物中，Hsf1在热休克时通过亮氨酸拉链结构域三聚化并与DNA结合。Hsf1是如何从DNA中脱落并单体化的仍然是个谜。在这里，使用纯化的蛋白质，我们证明了未修饰的三聚体Hsf1是解离DNA在体外由Hsc70和DnaJB1。Hsc70以不同的亲和力与Hsf1中的多个位点结合。Hsf1三聚体通过连续的熵拉循环而单体化，解开三重亮氨酸拉链。在Hsf1三聚体的几个原聚体处开始这种解链导致更快的单体化。该过程直接监测Hsc70和DnaJB1的浓度。在热休克适应过程中，Hsc70首先与反式激活结构域中的高亲和力位点结合，导致反应的部分减弱，随后，在较高浓度下，Hsc70从DNA中去除Hsf1以恢复静息状态。
The heat shock response is a universal transcriptional response to proteotoxic stress orchestrated by heat shock transcription factor Hsf1 in all eukaryotic cells. Despite over 40 years of intense research, the mechanism of Hsf1 activity regulation remains poorly understood at the molecular level. In metazoa, Hsf1 trimerizes upon heat shock through a leucine-zipper domain and binds toDNA. How Hsf1 is dislodged fromDNAand monomerized remained enigmatic. Here, using purified proteins, we demonstrate that unmodified trimeric Hsf1 is dissociated fromDNAin vitroby Hsc70 and DnaJB1. Hsc70 binds to multiple sites in Hsf1 with different affinities. Hsf1 trimers are monomerized by successive cycles of entropic pulling, unzipping the triple leucine-zipper. Starting this unzipping at several protomers of the Hsf1 trimer results in faster monomerization. This process directly monitors the concentration of Hsc70 and DnaJB1. During heat shock adaptation, Hsc70 first binds to a high-affinity site in the transactivation domain, leading to partial attenuation of the response, and subsequently, at higher concentrations, Hsc70 removes Hsf1 fromDNAto restore the resting state.