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 to DNA . How Hsf1 is dislodged from DNA and monomerized remained enigmatic. Here, using purified proteins, we demonstrate that unmodified trimeric Hsf1 is dissociated from DNA in vitro by Hsc70 and DnaJB 1. 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 DnaJB 1. 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 from DNA to restore the resting state.

中文翻译：

---

Hsp70介导的三聚体的解压缩和与DNA的解离对热休克因子1（Hsf1）活性的反馈调节。

热休克反应是对所有真核细胞中由热休克转录因子Hsf1调控的蛋白毒性应激的普遍转录反应。尽管进行了40多年的深入研究，但Hsf1活性调节的机制在分子水平上仍知之甚少。在后生动物中，Hsf1在热冲击下通过亮氨酸拉链结构域三聚化并与DNA结合。Hsf1如何从DNA脱位并单体化仍然是个谜。在这里，使用纯化的蛋白质，我们证明了未修饰的三聚体Hsf1在体外从DNA上解离了通过Hsc70和DnaJB1。Hsc70结合到Hsf1中具有不同亲和力的多个位点。Hsf1三聚体通过连续的熵拉周期单体化，解开三亮氨酸拉链。在Hsf1三聚体的几个启动子处开始解压缩会导致更快的单体化。此过程直接监控Hsc70和DnaJB 1的浓度。在热激适应过程中，Hsc70首先结合至反式激活域中的高亲和力位点，导致响应部分减弱，随后，在更高的浓度下，Hsc70会从中去除Hsf1。 DNA恢复静息状态。