Hierarchical Functional Specificity of Cytosolic Heat Shock Protein 70 ( Hsp70) Nucleotide Exchange Factors in Yeast
Hierarchical Functional Specificity of Cytosolic Heat Shock Protein 70 ( Hsp70) Nucleotide Exchange Factors in Yeast
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DOI：
10.1074/jbc.m113.530014
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发表时间：
2014-05-09
影响因子：
4.8
通讯作者：
Morano, Kevin A.
中科院分区：
文献类型：
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作者：
Abrams, Jennifer L.;Verghese, Jacob;Morano, Kevin A.
背景：核苷酸交换因子的几个保守家族与热休克蛋白70（Hsp 70）相互作用，但功能偏好未知。结果如下：Hsp 70依赖的细胞活性的多个测定揭示主要在缺乏热休克蛋白110（Hsp 110）的细胞中的主要功能缺陷。结论：Hsp 110 NEF在Hsp 70介导的细胞凋亡过程中起主导作用。重要性：热休克蛋白110可能是治疗蛋白质错误折叠疾病的一个很有价值的靶点，热休克蛋白70（Hsp 70）分子伴侣在蛋白质稳态中起着重要作用。在芽殖酵母酿酒酵母（Saccharomyces cerevisiae）中，胞质Hsp 70与多达三种与人类同源的核苷酸交换因子（NEF）相互作用：Sse 1/Sse 2（热休克蛋白110（Hsp 110））、Fes 1（HspBP 1）和Snl 1（Bag-1）。所有三个NEFs刺激ADP释放，但是，目前还不清楚为什么多个不同的家庭一直保持在整个真核生物进化。在这项研究中，我们调查NEF的作用，热休克蛋白70细胞生物学使用的NEF缺失突变体的等基因组合收集。利用良好的模型基板，我们发现，Sse 1参与大多数热休克蛋白70介导的过程，是特别重要的蛋白质的生物合成和降解，而Fes 1有助于在最小程度上。令人惊讶的是，解聚和重新溶解的热变性萤火虫荧光素酶发生独立的NEF活性。SSE 1和FES 1的同时缺失导致转录因子Hsf 1介导的热休克蛋白表达的组成性激活，表明这两个因子对于调节应激反应是重要的。Fes 1被发现在体内优先与胞质Hsp 70的Ssa家族而不是共翻译的Ssb同源物相互作用，这与Fes 1细胞缺乏冷敏感性和蛋白质生物合成表型相一致。没有显着的后果可以归因于删除次要的Hsp 110 SSE 2或袋同源SNL 1。总之，这些调查线提供了酵母中NEF功能的比较分析，这意味着Hsp 110是胞质Hsp 70的主要NEF，使其成为人类蛋白质折叠障碍治疗干预的理想候选者。
Background: Several conserved families of nucleotide exchange factor interact with heat shock protein 70 (Hsp70) with unknown functional preferences. Results: Multiple assays for Hsp70-dependent cellular activities reveal major functional defects primarily in cells lacking heat shock protein 110 (Hsp110). Conclusion: The Hsp110 NEF plays a dominant role in Hsp70-mediated processes. Significance: Hsp110 may be a high value target for therapies to treat protein misfolding diseases.Heat shock protein 70 (Hsp70) molecular chaperones play critical roles in protein homeostasis. In the budding yeast Saccharomyces cerevisiae, cytosolic Hsp70 interacts with up to three types of nucleotide exchange factors (NEFs) homologous to human counterparts: Sse1/Sse2 (Heat shock protein 110 (Hsp110)), Fes1 (HspBP1), and Snl1 (Bag-1). All three NEFs stimulate ADP release; however, it is unclear why multiple distinct families have been maintained throughout eukaryotic evolution. In this study we investigate NEF roles in Hsp70 cell biology using an isogenic combinatorial collection of NEF deletion mutants. Utilizing well characterized model substrates, we find that Sse1 participates in most Hsp70-mediated processes and is of particular importance in protein biogenesis and degradation, whereas Fes1 contributes to a minimal extent. Surprisingly, disaggregation and resolubilization of thermally denatured firefly luciferase occurred independently of NEF activity. Simultaneous deletion of SSE1 and FES1 resulted in constitutive activation of heat shock protein expression mediated by the transcription factor Hsf1, suggesting that these two factors are important for modulating stress response. Fes1 was found to interact in vivo preferentially with the Ssa family of cytosolic Hsp70 and not the co-translational Ssb homolog, consistent with the lack of cold sensitivity and protein biogenesis phenotypes for fes1 cells. No significant consequence could be attributed to deletion of the minor Hsp110 SSE2 or the Bag homolog SNL1. Together, these lines of investigation provide a comparative analysis of NEF function in yeast that implies Hsp110 is the principal NEF for cytosolic Hsp70, making it an ideal candidate for therapeutic intervention in human protein folding disorders.