Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada; Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health System, Toronto, ON M5G 1X5, Canada; Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada.
Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada; Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada.
Mol Cell. 2021 Jun 17;81(12):2549-2565.e8. doi: 10.1016/j.molcel.2021.04.012. Epub 2021 May 5.
Hsp70s comprise a deeply conserved chaperone family that has a central role in maintaining protein homeostasis. In humans, Hsp70 client specificity is provided by 49 different co-factors known as J domain proteins (JDPs). However, the cellular function and client specificity of JDPs have largely remained elusive. We have combined affinity purification-mass spectrometry (AP-MS) and proximity-dependent biotinylation (BioID) to characterize the interactome of all human JDPs and Hsp70s. The resulting network suggests specific functions for many uncharacterized JDPs, and we establish a role of conserved JDPs DNAJC9 and DNAJC27 in histone chaperoning and ciliogenesis, respectively. Unexpectedly, we find that the J domain of DNAJC27 but not of other JDPs can fully replace the function of endogenous DNAJC27, suggesting a previously unappreciated role for J domains themselves in JDP specificity. More broadly, our work expands the role of the Hsp70-regulated proteostasis network and provides a platform for further discovery of JDP-dependent functions.
Hsp70s 组成了一个高度保守的伴侣家族，在维持蛋白质平衡方面起着核心作用。在人类中，Hsp70 的客户特异性由 49 种不同的辅助因子（称为 J 结构域蛋白（JDPs））提供。然而，JDP 的细胞功能和客户特异性在很大程度上仍然难以捉摸。我们结合了亲和纯化-质谱（AP-MS）和邻近依赖性生物素化（BioID）技术，以鉴定所有人类 JDPs 和 Hsp70s 的相互作用组。由此产生的网络表明许多未被表征的 JDPs 具有特定的功能，我们分别确定了保守的 JDPs DNAJC9 和 DNAJC27 在组蛋白伴侣和纤毛发生中的作用。出乎意料的是，我们发现 DNAJC27 的 J 结构域而不是其他 JDPs 的 J 结构域可以完全取代内源性 DNAJC27 的功能，这表明 J 结构域本身在 JDP 特异性中具有以前未被认识到的作用。更广泛地说，我们的工作扩展了 Hsp70 调节的蛋白质平衡网络的作用，并为进一步发现 JDP 依赖性功能提供了一个平台。
