INO80染色质重塑复合物内的一个结构域对Rvb1/Rvb2的调控表明酵母Rvbs作为蛋白质组装伴侣。
Regulation of Rvb1/Rvb2 by a Domain within the INO80 Chromatin Remodeling Complex Implicates the Yeast Rvbs as Protein Assembly Chaperones.
作者信息
Zhou Coral Y, Stoddard Caitlin I, Johnston Jonathan B, Trnka Michael J, Echeverria Ignacia, Palovcak Eugene, Sali Andrej, Burlingame Alma L, Cheng Yifan, Narlikar Geeta J
机构信息
Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA; Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA.
Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94158, USA.
出版信息
Cell Rep. 2017 Jun 6;19(10):2033-2044. doi: 10.1016/j.celrep.2017.05.029.
The hexameric AAA+ ATPases Rvb1 and Rvb2 (Rvbs) are essential for diverse processes ranging from metabolic signaling to chromatin remodeling, but their functions are unknown. While originally thought to act as helicases, recent proposals suggest that Rvbs act as protein assembly chaperones. However, experimental evidence for chaperone-like behavior is lacking. Here, we identify a potent protein activator of the Rvbs, a domain in the Ino80 ATPase subunit of the INO80 chromatin-remodeling complex, termed Ino80INS. Ino80INS stimulates Rvbs' ATPase activity by 16-fold while concomitantly promoting their dodecamerization. Using mass spectrometry, cryo-EM, and integrative modeling, we find that Ino80INS binds asymmetrically along the dodecamerization interface, resulting in a conformationally flexible dodecamer that collapses into hexamers upon ATP addition. Our results demonstrate the chaperone-like potential of Rvb1/Rvb2 and suggest a model where binding of multiple clients such as Ino80 stimulates ATP-driven cycling between hexamers and dodecamers, providing iterative opportunities for correct subunit assembly.
六聚体AAA+ ATP酶Rvb1和Rvb2（Rvbs）对于从代谢信号传导到染色质重塑等多种过程至关重要，但其功能尚不清楚。虽然最初认为它们作为解旋酶发挥作用，但最近的观点认为Rvbs作为蛋白质组装伴侣。然而，缺乏类似伴侣行为的实验证据。在此，我们鉴定出Rvbs的一种强效蛋白质激活剂，即INO80染色质重塑复合物的Ino80 ATP酶亚基中的一个结构域，称为Ino80INS。Ino80INS将Rvbs的ATP酶活性提高16倍，同时促进其十二聚体化。通过质谱、冷冻电镜和整合建模，我们发现Ino80INS沿着十二聚体化界面不对称结合，产生一种构象灵活的十二聚体，在添加ATP后会折叠成六聚体。我们的结果证明了Rvb1/Rvb2的类似伴侣的潜力，并提出了一个模型，其中多个客户（如Ino80）的结合刺激ATP驱动的六聚体和十二聚体之间的循环，为正确的亚基组装提供迭代机会。
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