Hauptman-Woodward Medical Research Institute, Buffalo, NY, USA; Department of Structural Biology, University at Buffalo, Buffalo, NY, USA.
Hauptman-Woodward Medical Research Institute, Buffalo, NY, USA.
Cell Rep. 2017 Sep 19;20(12):2800-2809. doi: 10.1016/j.celrep.2017.08.079.
Hsp90 chaperones undergo ATP-driven conformational changes during the maturation of client proteins, populating a closed state upon ATP binding in which the N-terminal domains of the homodimer form a second inter-protomer dimer interface. A structure of GRP94, the endoplasmic reticulum hsp90, in a closed conformation has not been described, and the determinants that regulate closure are not well understood. Here, we determined the 2.6-Å structure of AMPPNP-bound GRP94 in the closed dimer conformation. The structure includes the pre-N domain, a region preceding the N-terminal domain that is highly conserved in GRP94, but not in other hsp90s. We show that the GRP94 pre-N domain is essential for client maturation, and we identify the pre-N domain as an important regulator of ATPase rates and dimer closure. The structure also reveals a GRP94:polypeptide interaction that partially mimics a client-bound state. The results provide structural insight into the ATP-dependent client maturation process of GRP94.
Hsp90 伴侣蛋白在客户蛋白成熟过程中经历 ATP 驱动的构象变化，在结合 ATP 时进入封闭状态，同源二聚体的 N 端结构域形成第二个蛋白间二聚体界面。尚未描述内质网 hsp90 GRP94 的封闭构象结构，并且调控封闭的决定因素也不是很清楚。在这里，我们确定了结合 AMPPNP 的 GRP94 在封闭二聚体构象中的 2.6 Å 结构。该结构包括预 N 结构域，该结构域位于 N 端结构域之前，在 GRP94 中高度保守，但在其他 hsp90 中则不然。我们表明，GRP94 的预 N 结构域对于客户蛋白成熟是必需的，并且我们将预 N 结构域鉴定为调节 ATP 酶速率和二聚体封闭的重要调节剂。该结构还揭示了 GRP94：多肽相互作用，部分模拟了客户结合状态。该结果为 GRP94 的 ATP 依赖性客户成熟过程提供了结构见解。
