Department of Immunobiology and Cancer Immunology, Division of Basic Sciences, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
Nat Commun. 2010 Sep 21;1(6):79. doi: 10.1038/ncomms1070.
Cytosolic HSP90 requires multiple cochaperones in folding client proteins. However, the function of gp96 (HSP90b1, grp94), an HSP90 paralogue in the endoplasmic reticulum (ER), is believed to be independent of cochaperones. Here, we demonstrate that gp96 chaperones multiple Toll-like receptors (TLRs), but not TLR3, in a manner that is dependent on another ER luminal protein, CNPY3. gp96 directly interacts with CNPY3, and the complex dissociates in the presence of adenosine triphosphate (ATP). Genetic disruption of gp96-CNPY3 interaction completely abolishes their TLR chaperone function. Moreover, we demonstrate that TLR9 forms a multimolecular complex with gp96 and CNPY3, and the binding of TLR9 to either molecule requires the presence of the other. We suggest that CNPY3 interacts with the ATP-sensitive conformation of gp96 to promote substrate loading. Our study has thus established CNPY3 as a TLR-specific cochaperone for gp96.
细胞质 HSP90 需要多个共伴侣来折叠客户蛋白。然而，内质网 (ER) 中的 HSP90 同源物 gp96 (HSP90b1、grp94) 的功能被认为独立于共伴侣。在这里，我们证明 gp96 以依赖另一种 ER 腔蛋白 CNPY3 的方式伴侣多个 Toll 样受体 (TLR)，但不是 TLR3。gp96 与 CNPY3 直接相互作用，并且在三磷酸腺苷 (ATP) 的存在下复合物解离。gp96-CNPY3 相互作用的遗传破坏完全消除了它们的 TLR 伴侣功能。此外，我们证明 TLR9 与 gp96 和 CNPY3 形成多分子复合物，并且 TLR9 与任一分子的结合都需要另一个分子的存在。我们假设 CNPY3 与 gp96 的 ATP 敏感构象相互作用以促进底物加载。因此，我们的研究确立了 CNPY3 作为 gp96 的 TLR 特异性共伴侣。
