Folding of Toll-like receptors by the HSP90 paralogue gp96 requires a substrate-specific cochaperone.
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.
Liu
Bei
B
Department of Immunobiology and Cancer Immunology, Division of Basic Sciences, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
Yang
Yi
Y
Qiu
Zhijuan
Z
Staron
Matthew
M
Hong
Feng
F
Li
Yi
Y
Wu
Shuang
S
Li
Yunfeng
Y
Hao
Bing
B
Bona
Robert
R
Han
David
D
Li
Zihai
Z
D000818:Animals; D002850:Chromatography, Gel; D002853:Chromatography, Liquid; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D015151:Immunoblotting; D047468:Immunoprecipitation; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008856:Microscopy, Fluorescence; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011485:Protein Binding / Q000235:genetics / Q000502:physiology; D017510:Protein Folding; D053719:Tandem Mass Spectrometry; D051217:Toll-Like Receptor 9 / Q000235:genetics / Q000378:metabolism; D051193:Toll-Like Receptors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014161:Transduction, Genetic; D014162:Transfection
D008562:Membrane Glycoproteins; D018832:Molecular Chaperones; C495370:Tlr9 protein, mouse; D051217:Toll-Like Receptor 9; D051193:Toll-Like Receptors; C053387:endoplasmin