Hoskins Joel R, Wickramaratne Anushka C, Jewell Connor P, Jenkins Lisa M, Wickner Sue
Laboratory of Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892.
Laboratory of Cell Biology, National Cancer Institute, NIH, Bethesda, MD 20892.
Proc Natl Acad Sci U S A. 2025 Feb 4;122(5):e2422640122. doi: 10.1073/pnas.2422640122. Epub 2025 Jan 29.
Hsp70, Hsp90, and ClpB/Hsp100 are molecular chaperones that help regulate proteostasis. Bacterial and yeast Hsp70s and their cochaperones function synergistically with Hsp90s to reactivate inactive and aggregated proteins by a mechanism that requires a direct interaction between Hsp90 and Hsp70 both in vitro and in vivo. and yeast Hsp70s also collaborate in bichaperone systems with ClpB and Hsp104, respectively, to disaggregate and reactivate aggregated proteins and amyloids such as prions. These collaborations are dependent on direct interactions between ClpB/Hsp104 and Hsp70. We explored the possibility that homologs of Hsp70, Hsp90, and ClpB, referred to as DnaK, Hsp90, and ClpB, respectively, in combination with two DnaK cochaperones, DnaJ and GrpE, could promote protein disaggregation and reactivation under conditions where bichaperone systems are ineffective. Our results show that Hsp90 is able to overcome the inhibition of protein disaggregation and reactivation observed when the concentration of DnaK is approaching physiological concentrations. We found that ATP hydrolysis and substrate binding by all three chaperones are essential for the collaborative function. The work further shows that ClpB acts early in protein reactivation with DnaK and its cochaperones; Hsp90 acts at a later stage after ClpB. The results highlight the collaboration among chaperones to regulate and maintain proteostasis.
热休克蛋白70（Hsp70）、热休克蛋白90（Hsp90）和ClpB/Hsp100是有助于调节蛋白质稳态的分子伴侣。细菌和酵母的Hsp70及其共伴侣蛋白与Hsp90协同作用，通过一种在体外和体内都需要Hsp90与Hsp70直接相互作用的机制，使失活和聚集的蛋白质重新激活。酵母Hsp70还分别在双分子伴侣系统中与ClpB和Hsp104合作，以解开聚集的蛋白质和淀粉样蛋白（如朊病毒）并使其重新激活。这些合作依赖于ClpB/Hsp104与Hsp70之间的直接相互作用。我们探讨了分别称为DnaK、Hsp�0和ClpB的Hsp70、Hsp90和ClpB的同源物，与两种DnaK共伴侣蛋白DnaJ和GrpE结合，在双分子伴侣系统无效的条件下能否促进蛋白质解聚和重新激活的可能性。我们的结果表明，当DnaK的浓度接近生理浓度时，Hsp90能够克服观察到的对蛋白质解聚和重新激活的抑制作用。我们发现，所有三种分子伴侣的ATP水解和底物结合对于协同功能都是必不可少的。这项工作进一步表明，ClpB在与DnaK及其共伴侣蛋白一起进行蛋白质重新激活的过程中起早期作用；Hsp90在ClpB之后的后期起作用。这些结果突出了分子伴侣之间为调节和维持蛋白质稳态而进行的合作。
