Department of Integrative Structural and Computational Biology, Scripps Research, La Jolla, California.
Protein Sci. 2019 Nov;28(11):2020-2023. doi: 10.1002/pro.3726. Epub 2019 Sep 30.
The structured DNA-binding domain (DBD) of p53 is a well-known client protein of the chaperone Hsp90. The p53 DBD contains a single zinc ion, coordinated by the side chains of Cys176, His179, Cys238, and Cys242; zinc coordination plays a structural role to stabilize the DBD and is required for its DNA binding. The ambiguous nature of the p53-Hsp90 interaction, together with the stabilizing role of the zinc in the structure of the DBD, prompted us to examine the interaction of Hsp90 with zinc-free p53 DBD. NMR spectroscopy and native gel electrophoresis did not show any apparent preference for the interaction of the destabilized zinc-free form of p53 DBD with Hsp90. Intriguingly, however, at lower protein concentrations, closer to physiological concentrations, the addition of Hsp90, but not other chaperones such as Hsp70, Hsp40, p23, and HOP, appears to slow or prevent the aggregation of zinc-free p53 DBD. This result suggests that part of the function of the Hsp90-p53 interaction in the cell may be to stabilize the apoprotein in the absence of zinc.
p53 的结构 DNA 结合域（DBD）是伴侣蛋白 Hsp90 的知名客户蛋白。p53 DBD 包含一个单一的锌离子，由 Cys176、His179、Cys238 和 Cys242 的侧链配位；锌配位起到稳定 DBD 的结构作用，并且是其 DNA 结合所必需的。p53-Hsp90 相互作用的不明确性质，加上锌在 DBD 结构中的稳定作用，促使我们研究 Hsp90 与无锌 p53 DBD 的相互作用。NMR 光谱和天然凝胶电泳没有显示出无锌形式的 p53 DBD 与 Hsp90 相互作用的任何明显偏好。然而，有趣的是，在较低的蛋白质浓度下，更接近生理浓度时，添加 Hsp90，但不是其他伴侣蛋白，如 Hsp70、Hsp40、p23 和 HOP，似乎会减缓或防止无锌 p53 DBD 的聚集。这一结果表明，Hsp90-p53 相互作用在细胞中的部分功能可能是在没有锌的情况下稳定无辅基蛋白。
