Post-translational modifications of Hsp90

我们已经报道了一种在酵母中不保守的Hsp 90辅助分子伴侣， 多细胞真核生物在功能上被位点特异性翻译后 在人类细胞中的修饰。具体来说，高度保守的酪氨酸磷酸化 627在人Hsp 90 α中引起分子伴侣的长程构象变化， Hsp 90 N-结构域二聚化的损失。虽然酵母Hsp 90中的酪氨酸627不是 磷酸化的其磷酸化模拟突变对酵母Hsp 90构象的影响与 非保守性酵母共分子伴侣Hch 1的过度表达和 人Hsp 90 α中的酪氨酸627。我们的数据表明 这种翻译后修饰在高等真核生物中的出现， Hch 1蛋白的进化替代。(2)我们发现磷酸化诱导的 热休克蛋白90共伴侣Cdc 37的解折叠促进激酶向热休克蛋白90和客户端的募集 类特异性Hsp 90磷酸化。在Hsp 90介导的蛋白质伴侣过程中， 激酶，机器的核心组件，热休克蛋白90和辅伴侣Cdc 37，循环 不同的磷酸化状态之间调节伴侣循环的进展。我们 显示Cdc 37在Y298处的磷酸化导致C-末端结构域的部分解折叠 以及折叠中间体的数量。解折叠促进Hsp 90磷酸化， Y197通过暴露磷酸肽序列，其作为招募的对接位点， 非受体酪氨酸激酶通过它们的SH 2结构域与分子伴侣复合物结合。另一方面，HSP 90 Y197的磷酸化特异性地调节其与Cdc 37的相互作用，从而影响细胞的增殖。 仅对蛋白激酶客户进行监护。总之，我们发现通过提供客户端类 特异性，Hsp 90共分子伴侣如Cdc 37不仅有助于客户招募， 也塑造了Hsp 90在客户端类特异性的翻译后修饰景观 方式最近，我们发表了一个特定的酪氨酸残基的磷酸化 在热休克蛋白90的中间结构域， 辅助分子Aha 1通过诱导Hsp 90的独特和可逆构象。最近，我们 鉴定Hsp 90赖氨酸乳酸化作为一种新的糖酵解依赖性PTM。该修改 通过线粒体抑制而增加，并且通过LDH抑制而减少。我们目前正在使用 质谱法来鉴定人HSP 90上的特定赖氨酸残基， 这种方式。然后我们将突变这些赖氨酸并研究对HSP 90功能的影响。

We have reported that an Hsp90 co-chaperone in yeast that is not conserved in multi-cellular eukaryotes is functionally replaced by site-specific postranslational modification in human cells. Specifically, phosphorylation of the highly conserved tyrosine 627 in human Hsp90 alpha causes a long-range conformational change in the chaperone resulting in loss of dimerization of the Hsp90 N-domains. Although tyrosine 627 in yeast Hsp90 is not phosphorylated its phosphomimetic mutation has a similar effect on yeast Hsp90 conformation as does over-expression of the non-conserved yeast co-chaperone Hch1 and phosphorylation of tyrosine 627 in human Hsp90 alpha. Our data are consistent with the possibility that appearance of this posttranslational modification in higher eukaryotes represents an evolutionary substitution for Hch1 protein. (2) We showed that phosphorylation-induced unfolding of the Hsp90 co-chaperone Cdc37 promotes kinase recruitment to Hsp90 and client class-specific Hsp90 phosphorylation. During the Hsp90-mediated chaperoning of protein kinases, the core components of the machinery, Hsp90 and the cochaperone Cdc37, recycle between different phosphorylation states that regulate progression of the chaperone cycle. We show that Cdc37 phosphorylation at Y298 results in partial unfolding of the C-terminal domain and the population of folding intermediates. Unfolding facilitates Hsp90 phosphorylation at Y197 by unmasking a phosphopeptide sequence, which serves as a docking site to recruit non-receptor tyrosine kinases to the chaperone complex via their SH2 domains. In turn, Hsp90 phosphorylation at Y197 specifically regulates its interaction with Cdc37 and thus affects the chaperoning of only protein kinase clients. In summary, we find that by providing client class specificity, Hsp90 cochaperones such as Cdc37 do not merely assist in client recruitment but also shape the post-translational modification landscape of Hsp90 in a client class-specific manner. Most recently, we have published that phosphorylation of a specific tyrosine residue in the middle domain of Hsp90 dramatically enhances association of the stimulatory co-chaperone Aha1 by inducing a unique and reversible conformation of Hsp90. Most recently, we identified Hsp90 lysine lactylation as a novel, glycolysis-dependent PTM. This modification is increased by mitochondrial inhibition and decreased by LDH inhibition. We are currently using mass spectrometry to identify specific lysine residues on human HSP90 that are modified in this manner. We will then mutate these lysines and study impact on HSP90 function.