Critical Beginnings: Selective Tuning of Solubility and Structural Accuracy of Newly Synthesized Proteins by the Hsp70 Chaperone System
Critical Beginnings: Selective Tuning of Solubility and Structural Accuracy of Newly Synthesized Proteins by the Hsp70 Chaperone System
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DOI：
10.1021/acs.jpcb.2c08485
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发表时间：
2023-05-02
影响因子：
3.3
通讯作者：
Cavagnero，Silvia
中科院分区：
文献类型：
--
作者：
Addabbo，Rayna M.;Hutchinson，Rachel B.;Cavagnero，Silvia
蛋白质从核糖体释放后特别容易聚集，因此阐明伴侣在蛋白质生命的这些关键步骤中的作用是很重要的。Hsp70和触发因子(Tf)伴侣系统在生物发生过程中和翻译后立即与新生蛋白相互作用。然而，目前尚不清楚这些伴侣是否可以防止形成可溶和不可溶的聚集体。在这里，我们通过监测在含有不同浓度的细菌Hsp70和Tf伴侣的无大肠杆菌系统中生物合成的珠蛋白的溶解性和结构准确性来解决这个问题。我们发现，给予新合成的蛋白质溶解性所需的HSP70浓度对客户-蛋白质序列极其敏感。重要的是，产生可溶客户蛋白的HSP70浓度不足以防止可溶聚集体的形成。事实上，对于一些易于聚集的蛋白质变体，避免形成可溶性聚集体需要Hsp70浓度超过细胞水平。Coli.总而言之，我们的数据强调了可溶性聚集体在新生蛋白质从核糖体释放中的突出作用，并表明了Hsp70伴侣系统在高度聚集倾向的蛋白质的情况下的局限性。这些结果表明，需要设计更好的策略来防止从核糖体释放时形成可溶性聚集体。
Proteins are particularly prone to aggregation immediately after release from the ribosome, and it is therefore important to elucidate the role of chaperones during these key steps of protein life. The Hsp70 and trigger factor (TF) chaperone systems interact with nascent proteins during biogenesis and immediately post-translationally. It is unclear, however, whether these chaperones can prevent formation of soluble and insoluble aggregates. Here, we address this question by monitoring the solubility and structural accuracy of globin proteins biosynthesized in anEscherichia colicell-free system containing different concentrations of the bacterial Hsp70 and TF chaperones. We find that Hsp70 concentrations required to grant solubility to newly synthesized proteins are extremely sensitive to client-protein sequence. Importantly, Hsp70 concentrations yielding soluble client proteins are insufficient to prevent formation of soluble aggregates. In fact, for some aggregation-prone protein variants, avoidance of soluble-aggregate formation demands Hsp70 concentrations that exceed cellular levels inE. coli. In all, our data highlight the prominent role of soluble aggregates upon nascent-protein release from the ribosome and show the limitations of the Hsp70 chaperone system in the case of highly aggregation-prone proteins. These results demonstrate the need to devise better strategies to prevent soluble-aggregate formation upon release from the ribosome.