Paulina Kettel, Laura Marosits, Elena Spinetti, Michael Rechberger, Caterina Giannini, Philipp Radler, Isabell Niedermoser, Irmgard Fischer, Gijs A Versteeg, Martin Loose, Roberto Covino, G Elif Karagöz
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引用次数: 0
摘要
保守的信号级联可监控蛋白质折叠的平衡,以确保细胞的正常功能。IRE1是进化保守的关键参与者之一,它通过未折叠蛋白反应(UPR)维持内质网(ER)的平衡。当折叠错误的蛋白质在 ER 中积累时,IRE1 会在 ER 膜上形成簇,启动 UPR 信号。目前还不完全清楚是什么在调控 IRE1 簇的形成。在这里,我们发现人类 IRE1α 的 ER 腔域(LD)在体外形成了生物分子凝聚体。IRE1α LD凝聚物通过与未折叠的多肽结合以及与模型膜的系链而稳定,这表明它们在将IRE1α组装成具有信号传导能力的稳定团簇中发挥作用。分子动力学模拟表明,微弱的多价相互作用推动了 IRE1α LD 聚类。突变实验确定了IRE1α LD中的无序区域,以控制其在体外和细胞中的聚类。重要的是,IRE1α突变体的聚类失调导致了IRE1α信号传导的缺陷。我们的研究结果表明,IRE1α LD中的无序区域控制着它的聚类,并表明它们是调节蛋白质在膜上组装的一种常见策略。
Disordered regions in the IRE1α ER lumenal domain mediate its stress-induced clustering.
Conserved signaling cascades monitor protein-folding homeostasis to ensure proper cellular function. One of the evolutionary conserved key players is IRE1, which maintains endoplasmic reticulum (ER) homeostasis through the unfolded protein response (UPR). Upon accumulation of misfolded proteins in the ER, IRE1 forms clusters on the ER membrane to initiate UPR signaling. What regulates IRE1 cluster formation is not fully understood. Here, we show that the ER lumenal domain (LD) of human IRE1α forms biomolecular condensates in vitro. IRE1α LD condensates were stabilized both by binding to unfolded polypeptides as well as by tethering to model membranes, suggesting their role in assembling IRE1α into signaling-competent stable clusters. Molecular dynamics simulations indicated that weak multivalent interactions drive IRE1α LD clustering. Mutagenesis experiments identified disordered regions in IRE1α LD to control its clustering in vitro and in cells. Importantly, dysregulated clustering of IRE1α mutants led to defects in IRE1α signaling. Our results revealed that disordered regions in IRE1α LD control its clustering and suggest their role as a common strategy in regulating protein assembly on membranes.
期刊介绍:
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