Apoptosis signal-regulating kinase 1 (ASK1) is a crucial stress sensor, directing cells toward apoptosis, differentiation, and senescence via the p38 and JNK signaling pathways. ASK1 dysregulation has been associated with cancer and inflammatory, cardiovascular, and neurodegenerative diseases, among others. However, our limited knowledge of the underlying structural mechanism of ASK1 regulation hampers our ability to target this member of the MAP3K protein family towards developing therapeutic interventions for these disorders. Nevertheless, as a multidomain Ser/Thr protein kinase, ASK1 is regulated by a complex mechanism involving dimerization and interactions with several other proteins, including thioredoxin 1 (TRX1). Thus, the present study aims at structurally characterizing ASK1 and its complex with TRX1 using several biophysical techniques. As shown by cryo-EM analysis, in a state close to its active form, ASK1 is a compact and asymmetric dimer, which enables extensive interdomain and interchain interactions. These interactions stabilize the active conformation of the ASK1 kinase domain. In turn, TRX1 functions as a negative allosteric effector of ASK1, modifying the structure of the TRX1-binding domain and changing its interaction with the tetratricopeptide repeats domain. Consequently, TRX1 reduces access to the activation segment of the kinase domain. Overall, our findings not only clarify the role of ASK1 dimerization and inter-domain contacts but also provide key mechanistic insights into its regulation, thereby highlighting the potential of ASK1 protein-protein interactions as targets for anti-inflammatory therapy.

中文翻译：

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ASK1 的冷冻电镜结构揭示了由 TRX1 变构调制的不对称结构

凋亡信号调节激酶 1 (ASK1) 是一种重要的应激传感器，通过 p38 和 JNK 信号通路引导细胞凋亡、分化和衰老。 ASK1 失调与癌症、炎症、心血管和神经退行性疾病等有关。然而，我们对 ASK1 调节的潜在结构机制的了解有限，阻碍了我们针对 MAP3K 蛋白家族成员开发针对这些疾病的治疗干预措施的能力。然而，作为一种多域 Ser/Thr 蛋白激酶，ASK1 受到复杂机制的调节，涉及二聚化以及与包括硫氧还蛋白 1 (TRX1) 在内的几种其他蛋白质的相互作用。因此，本研究旨在使用多种生物物理技术对 ASK1 及其与 TRX1 的复合物进行结构表征。如冷冻电镜分析所示，在接近其活性形式的状态下，ASK1 是一种紧凑且不对称的二聚体，可实现广泛的域间和链间相互作用。这些相互作用稳定了 ASK1 激酶结构域的活性构象。反过来，TRX1 充当 ASK1 的负变构效应子，修改 TRX1 结合域的结构并改变其与四肽重复域的相互作用。因此，TRX1 减少了对激酶结构域激活片段的访问。总的来说，我们的研究结果不仅阐明了 ASK1 二聚化和域间接触的作用，而且还提供了对其调节的关键机制见解，从而强调了 ASK1 蛋白质-蛋白质相互作用作为抗炎治疗靶点的潜力。