Center for Healthy Aging, Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen, Denmark.
Cells. 2023 Mar 22;12(6):969. doi: 10.3390/cells12060969.
The kinase ZAKα acts as the proximal sensor of translational impairment and ribotoxic stress, which results in the activation of the MAP kinases p38 and JNK. Despite recent insights into the functions and binding partners of individual protein domains in ZAKα, the mechanisms by which ZAKα binds ribosomes and becomes activated have remained elusive. Here, we highlight a short, thrice-repeated, and positively charged peptide motif as critical for the ribotoxic stress-sensing function of the Sensor (S) domain of ZAKα. We use this insight to demonstrate that the mutation of the SAM domain uncouples ZAKα activity from ribosome binding. Finally, we use 3D structural comparison to identify and functionally characterize an additional folded domain in ZAKα with structural homology to YEATS domains. These insights allow us to formulate a model for ribosome-templated ZAKα activation based on the re-organization of interactions between modular protein domains. In sum, our work both advances our understanding of the protein domains and 3D architecture of the ZAKα kinase and furthers our understanding of how the ribotoxic stress response is activated.
激酶 ZAKα 作为翻译损伤和核糖体毒性应激的近端传感器发挥作用，导致 MAP 激酶 p38 和 JNK 的激活。尽管最近对 ZAKα 中单个蛋白结构域的功能和结合伙伴有了深入的了解，但 ZAKα 结合核糖体并被激活的机制仍然难以捉摸。在这里，我们强调一个短的、三倍重复的、带正电荷的肽基序对于 ZAKα 的传感器（S）结构域的核糖体毒性应激感应功能至关重要。我们利用这一认识来证明 SAM 结构域的突变将 ZAKα 的活性与核糖体结合分离。最后，我们使用 3D 结构比较来鉴定并功能表征 ZAKα 中另一个具有 YEATS 结构域结构同源性的折叠结构域。这些发现使我们能够根据模块蛋白结构域之间相互作用的重新组织，构建一个核糖体模板化 ZAKα 激活的模型。总之，我们的工作不仅推进了对 ZAKα 激酶的蛋白结构域和 3D 结构的理解，也加深了我们对核糖体毒性应激反应如何被激活的理解。
