Center for RNA Science and Therapeutics, Department of Biochemistry, Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44016, United States.
Center for RNA Science and Therapeutics, Department of Biochemistry, Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44016, United States.
J Mol Biol. 2023 Oct 1;435(19):168217. doi: 10.1016/j.jmb.2023.168217. Epub 2023 Jul 28.
The DEAD-box RNA helicase DDX3X promotes translation initiation and associates with stress granules. A range of diverse viruses produce proteins that target DDX3X, including hepatitis C, dengue, vaccinia, and influenza A. The interaction of some of these viral proteins with DDX3X has been shown to affect antiviral intracellular signaling, but it is unknown whether and how viral proteins impact the biochemical activities of DDX3X and its physical roles in cells. Here we show that the protein K7 from vaccinia virus, which binds to an intrinsically disordered region in the N-terminus of DDX3X, inhibits RNA helicase and RNA-stimulated ATPase activities, as well as liquid-liquid phase separation of DDX3X in vitro. We demonstrate in HCT 116 cells that K7 inhibits association of DDX3X with stress granules, as well as the formation of aberrant granules induced by expression of DDX3X with a point mutation linked to medulloblastoma and DDX3X syndrome. The results show that targeting of the intrinsically disordered N-terminus is an effective viral strategy to modulate the biochemical functions and subcellular localization of DDX3X. Our findings also have potential therapeutic implications for diseases linked to aberrant DDX3X granule formation.
DEAD -box RNA 解旋酶 DDX3X 促进翻译起始并与应激颗粒相关联。多种不同的病毒产生靶向 DDX3X 的蛋白质，包括丙型肝炎、登革热、牛痘和甲型流感。已经表明，这些病毒蛋白中的一些与 DDX3X 的相互作用会影响抗病毒的细胞内信号转导，但尚不清楚病毒蛋白是否以及如何影响 DDX3X 的生化活性及其在细胞中的物理作用。在这里，我们表明，来自牛痘病毒的蛋白 K7 与 DDX3X 氨基末端的一个固有无序区域结合，可抑制 RNA 解旋酶和 RNA 刺激的 ATP 酶活性，以及 DDX3X 在体外的液-液相分离。我们在 HCT 116 细胞中证明，K7 抑制 DDX3X 与应激颗粒的关联，以及由与髓母细胞瘤和 DDX3X 综合征相关的点突变表达的 DDX3X 诱导的异常颗粒的形成。研究结果表明，靶向固有无序的 N 末端是一种有效的病毒策略，可调节 DDX3X 的生化功能和亚细胞定位。我们的研究结果也可能对与异常 DDX3X 颗粒形成相关的疾病具有潜在的治疗意义。
