Department of Molecular Biology, College of Natural Sciences, Pusan National University, 2, Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan, 46241, Republic of Korea.
Insitute of Systems Biology, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan, 46241, Republic of Korea.
Biochem Biophys Res Commun. 2023 Jul 12;665:1-9. doi: 10.1016/j.bbrc.2023.04.107. Epub 2023 Apr 29.
E3L (RNA-binding protein E3) is one of the key IFN resistance genes encoded by VV and consists of 190 amino acids with a highly conserved carboxy-terminal double-stranded RNA-binding domain (dsRBD). PKR (dsRNA-dependent protein kinase) is an IFN-induced protein involved in anti-cell and antiviral activity. PKR inhibits the initiation of translation through alpha subunit of the initiation factor eIF2 (eIF2α) and mediates several transcription factors such as NF-κB, p53 or STATs. Activated PKR also induces apoptosis in vaccinia virus infection. E3L is required for viral IFN resistance and directly binds to PKR to block activation of PKR. In this work, we determined the three-dimensional complex structure of E3L and PKR using cryo-EM and determined the important residues involved in the interaction. In addition, PKR peptide binds to E3L and can increase protein levels of phosphorus-PKR and phosphorus-eIF2α-induced cell apoptosis through upregulation of phosphorus-PKR in HEK293 cells. Taken together, structural insights into E3L and PKR will provide a new optimization and development of vaccinia virus drugs.
E3L（RNA 结合蛋白 E3）是 VV 编码的 IFN 耐药基因之一，由 190 个氨基酸组成，具有高度保守的羧基末端双链 RNA 结合域（dsRBD）。PKR（双链 RNA 依赖性蛋白激酶）是一种 IFN 诱导的蛋白，参与抗细胞和抗病毒活性。PKR 通过起始因子 eIF2 的 α 亚基（eIF2α）抑制翻译的起始，并介导多种转录因子，如 NF-κB、p53 或 STATs。激活的 PKR 也会诱导痘苗病毒感染中的细胞凋亡。E3L 是病毒 IFN 耐药所必需的，它直接与 PKR 结合以阻止 PKR 的激活。在这项工作中，我们使用冷冻电镜确定了 E3L 和 PKR 的三维复合物结构，并确定了相互作用中涉及的重要残基。此外，PKR 肽与 E3L 结合，并可通过上调 HEK293 细胞中磷 PKR 来增加磷 PKR 和磷 eIF2α诱导细胞凋亡的蛋白水平。总之，对 E3L 和 PKR 的结构见解将为痘苗病毒药物的新优化和开发提供依据。
