Zheng Wei-Hua, Ni Run-Ze, Ran Xiang-Hong, Mu Dan
Institute of Life Sciences, Chongqing Medical University, Chongqing, 400016, China; Institute of Primate Translational Medicine, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China.
Institute of Life Sciences, Chongqing Medical University, Chongqing, 400016, China.
Biochem Biophys Res Commun. 2025 Sep 1;777:152244. doi: 10.1016/j.bbrc.2025.152244. Epub 2025 Jun 21.
Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection has claimed millions of lives and has been a global threat since its emergence. Multiple SARS-CoV-2-encoded proteins have been shown to exert interferon-I (IFN-I)-antagonizing effects, which contribute to severe pathogenesis. We previously reported that the papain-like protease (PLpro) of SARS-CoV-2 and SARS-CoV, a closely related highly pathogenic coronavirus, counteracts IFN production via its deubiquitinating (DUB) activity. In this study, we reveal a new mechanism by which SARS-CoV-2 negatively regulates host innate antiviral responses. Both PLpro proteins from SARS-CoV and SARS-CoV-2 mediated the proteolytic cleavage of TBK1, the hub kinase in the IFN-I signaling pathway. Using point mutants, we demonstrated that the catalytic triad, which is composed of C111, H272, and D286, and the enzyme activity regulatory site, W93, are essential for the ability of SARS-CoV-2 PLpro to cleave the TBK1 protein and for the inhibitory effect on TBK1-triggered IFN expression. However, the mutants failed to abrogate the suppressive effect of SARS-CoV PLpro on Sendai virus (SeV)-induced IFN-I promoter activation, indicating that PLpro inhibits the dsRNA-induced IFN response partly by cleaving TBK1. Collectively, our findings suggest a conserved mechanism through which highly pathogenic SARS-CoV and SARS-CoV-2 harness their PLpro proteins to suppress IFN expression at the level of TBK1, resulting in the evasion of the host innate antiviral response.
严重急性呼吸综合征冠状病毒2（SARS-CoV-2）感染已导致数百万人死亡，自出现以来一直是全球威胁。多种SARS-CoV-2编码蛋白已被证明具有干扰素-I（IFN-I）拮抗作用，这有助于严重发病机制。我们之前报道过，SARS-CoV-2和SARS-CoV（一种密切相关的高致病性冠状病毒）的木瓜样蛋白酶（PLpro）通过其去泛素化（DUB）活性抵消IFN的产生。在本研究中，我们揭示了SARS-CoV-2负向调节宿主先天性抗病毒反应的新机制。SARS-CoV和SARS-CoV-2的PLpro蛋白均介导了IFN-I信号通路中的枢纽激酶TBK1的蛋白水解切割。使用点突变体，我们证明由C111、H272和D286组成的催化三联体以及酶活性调节位点W93对于SARS-CoV-2 PLpro切割TBK1蛋白的能力以及对TBK1触发的IFN表达的抑制作用至关重要。然而，这些突变体未能消除SARS-CoV PLpro对仙台病毒（SeV）诱导的IFN-I启动子激活的抑制作用，表明PLpro部分通过切割TBK1来抑制双链RNA诱导的IFN反应。总的来说，我们的研究结果表明了一种保守机制，通过该机制高致病性的SARS-CoV和SARS-CoV-2利用它们的PLpro蛋白在TBK1水平抑制IFN表达，从而逃避宿主先天性抗病毒反应。
