Rao Youliang, Wang Ting-Yu, Qin Chao, Espinosa Bianca, Liu Qizhi, Ekanayake Arunika, Zhao Jun, Savas Ali Can, Zhang Shu, Zarinfar Mehrnaz, Liu Yongzhen, Zhu Wenjie, Graham Nicholas, Jiang Taijiao, Zhang Chao, Feng Pinghui
Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90089, USA.
Department of Chemistry, Dornsife College of Arts, Letters and Sciences, University of Southern California, Los Angeles, CA 90089, USA.
bioRxiv. 2021 Feb 7:2021.02.05.429959. doi: 10.1101/2021.02.05.429959.
The newly emerged SARS-CoV-2 caused a global pandemic with astonishing mortality and morbidity. The mechanisms underpinning its highly infectious nature remain poorly understood. We report here that SARS-CoV-2 exploits cellular CTP synthetase 1 (CTPS1) to promote CTP synthesis and suppress interferon (IFN) induction. Screening a SARS-CoV-2 expression library identified ORF7b and ORF8 that suppressed IFN induction via inducing the deamidation of interferon regulatory factor 3 (IRF3). Deamidated IRF3 fails to bind the promoters of classic IRF3-responsible genes, thus muting IFN induction. Conversely, a shRNA-mediated screen focused on cellular glutamine amidotransferases corroborated that CTPS1 deamidates IRF3 to inhibit IFN induction. Functionally, ORF7b and ORF8 activate CTPS1 to promote CTP synthesis while shutting down IFN induction. synthesis of small-molecule inhibitors of CTPS1 enabled CTP depletion and IFN induction in SARS-CoV-2 infection, thus impeding SARS-CoV-2 replication. Our work uncovers a strategy that a viral pathogen couples immune evasion to metabolic activation to fuel viral replication. Inhibition of the cellular CTPS1 offers an attractive means for developing antiviral therapy that would be resistant to SARS-CoV-2 mutation.
新出现的严重急性呼吸综合征冠状病毒2（SARS-CoV-2）引发了一场全球大流行，其死亡率和发病率惊人。其高传染性背后的机制仍知之甚少。我们在此报告，SARS-CoV-2利用细胞胞苷三磷酸合成酶1（CTPS1）来促进CTP合成并抑制干扰素（IFN）诱导。筛选SARS-CoV-2表达文库鉴定出通过诱导干扰素调节因子3（IRF3）脱酰胺作用来抑制IFN诱导的开放阅读框7b（ORF7b）和开放阅读框8（ORF8）。脱酰胺的IRF3无法结合经典的IRF3相关基因的启动子，从而使IFN诱导沉默。相反，针对细胞谷氨酰胺酰胺转移酶的短发夹RNA介导的筛选证实CTPS1使IRF3脱酰胺以抑制IFN诱导。在功能上，ORF7b和ORF8激活CTPS1以促进CTP合成，同时关闭IFN诱导。CTPS1小分子抑制剂的合成能够在SARS-CoV-2感染中实现CTP消耗和IFN诱导，从而阻碍SARS-CoV-2复制。我们的工作揭示了一种病毒病原体将免疫逃避与代谢激活相结合以促进病毒复制的策略。抑制细胞CTPS1为开发对SARS-CoV-2突变具有抗性的抗病毒疗法提供了一种有吸引力的手段。
