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J Immunol ; 208(3): 753-761, 2022 02 01.
Article in English | MEDLINE | ID: covidwho-1614089


Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), has seriously threatened global public health. Severe COVID-19 has been reported to be associated with an impaired IFN response. However, the mechanisms of how SARS-CoV-2 antagonizes the host IFN response are poorly understood. In this study, we report that SARS-CoV-2 helicase NSP13 inhibits type I IFN production by directly targeting TANK-binding kinase 1 (TBK1) for degradation. Interestingly, inhibition of autophagy by genetic knockout of Beclin1 or pharmacological inhibition can rescue NSP13-mediated TBK1 degradation in HEK-293T cells. Subsequent studies revealed that NSP13 recruits TBK1 to p62, and the absence of p62 can also inhibit TBK1 degradation in HEK-293T and HeLa cells. Finally, TBK1 and p62 degradation and p62 aggregation were observed during SARS-CoV-2 infection in HeLa-ACE2 and Calu3 cells. Overall, our study shows that NSP13 inhibits type I IFN production by recruiting TBK1 to p62 for autophagic degradation, enabling it to evade the host innate immune response, which provides new insights into the transmission and pathogenesis of SARS-CoV-2 infection.

Autophagy , COVID-19/immunology , Coronavirus RNA-Dependent RNA Polymerase/physiology , Interferon Type I/biosynthesis , Methyltransferases/physiology , Protein Serine-Threonine Kinases/metabolism , RNA Helicases/physiology , SARS-CoV-2/physiology , Sequestosome-1 Protein/metabolism , Viral Nonstructural Proteins/physiology , Beclin-1/antagonists & inhibitors , Cell Line , Down-Regulation , Humans , Immune Evasion , Immunity, Innate , Immunoprecipitation , Interferon Type I/genetics , Multiprotein Complexes , Protein Aggregates , Protein Interaction Mapping
Cell Rep ; 36(9): 109650, 2021 08 31.
Article in English | MEDLINE | ID: covidwho-1363915


Coronaviruses have evolved elaborate multisubunit machines to replicate and transcribe their genomes. Central to these machines are the RNA-dependent RNA polymerase subunit (nsp12) and its intimately associated cofactors (nsp7 and nsp8). We use a high-throughput magnetic-tweezers approach to develop a mechanochemical description of this core polymerase. The core polymerase exists in at least three catalytically distinct conformations, one being kinetically consistent with incorporation of incorrect nucleotides. We provide evidence that the RNA-dependent RNA polymerase (RdRp) uses a thermal ratchet instead of a power stroke to transition from the pre- to post-translocated state. Ultra-stable magnetic tweezers enable the direct observation of coronavirus polymerase deep and long-lived backtracking that is strongly stimulated by secondary structures in the template. The framework we present here elucidates one of the most important structure-dynamics-function relationships in human health today and will form the grounds for understanding the regulation of this complex.

COVID-19/virology , Coronavirus RNA-Dependent RNA Polymerase/physiology , Nucleotides/metabolism , RNA, Viral/biosynthesis , SARS-CoV-2/physiology , Coronavirus RNA-Dependent RNA Polymerase/chemistry , High-Throughput Screening Assays , Humans , Models, Molecular , Molecular Conformation , Nucleotides/chemistry , RNA, Viral/chemistry , Single Molecule Imaging , Viral Nonstructural Proteins/chemistry , Viral Nonstructural Proteins/physiology