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Title | Coupling of N7-methyltransferase and 3'-5' exoribonuclease with SARS-CoV-2 polymerase reveals mechanisms for capping and proofreading. |
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Journal, issue, pages | Cell, Vol. 184, Issue 13, Page 3474-3485.e11, Year 2021 |
Publish date | Jun 24, 2021 |
Authors | Liming Yan / Yunxiang Yang / Mingyu Li / Ying Zhang / Litao Zheng / Ji Ge / Yucen C Huang / Zhenyu Liu / Tao Wang / Shan Gao / Ran Zhang / Yuanyun Y Huang / Luke W Guddat / Yan Gao / Zihe Rao / Zhiyong Lou / |
PubMed Abstract | The capping of mRNA and the proofreading play essential roles in SARS-CoV-2 replication and transcription. Here, we present the cryo-EM structure of the SARS-CoV-2 replication-transcription complex ...The capping of mRNA and the proofreading play essential roles in SARS-CoV-2 replication and transcription. Here, we present the cryo-EM structure of the SARS-CoV-2 replication-transcription complex (RTC) in a form identified as Cap(0)-RTC, which couples a co-transcriptional capping complex (CCC) composed of nsp12 NiRAN, nsp9, the bifunctional nsp14 possessing an N-terminal exoribonuclease (ExoN) and a C-terminal N7-methyltransferase (N7-MTase), and nsp10 as a cofactor of nsp14. Nsp9 and nsp12 NiRAN recruit nsp10/nsp14 into the Cap(0)-RTC, forming the N7-CCC to yield cap(0) (GpppA) at 5' end of pre-mRNA. A dimeric form of Cap(0)-RTC observed by cryo-EM suggests an in trans backtracking mechanism for nsp14 ExoN to facilitate proofreading of the RNA in concert with polymerase nsp12. These results not only provide a structural basis for understanding co-transcriptional modification of SARS-CoV-2 mRNA but also shed light on how replication fidelity in SARS-CoV-2 is maintained. |
External links | Cell / PubMed:34143953 / PubMed Central |
Methods | EM (single particle) |
Resolution | 3.35 Å |
Structure data | EMDB-31138, PDB-7egq: EMDB-31146, PDB-7eiz: |
Chemicals | ChemComp-ZN: ChemComp-MG: |
Source |
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Keywords | VIRAL PROTEIN/RNA / SARS-CoV-2 / Replication-Transcription Complex / nsp10 and nsp14 / VIRAL PROTEIN-RNA COMPLEX |