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Coupling of N7-methyltransferase and 3′-5′ exoribonuclease with SARS-CoV-2 polymerase reveals mechanisms for capping and proofreading

Yan, Liming and Yang, Yunxiang and Li, Mingyu and Zhang, Ying and Zheng, Litao and Ge, Jin and Huang, Yucen C. and Liu, Zhenyu and Wang, Tao and Gao, Shan and Zhang, Ran and Huang, Yuanyun Y. and Guddat, Luke W. and Gao, Yan and Rao, Zihe and Lou, Zhiyong (2021) Coupling of N7-methyltransferase and 3′-5′ exoribonuclease with SARS-CoV-2 polymerase reveals mechanisms for capping and proofreading. Cell, 184 (13). pp. 3474-3485. ISSN 0092-8674. PMCID PMC8142856. doi:10.1016/j.cell.2021.05.033. https://resolver.caltech.edu/CaltechAUTHORS:20210701-155032256

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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 (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) (^(7Me)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.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.cell.2021.05.033DOIArticle
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8142856PubMed CentralArticle
Additional Information:© 2021 Elsevier Inc. Received 1 April 2021, Revised 20 April 2021, Accepted 19 May 2021, Available online 24 May 2021. This work was supported by the National Natural Science Foundation of China (U20A20135), the National Program on Key Research Project of China (2020YFA0707500 and 2017YFC0840300), Tsinghua University Spring Breeze Fund (2020Z99CFG015), and the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB37030201). Author contributions: Z.R. and Z. Lou conceived the project and designed the experiments. L.Y., Y.Y., M.L., J.G., Y.C.H., L.Z., Y.Z., S.G., Y.Y.H., and R.Z. performed sample purification, and L.Y. prepared for RTC assembly. L.Y., Y.Y., and Y.Z. for sample native electrophoretic mobility shift assays. Y.G., Z. Liu, and T.W. collected cryo-EM data. L.Y., Z. Lou, and Z.R. analyzed the data. Z.R., Z. Lou, L.Y., and L.W.G. wrote the manuscript. All authors discussed the experiments, read, and approved the manuscript. The authors declare no competing interests.
Group:COVID-19
Funders:
Funding AgencyGrant Number
National Natural Science Foundation of ChinaU20A20135
National Program on Key Research Project of China2020YFA0707500
National Program on Key Research Project of China2017YFC0840300
Tsinghua University2020Z99CFG015
Chinese Academy of SciencesXDB37030201
Subject Keywords:SARS-CoV-2; replication-transcription complex; mRNA capping; proofreading; cryo-EM
Issue or Number:13
PubMed Central ID:PMC8142856
DOI:10.1016/j.cell.2021.05.033
Record Number:CaltechAUTHORS:20210701-155032256
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20210701-155032256
Official Citation: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, Coupling of N7-methyltransferase and 3′-5′ exoribonuclease with SARS-CoV-2 polymerase reveals mechanisms for capping and proofreading, Cell, Volume 184, Issue 13, 2021, Pages 3474-3485.e11, ISSN 0092-8674, https://doi.org/10.1016/j.cell.2021.05.033. (https://www.sciencedirect.com/science/article/pii/S0092867421006632)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109697
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:02 Jul 2021 19:50
Last Modified:06 Jul 2021 22:07

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