Abstract
The coronavirus SARS-CoV-2 uses an RNA-dependent RNA polymerase (RdRp) to replicate and transcribe its genome. Previous structures of the RdRp revealed a monomeric enzyme composed of the catalytic subunit nsp12, two copies of subunit nsp8, and one copy of subunit nsp7. Here we report an alternative, dimeric form of the enzyme and resolve its structure at 5.5 Å resolution. In this structure, the two RdRps contain only one copy of nsp8 each and dimerize via their nsp7 subunits to adopt an antiparallel arrangement. We speculate that the RdRp dimer facilitates template switching during production of sub-genomic RNAs.
Highlights
The coronavirus SARS-CoV-2 uses an RNA-dependent RNA polymerase (RdRp) to replicate and transcribe its genome
Replication and transcription of the RNA genome of the coronavirus SARS-CoV-2 rely on the viral RNA-dependent RNA polymerase (RdRp)[1,2,3,4,5]
Following the structure of the RdRp of SARS-CoV6, structures of the RdRp of SARS-CoV-2 were obtained in free form[7] and as a complex with bound RNA template–product duplex[8,9,10,11]
Summary
The coronavirus SARS-CoV-2 uses an RNA-dependent RNA polymerase (RdRp) to replicate and transcribe its genome. In one of our published data sets (structure 311), we detected many particles that showed RdRps with a preferred NN distance of 80 Å and a relative orientation of 180° (Supplementary Fig. 1a, b), indicating the existence of a structurally defined RdRp dimer. The structure of the antiparallel RdRp dimer showed that the two polymerases interact via their nsp[7] subunits, with the nsp[7] helices α1 and α3 (residues 2–20 and 44–62, respectively) contacting each other (Fig. 1).
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