Journal: Nature / Year: 2020 Title: Structure of replicating SARS-CoV-2 polymerase. Authors: Hauke S Hillen / Goran Kokic / Lucas Farnung / Christian Dienemann / Dimitry Tegunov / Patrick Cramer / Abstract: The new coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) uses an RNA-dependent RNA polymerase (RdRp) for the replication of its genome and the transcription of its genes. ...The new coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) uses an RNA-dependent RNA polymerase (RdRp) for the replication of its genome and the transcription of its genes. Here we present a cryo-electron microscopy structure of the SARS-CoV-2 RdRp in an active form that mimics the replicating enzyme. The structure comprises the viral proteins non-structural protein 12 (nsp12), nsp8 and nsp7, and more than two turns of RNA template-product duplex. The active-site cleft of nsp12 binds to the first turn of RNA and mediates RdRp activity with conserved residues. Two copies of nsp8 bind to opposite sides of the cleft and position the second turn of RNA. Long helical extensions in nsp8 protrude along exiting RNA, forming positively charged 'sliding poles'. These sliding poles can account for the known processivity of RdRp that is required for replicating the long genome of coronaviruses. Our results enable a detailed analysis of the inhibitory mechanisms that underlie the antiviral activity of substances such as remdesivir, a drug for the treatment of coronavirus disease 2019 (COVID-19).
Name: RNA product / Class: RNA / Structure: OTHER / Synthetic: No Sequence:
UUUUCAUGCU ACGCGUAG
Mass
Theoretical: 5.687372 kDa
Source
Species: synthetic construct (others)
+
Component #9: ligand, ZINC ION
Ligand
Name: ZINC ION / Number of Copies: 2 / Recombinant expression: No
Mass
Theoretical: 6.540905 MDa
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Experimental details
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Sample preparation
Specimen
Specimen state: Particle / Method: cryo EM
Sample solution
pH: 7.4
Support film
15 mA, Pelco EasyGlow
Vitrification
Instrument: FEI VITROBOT MARK IV / Cryogen name: ETHANE / Temperature: 277 K / Humidity: 100 %
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Electron microscopy imaging
Experimental equipment
Model: Titan Krios / Image courtesy: FEI Company
Imaging
Microscope: FEI TITAN KRIOS
Electron gun
Electron source: FIELD EMISSION GUN / Accelerating voltage: 300 kV / Electron dose: 60 e/Å2 / Illumination mode: SPOT SCAN
Lens
Magnification: 105000 X (nominal), 105000 X (calibrated) / Cs: 2.7 mm / Imaging mode: BRIGHT FIELD / Defocus: 500.0 - 1500.0 nm / Energy filter: GIF Quantum LS
Specimen Holder
Model: FEI TITAN KRIOS AUTOGRID HOLDER
Camera
Detector: OTHER
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Image acquisition
Image acquisition
Number of digital images: 8168 Details: Images were collected at 30 degree stage tilt. Non-superres.
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Image processing
Processing
Method: single particle reconstruction / Applied symmetry: C1 (asymmetric) / Number of projections: 418000
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