Biotechnology and Biological Sciences Research Council (BBSRC)
BB/X017028/1
United Kingdom
Wellcome Trust
WT207446/Z/17/Z
United Kingdom
Wellcome Trust
WT108877/B/15/Z
United Kingdom
Citation
Journal: Nat Commun / Year: 2024 Title: Structure of the recombinant RNA polymerase from African Swine Fever Virus. Authors: Simona Pilotto / Michal Sýkora / Gwenny Cackett / Christopher Dulson / Finn Werner / Abstract: African Swine Fever Virus is a Nucleo-Cytoplasmic Large DNA Virus that causes an incurable haemorrhagic fever in pigs with a high impact on global food security. ASFV replicates in the cytoplasm of ...African Swine Fever Virus is a Nucleo-Cytoplasmic Large DNA Virus that causes an incurable haemorrhagic fever in pigs with a high impact on global food security. ASFV replicates in the cytoplasm of the infected cell and encodes its own transcription machinery that is independent of cellular factors, however, not much is known about how this system works at a molecular level. Here, we present methods to produce recombinant ASFV RNA polymerase, functional assays to screen for inhibitors, and high-resolution cryo-electron microscopy structures of the ASFV RNAP in different conformational states. The ASFV RNAP bears a striking resemblance to RNAPII with bona fide homologues of nine of its twelve subunits. Key differences include the fusion of the ASFV assembly platform subunits RPB3 and RPB11, and an unusual C-terminal domain of the stalk subunit vRPB7 that is related to the eukaryotic mRNA cap 2´-O-methyltransferase 1. Despite the high degree of structural conservation with cellular RNA polymerases, the ASFV RNAP is resistant to the inhibitors rifampicin and alpha-amanitin. The cryo-EM structures and fully recombinant RNAP system together provide an important tool for the design, development, and screening of antiviral drugs in a low biosafety containment environment.
Name: DNA-directed RNA polymerase RPB2 homolog / type: protein_or_peptide / ID: 2 Details: The protein was tagged at the N-terminus with a His-ZZ cleavable tag. The tag was cleaved with TEV protease leaving a G as the first residue Number of copies: 1 / Enantiomer: LEVO
Name: ZINC ION / type: ligand / ID: 9 / Number of copies: 6 / Formula: ZN
Molecular weight
Theoretical: 65.409 Da
+
Macromolecule #10: MAGNESIUM ION
Macromolecule
Name: MAGNESIUM ION / type: ligand / ID: 10 / Number of copies: 1 / Formula: MG
Molecular weight
Theoretical: 24.305 Da
-
Experimental details
-
Structure determination
Method
cryo EM
Processing
single particle reconstruction
Aggregation state
particle
-
Sample preparation
Concentration
0.05 mg/mL
Buffer
pH: 8 Component:
Concentration
Formula
Name
50.0 mM
C4H11NO3
tris
250.0 mM
NaCl
sodium chloride
1.0 mM
MgCl2
magnesium chloride
0.1 mM
ZnSO4
zinc sulfate
1.0 mM
C4H10O2S2
DTT
Grid
Model: C-flat-1.2/1.3 / Material: COPPER / Mesh: 400 / Support film - Material: CARBON / Support film - topology: HOLEY / Pretreatment - Type: GLOW DISCHARGE / Pretreatment - Time: 60 sec. / Pretreatment - Atmosphere: AIR Details: The grid was covered with freshly prepared graphene oxide prior to use
Vitrification
Cryogen name: ETHANE / Chamber humidity: 95 % / Chamber temperature: 277 K / Instrument: FEI VITROBOT MARK IV
Details
This sample was monodisparse
-
Electron microscopy
Microscope
FEI TITAN KRIOS
Specialist optics
Energy filter - Name: GIF Bioquantum / Energy filter - Slit width: 20 eV
Image recording
Film or detector model: GATAN K3 (6k x 4k) / Number real images: 14638 / Average exposure time: 2.6 sec. / Average electron dose: 48.152 e/Å2 Details: Images were collected in movie-mode for a total of 50 frames per image. The data collection was carried out in super-resolution mode and binned 2 on-the-fly.
Electron beam
Acceleration voltage: 300 kV / Electron source: FIELD EMISSION GUN
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