+Open data
-Basic information
Entry | Database: PDB / ID: 8cfa | ||||||
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Title | HK97 Prohead II as part of a DNA packaging complex | ||||||
Components | Major capsid subunit | ||||||
Keywords | VIRAL PROTEIN / prohead / HK97 / bacteriophage / packaging | ||||||
Function / homology | Phage capsid / Phage capsid family / Major capsid subunit Function and homology information | ||||||
Biological species | Hendrixvirus | ||||||
Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 3.06 Å | ||||||
Authors | Hawkins, D.E.D.P. / Antson, A.A. | ||||||
Funding support | United Kingdom, 1items
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Citation | Journal: Nucleic Acids Res / Year: 2023 Title: Insights into a viral motor: the structure of the HK97 packaging termination assembly. Authors: Dorothy E D P Hawkins / Oliver W Bayfield / Herman K H Fung / Daniel N Grba / Alexis Huet / James F Conway / Alfred A Antson / Abstract: Double-stranded DNA viruses utilise machinery, made of terminase proteins, to package viral DNA into the capsid. For cos bacteriophage, a defined signal, recognised by small terminase, flanks each ...Double-stranded DNA viruses utilise machinery, made of terminase proteins, to package viral DNA into the capsid. For cos bacteriophage, a defined signal, recognised by small terminase, flanks each genome unit. Here we present the first structural data for a cos virus DNA packaging motor, assembled from the bacteriophage HK97 terminase proteins, procapsids encompassing the portal protein, and DNA containing a cos site. The cryo-EM structure is consistent with the packaging termination state adopted after DNA cleavage, with DNA density within the large terminase assembly ending abruptly at the portal protein entrance. Retention of the large terminase complex after cleavage of the short DNA substrate suggests that motor dissociation from the capsid requires headful pressure, in common with pac viruses. Interestingly, the clip domain of the 12-subunit portal protein does not adhere to C12 symmetry, indicating asymmetry induced by binding of the large terminase/DNA. The motor assembly is also highly asymmetric, showing a ring of 5 large terminase monomers, tilted against the portal. Variable degrees of extension between N- and C-terminal domains of individual subunits suggest a mechanism of DNA translocation driven by inter-domain contraction and relaxation. | ||||||
History |
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-Structure visualization
Structure viewer | Molecule: MolmilJmol/JSmol |
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-Downloads & links
-Download
PDBx/mmCIF format | 8cfa.cif.gz | 542.3 KB | Display | PDBx/mmCIF format |
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PDB format | pdb8cfa.ent.gz | 452.3 KB | Display | PDB format |
PDBx/mmJSON format | 8cfa.json.gz | Tree view | PDBx/mmJSON format | |
Others | Other downloads |
-Validation report
Summary document | 8cfa_validation.pdf.gz | 1.6 MB | Display | wwPDB validaton report |
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Full document | 8cfa_full_validation.pdf.gz | 1.6 MB | Display | |
Data in XML | 8cfa_validation.xml.gz | 64.6 KB | Display | |
Data in CIF | 8cfa_validation.cif.gz | 95.6 KB | Display | |
Arichive directory | https://data.pdbj.org/pub/pdb/validation_reports/cf/8cfa ftp://data.pdbj.org/pub/pdb/validation_reports/cf/8cfa | HTTPS FTP |
-Related structure data
Related structure data | 16624MC 8cezC C: citing same article (ref.) M: map data used to model this data |
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Similar structure data | Similarity search - Function & homologyF&H Search |
-Links
-Assembly
Deposited unit |
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-Components
#1: Protein | Mass: 42286.453 Da / Num. of mol.: 7 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Hendrixvirus / Gene: HK022_5 / Cell line (production host): LE392 / Production host: Escherichia phage EcSzw-2 (virus) / References: UniProt: Q77WA0 |
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-Experimental details
-Experiment
Experiment | Method: ELECTRON MICROSCOPY |
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EM experiment | Aggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction |
-Sample preparation
Component | Name: Hendrixvirus / Type: VIRUS Details: Proheads were produced by infection of E. coli 594 cells with HK97 amber mutant amC2, propagated using Escherichia LE392 cells. This map was derived from a prohead with portal and large terminase bound. Entity ID: all / Source: RECOMBINANT |
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Molecular weight | Value: 0.56 MDa / Experimental value: NO |
Source (natural) | Organism: Hendrixvirus / Strain: HK97 |
Source (recombinant) | Organism: Escherichia phage EcSzw-2 (virus) / Strain: LE392 / Cell: E.coli |
Details of virus | Empty: NO / Enveloped: NO / Isolate: STRAIN / Type: VIRION |
Natural host | Organism: Escherichia phage EcSzw-2 |
Buffer solution | pH: 7.5 Details: final buffer = 20 mM Tris pH 7.5, 10 mM MgCl2, 50 mM KGlu, 5 mM ATP-gamma-S |
Specimen | Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES Details: Packaging reactions 30 nM hk97 proheads, 2.5 micromolar large terminase, 5 micromolar small terminase and 30 nM DNA, 75 micromolar ATP were incubated for 2 mins then 5 micromolar ATP-gamma-S was added. |
Specimen support | Grid material: COPPER / Grid mesh size: 200 divisions/in. / Grid type: Quantifoil |
Vitrification | Instrument: FEI VITROBOT MARK IV / Cryogen name: ETHANE / Humidity: 90 % |
-Electron microscopy imaging
Experimental equipment | Model: Titan Krios / Image courtesy: FEI Company |
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Microscopy | Model: TFS KRIOS |
Electron gun | Electron source: FIELD EMISSION GUN / Accelerating voltage: 300 kV / Illumination mode: FLOOD BEAM |
Electron lens | Mode: BRIGHT FIELD / Nominal defocus max: 2500 nm / Nominal defocus min: 500 nm |
Image recording | Electron dose: 40 e/Å2 / Film or detector model: GATAN K3 (6k x 4k) / Num. of grids imaged: 1 |
-Processing
EM software |
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CTF correction | Type: PHASE FLIPPING AND AMPLITUDE CORRECTION | ||||||||||||||||||||||||
Particle selection | Num. of particles selected: 82279 | ||||||||||||||||||||||||
Symmetry | Point symmetry: I (icosahedral) | ||||||||||||||||||||||||
3D reconstruction | Resolution: 3.06 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 82275 / Num. of class averages: 1 / Symmetry type: POINT | ||||||||||||||||||||||||
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