Major capsid protein VP1

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Major capsid protein VP1
A rendering of an icosahedral viral capsid comprising 72 pentamers of murine polyomavirus VP1, colored such that areas of the surface closer to the interior center appear blue and areas further away appear red. Rendered from PDB: 1SIE​.
Identifiers
SymbolVP1
PfamPF00718
InterProIPR000662
Available protein structures:
Pfam  structures / ECOD  
PDBRCSB PDB; PDBe; PDBj
PDBsumstructure summary

Major capsid protein VP1 is a

icosahedral structure consisting of 360 VP1 molecules organized into 72 pentamers. VP1 molecules possess a surface binding site that interacts with sialic acids attached to glycans, including some gangliosides, on the surfaces of cells to initiate the process of viral infection. The VP1 protein, along with capsid components VP2 and VP3, is expressed from the "late region" of the circular viral genome.[1][2][3]

Structure

VP1 is the major structural component of the

disulfide bonds.[7]

The structure of an individual pentamer of the murine polyomavirus VP1 protein. Each monomer is colored differently. The conformationally flexible C-terminal arms are shown here in conformations compatible with binding to neighboring molecules. Superposed is a fragment of the polyomavirus VP2 protein (white), which binds to a pentamer oriented toward the central cavity. VP1 is from PDB: 1SIE​; VP2 is from PDB: 1CN3 1CN3​.

The VP1 protein monomer is primarily composed of

disordered and forms interactions between neighboring pentamers in the assembled capsid. The flexibility of the C-terminal arm will enable it to adopt different conformations in the six distinct interaction environments imposed by the symmetry of the icosahedral assembly.[4][8] The C-terminus also contains a basic nuclear localization sequence,[5]: 316  while the N-terminus - which is oriented toward the center of the assembled capsid - contains basic residues that facilitate non-sequence-specific interactions with DNA.[9]

A rendered capsid image with the symmetry-related VP1 monomers shown in different colors and centered on a strict pentamer, producing a radial symmetry effect.
The same capsid structure as above, colored to illustrate the assembly of the icosahedral architecture from VP1 pentamers. Each symmetry-related VP1 monomer is shown in a different color. From PDB: 1SIE​.

Function and trafficking

Murine polyomavirus VP1 in complex with the GT1a glycan. GT1a is shown in yellow and the VP1 monomer with a white surface and a blue protein backbone. A complex network of hydrogen bonds, many water-mediated, is shown at the binding surface by orange lines, with participating protein residues shown as sticks. Mutations of the two residues shown in cyan at the bottom of the figure can significantly affect pathogenicity. From PDB: 5CPW​.[3]

The VP1 protein is responsible for initiating the process of infecting a cell by binding to

disulfide bonds, likely occur in the ER. For some polyomaviruses, VP1 has been detected reaching the nucleus along with the viral genome, though it is unclear how the genomic DNA disengages from VP1.[12]

All of the capsid proteins are expressed from the late region of the viral genome, so named because expression occurs only late in the infection process. VP1 has a

oligomerization to form capsids occurs in the nucleus.[5]
: 316–17 

References

  1. ^
    PMID 19505651
    .
  2. ^
    PMID 20332429
    .
  3. ^
    PMID 26474293
    .
  4. ^
    PMID 9628860
    .
  5. ^
    ISBN 978-94-007-6552-8
    .
  6. S2CID 25800023
    .
  7. PMID 10644335
    .
  8. ^
    PMID 8805524
    .
  9. PMID 1847446
    .
  10. PMID 12941687
    .
  11. PMID 25078361
    .
  12. ^
    PMID 20373089
    .
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