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Characterization of the minor polypeptides in the foot-and-mouth disease particle
Abstract:
In addition to the four major polypeptides VP1 and VP4, foot-and-mouth disease virus particles contain two minor polypeptides, mol. wt. 40 X 10(3) (P40) and 52 X 10(3) (P52). Extensive purification procedures failed to remove these minor polypeptides from the virus particles. Polypeptide P40 co-electrophoresed in SDS-polyacrylamide gels with VP0, the probable precursor of VP2 and VP4 and was inaccessible to iodination in situ. The second minor polypeptide, P52, co-electrophoresed with the virus infection associated (VIA) antigen found in large amounts in harvests of the virus grown in BHK 21 cells. Polypeptide P52 was shown to be located near the surface of the virus particle by iodination experiments and by its removal on incubating the particles with trypsin or chymotrypsin. Pactamycin mapping showed that this polypeptide was not a precursor of the structural polypeptides. About one copy of P52 and 4 copies of P40 were found in the virus particles sedimenting at 146S. However a larger number of copies was found in those virus particles sedimenting faster than the 146S peak.
Insights
Foot-and-mouth disease virus contains minor polypeptides P40 and P52. P40 is inaccessible to iodination, while P52 is surface-located and not a structural polypeptide precursor.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Foot-and-mouth disease virus (FMDV) particles are primarily composed of four major polypeptides: VP1, VP4, VP0, VP2, and VP3.
- Minor polypeptides P40 and P52 are consistently found in purified FMDV particles, suggesting their potential association with the virus structure or replication.
Purpose of the Study:
- To characterize the identity and location of minor polypeptides P40 and P52 in FMDV particles.
- To determine if P40 and P52 are precursors of structural viral polypeptides.
Main Methods:
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for polypeptide separation and identification.
- In situ iodination to assess polypeptide surface accessibility.
- Enzymatic digestion with trypsin and chymotrypsin to evaluate polypeptide location.
- Pactamycin mapping to investigate polypeptide precursor relationships.
Main Results:
- Polypeptide P40 co-migrated with VP0 and was not accessible to iodination, indicating an internal location.
- Polypeptide P52 co-migrated with the virus infection associated (VIA) antigen and was accessible to iodination and enzymatic removal, suggesting surface localization.
- Pactamycin mapping confirmed that neither P40 nor P52 are precursors of the major structural viral polypeptides.
- Approximately one copy of P52 and four copies of P40 were detected per 146S FMDV particle, with higher amounts in faster sedimenting particles.
Conclusions:
- The minor polypeptides P40 and P52 are distinct components of FMDV particles, not precursors of structural proteins.
- P40 appears to be an internal component, possibly related to VP0, while P52 is a surface-associated protein, potentially the VIA antigen.
- These findings contribute to a deeper understanding of FMDV particle composition and assembly.