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Cleavage of Rous sarcoma viral polypeptide precursor into internal structural proteins in vitro involves viral
Abstract:
The polypeptide precursor pr76 to the internal viral group specific (gs) antigen proteins of Rous sarcoma virus, synthesized in a cell-free system of ascites cells, has been processed in vitro into the viral proteins by purified viral protein p15 as well as by disrupted Rous sarcoma virus. Disrupted Rauscher murine leukemia virus does not stimulate the cleavage process in vitro. Autocatalytic cleavage of the polypeptide precursor pr76 or Rous sarcoma virus, which contains the peptide sequence of p15, is not observed.
Insights
Rous sarcoma virus precursor pr76 is processed into viral proteins by viral protein p15 in vitro. This cleavage is not induced by Rauscher murine leukemia virus or by self-cleavage of the precursor.
Area of Science:
- Molecular Virology
- Protein Biochemistry
- Retrovirus Research
Background:
- Rous sarcoma virus (RSV) produces viral proteins from a precursor polypeptide.
- Understanding the processing of viral precursors is crucial for retrovirus biology.
- The internal group-specific (gs) antigen proteins are key viral components.
Purpose of the Study:
- To investigate the in vitro processing of the Rous sarcoma virus pr76 precursor.
- To identify the factors responsible for cleaving the pr76 precursor into functional viral proteins.
- To determine if other retroviruses or self-cleavage mechanisms are involved.
Main Methods:
- Synthesis of the pr76 precursor in a cell-free system using ascites cells.
- In vitro incubation of pr76 with purified viral protein p15 from RSV.
- Incubation of pr76 with disrupted Rous sarcoma virus and disrupted Rauscher murine leukemia virus.
Main Results:
- Purified viral protein p15 effectively processed the pr76 precursor into viral proteins in vitro.
- Disrupted Rous sarcoma virus also induced the cleavage of the pr76 precursor.
- Disrupted Rauscher murine leukemia virus did not stimulate the cleavage of the pr76 precursor.
Conclusions:
- Viral protein p15 is a key enzyme responsible for processing the Rous sarcoma virus pr76 precursor.
- The cleavage mechanism is specific to Rous sarcoma virus components and not cross-reactive with Rauscher murine leukemia virus.
- Autocatalytic cleavage of pr76, even with the p15 sequence present, was not observed under these conditions.