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Cleavage of a viral envelope precursor during the morphogenesis of Sindbis virus
Abstract:
In cells infected with a temperature-sensitive mutant of Sindbis virus, the cleavage of the precursor to one of the viral envelope proteins does not occur at the nonpermissive temperature. This precursor is found associated with the plasma membrane fraction obtained from the infected cell. Since this is the site at which the virus matures, this finding suggests that during Sindbis virus replication the precursor to the smaller proteins associates with the cell membrane and is then cleaved during the maturation of the virus.
Insights
In Sindbis virus-infected cells, a viral envelope protein precursor fails to cleave at nonpermissive temperatures. This precursor binds to the plasma membrane, indicating its role in viral maturation and Sindbis virus replication.
Area of Science:
- Virology
- Cell Biology
- Molecular Biology
Background:
- Sindbis virus is an enveloped RNA virus that replicates in the cytoplasm of infected cells.
- Viral envelope proteins are synthesized as precursors that undergo proteolytic cleavage to form mature, functional proteins.
- The precise mechanisms and cellular locations of Sindbis virus protein processing are not fully understood.
Purpose of the Study:
- To investigate the cleavage and cellular localization of Sindbis virus envelope protein precursors during infection.
- To determine the role of the plasma membrane in Sindbis virus protein maturation.
Main Methods:
- Utilizing a temperature-sensitive mutant of Sindbis virus.
- Infecting cells and incubating them at permissive and nonpermissive temperatures.
- Fractionating infected cells to isolate the plasma membrane component.
- Analyzing the association and cleavage of viral protein precursors.
Main Results:
- Cleavage of a specific Sindbis virus envelope protein precursor was inhibited at the nonpermissive temperature.
- This uncleaved precursor was found to be associated with the plasma membrane fraction of infected cells.
- The site of viral maturation is the plasma membrane.
Conclusions:
- The precursor to Sindbis virus envelope proteins associates with the host cell plasma membrane.
- Proteolytic cleavage of this precursor occurs during the final stages of viral maturation at the plasma membrane.
- This finding provides insight into the molecular events governing Sindbis virus assembly and release.