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SV40 large T antigen functions at two distinct steps in virion assembly
1Department of Biological Sciences, University of Pittsburgh, Pennsylvania 15260.
Virology
|October 1, 1994
Summary
The SV40 large T antigen mutant 5002 shows defects in viral assembly, accumulating as 150S previrions. This indicates distinct functions for SV40 large T antigen in virion production.
Area of Science:
- Virology
- Molecular Biology
- Structural Biology
Background:
- Simian virus 40 (SV40) large T antigen is crucial for viral replication and assembly.
- Viral assembly involves the maturation of 75S chromatin complexes into 240S virions.
Purpose of the Study:
- To investigate the specific defect in viral assembly caused by the SV40 large T antigen mutant 5002.
- To elucidate the distinct functional activities of SV40 large T antigen in the viral assembly pathway.
Main Methods:
- Characterization of SV40 large T antigen mutant 5002's plaque morphology and progeny yield.
- Analysis of viral DNA replication and capsid protein accumulation.
- Investigation of viral particle assembly intermediates using sedimentation analysis.
Main Results:
- Mutant 5002 exhibits late, small plaques and a 100-fold reduction in infectious progeny.
- Viral DNA replication and capsid protein levels are largely unaffected.
- 5002 infection halts viral assembly at a 150S previrion stage, distinct from 75S particles seen in HR mutants.
Conclusions:
- SV40 large T antigen mutant 5002 is blocked at a specific step in viral assembly, forming 150S previrions.
- Cooperation between 5002 and HR mutants in trans complementation suggests distinct T antigen functions.
- SV40 large T antigen possesses at least two distinct activities essential for different stages of virion assembly.