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SV40 T-antigen binding to site II is functionally separated from binding to site I
G Stetter1, D Müller, M Montenarh
1Department of Biochemistry, University of Ulm, Federal Republic of Germany.
Virology
|June 1, 1988
Summary
Simian virus 40 (SV40) T-antigen binding to DNA sites II and I occurs differentially during infection. Site II binding correlates with viral DNA replication, suggesting distinct T-antigen subclasses.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- SV40 T-antigen plays a crucial role in viral DNA replication and transcription regulation.
- T-antigen binds to specific DNA sites to initiate these processes.
Purpose of the Study:
- To investigate the differential binding of SV40 T-antigen to its specific DNA binding sites (I, II, and III) during lytic infection.
- To understand the temporal relationship between T-antigen binding and SV40 DNA replication.
Main Methods:
- Utilized plasmids containing specific SV40 T-antigen binding sites (pKB1 for site I, pdl1085 for sites II and III, pATC for all three).
- Analyzed T-antigen binding kinetics in SV40-infected cells over time.
- Employed a temperature-sensitive mutant (tsA58) to assess T-antigen binding at non-permissive temperatures.
Main Results:
- T-antigen binding increased with its concentration, reaching a plateau around 20 hours post-infection.
- Binding to site II showed a delay of 8-9 hours compared to site I, coinciding with the onset of viral DNA replication.
- The tsA58 mutant failed to bind site II at non-permissive temperatures but retained partial binding to site I, which was insufficient for autorepression.
Conclusions:
- SV40 T-antigen exhibits differential binding kinetics to its DNA recognition sites.
- Binding to site II is closely linked to viral DNA replication.
- Distinct subclasses of T-antigen may be involved in binding to site I versus site II.