Interaction of the Transcription Factor TFIID with Simian Virus 40 (SV40) Large T Antigen Interferes with Replication of SV40 DNA In Vitro
AUTOR(ES)
Herbig, Utz
FONTE
American Society for Microbiology
RESUMO
Simian virus 40 (SV40) large tumor (T) antigen is the major regulatory protein that directs the course of viral infection, primarily by interacting with host cell proteins and modulating their functions. Initiation of viral DNA replication requires specific interactions of T antigen bound to the viral origin of DNA replication with cellular replication proteins. Transcription factors are thought to stimulate initiation of viral DNA replication, but the mechanism of stimulation is poorly understood. Since the transcription factor TATA-binding protein (TBP) binds to sequences within the origin of replication and interacts specifically with T antigen, we examined whether TBP complexes stimulate SV40 DNA replication in vitro. On the contrary, we found that depletion of TBP complexes from human cell extracts increased their ability to support viral DNA replication, and readdition of TBP complexes to the depleted extracts diminished their activity. We have mapped the sites of interaction between the proteins to residues 181 to 205 of T antigen and 184 to 220 of TBP. Titration of fusion proteins containing either of these peptides into undepleted cell extracts stimulated their replication activity, suggesting that they prevented the T antigen-TBP interaction that interfered with replication activity. TBP complexes also interfered with origin DNA unwinding by purified T antigen, and addition of either the T antigen or the TBP fusion peptide relieved the inhibition. These results suggest that TBP complexes associate with a T-antigen surface that is also required for origin DNA unwinding and viral DNA replication. We speculate that competition among cellular proteins for T antigen may play a role in regulating the course of viral infection.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=103930Documentos Relacionados
- Simian virus 40 (SV40) DNA replication: SV40 large T antigen unwinds DNA containing the SV40 origin of replication.
- Simian virus 40 (SV40) small t antigen inhibits SV40 DNA replication in vitro.
- Mechanisms of interference with simian virus 40 (SV40) DNA replication by trans-dominant mutants of SV40 large T antigen.
- Simian virus 40 (SV40) large tumor antigen causes stepwise changes in SV40 origin structure during initiation of DNA replication.
- ATP stimulates the binding of simian virus 40 (SV40) large tumor antigen to the SV40 origin of replication.