p53 Stimulates TFIID-TFIIA-Promoter Complex Assembly, and p53-T Antigen Complex Inhibits TATA Binding Protein-TATA Interaction

Abstract

Simian virus 40 large T antigen has been shown to inhibit p53-mediated transcription once tethered to p53-responsive promoters through interaction with p53. In this study we report that p53 stimulates transcription by enhancing the recruitment of the basal transcription factors, TFIIA and TFIID, on the promoter (the DA complex) and by inducing a conformational change in the DA complex. Significantly, we have demonstrated that T antigen inhibits p53-mediated transcription by blocking this ability of p53. We investigated the mechanism for this inhibition and found that DA complex formation was resistant to T-antigen repression when the TFIID-DNA complex was formed prior to addition of p53-T antigen complex, indicating that the T antigen, once tethered to the promoter by p53, targets TFIID. Further, we have shown that the p53-T antigen complex prevents the TATA binding protein from binding to the TATA box. Thus, these data suggest a detailed mechanism by which p53 activates transcription and by which T antigen inhibits p53-mediated transcription.

ACKNOWLEDGMENTS

We are very grateful to A. Berk, N. Kobayashi (University of California, Los Angeles), P. Lieberman (Wistar), J. Ross, and B. Dynlacht (Harvard) for many helpful discussions. We thank A. Berk and N. Kobayashi for providing TFIIA expression vectors and anti-TFIIA antibody, L. Anton for LTRα3 nuclear extracts, and E. Martinez for valuable comments on the manuscript.

This work was supported by grants from the National Cancer Institute (CA75180) and the U.S. Army Breast Cancer Research Program (DAMD17-96-6076) to X.L. S.I.C is supported by a postdoctoral fellowship from the California Cancer Research Program.