Conserved interaction of the papillomavirus E2 transcriptional activator proteins with human and yeast TFIIB proteins

Abstract

Papillomavirus early gene expression is regulated by the virus gene-encoded E2 proteins. The best-characterized E2 protein, encoded by bovine papillomavirus type 1 (BPV-1), has been shown to interact with basal transcription factor IIB (TFIIB) and the TATA binding protein basal transcription factor (N. M. Rank and P. F. Lambert, J. Virol. 69:6323-6334, 1995). We demonstrate that the potent E2 transcriptional activator protein encoded by a gene of human PV type 16 also interacts with TFIIB in vitro. Moreover, a direct comparison of domains within human TFIIB (hTFIIB) required for VP16 and BPV-1 E2 indicates that these acidic activators interact with hTFIIB in a qualitatively similar manner. Our mapping experiments identify hTFIIB interaction domains within the amino-terminal activation domain of BPV-1 E2. Finally, we demonstrate in vitro interaction between Saccharomyces cerevisiae TFIIB and BPV-1 E2, an observation that is consistent with the importance of the E2-TFIIB interaction for BPV-1 E2 transactivation in both systems.