Analysis of the interaction between human papillomavirus type 16 E7 and the TATA-binding protein, TBP.

The E7 protein encoded by human papillomavirus type 16 shows transforming and immortalizing activities which are mediated, in part, through the interaction of the viral oncoprotein with the pRB protein family. This interaction is not solely responsible for E7 function, however, and other properties of E7, such as the interaction with basal transcription factors such as TBP, are likely to be of importance. We show here that three regions of the viral protein contribute to the interaction between E7 and TBP; the pRB-binding domain, the casein kinase II phosphorylation region and the C-terminal dimerization domain. Mutations within each region reduced the interaction of E7 with TBP in vitro, and simultaneous alterations within each of these regions completely abrogated binding. Unlike the pRB interaction, the association of E7 with TBP was enhanced following phosphorylation of E7 by casein kinase II, demonstrating a functional significance for phosphorylation of the viral protein.