Interaction of Human Papillomavirus 8 Regulatory Proteins E2, E6 and E7 with Components of the TFIID Complex

Human papillomavirus 8 (HPV8) is one of the oncogenic HPV types specifically associated with skin cancers of epidermodysplasia verruciformis patients. The early gene products of this virus exert functions in transformation (E2, E6, E7), replication (E1, E2) and in the control of viral transcription (E2, E7). Many viral and cellular transactivators of transcription have been shown to interact selectively and directly with a number of TATA-box-binding protein (TBP)-associated factors (TAF_IIs), which then play a role as coactivators. Using glutathione-S-transferase (GST) pull-down experiments, we tested in vitro interactions between GST-HPV8-E1, -E2, -E6 and -E7 and 7 in-vitro-translated TAF_IIs in the human (h) system (hTAF_II18, hTAF_II20, hTAF_II28, hTAF_II30, hTAF_II55, hTAF_II100, hTAF_IIΔN135) or TBP. We could show that GST-HPV8-E2 interacts directly at least with hTAF_II55 and TBP. Deletion analysis indicated that a domain overlapping with the C-terminal moiety of HPV8-E2 is required for binding to TBP, whereas determinants for interactions with hTAF_II55 are in the central and C-terminal part of the E2 protein. In similar binding studies, GST-HPV8-E6 interacted with hTAF_II28, hTAF_IIΔN135 and TBP, and more weakly with hTAF_II20, whereas GST- HPV8-E7 bound to hTAF_II20, hTAF_II28, hTAF_II55, hTAF_IIΔN135 and TBP. Deletion analysis revealed that the C-terminal part of HPV8-E7 is required for the interaction with these hTAF_IIs. In contrast, no interactions were observed between GST-HPV8-E1 and in-vitro-translated hTAF_IIs.