Interaction of human papillomavirus 8 regulatory proteins E2, E6 and E7 with components of the TFIID complex

Abstract

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 (TAFIIs), 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 TAFIIs in the human (h) system (hTAFII18, hTAFII20, hTAFII28, hTAFII30, hTAFII55, hTAFII100, hTAFIIDeltaN135) or TBP. We could show that GST-HPV8-E2 interacts directly at least with hTAFII55 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 hTAFII55 are in the central and C-terminal part of the E2 protein. In similar binding studies, GST-HPV8-E6 interacted with hTAFII28, hTAFIIDeltaN135 and TBP, and more weakly with hTAFII20, whereas GST- HPV8-E7 bound to hTAFII20, hTAFII28, hTAFII55, hTAFIIDeltaN135 and TBP. Deletion analysis revealed that the C-terminal part of HPV8-E7 is required for the interaction with these hTAFIIs. In contrast, no interactions were observed between GST-HPV8-E1 and in-vitro-translated hTAFIIs.