Human papillomavirus-16 E7 protein inhibits the DNA interaction of the TATA binding transcription factor.
Previous studies have shown that the HPV-16 E7 protein interacts with TBP. This interaction was found to take place through residues in the carboxy terminal half of E7, mutation of which resulted in weaker transforming activity. In addition, binding of E7 to TBP was found to be increased following protein kinase CK2 (casein kinase II) phosphorylation of E7, and mutation of this CK2 site also reduces E7's transforming activity. To date, however, there is no information on the effects of E7 upon TBP function. In order to address this we have performed a series of assays to investigate the effects of E7 upon the ability of human and S. pombe TBP to bind DNA. We show that HPV-16 E7 is indeed a potent inhibitor of TBP DNA binding activity. Further, this activity of E7 is increased following CK2 phosphorylation of E7, consistent with it having an increased affinity for TBP. Finally, a mutant E7 protein defective in its ability to bind TBP, has no effect upon TBP binding to DNA. These results demonstrate that one consequence of the E7-TBP interaction is abolition of TBP DNA binding activity, and may provide an explanation for the transcriptional inhibitory effects of E7.
Maldonado
Edio
E
Programa de Biologìa Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile. emaldona@machi.med.uchile.cl
Cabrejos
María Eugenia
ME
Banks
Lawrence
L
Allende
Jorge E
JE
D000818:Animals; D001665:Binding Sites; D047390:Casein Kinase II; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D009154:Mutation; D009856:Oncogene Proteins, Viral / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D027383:Papillomaviridae / Q000235:genetics / Q000378:metabolism*; D050725:Papillomavirus E7 Proteins; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016385:TATA Box; D035181:TATA-Box Binding Protein; D014157:Transcription Factors / Q000378:metabolism*; D014982:Xenopus laevis
D004268:DNA-Binding Proteins; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D011993:Recombinant Fusion Proteins; D035181:TATA-Box Binding Protein; D014157:Transcription Factors; C059731:oncogene protein E7, Human papillomavirus type 16; D004247:DNA; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases