title: Inhibition of p53 DNA binding by human papillomavirus E6 proteins.
abstract: Transformation by the human papillomavirus (HPV) early gene products, E6 and E7, involves their interaction with cellular proteins p53 and Rb. Using glutathione S-transferase (GST) fusion proteins, we found that HPV E6 bound human p53 and that the relative efficiency of binding varied such that the GST-HPV type 16 E6 (16E6) protein bound p53 with highest affinity, followed by GST-31E6, GST-18E6, and GST-11E6. The GST-E6 fusion proteins were sufficient for binding p53 purified from a baculovirus expression system as well as in vitro translation sources, while no association was observed with GST-18E7 or a GST-16E6 mutant bearing a five-amino-acid deletion in E6. When the site-specific DNA binding activity of p53 was examined in the presence of GST-E6 proteins, an inhibition of DNA binding was observed. The degree of inhibition correlated with the relative affinity of different E6 proteins for p53; thus, GST-16E6 was the most potent inhibitor of p53 DNA binding activity, and GST-11E6 was the least effective. Prevention of p53 DNA binding is likely to play a role in the abrogation of the transcriptional activity of p53 by HPV E6 and provides a further mechanism for E6 disruption of p53 growth suppressor function in addition to its role in directing specific degradation of p53 through the ubiquitin-mediated pathway. The variation in inhibition of DNA binding seen with the various E6 proteins may thus contribute to the differences in oncogenic potential seen among the HPV types.
authors.affiliation: Department of Molecular Genetics and Cell Biology, University of Chicago, Illinois 60637.
authors.forename: M S
authors.initials: MS
authors.lastname: Lechner
authors.forename: L A
authors.initials: LA
authors.lastname: Laimins
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D001483:Base Sequence; D002460:Cell Line; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009036:Moths; D009856:Oncogene Proteins, Viral / Q000378:metabolism*; D027383:Papillomaviridae / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; C052603:E6 protein, Human papillomavirus type 18; D009856:Oncogene Proteins, Viral; D011993:Recombinant Fusion Proteins; D016159:Tumor Suppressor Protein p53; D004247:DNA; D005982:Glutathione Transferase