HPV oncoprotein E6 is a structure-dependent DNA-binding protein that recognizes four-way junctions.
E6 is an oncoprotein implicated in cervical cancers, produced by "high-risk" human papillomaviruses. E6 is thought to promote tumorigenesis by stimulating cellular degradation of the tumour suppressor p53, but it might display other activities. Sequence similarity was recently detected between E6 and endonuclease VII, a protein of phage T4 that recognizes and cleaves four-way DNA junctions. Here, we purified recombinant E6 proteins and demonstrated that high-risk E6 s bind selectively to four-way junctions in a structure-dependent manner. Several residues in the C-terminal zinc-binding domain, the region of E6 similar to endonuclease VII, are necessary for the junction-binding activity. E6 binds to the junction as a monomer. Comparative electrophoresis shows that E6-bound junctions migrate in an extended square conformation. Magnesium inhibits the electrophoretic migration of the complexes but does not seem to influence their formation at equilibrium. This work is the first demonstration of specific binding of purified active E6 to a well-characterized DNA ligand, and suggests new modes of action of E6 in oncogenesis.
Ristriani
T
T
Laboratoire d'Immunotechnologie, UPRES 1329, Ecole Superieure de Biotechnologie de Strasbourg, Illkirch, 67400, France.
Masson
M
M
Nominé
Y
Y
Laurent
C
C
Lefevre
J F
JF
Weiss
E
E
Travé
G
G
D000595:Amino Acid Sequence; D001665:Binding Sites / Q000187:drug effects; D004247:DNA / Q000138:chemical synthesis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015342:DNA Probes / Q000138:chemical synthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004706:Endodeoxyribonucleases / Q000737:chemistry / Q000378:metabolism; D008274:Magnesium / Q000494:pharmacology; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009690:Nucleic Acid Conformation / Q000187:drug effects; D009856:Oncogene Proteins, Viral / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D027383:Papillomaviridae / Q000145:classification / Q000235:genetics / Q000472:pathogenicity; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary / Q000187:drug effects; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity; D013379:Substrate Specificity; D013816:Thermodynamics; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D015032:Zinc / Q000378:metabolism
D015342:DNA Probes; D004268:DNA-Binding Proteins; C118860:E6 protein, Human papillomavirus type 6; D009856:Oncogene Proteins, Viral; D011993:Recombinant Fusion Proteins; D016159:Tumor Suppressor Protein p53; D004247:DNA; D004706:Endodeoxyribonucleases; C035571:endodeoxyribonuclease VII; D008274:Magnesium; D015032:Zinc