title: Papillomavirus polypeptides E6 and E7 are zinc-binding proteins.
abstract: Papillomavirus proteins E6 and E7 have Cys-X-X-Cys repeats which have been suggested to mediate zinc binding. We have developed a modification of an assay that detects zinc binding to proteins immobilized on filters. Using well-characterized metalloproteins, we show that, under reducing conditions, this assay distinguishes proteins that coordinate zinc through cysteine residues from those that bind the metal through other amino acids. Under these conditions, E6 and E7 polypeptides of human papillomavirus type 18 and bovine papillomavirus type 1 exhibited high-affinity zinc binding. Our results suggest that E6 and E7 are metalloproteins and may coordinate the metal ions through cysteine residues.
authors.affiliation: Laboratory of Cellular Oncology, National Cancer Institute, Bethesda, Maryland 20892.
authors.forename: M S
authors.initials: MS
authors.lastname: Barbosa
authors.forename: D R
authors.initials: DR
authors.lastname: Lowy
authors.forename: J T
authors.initials: JT
authors.lastname: Schiller
mesh_terms: D002352:Carrier Proteins / Q000378:metabolism*; D003545:Cysteine / Q000378:metabolism; D004268:DNA-Binding Proteins; D009856:Oncogene Proteins, Viral / Q000378:metabolism*; D027383:Papillomaviridae / Q000378:metabolism*; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015032:Zinc / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C052633:E7 protein, Human papillomavirus type 18; D009856:Oncogene Proteins, Viral; D011993:Recombinant Fusion Proteins; C017800:zinc-binding protein; D015032:Zinc; D003545:Cysteine