title: E6 proteins from diverse papillomaviruses self-associate both in vitro and in vivo.
abstract: Papillomavirus E6 oncoproteins bind and often provoke the degradation of many cellular proteins important for the control of cell proliferation and/or cell death. Structural studies on E6 proteins have long been hindered by the difficulties of obtaining highly concentrated samples of recombinant E6. Here, we show that recombinant E6 proteins from eight human papillomavirus strains and one bovine papillomavirus strain exist as oligomeric and multimeric species. These species were characterized using a variety of biochemical and biophysical techniques, including analytical gel filtration, activity assays, surface plasmon resonance, electron microscopy and Fourier transform infrared spectroscopy. The characterization of E6 oligomers is facilitated by the fusion to the maltose binding protein, which slows the formation of higher-order multimeric species. The proportion of each oligomeric form varies depending on the viral strain considered. Oligomers appear to consist of folded units, which, in the case of high-risk mucosal human papillomavirus E6, retain binding to the ubiquitin ligase E6-associated protein and the capacity to degrade the proapoptotic protein p53. In addition to the small-size oligomers, E6 proteins spontaneously assemble into large organized multimeric structures, a process that is accompanied by a significant increase in the beta-sheet secondary structure content. Finally, co-localisation experiments using E6 equipped with different tags further demonstrate the occurrence of E6 self-association in eukaryotic cells. The ensemble of these data suggests that self-association is a general property of E6 proteins that occurs both in vitro and in vivo and might therefore be functionally relevant.
authors.affiliation: Ecole Supérieure de Biotechnologie de Strasbourg (IREBS, FRE 3211), Boulevard Sébastien Brant, BP 10413, 67412 Illkirch Cedex, France. zanier@esbs.u-strasbg.fr
authors.forename: Katia
authors.initials: K
authors.lastname: Zanier
authors.forename: Christine
authors.initials: C
authors.lastname: Ruhlmann
authors.forename: Frederic
authors.initials: F
authors.lastname: Melin
authors.forename: Murielle
authors.initials: M
authors.lastname: Masson
authors.forename: Abdellahi
authors.initials: A
authors.lastname: Ould M'hamed Ould Sidi
authors.forename: Xavier
authors.initials: X
authors.lastname: Bernard
authors.forename: Benoit
authors.initials: B
authors.lastname: Fischer
authors.forename: Laurent
authors.initials: L
authors.lastname: Brino
authors.forename: Tutik
authors.initials: T
authors.lastname: Ristriani
authors.forename: Vladimir
authors.initials: V
authors.lastname: Rybin
authors.forename: Mireille
authors.initials: M
authors.lastname: Baltzinger
authors.forename: Scott
authors.initials: S
authors.lastname: Vande Pol
authors.forename: Petra
authors.initials: P
authors.lastname: Hellwig
authors.forename: Patrick
authors.initials: P
authors.lastname: Schultz
authors.forename: Gilles
authors.initials: G
authors.lastname: Travé
mesh_terms: D002352:Carrier Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002850:Chromatography, Gel; D006801:Humans; D058619:Maltose-Binding Proteins; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D055550:Protein Stability; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D014764:Viral Proteins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D015032:Zinc / Q000737:chemistry
chemical_list: D002352:Carrier Proteins; D058619:Maltose-Binding Proteins; D050505:Mutant Proteins; D011993:Recombinant Fusion Proteins; D014764:Viral Proteins; D015032:Zinc