E6 Proteins from Diverse Papillomaviruses Self-Associate Both In Vitro and In Vivo

Katia Zanier (1) , Christine Ruhlmann (2) , Frederic Melin (3) , Murielle Masson (1) , Abdellahi Ould M'Hamed Ould Sidi (1) , Xavier Bernard (1) , Benoit Fischer (4, 2) , Laurent Brino (4, 2) , Tutik Ristriani (1) , Vladimir Rybin (5) , Mireille Baltzinger (1) , Scott Vande Pol (6) , Petra Hellwig (3) , Patrick Schultz (2) , Gilles Travé (1)

1 ESBS - Ecole Supérieure de Biotechnologie de Strasbourg
2 IGBMC - Institut de génétique et biologie moléculaire et cellulaire
3 Institut de Chimie de Strasbourg
4 PCT - Plate-forme de R&D - Puces à Cellules Transfectées
5 EMBL Heidelberg
6 Department of Pathology [Charlottesville, US]

Papillomavirus (PV) 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 and one bovine PV strains exist as oligomeric as well as multimeric species. These species were characterized using a variety of biochemical and biophysical techniques including analytical gel filtration, activity assays, SPR, EM and FTIR. The characterization of E6 oligomers is facilitated by the fusion to the maltose binding protein (MBP), which slows down the formation of higher-order multimeric species. The proportion of each oligomeric form vary depending on the viral strain considered. Oligomers appear to consist of folded units, which, in the case of high-risk mucosal HPV E6, retain binding to the ubiquitin ligase E6AP and the capacity to degrade the pro-apoptotic protein p53. In addition to the small-size oligomers, E6 proteins spontaneously assemble into large organized multimeric structures, a process which is accompanied by a significant increase in the βsheet 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 suggest that self-association is a general property of E6 proteins which occurs both in vitro and in vivo and might therefore be functionally relevant.

Mots clés: HPV; E6; cervical cancer; self-association; HPV; oligomerization; ordered aggregation

Domaines: Sciences du Vivant [q-bio]

Katia Zanier, Christine Ruhlmann, Frederic Melin, Murielle Masson, Abdellahi Ould M'Hamed Ould Sidi, et al.. E6 Proteins from Diverse Papillomaviruses Self-Associate Both In Vitro and In Vivo. Journal of Molecular Biology, 2010, 396 (1), pp.90-104. ⟨10.1016/j.jmb.2009.11.022⟩. ⟨hal-03050609⟩