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Journal of Virology, September 2009, p. 8759-8770, Vol. 83, No. 17
0022-538X/09/$08.00+0 doi:10.1128/JVI.01777-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Identification of Unusual E6 and E7 Proteins within Avian Papillomaviruses: Cellular Localization, Biophysical Characterization, and Phylogenetic Analysis
,
Koenraad Van Doorslaer,1,2,#
Abdellahi Ould M'hamed Ould Sidi,3,#
Katia Zanier,3
Vladimir Rybin,4
François Deryckère,3
Annabel Rector,1
Robert D. Burk,2
E. Kurt Lienau,2,
Marc van Ranst,1, and
Gilles Travé3,*
Laboratory of Clinical Virology, Rega Institute for Medical Research, University of Leuven, Minderbroedersstraat 10, 3000 Leuven, Belgium,1 Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461,2 Equipe Oncoprotéines, CNRS-UMR 7175, ESBS, Boulevard Sébastien Brant, BP10413, 67412 Illkirch, France,3 EMBL Heidelberg, Meyerhofstrasse 1, 69117 Heidelberg, Germany4
Received 22 August 2008/ Accepted 12 May 2009
Papillomaviruses (PVs) are a large family of small DNA viruses infecting mammals, reptiles, and birds. PV infection induces cell proliferation that may lead to the formation of orogenital or skin tumors. PV-induced cell proliferation has been related mainly to the expression of two small oncoproteins, E6 and E7. In mammalian PVs, E6 contains two 70-residue zinc-binding repeats, whereas E7 consists of a natively unfolded N-terminal region followed by a zinc-binding domain which folds as an obligate homodimer. Here, we show that both the novel francolin bird PV Francolinus leucoscepus PV type 1 (FlPV-1) and the chaffinch bird PV Fringilla coelebs PV contain unusual E6 and E7 proteins. The avian E7 proteins contain an extended unfolded N terminus and a zinc-binding domain of reduced size, whereas the avian E6 proteins consist of a single zinc-binding domain. A comparable single-domain E6 protein may have existed in a common ancestor of mammalian and avian PVs. Mammalian E6 C-terminal domains are phylogenetically related to those of single-domain avian E6, whereas mammalian E6 N-terminal domains seem to have emerged by duplication and subsequently diverged from the original ancestral domain. In avian and mammalian cells, both FlPV-1 E6 and FlPV-1 E7 were evenly expressed in the cytoplasm and the nucleus. Finally, samples of full-length FlPV-1 E6 and the FlPV-1 E7 C-terminal zinc-binding domain were prepared for biophysical analysis. Both constructs were highly soluble and well folded, according to nuclear magnetic resonance spectroscopy measurements.
* Corresponding author. Mailing address: ESBS, Boulevard Sébastien Brant, BP10413, 67412 Illkirch, France. Phone: 333 90244720. Fax: 333 90244718. E-mail: gtrave{at}igbmc.u-strasbg.fr
Published ahead of print on 24 June 2009.
Supplemental material for this article may be found at http://jvi.asm.org/.
# Equal contributors for experimental work.
Equal contributors for scientific supervision.
Journal of Virology, September 2009, p. 8759-8770, Vol. 83, No. 17
0022-538X/09/$08.00+0 doi:10.1128/JVI.01777-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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