Research

Intrinsic disorder in Viral Proteins Genome-Linked: experimental and predictive analyses

Eugénie Hébrard¹ , Yannick Bessin² , Thierry Michon³ , Sonia Longhi⁴ , Vladimir N Uversky^5,6 , François Delalande⁷ , Alain Van Dorsselaer⁷ , Pedro Romero⁵ , Jocelyne Walter³ , Nathalie Declerck² and Denis Fargette¹

¹  UMR 1097 Résistance des Plantes aux Bio-agresseurs, IRD, CIRAD, Université de Montpellier II, BP 64501, 34394 Montpellier cedex 5, France

²  Centre de Biochimie Structurale, UMR 5048, 29 rue de Navacelles, 34090 Montpellier, France

³  UMR1090 Génomique Diversité Pouvoir Pathogène, INRA, Université de Bordeaux 2, F-33883 Villenave D'Ornon, France

⁴  UMR 6098 Architecture et Fonction des Macromolécules Biologiques, CNRS, Universités Aix-Marseille I et II, Campus de Luminy, 13288 Marseille Cedex 09, France

⁵  Center for Computational Biology and Bioinformatics, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA

⁶  Institute for Biological Instrumentation, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia

⁷  Laboratoire de Spectrométrie de Masse Bio-Organique, ECPM, 67087 Strasbourg, France

author email corresponding author email

Virology Journal 2009, 6:23doi:10.1186/1743-422X-6-23

Published:	16 February 2009

Abstract

Background

VPgs are viral proteins linked to the 5' end of some viral genomes. Interactions between several VPgs and eukaryotic translation initiation factors eIF4Es are critical for plant infection. However, VPgs are not restricted to phytoviruses, being also involved in genome replication and protein translation of several animal viruses. To date, structural data are still limited to small picornaviral VPgs. Recently three phytoviral VPgs were shown to be natively unfolded proteins.

Results

In this paper, we report the bacterial expression, purification and biochemical characterization of two phytoviral VPgs, namely the VPgs of Rice yellow mottle virus (RYMV, genus Sobemovirus) and Lettuce mosaic virus (LMV, genus Potyvirus). Using far-UV circular dichroism and size exclusion chromatography, we show that RYMV and LMV VPgs are predominantly or partly unstructured in solution, respectively. Using several disorder predictors, we show that both proteins are predicted to possess disordered regions. We next extend theses results to 14 VPgs representative of the viral diversity. Disordered regions were predicted in all VPg sequences whatever the genus and the family.

Conclusion

Based on these results, we propose that intrinsic disorder is a common feature of VPgs. The functional role of intrinsic disorder is discussed in light of the biological roles of VPgs.