Structural characterization of HC-Pro, a plant virus multifunctional protein.

Célia Plisson (1) , M. Drucker , S. Blanc , S. German-Retana , O. Le Gall , Daniel Thomas (1) , Patrick Bron (1)

1 ICM - Interactions cellulaires et moléculaires

The helper component proteinase (HC-Pro) is a key protein encoded by plant viruses of the genus Potyvirus. HC-Pro is involved in different steps of the viral cycle, aphid transmission, replication, and virus cell-to-cell and systemic movement and is a suppressor of post-transcriptional gene silencing. Structural knowledge of HC-Pro is required to better understand its multiple functions. To this aim, we purified His-tagged wild-type HC-Pro and a N-terminal deletion mutant (DeltaHC-Pro) from plants infected with recombinant potyviruses. Biochemical analysis of the recombinant proteins confirmed that HC-Pro is a dimer in solution, that the N terminus is not essential for self-interaction, and that a large C-terminal domain is highly resistant to proteolysis. Two-dimensional crystals of the recombinant proteins were successfully grown on Ni2+-chelating lipid monolayers. Comparison of projection maps of negatively stained crystals revealed that HC-Pro is composed of two domains separated by a flexible constriction. Cryo-electron crystallography of DeltaHC-Pro allowed us to calculate a projection map at 9-A resolution. Our data from electron microscopy, biochemical analysis, and secondary structure predictions lead us to suggest a model for structure/function relationships in the HC-Pro protein

Mots clés: HC-PRO; CARACTERISATION STRUCURALE

Mots clés: VIROLOGIE

Domaines: Biochimie, Biologie Moléculaire

Célia Plisson, M. Drucker, S. Blanc, S. German-Retana, O. Le Gall, et al.. Structural characterization of HC-Pro, a plant virus multifunctional protein.. Journal of Biological Chemistry, 2003, 278 (26), pp.23761. ⟨10.1074/jbc.M302512200⟩. ⟨hal-00108282⟩