A structural study of potential plant virus receptors
Résumé
Many plant viruses of agricultural importance are transmitted to host plants by noncirculative aphid transmission, meaning that viruses do not penetrate the aphid body but are retained on the cuticle of the insect and released and inoculated into a new host plant together with the aphid saliva. Recently, our collaborators have reported the identification of two closely related and highly conserved RR-1 cuticular proteins, Stylin-01 and Stylin-02, in the acrostyle of both Myzus persicae and Acyrthosiphon pisum. Stylin-01 and Stylin-02 belong to the CPR proteins, cuticular proteins bearing the Rebers and Riddiford consensus sequence (RR). They showed that Stylin-01 is involved in CaMV transmission and could be the prime candidate receptor for the vector transmission of noncirculative plant viruses. CPR proteins in aphids can be divided into subgroups RR-1, RR-2, and RR-3, proteins of RR-2 being also detected within the acrostyle. Deciphering virus–vector interactions at molecular level is essential to understand transmission mechanisms and develop new strategies to control viral spread. In this context, we decided to perform a structural characterization of various proteins belonging to the RR1 subgroup of CPRs, including Stylin-1 and 2. From predictive models, nuclear magnetic resonance experiments and molecular dynamics, we propose a structural model for this family of proteins.