The central and C-terminal domains of VPg of Clover yellow vein virus are important for VPg-HCPro and VPg-VPg interactions

Interactions between the major proteins of Clover yellow vein virus (ClYVV) were investigated using a GAL4 transcription activator-based yeast two-hybrid system (YTHS). Self-interactions manifested by VPg and HCPro and an interaction between Nib and NlaPro were observed in ClYVV. In addition, a strong HCPro-VPg interaction was detected by both YTHS and by in vitro far-Western blot analysis in ClYVV. A potyvirus HCPro-VPg interaction has not been reported previously. Using YTHS, domains in ClYVV for the VPg self-interaction and the HCPro-VPg interaction were mapped. The VPg C-terminal region (38 amino acids) was important for the VPg-VPg interaction and the central 19 amino acids were needed for the HCPro-VPg interaction.