Cysteine protease domain of potato virus Y: The potential target for urea derivatives

The cysteine protease structural domain (CPD) encoded by the potato virus Y (PVY) accessory component protein helper component-proteinase (HC-Pro) is an auxiliary component of aphid virus transmission and plays an important role in virus infection and replication. Urea derivatives have potential antiviral activities. In this study, the PVY HC-Pro C-terminal truncated recombinant protein (residues 307-465) was expressed and purified. The interactions of PVY CPD with urea derivatives HD1-36 were investigated. Microscale thermophoresis experiments showed that HD6, -19, -21 and - 25 had the strongest binding forces to proteins, with K_d values of 2.16, 1.40, 1.97 and 1.12 μM, respectively. An experiment verified the microscale thermophoresis results, and the results were as expected, with K_d values of 6.10, 4.78, 5.32, and 4.52 μM for HD6, -19, -21, and - 25, respectively. Molecular docking studies indicated that the interaction sites between PVY CPD and HD6, -19, -21, and - 25, independently, were aspartic acid 121, asparagine 48, and tyrosine 38, which played important roles in their binding. In vivo experiments verified that HD25 inhibited PVY more than the control agents ningnanmycin and urea. These data have important implications for the design and synthesis of novel urea derivatives.