A single amino acid substitution in the conserved CDNQLD motif causes both differences in RNA silencing suppression activity of the turnip mosaic virus HC-Pro protein and variations in symptom severity

Abstract

We examined two variants of turnip mosaic virus (TuMV) KJS 5 and KJS 5 − 1, the polyproteins of which differ by only a single amino acid residue, located in HC-Pro motif CDNQLD. When KJS 5 and KJS 5 − 1 were inoculated to Nicotiana benthamiana and Raphanus sativus differential symptom severity were observed in each host. To complement these results, smGFP and the variant HC-Pros were co-expressed in N. benthamiana leaves by agro-infiltration. Real-time qPCR analysis showed that the relative expression levels of smGFP differed. This shows that a single amino acid substitution affects both symptom severity and RNA silencing suppression efficiency.

Potyviral Helper-Component Protease: Multifaced Functions and Interactions with Host Proteins

“…In addition to E419, the residue N339 of HC-Pro is a PVY molecular determinant of vein necrosis induction in tobacco [57]. A single amino acid substitution in HC-Pro can affect both symptom severity and the RNA silencing suppression efficiency [52]. For instance, symptom severity and virus accumulation can be altered by a single amino acid change in the HC-Pro sequence of the plum pox virus (PPV) [58,59].…”