Plant Translation Elongation Factor 1Bβ Facilitates Potato Virus X (PVX) Infection and Interacts with PVX Triple Gene Block Protein 1

Abstract

The eukaryotic translation elongation factor 1 (eEF1) has two components: the G-protein eEF1A and the nucleotide exchange factor eEF1B. In plants, eEF1B is itself composed of a structural protein (eEF1B.) and two nucleotide exchange subunits (eEF1B alpha and eEF1B beta). To test the effects of elongation factors on virus infection, we isolated eEF1A and eEF1B genes from pepper (Capsicum annuum) and suppressed their homologs in Nicotiana benthamiana using virus-induced gene silencing (VIGS). The accumulation of a green fluorescent protein (GFP)-tagged Potato virus X (PVX) was significantly reduced in the eEF1B beta-or eEF1B gamma-silenced plants as well as in eEF1A-silenced plants. Yeast two-hybrid and co-immunoprecipitation analyses revealed that eEF1B alpha and eEF1B beta interacted with eEF1A and that eEF1A and eEF1B beta interacted with triple gene block protein 1 (TGBp1) of PVX. These results suggest that both eEF1A and eEF1B beta play essential roles in the multi-plication of PVX by physically interacting with TGBp1. Furthermore, using eEF1B beta deletion constructs, we found that both N-(1-64 amino acids) and C-terminal (150-195 amino acids) domains of eEF1B beta are important for the interaction with PVX TGBp1 and that the C-terminal domain of eEF1B beta is involved in the interaction with eEF1A. These results suggest that eEF1B beta could be a potential target for engineering virus-resistant plants.