The Poly(A) Binding Protein Is Internalized in Virus-Induced Vesicles or Redistributed to the Nucleolus during Turnip Mosaic Virus Infection

Abstract

Poly(A) binding protein 2 (PABP2) of Arabidopsis thaliana was previously shown to interact with VPg-Pro of turnip mosaic virus (TuMV) and may consequently play an important role during infection. Subcellular fractionation experiments revealed that PABP2 was predominantly a cytoplasmic soluble protein in healthy plants. However, in TuMV-infected plants, a subpopulation of PABP2 was membrane associated or was localized in the nucleus. Confocal microscopy experiments indicated that PABP2 was partially retargeted to the nucleolus in the presence of TuMV VPg-Pro. In addition, the membrane association of PABP2 during TuMV infection resulted from the internalization of the host protein in 6K-VPg-Pro-induced vesicles, as shown by a combination of confocal microscopy and sucrose gradient fractionation experiments. This redistribution of an important translation initiation factor to the nucleolus and to membrane structure likely underlies two important processes of the TuMV replication cycle.