Silencing suppressor protein VPg of a potyvirus interacts with the plant silencing-related protein SGS3

Mol Plant Microbe Interact. 2014 Nov;27(11):1199-210. doi: 10.1094/MPMI-04-14-0109-R.

Abstract

Viral genome-linked protein (VPg) of potyviruses is involved in multiple steps of the potyvirus infection cycle, including viral multiplication and movement in plants. Recently, we showed that VPg of Potato virus A (PVA; genus Potyvirus) suppresses sense-mediated RNA silencing, which is linked to one or both nuclear or nucleolar localization. Here, we studied interactions between VPg and components of the plant RNA silencing pathway. Results showed that VPg interacts with the SGS3 protein of Solanum tuberosum and Arabidopsis thaliana, as shown by yeast two-hybrid analysis and bimolecular fluorescence complementation assays. VPg-SGS3 interactions co-localized with small cytoplasmic bodies that contained plant RNA-dependent RNA polymerase 6 (RDR6) (likely SGS3/RDR6 bodies). The N-terminal zinc finger (ZF) domain of SGS3 was the main determinant of the VPg interaction. Our data also suggest that the ZF domain controls SGS3 localization. SGS3 homodimerization was controlled by multiple protein regions. The VPg-SGS3 interaction appeared beneficial for PVA, as viral RNA levels correlated positively with sgs3 mRNA levels in the SGS3-silenced and SGS3-overexpressing leaves of Nicotiana benthamiana. The data support the idea that VPg acts as a suppressor of RNA silencing and suggest that an interaction with SGS3 may be important, especially in suppression of sense-mediated RNA silencing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics*
  • Arabidopsis / virology
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Base Sequence
  • Molecular Sequence Data
  • Nicotiana / cytology
  • Nicotiana / genetics
  • Nicotiana / virology
  • Plant Diseases / virology*
  • Plant Leaves / cytology
  • Plant Leaves / genetics
  • Plant Leaves / virology
  • Plant Proteins / genetics
  • Plant Proteins / metabolism
  • Potyvirus / genetics*
  • Potyvirus / metabolism
  • RNA Interference
  • RNA, Plant / genetics
  • RNA, Viral / genetics
  • RNA-Dependent RNA Polymerase / genetics
  • RNA-Dependent RNA Polymerase / metabolism
  • Recombinant Fusion Proteins
  • Sequence Analysis, DNA
  • Sequence Deletion
  • Solanum tuberosum / genetics*
  • Solanum tuberosum / virology
  • Two-Hybrid System Techniques
  • Viral Nonstructural Proteins / genetics
  • Viral Nonstructural Proteins / metabolism*
  • Zinc Fingers

Substances

  • Arabidopsis Proteins
  • Plant Proteins
  • RNA, Plant
  • RNA, Viral
  • Recombinant Fusion Proteins
  • SGS3 protein, Arabidopsis
  • Viral Nonstructural Proteins
  • RDR6 protein, Arabidopsis
  • RNA-Dependent RNA Polymerase

Associated data

  • GENBANK/HG970650
  • GENBANK/HG970651