A viral protein suppresses RNA silencing and binds silencing-generated, 21- to 25-nucleotide double-stranded RNAs

Dániel Silhavy, Attila Molnár, Alessandra Lucioli, György Szittya, Csaba Hornyik, Mario Tavazza, József Burgyán

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Abstract

Posttranscriptional gene silencing (PTGS) processes double-stranded (ds) RNAs into 21-25 nucleotide (nt) RNA fragments that direct ribonucleases to target cognate mRNAs. In higher plants, PTGS also generates mobile signals conferring sequence-specific silencing in distant organs. Since PTGS acts as an antiviral system in plants, successful virus infection requires evasion or suppression of gene silencing. Here we report that the 19 kDa protein (p19) of tombusviruses is a potent silencing suppressor that prevents the spread of mobile silencing signal. In vitro, p19 binds PTGS-generated, 21-25 nt dsRNAs and 21-nt synthetic dsRNAs with 2-nt 3′ overhanging end(s), while it barely interacts with single-stranded (ss) RNAs, long dsRNAs or blunt-ended 21-nt dsRNAs. We propose that p19 mediates silencing suppression by sequestering the PTGS-generated 21-25 nt dsRNAs, thus depleting the specificity determinants of PTGS effector complexes. Moreover, the observation that pl9-expressing transgenic plants show altered leaf morphology might indicate that the p19-targeted PTGS pathway is also important in the regulation of plant development.

Original languageEnglish
Pages (from-to)3070-3080
Number of pages11
JournalEMBO Journal
Volume21
Issue number12
DOIs
Publication statusPublished - Jun 17 2002

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Keywords

  • Silencing
  • Suppressor
  • Tombusvirus
  • dsRNA binding
  • p19

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

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