Virus-encoded suppressor of posttranscriptional gene silencing targets a maintenance step in the silencing pathway

  • Cesar Llave
  • , Kristin D. Kasschau
  • , James C. Carrington

Research output: Contribution to journalArticlepeer-review

Abstract

Certain plant viruses encode suppressors of posttranscriptional gene silencing (PTGS), an adaptive antiviral defense response that limits virus replication and spread. The tobacco etch potyvirus protein, helper component-proteinase (HC-Pro), suppresses PTGS of silenced transgenes. The effect of HC-Pro on different steps of the silencing pathway was analyzed by using both transient Agrobacterium tumefaciens-based delivery and transgenic systems. HC-Pro inactivated PTGS in plants containing a preexisting silenced β-glucuronidase (GUS) transgene. PTGS in this system was associated with both small RNA molecules (21-26 nt) corresponding to the 3' proximal region of the transcribed GUS sequence and cytosine methylation of specific sites near the 3' end of the GUS transgene. Introduction of HC-Pro into these plants resulted in loss of PTGS, loss of small RNAs, and partial loss of methylation. These results suggest that HC-Pro targets a PTGS maintenance (as opposed to an initiation or signaling) component at a point that affects accumulation of small RNAs and methylation of genomic DNA.

Original languageEnglish
Pages (from-to)13401-13406
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume97
Issue number24
DOIs
StatePublished - Nov 21 2000

Keywords

  • HC-Pro
  • Methylation
  • PTGS Suppression
  • Short RNA

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