Cucumber mosaic virus-encoded 2b suppressor inhibits Arabidopsis Argonaute1 cleavage activity to counter plant defense Journal Article

Authors: Zhang, X.; Yuan, Y. R.; Pei, Y.; Lin, S. S.; Tuschl, T.; Patel, D. J.; Chua, N. H.
Article Title: Cucumber mosaic virus-encoded 2b suppressor inhibits Arabidopsis Argonaute1 cleavage activity to counter plant defense
Abstract: RNA silencing refers to small regulatory RNA-mediated processes that repress endogenous gene expression and defend hosts from offending viruses. As an anti-host defense mechanism, viruses encode suppressors that can block RNA silencing pathways. Cucumber mosaic virus (CMV)-encoded 2b protein was among the first suppressors identified that could inhibit post-transcriptional gene silencing (PTGS), but with little or no effect on miRNA functions. The mechanisms underlying 2b suppression of RNA silencing are unknown. Here, we demonstrate that the CMV 2b protein also interferes with miRNA pathways, eliciting developmental anomalies partially phenocopying ago1 mutant alleles. In contrast to most characterized suppressors, 2b directly interacts with Argonaute1 (AGO1) in vitro and in vivo, and this interaction occurs primarily on one surface of the PAZ-containing module and part of the PIWI-box of AGO1. Consistent with this interaction, 2b specifically inhibits AGO1 cleavage activity in RISC reconstitution assays. In addition, AGO1 recruits virus-derived small interfering RNAs (siRNAs) in vivo, suggesting that AGO1 is a major factor in defense against CMV infection. We conclude that 2b blocks AGO1 cleavage activity to inhibit miRNA pathways, attenuate RNA silencing, and counter host defense. These findings provide insight on the molecular arms race between host antiviral RNA silencing and virus counterdefense. © 2006 by Cold Spring Harbor Laboratory Press.
Keywords: nonhuman; small interfering rna; rna interference; in vivo study; in vitro study; adaptor proteins, signal transducing; base sequence; gene silencing; dna primers; micrornas; host resistance; virus protein; viral proteins; arabidopsis; virulence; arabidopsis proteins; suppression, genetic; viral suppressor; cleavage activity; arabidopsis protein; atago1; counter defense; cucumber mosaic virus 2b; rna silencing; protein 2b; protein argonaute1; cucumber mosaic virus; cucumovirus; plant diseases; plants, genetically modified; rna, plant
Journal Title: Genes and Development
Volume: 20
Issue: 23
ISSN: 0890-9369
Publisher: Cold Spring Harbor Laboratory Press  
Date Published: 2006-12-01
Start Page: 3255
End Page: 3268
Language: English
DOI: 10.1101/gad.1495506
PUBMED: 17158744
PROVIDER: scopus
PMCID: PMC1686603
Notes: --- - "Cited By (since 1996): 195" - "Export Date: 4 June 2012" - "CODEN: GEDEE" - "Source: Scopus"
Citation Impact
MSK Authors
  1. Yu-Ren Yuan
    8 Yuan
  2. Dinshaw J Patel
    465 Patel