Cucumber mosaic virus-encoded 2b suppressor inhibits Arabidopsis Argonaute1 cleavage activity to counter plant defense.
By Xiuren Zhang, Yu-Ren Yuan, Y. Pei, Shih-Shun Lin, Thomas Tuschl, Dinshaw J. Patel, Nam-Hai Chua. Genes & Development, 2006
700 citations recorded by the source corpus.
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.
Subfields: Plant Science
View Paper: https://www.semanticscholar.org/paper/b9ac84f76301d5e34ab09ad15aa2f6f286c93b6d
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Citations in the corpus
- Specificity of ARGONAUTE7-miR390 interaction and dual functionality in TAS3 trans-acting siRNA formation. (2008, background): “The AGO7 cleavage, but not the noncleavage, function could be provided by AGO1, the dominant miRNA-associated AGO, but only when AGO1 was guided to a modified target site through an alternate miRNA.”
- Antiviral immunity directed by small RNAs. (2007, neutral): “The geminivirus VSR AC4 seems to prevent holoRISC assembly by capturing single-stranded small RNAs normally bound by AGOs (Chellappan et al., 2005), whereas the Cucumber mosaic virus 2b protein physically interacts with siRNA-loaded AGO1 and inhibits slicing (Zhang et al., 2006).”
- Roles of plant small RNAs in biotic stress responses. (2009, background): “Moreover, a similarly sized complex containing vsRNAs from a CyRSV-related virus exhibits virus sequence– preferential and ssRNA-specific nuclease activity (55), and AGO1 immunoprecipitates isolated from Cucumber mosaic virus (CMV)infected Arabidopsis contain CMV-derived vsRNAs (84).”