Premium
Molecular mechanism of RNA silencing suppression mediated by p19 protein of tombusviruses
Author(s) -
Lakatos Lóránt,
Szittya György,
Silhavy Dániel,
Burgyán József
Publication year - 2004
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600096
Subject(s) - biology , mechanism (biology) , gene silencing , rna , genetics , rna induced silencing complex , rna silencing , rna induced transcriptional silencing , trans acting sirna , rna interference , microbiology and biotechnology , gene , philosophy , epistemology
RNA silencing is an evolutionarily conserved surveillance system that occurs in a broad range of eukaryotic organisms. In plants, RNA silencing acts as an antiviral system; thus, successful virus infection requires suppression of gene silencing. A number of viral suppressors have been identified so far; however, the molecular bases of silencing suppression are still poorly understood. Here we show that p19 of Cymbidium ringspot virus (CymRSV) inhibits RNA silencing via its small RNA‐binding activity in vivo . Small RNAs bound by p19 in planta are bona fide double‐stranded siRNAs and they are silencing competent in the in vitro RNA‐silencing system. p19 also suppresses RNA silencing in the heterologous Drosophila in vitro system by preventing siRNA incorporation into RISC. During CymRSV infection, p19 markedly diminishes the amount of free siRNA in cells by forming p19–siRNA complexes, thus making siRNAs inaccessible for effector complexes of RNA‐silencing machinery. Furthermore, the obtained results also suggest that the p19‐mediated sequestration of siRNAs in virus‐infected cells blocks the spread of the mobile, systemic signal of RNA silencing.