Polerovirus protein P0 prevents the assembly of small RNA-containing RISC complexes and leads to degradation of ARGONAUTE1

RNA silencing plays an important role in plants in defence against viruses. To overcome this defence, plant viruses encode suppressors of RNA silencing. The most common mode of silencing suppression is sequestration of double-stranded RNAs involved in the antiviral silencing pathways. Viral suppress...

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Bibliographic Details
Published in:The Plant journal : for cell and molecular biology 2010-05, Vol.62 (3), p.463-472
Main Authors: Csorba, Tibor, Lózsa, Rita, Hutvágner, György, Burgyán, József
Format: Article
Language:English
Subjects:
AGO1
Arabidopsis Proteins - metabolism
Argonaute Proteins
Biodegradation
Biological and medical sciences
Flowers & plants
Fundamental and applied biological sciences. Psychology
Luteoviridae - metabolism
Luteoviridae - physiology
Nicotiana - genetics
Nicotiana - virology
P0 silencing suppressor
Plant physiology and development
Polerovirus
protein ubiquitination
Proteins
Ribonucleic acid
RISC assembly
RNA
RNA Interference
RNA silencing
RNA, Plant
RNA, Small Interfering - metabolism
RNA-Induced Silencing Complex - metabolism
Viral Proteins - metabolism
Viruses
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Summary:RNA silencing plays an important role in plants in defence against viruses. To overcome this defence, plant viruses encode suppressors of RNA silencing. The most common mode of silencing suppression is sequestration of double-stranded RNAs involved in the antiviral silencing pathways. Viral suppressors can also overcome silencing responses through protein-protein interaction. The poleroviral P0 silencing suppressor protein targets ARGONAUTE (AGO) proteins for degradation. AGO proteins are the core component of the RNA-induced silencing complex (RISC). We found that P0 does not interfere with the slicer activity of pre-programmed siRNA/miRNA containing AGO1, but prevents de novo formation of siRNA/miRNA containing AGO1. We show that the AGO1 protein is part of a high-molecular-weight complex, suggesting the existence of a multi-protein RISC in plants. We propose that P0 prevents RISC assembly by interacting with one of its protein components, thus inhibiting formation of siRNA/miRNA-RISC, and ultimately leading to AGO1 degradation. Our findings also suggest that siRNAs enhance the stability of co-expressed AGO1 in both the presence and absence of P0.
ISSN:0960-7412
1365-313X
DOI:10.1111/j.1365-313X.2010.04163.x