RT Journal Article
SR Electronic
T1 The Arabidopsis F-box protein FBW2 degrades AGO1 to avoid spurious loading of illegitimate small RNA
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2021.03.24.436811
DO 10.1101/2021.03.24.436811
A1 Thibaut Hacquard
A1 Marion Clavel
A1 Patricia Baldrich
A1 Esther Lechner
A1 Imma Pérez-Salamó
A1 Mikhail Schepetilnikov
A1 Benoît Derrien
A1 Marieke Dubois
A1 Philippe Hammann
A1 Lauriane Kuhn
A1 Danaé Brun
A1 Nathalie Bouteiller
A1 Hervé Vaucheret
A1 Blake C. Meyers
A1 Pascal Genschik
YR 2021
UL http://biorxiv.org/content/early/2021/03/24/2021.03.24.436811.abstract
AB RNA silencing is a conserved mechanism in eukaryotes and is involved in development, heterochromatin maintenance and defense against viruses. In plants, ARGONAUTE1 (AGO1) protein plays a central role in both microRNA (miRNA) and small interfering RNA (siRNA)-directed silencing and its expression is regulated at multiple levels. Here, we report that the F-box protein FBW2 targets proteolysis of AGO1 by a CDC48-mediated mechanism. We found that FBW2 assembles an SCF complex that recognizes the MID-PIWI domain of AGO1 and requires its C-terminal domain containing a GW motif for AGO1 turnover. We showed that FBW2 prefers the unloaded and some mutated forms of AGO1 protein. While FBW2 loss of function does not lead to strong growth or developmental defects, it significantly increases RNA silencing activity. Interestingly, under conditions in which small RNA production or accumulation is affected, the failure to degrade AGO1 in fbw2 mutants becomes more deleterious for the plant. Hence, the non-degradable AGO1 protein assembles high molecular weight complexes and binds illegitimate small RNA leading to the cleavage of new target genes that belong to stress responses and cellular metabolic processes. Therefore, the control of AGO1 homeostasis by ubiquitin ligases plays an important role in quality control to avoid off-target cleavage.Competing Interest StatementThe authors have declared no competing interest.