Open AccessA specific dsRNA-binding protein complex selectively sequesters endogenous inverted-repeat siRNA precursors and inhibits their processing
Author(s) -
Thomas Montavon,
Yerim Kwon,
Aude Zimmermann,
Philippe Hammann,
Timothée Vincent,
Valérie Cognat,
Fabrice Michel,
Patrice Dunoyer
Publication year - 2016
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/gkw1264
Subject(s) - biology , rna silencing , trans acting sirna , gene silencing , small interfering rna , rna , argonaute , rna binding protein , microbiology and biotechnology , dicer , rna interference , rna induced silencing complex , endogeny , genetics , gene , biochemistry
In plants, several dsRNA-binding proteins (DRBs) have been shown to play important roles in various RNA silencing pathways, mostly by promoting the efficiency and/or accuracy of Dicer-like proteins (DCL)-mediated small RNA production. Among the DRBs encoded by the Arabidopsis genome, we recently identified DRB7.2 whose function in RNA silencing was unknown. Here, we show that DRB7.2 is specifically involved in siRNA production from endogenous inverted-repeat (endoIR) loci. This function requires its interacting partner DRB4, the main cofactor of DCL4 and is achieved through specific sequestration of endoIR dsRNA precursors, thereby repressing their access and processing by the siRNA-generating DCLs. The present study also provides multiple lines of evidence showing that DRB4 is partitioned into, at least, two distinct cellular pools fulfilling different functions, through mutually exclusive binding with either DCL4 or DRB7.2. Collectively, these findings revealed that plants have evolved a specific DRB complex that modulates selectively the production of endoIR-siRNAs. The existence of such a complex and its implication regarding the still elusive biological function of plant endoIR-siRNA will be discussed.