A specific dsRNA-binding protein complex selectively sequesters endogenous inverted-repeat siRNA precursors and inhibits their processing.
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.
Université de Strasbourg, CNRS, IBMP UPR 2357, F-67000 Strasbourg, France.
Thomas
T
Montavon
Université de Strasbourg, CNRS, IBMP UPR 2357, F-67000 Strasbourg, France.
Yerim
Y
Kwon
Université de Strasbourg, CNRS, IBMP UPR 2357, F-67000 Strasbourg, France.
Aude
A
Zimmermann
Université de Strasbourg, CNRS, IBMC FRC1589, Plateforme Protéomique Strasbourg - Esplanade, F-67000 Strasbourg, France.
Philippe
P
Hammann
Université de Strasbourg, CNRS, IBMP UPR 2357, F-67000 Strasbourg, France.
Timothée
T
Vincent
Université de Strasbourg, CNRS, IBMP UPR 2357, F-67000 Strasbourg, France.
Valérie
V
Cognat
Université de Strasbourg, CNRS, IBMP UPR 2357, F-67000 Strasbourg, France.
Fabrice
F
Michel
Université de Strasbourg, CNRS, IBMP UPR 2357, F-67000 Strasbourg, France.
Patrice
P
Dunoyer
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D055029:Inverted Repeat Sequences; D046912:Multiprotein Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D034622:RNA Interference; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D043244:Ribonuclease III / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins; C511456:DRB4 protein, Arabidopsis; C000623015:DRB7.2 protein, Arabidopsis; D046912:Multiprotein Complexes; D012322:RNA Precursors; D018749:RNA, Plant; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; C504982:DCL4 protein, Arabidopsis; D043244:Ribonuclease III