Liu Q, Yan Q, Liu Y, Hong F, Sun Z, Shi L, Huang Y, Fang Y

MiRNAs are a class of small, regulatory RNAs that are found in almost all of the eukaryotes. Arabidopsis (Arabidopsis thaliana) miRNAs are processed from primary microRNAs (pri-miRNAs) mainly by the RNase III-like enzyme DICER-LIKE1 (DCL1) and its specific partner HYPONASTIC LEAVES1 (HYL1), a double-strand RNA-binding protein, both contain two double-strand ...

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RNA-binding domains (dsRBDs). These dsRBDs are essential for miRNA processing, but the functions of them are not clear. Here we report that the two dsRBDs (DCL1-D1D2) of DCL1, and to some extent the second dsRBD (DCL1-D2), complement hyl1 mutant, but not the first dsRBD of DCL1 (DCL1-D1). DCL1-D1 is diffusely distributed throughout the nucleoplasm, whereas DCL1-D2 and DCL1-D1D2 concentrate in nuclear dicing bodies (D-bodies) in which DCL1 and HYL1 colocalize. We show further that protein-protein interaction is mainly mediated by DCL1-D2, while DCL1-D1 plays a major role in binding of pri-miRNAs. These results suggest parallel roles between C-terminal dsRBDs of DCL1 and N-terminal dsRBDs of HYL1, and support a model in which Arabidopsis pri-microRNAs are recruited to D-bodies through functionally divergent dsRBDs of microprocessor for accurate processing of plant pri-miRNAs.

Date: Jul. 25, 2013

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