Abstract
Proteins that specifically bind dsRNA are involved in RNAi, and are characterized by a conserved dsRNA-binding motif (dsRBM). We have studied the biochemical properties of such gene products, each containing dsRBMs: four Arabidopsis Dicer-like proteins (DCL1-4), HYL1/DRB1 and three of its Arabidopsis homologs (DRB2, DRB4 and DRB5). Previously, we reported that DCL1, DCL3, HYL1/DRB1 and the four HYL1 homologs exhibit dsRNA-binding activity. The dsRBMs of human dsRNA-binding proteins is reported to function as a protein-protein interaction domain. We show that DRB4 interacts specifically with DCL4, and HYL1/DRB1 most strongly interacts with DCL1. Localization studies using GFP fusion proteins demonstrate that DCL1, DCL4, HYL1/DRB1 and DRB4 localize in the nucleus. The presented data suggest that each member of the DRB protein family may individually modulate Dicer function through heterodimerization in vivo. We are now undertaking immunoprecipitation assay to prove such specifically interactions in vivo.
