THE DOUBLE-STRANDED RNA BINDING DOMAINS OF DCL1: NON-CANONNICAL FEATURES ON A COMMON MOTIF

RASIA, RODOLFO M.; BURDISSO, PAULA; SUAREZ, IRINA; BOLOGNA, NICOLAS G.; PALATNIK, JAVIER F.; BOISBOUVIER, JEROME; BERSCH, BEATE

Viena

Conferencia; 23rd International Conference on Arabidopsis Research (ICAR); 2012

THE DOUBLE-STRANDED RNA BINDING DOMAINS OF DCL1: NON-CANONNICAL FEATURES ON A COMMON MOTIF. Rodolfo M. Rasia* (Institute of Molecular and Cell Biology of Rosario (IBR), Argentina), Paula Burdisso (IBR), Irina P. Suarez (IBR), Nicolás G. Bologna (IBR), Javier F. Palatnik (IBR), Jérôme Boisbouvier (Instute of Structural Biology (IBS), France), Beate Bersch (IBS). rasia@ibr.gov.ar MicroRNAs are essential gene regulators in multicellular organisms. Plant miRNAs are processed in the nucleus by a protein complex formed by DICER-LIKE1 (DCL1), HYL1 and SERRATE. DCL1 has a central role in the recognition and processing of the heterogeneous plant precursors, yet little is known about the structural aspects of this protein. We present a structural characterization of the two double-stranded RNA binding domains (dsRBDs) of DCL1, which are presumed to participate in pri-miRNA recognition and binding. The first dsRBD is intrinsically disordered, but folds upon binding substrate RNA. We solved the solution structure of the second dsRBD, and found that it has a canonical fold but bears some variation with respect to other homologous domains. In constrast with canonical dsRBDs both domains from DCL1 bind dsDNA with a similar affinity as dsRNA. Analysis of the sequences of the C-terminal dsRBDs present in DCL1-4 proteins from different plants shows a much higher conservation among DCL1 homologs. This suggests that the peculiar properties of this double domain were conserved through evolution, and that they have to be essential for pri-miRNA processing by DCL1. Our characterization of DCL1 dsRBDs show that these domains should have functions other than substrate recognition and binding, which are conferred by their unusual structural features.