Structural determinants of Arabidopsis thaliana Hyponastic leaves 1 function in vivo

BURDISSO, PAULA; MILIA, FERNANDO; SCHAPIRE, ARNALDO; BOLOGNA, NICOLAS G.; PALATNIK, JAVIER F.; RASIA, RODOLFO M.

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2014 vol. 9 p. 113243 - 113243

1932-6203

MicroRNAs have turned out to be important regulators of gene expression. These molecules originate from longertranscripts that are processed by ribonuclease III (RNAse III) enzymes. Dicer proteins are essential RNAse III enzymes that areinvolved in the generation of microRNAs (miRNAs) and other small RNAs. The correct function of Dicer relies on theparticipation of accessory dsRNA binding proteins, the exact function of which is not well-understood so far. In plants, thedouble stranded RNA binding protein Hyponastic Leaves 1 (HYL1) helps Dicer Like protein (DCL1) to achieve an efficient andprecise excision of the miRNAs from their primary precursors. Here we dissected the regions of HYL1 that are essential for itsfunction in Arabidopsis thaliana plant model. We generated mutant forms of the protein that retain their structure but affectits RNA-binding properties. The mutant versions of HYL1 were studied both in vitro and in vivo, and we were able to identifyessential aminoacids/residues for its activity. Remarkably, mutation and even ablation of one of the purportedly main RNAbinding determinants does not give rise to any major disturbances in the function of the protein. We studied the function ofthe mutant forms in vivo, establishing a direct correlation between affinity for the pri-miRNA precursors and protein activity.