Differential regulation of microRNA miR398 targets in Arabidopsis

MARTIN, ANA PAULA; LODEYRO, ANABELLA F.; CARRILLO, NÉSTOR; PALATNIK, JAVIER F.

San Miguel de Tucumán

Congreso; 45th Annual Meeting - Argentine Society for Biochemestry and Molecular Biology Research; 2009

SOCIEDAD ARGENTINA DE DE INVESTIGACIÓN EN BIOQUÍMICA Y BIOLOGÍA MOLECULAR (SAIB)

MicroRNAs (miRNAs) are a class of regulatory RNAs of ~21 nucleotides that posttranscriptionally regulate eukaryotic gene expression by directing mRNA cleavage or translational inhibition. They are involved in diverse physiological processes like development, differentiation and metabolism. MiRNA miR398 targets two closely related Cu/Zn superoxide dismutases (cytosolic CSD1 and chloroplastic CSD2) that can detoxify superoxide radicals; and a subunit of Cytochrome C Oxidase, COX5b1. All these proteins bind Cu as a cofactor. Copper deficiency in the growth media induces miR398, which causes the degradation of its targets, so that the available copper is re-directed to essential proteins. It has been observed that miR398 exhibits differential activity to its targets, being CSD1 and CSD2 more sensitive than COX5b1 to the miRNA levels. Interestingly, genes regulated by miR398 have target sites with specific sequences that have been conserved throw evolution. To study this complex system we prepared transgenic plants that act as sensors of miR398 activity by overexpressing CSD2 and COX5b1 fused to GFP. Next, we introduced specific mutations in the miRNA target site of the sensors to study the mechanisms underlying miR398 activity. The action mechanism of miR398 will be discussed.