SPECIFICITY DETERMINANTS OF microRNA-TARGET INTERACTION IN PLANTS

MARTIN MECCHIA; RAMIRO ESTEBAN RODRIGUEZ; JAVIER PALATNIK

Rosario, Argentina

Congreso; XLII Reunión Anual Nacional de la Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular; 2007

SAIB

MicroRNAs (miRNAs) have been recognized as a novel mechanism to regulate gene expression in multicellular organisms. They are small RNAs of ~21 nucleotides in length that recognize partially complementary sequences in target mRNAs and guide them to cleavage or translational arrest. They have been implicated in many key processes such as development and stress responses. miRNAs are generally encoded by small gene families of identical or similar sequence.   It is currently unknown if all members of a certain miRNA family regulate their putative targets with the same efficiency or if there is miRNA sub-functionalization. Although plant miRNAs are largely conserved during evolution we have observed that specific miRNA variants are found only in certain species. We performed a bioinformatic analysis of miRNAs from different plants in order to systematically classify this natural variation.   To study the role of these changes during evolution we are modifying Arabidopsis miRNAs in order to express these new variants. These transgenic miRNAs are then expressed ectopically in Arabidopsis and their effects are compared to the wild type versions.   We developed a novel technique to detect miRNA cleavage that allows us to differentiate between the activities of some closely related miRNAs in vivo. The effects of small sequence changes on miRNA activity will be discussed.