Revisiting the structural determinants required for microRNA biogenesis in plants

SCHAPIRE, ARNALDO L; MATEOS, JULIETA; ROJAS, ARANTXA M. L.; MORO, BELEN; PALATNIK, JAVIER; BRESSO, EDGARDO; CHOROSTECKI, UCIEL

Bernal, Quilmes

Congreso; II Reunión Argentina de Biología de ARNs no codificantes; 2018

MicroRNAs (miRNAs) are endogenous small RNAs of 20-22 nt that play a role as post-transcriptional gene regulators. They recognize target sequences in other RNAs by base complementarity and guide them to cleavage or translational arrest. MiRNAs are generated from longer precursors that harbor a fold-back structure with the miRNA located in one of their arms. In plants, miRNA precursors are processed in the nuclei by a complex including DICER-LIKE1 (DCL1). This complex recognizes structural determinants in the precursors to produce the cuts that release the mature miRNAs. To gain insights into miRNA processing, we performed a random mutagenesis to improve the biogenesis of a plant microRNA. We focused on Arabidopsis miR172, a miRNA that regulates flowering time and flower patterning. We found that a single change in the MIR172 precursor can significantly improve the biogenesis of the small RNA. We identified and characterized hot spots in MIRNA precursors, where small changes significantly affect the efficiency of the miRNA biogenesis in plants. We extended our results to several precursors including MIR156/7, MIR171, MIR164 and MIR165/6. In animal species, primary sequence motifs that affect the biogenesis of miRNAs have been reported, in this work it is shown that the identity of the bases is also important for the bogenesis of plant miRNAs