Biogenesis of Plant MicroRNAs

MATEOS, J. L.; BOLOGNA,N.G; PALATNIK, J.F

Non coding RNAs in plants

Springer

Año: 2011; p. 251 - 268

MicroRNAs (miRNAs) are small RNAs of ∼21 nt that regulate multiple biological pathways in complex organisms. They are defined by their specific biogenesis that involves the precise excision from an imperfect fold-back precursor. In plants, the ribonuclease III DICER-LIKE1 (DCL1) assisted by accessory proteins cleaves the precursor to release the miRNA. In general, the processing complex recognizes a 15-nt lower stem located below the miRNA in the precursors to produce the first cleavage, which is then followed by a second cut that releases the small RNA. Plant precursors are, however, very variable in size and shape, and not all of them are processed in the same way. The conserved miR319/159 precursors are cleaved in a loop-to-base direction by several successive DCL1 cuts. The situation seems to be even more complex if newly evolved miRNAs are also taken into account. The emerging picture suggests a high plasticity of the miRNA processing machinery.