Efficiency and precision of microRNA biogenesis modes in plants
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2018-10-05
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Oxford University Press
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Descripción
Many evolutionarily conserved microRNAs (miRNAs)
in plants regulate transcription factors with key functions in development. Hence, mutations in the core
components of the miRNA biogenesis machinery
cause strong growth defects. An essential aspect
of miRNA biogenesis is the precise excision of the
small RNA from its precursor. In plants, miRNA precursors are largely variable in size and shape and
can be processed by different modes. Here, we optimized an approach to detect processing intermediates during miRNA biogenesis. We characterized
a miRNA whose processing is triggered by a terminal branched loop. Plant miRNA processing can
be initiated by internal bubbles, small terminal loops
or branched loops followed by dsRNA segments of
15–17 bp. Interestingly, precision and efficiency vary
with the processing modes. Despite the various potential structural determinants present in a single a
miRNA precursor, DCL1 is mostly guided by a predominant structural region in each precursor in wildtype plants. However, our studies in fiery1, hyl1 and
se mutants revealed the existence of cleavage signatures consistent with the recognition of alternative
processing determinants. The results provide a general view of the mechanisms underlying the specificity of miRNA biogenesis in plants.
This article has been accepted for publication in Nucleic Acids Research Published by Oxford University Press.
This article has been accepted for publication in Nucleic Acids Research Published by Oxford University Press.
Palabras clave
Gene Expression Regulation, Plant, Transcription, Genetic, Binding Sites, Transgenes, RNA-Binding Proteins, RNA, Double-Stranded