Micro (mi)RNAs are 20-22nt long non-coding RNA molecules involved in post-transcriptional silencing of targets having high base-pair complementarity. Plant miRNAs are processed from long Pol II-transcripts with specific stem-loop structures by Dicer-like (DCL) 1 protein. Although there were reports indicating how a specific region is selected for miRNA biogenesis, molecular details were unclear. Here, we show that the presence of specific GC-rich sequence signature within miRNA/miRNA* region is required for the precise miRNA biogenesis. The involvement of GC-rich signatures in precise processing and abundance of miRNAs was confirmed through detailed molecular and functional analysis. Consistent with the presence of the miRNA-specific GC signature, target RNAs of miRNAs also possess conserved complementary sequence signatures in their miRNA binding motifs. The selection of these GC signatures was dependent on an RNA binding protein partner of DCL1 named HYL1. Finally, we demonstrate a direct application of this discovery for enhancing the abundance and efficiency of artificial miRNAs that are popular in plant functional genomic studies.

中文翻译：

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保守的序列签名对于健壮的植物miRNA生物发生至关重要。

微小（mi）RNA是20-22nt长的非编码RNA分子，参与具有高碱基对互补性的靶标的转录后沉默。通过micer-like（DCL）1蛋白从具有特定茎环结构的长Pol II转录本中加工植物miRNA。尽管有报道表明如何选择特定区域进行miRNA生物发生，但分子细节尚不清楚。在这里，我们显示miRNA / miRNA *区域内特定GC丰富的序列签名的存在是精确的miRNA生物发生所必需的。通过详细的分子和功能分析，证实了富含GC的标记物在miRNA的精确加工和丰度中的参与。与miRNA特异性GC标记的存在一致，miRNA的靶RNA在其miRNA结合基序中也具有保守的互补序列标记。这些GC签名的选择取决于DCL1的RNA结合蛋白伴侣HYL1。最后，我们证明了这一发现在增强植物功能基因组研究中流行的人工miRNA的丰度和效率方面的直接应用。