Arabidopsis encodes 10 ARGONAUTE (AGO) effectors of RNA silencing, canonically loaded with either 21–22 nucleotide (nt) long small RNAs (sRNAs) to mediate post‐transcriptional gene silencing (PTGS) or 24 nt sRNAs to promote RNA‐directed DNA methylation. Using full‐locus constructs, we characterized the expression, biochemical properties and possible modes of action of AGO3. Although AGO3 arose from a recent duplication at the AGO2 locus, their expression patterns differ drastically, with AGO2 being expressed in both male and female gametes whereas AGO3 accumulates in aerial vascular terminations and specifically in chalazal seed integuments. Accordingly, AGO3 downregulation alters gene expression in siliques. Similar to AGO2, AGO3 binds sRNAs with a strong 5′ adenosine bias, but unlike Arabidopsis AGO2, it binds 24 nt sRNAs most efficiently. AGO3 immunoprecipitation experiments in siliques revealed that these sRNAs mostly correspond to genes and intergenic regions in a manner reflecting their respective accumulation from their loci of origin. AGO3 localizes to the cytoplasm and co‐fractionates with polysomes to possibly mediate PTGS via translation inhibition.

中文翻译：

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拟南芥属ARGONAUTE 3在生殖组织中的功能表征。

拟南芥编码10种RNA沉默的ARGONAUTE（AGO）效应子，经典装载21–22个核苷酸（nt）长的小RNA（sRNA）来介导转录后基因沉默（PTGS）或24 nt sRNA，以促进RNA定向的DNA甲基化。 。使用全基因座构建体，我们表征了AGO3的表达，生化特性和可能的​​作用方式。尽管AGO3是由于最近在AGO2基因座上的重复而引起的，但它们的表达方式却截然不同，AGO2在雄性和雌性配子中都表达，而AGO3则在气生血管末端特别是在la子种子被膜中积累。因此，AGO3下调改变孤岛中的基因表达。与AGO2相似，AGO3以强5'腺苷偏向结合sRNA，但与拟南芥AGO2不同，它最有效地结合24 nt sRNA。AGO3在组群中的免疫沉淀实验表明，这些sRNA大部分对应于基因和基因间区域，其反映方式是从其起源位点反映出它们各自的积累。AGO3定位于细胞质，并与多核糖体共分离，可能通过翻译抑制介导PTGS。