The molecular mechanism of microRNA duplex selectivity of Arabidopsis ARGONAUTE10.
The molecular mechanism of microRNA duplex selectivity of Arabidopsis ARGONAUTE10.
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DOI：
10.1093/nar/gkac571
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发表时间：
2022-09-23
影响因子：
14.9
通讯作者：
MacRae, Ian J.
中科院分区：
文献类型：
--
作者：
Xiao, Yao;MacRae, Ian J.
小分子RNA（small RNA，sRNA）包括微小RNA（microRNA，miRNAs）和小干扰RNA（small interfering RNA，siRNAs），是动植物发育过程中必不可少的基因调控因子。将sRNA双链体装载到适当的ARGONAUTE（AGO）蛋白中是形成功能性沉默复合物的关键步骤。在拟南芥中，miR 166/165特异性装载到AGO 10（AtAGO 10）中对于维持茎顶端分生组织（所有茎器官的来源）至关重要，但AtAGO 10区分miR 166/165与其他细胞的机制尚不清楚。在这里，我们显示单独纯化的AtAGO 10缺乏对miR 166/165双链体的装载选择性。然而，磷酸盐和HSP分子伴侣系统重塑了AtAGO 10对其生理底物的选择性。AtAGO 10中央裂隙中的环对于识别miR 166/165双链体中引导链3′区域对面的特异性错配至关重要。用来自智人AGO 2（HsAGO 2）的等效环替换该环改变了AtAGO 10 miRNA的加载行为，使得3′区域错配被忽略，而与指导5′端相对的错配反而驱动加载，如HsAGO 2中那样。因此，这项研究揭示了AtAGO 10的miR 166/165选择性的分子机制，这对植物发育至关重要，并为如何识别miRNA双链体结构进行sRNA分选提供了新的见解。
Small RNAs (sRNAs), including microRNAs (miRNAs) and small interfering RNAs (siRNAs), are essential gene regulators for plant and animal development. The loading of sRNA duplexes into the proper ARGONAUTE (AGO) protein is a key step to forming a functional silencing complex. In Arabidopsis thaliana, the specific loading of miR166/165 into AGO10 (AtAGO10) is critical for the maintenance of the shoot apical meristem, the source of all shoot organs, but the mechanism by which AtAGO10 distinguishes miR166/165 from other cellular miRNAs is not known. Here, we show purified AtAGO10 alone lacks loading selectivity towards miR166/165 duplexes. However, phosphate and HSP chaperone systems reshape the selectivity of AtAGO10 to its physiological substrates. A loop in the AtAGO10 central cleft is essential for recognizing specific mismatches opposite the guide strand 3′ region in miR166/165 duplexes. Replacing this loop with the equivalent loop from Homo sapiens AGO2 (HsAGO2) changes AtAGO10 miRNA loading behavior such that 3′ region mismatches are ignored and mismatches opposite the guide 5′ end instead drive loading, as in HsAGO2. Thus, this study uncovers the molecular mechanism underlying the miR166/165 selectivity of AtAGO10, essential for plant development, and provides new insights into how miRNA duplex structures are recognized for sRNA sorting.
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