Center for RNA Research, Institute for Basic Science, Seoul 08826, Korea.
School of Biological Sciences, Seoul National University, Seoul 08826, Korea.
Nucleic Acids Res. 2020 Nov 4;48(19):11097-11112. doi: 10.1093/nar/gkaa827.
The microprocessor complex cleaves the primary transcript of microRNA (pri-miRNA) to initiate miRNA maturation. Microprocessor is known to consist of RNase III DROSHA and dsRNA-binding DGCR8. Here, we identify Enhancer of Rudimentary Homolog (ERH) as a new component of Microprocessor. Through a crystal structure and biochemical experiments, we reveal that ERH uses its hydrophobic groove to bind to a conserved region in the N-terminus of DGCR8, in a 2:2 stoichiometry. Knock-down of ERH or deletion of the DGCR8 N-terminus results in a reduced processing of suboptimal pri-miRNAs in polycistronic miRNA clusters. ERH increases the processing of suboptimal pri-miR-451 in a manner dependent on its neighboring pri-miR-144. Thus, the ERH dimer may mediate 'cluster assistance' in which Microprocessor is loaded onto a poor substrate with help from a high-affinity substrate in the same cluster. Our study reveals a role of ERH in the miRNA biogenesis pathway.
微处理器复合物切割 microRNA (pri-miRNA) 的初级转录本，以启动 miRNA 的成熟。已知微处理器由 RNase III DROSHA 和 dsRNA 结合蛋白 DGCR8 组成。在这里，我们鉴定 Enhancer of Rudimentary Homolog (ERH) 为微处理器的一个新组件。通过晶体结构和生化实验，我们揭示 ERH 利用其疏水性凹槽以 2:2 的比例结合到 DGCR8 N 端的保守区域。ERH 的敲低或 DGCR8 N 端的缺失导致多顺反子 miRNA 簇中次优 pri-miRNA 的加工减少。ERH 以依赖于其相邻 pri-miR-144 的方式增加次优 pri-miR-451 的加工。因此，ERH 二聚体可能介导“簇辅助”，其中微处理器在同一簇中高亲和力底物的帮助下加载到较差的底物上。我们的研究揭示了 ERH 在 miRNA 生物发生途径中的作用。
