A role for SUMOylation in the biogenesis and/or function of Box C/D snoRNPs has been reported, mediated via SUMO2 conjugation to the core snoRNP protein, Nop58. A quantitative proteomics screen, based on SILAC (stable-isotope labeling by amino acids in cell culture) and mass spectrometry using extracts prepared from cultured mammalian cells expressing either 6His-SUMO1 or -SUMO2, revealed that the snoRNP-related proteins Nop58, Nhp2, DKC1 and NOLC1 are amongst the main SUMO-modified proteins in the nucleolus. SUMOylation of Nhp2 and endogenous Nop58 was confirmed using a combination of in vitro and cell-based assays and the modified lysines identified by site-directed mutagenesis. SUMOylation of Nop58 was found to be important for high-affinity Box C/D snoRNA binding and the localization of newly transcribed snoRNAs to the nucleolus. Here, these findings are reviewed and a model for understanding Nop58 SUMOylation in the context of Box C/D snoRNP biogenesis is presented. Given the essential role of snoRNPs in the modification of pre-ribosomal RNA, this work suggests that SUMO, snoRNPs and ribosome assembly, and thus cellular translation, growth and proliferation, may be linked via novel mechanisms which warrant further investigation.

中文翻译：

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定量蛋白质组学揭示了 SUMO 化在 snoRNP 生物发生中的作用

已经报道了 SUMO 化在 Box C/D snoRNPs 的生物发生和/或功能中的作用，通过 SUMO2 与核心 snoRNP 蛋白 Nop58 的结合介导。定量蛋白质组学筛选，基于 SILAC（细胞培养物中氨基酸的稳定同位素标记）和质谱分析，使用从表达 6His-SUMO1 或 -SUMO2 的培养哺乳动物细胞制备的提取物，揭示了 snoRNP 相关蛋白 Nop58、Nhp2、 DKC1 和 NOLC1 是核仁中主要的 SUMO 修饰蛋白之一。Nhp2 和内源性 Nop58 的 SUMO 化通过结合体外和基于细胞的测定以及通过定点诱变鉴定的修饰赖氨酸得到证实。发现 Nop58 的 SUMO 化对于高亲和力 Box C/D snoRNA 结合和新转录的 snoRNA 到核仁的定位很重要。这里，回顾了这些发现，并提出了在 Box C/D snoRNP 生物发生的背景下理解 Nop58 SUMOylation 的模型。鉴于 snoRNPs 在前核糖体 RNA 修饰中的重要作用，这项工作表明 SUMO、snoRNPs 和核糖体组装以及细胞翻译、生长和增殖可能通过值得进一步研究的新机制联系起来。