Yeast Nop15p is an RNA-binding protein required for pre-rRNA processing and cytokinesis
Yeast Nop15p is an RNA-binding protein required for pre-rRNA processing and cytokinesis
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DOI：
10.1093/emboj/cdg616
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发表时间：
2003-12-15
期刊：
影响因子：
11.4
通讯作者：
Tollervey, D
中科院分区：
文献类型：
--
作者：
Oeffinger, M;Tollervey, D
Nop15p是一种包含RNA识别基序（RRM）并定位于核质和核仁的必需蛋白。缺失Nop15p的细胞无法合成60S核糖体亚基的25S和5.8S rRNA组分，5.8S rRNA的外核分解5′加工受到强烈抑制。与标记的Nop15p共沉淀的pre-rRNA证实了其与早期pre-60S颗粒的关联，并且Nop15p在体外结合了pre-rRNA转录物。nop15p耗竭的细胞在核糖体亚基大量耗竭之前表现出异常突然的生长停滞。在有丝分裂过程中，随着细胞同步，nop15p缺失的细胞以野生型动力学进行核分裂，激活有丝分裂退出网络并拆卸其有丝分裂纺锤体。然而，它们均匀地在细胞质分裂时停止，不能在芽颈处形成可收缩的肌动蛋白环。在野生型细胞分裂过程中，核仁蛋白在核质分离后向子核分离。在这些有丝分裂后期的细胞中，Nop15p部分从核核转移到核质，除了在核糖体合成中起作用外，还在细胞分裂中具有特定的功能。
Nop15p is an essential protein that contains an RNA recognition motif (RRM) and localizes to the nucleoplasm and nucleolus. Cells depleted of Nop15p failed to synthesize the 25S and 5.8S rRNA components of the 60S ribosomal subunit, and exonucleolytic 5' processing of 5.8S rRNA was strongly inhibited. Pre-rRNAs co-precipitated with tagged Nop15p confirmed its association with early pre-60S particles and Nop15p bound a pre-rRNA transcript in vitro. Nop15p-depleted cells show an unusually abrupt growth arrest prior to substantial depletion of ribosomal subunits. Following cell synchronization in mitosis, Nop15p-depleted cells undergo nuclear division with wild-type kinetics, activate the mitotic exit network and disassemble their mitotic spindle. However, they uniformly arrest at cytokinesis and fail to assemble a contractile actin ring at the bud neck. In dividing wild-type cells, segregation of nucleolar proteins to the daughter nuclei occurs after separation of the nucleoplasm. In these late mitotic cells, Nop15p was partially delocalized from the nucleolus to the nucleoplasm, consistent with a specific function in cell division in addition to its role in ribosome synthesis.