PIN domain of Nob1p is required for D-site cleavage in 20S pre-rRNA
PIN domain of Nob1p is required for D-site cleavage in 20S pre-rRNA
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DOI：
10.1261/rna.7123504
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发表时间：
2004-11-01
期刊：
影响因子：
4.5
通讯作者：
Dlakic, M
中科院分区：
文献类型：
--
作者：
Fatica, A;Tollervey, D;Dlakic, M
Nob1p (Yor056c) 对于将 20S pre-rRNA 加工成成熟 18S rRNA 至关重要。它是前 40S 核糖体颗粒的一部分，被转运到细胞质，随后在成熟 18S rRNA（D 位点）的 3' 端被切割。据报道，Nob1p 也参与蛋白酶体生物合成，因此尚不清楚其主要活性是否参与核糖体合成。在这项工作中，我们描述了 Nob1p PIN 结构域的同源模型，该模型在结构上模仿 Mg2+ 依赖性核酸外切酶，尽管一级序列的相似性可以忽略不计。从该模型中获得的见解被用来设计一个点突变，预计该突变会消除假定的酶活性。表达带有此突变的 Nob1p 的细胞无法切割 20S pre-rRNA。这既支持了结构模型的重要性，也支持了 Nob1p 是长期寻找的 D 位核酸内切酶的观点。
Nob1p (Yor056c) is essential for processing of the 20S pre-rRNA to the mature 18S rRNA. It is part of a pre-40S ribosomal particle that is transported to the cytoplasm and subsequently cleaved at the 3' end of mature 18S rRNA (D-site). Nob1p is also reported to participate in proteasome biogenesis, and it was therefore unclear whether its primary activity is in ribosome synthesis. In this work, we describe a homology model of the PIN domain of Nob1p, which structurally Mimics Mg2+-dependent exonucleases despite negligible similarity in primary sequence. Insights gained from this model were used to design a point mutation that was predicted to abolish the postulated enzymatic activity. Cells expressing Nob1p with this mutation failed to cleave the 20S pre-rRNA. This supports both the significance of the structural model and the idea that Nob1p is the long-sought D-site endonuclease.