Nhp2p and Nop10p are essential for the function of H/ACA snoRNPs
Nhp2p and Nop10p are essential for the function of H/ACA snoRNPs
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DOI：
10.1093/emboj/17.23.7078
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发表时间：
1998-12-01
期刊：
影响因子：
11.4
通讯作者：
Caizergues-Ferrer, M
中科院分区：
文献类型：
--
作者：
Henras, A;Henry, Y;Caizergues-Ferrer, M
含有H/ACA型snoRNA的核仁核糖核蛋白小颗粒（H/ACA snoRNP）是真核生物核糖体合成中的重要反式作用因子，它们中的大多数产生rRNA的位点特异性假尿苷化，而18 S rRNA的合成则需要一个亚类。为此，我们亲和纯化的复合物含有表位标记的Gar 1 p蛋白，以前被证明是H/ACA snoRNP的一部分，在所使用的条件下，三个多肽的65，22和10 kDa的表观分子量特异性copurify与表位标记的Gar 1 p，22和10 kDa的多肽被鉴定为Nhp 2 p和一个新的蛋白，我们称之为Nop 10 p，分别。这两种蛋白质都是保守的，必需的，存在于核仁的致密纤维成分中，Nhp 2 p和Nop 10 p与所有H/ACA snoRNA特异性相关，并且对H/ACA snoRNP的功能是必需的。缺乏Nhp 2 p或Nop 10 p的细胞在合成成熟18 SrRNA所需的总rRNA假尿苷化和pre-rRNA的A1和A2切割步骤中受损，这些表型可能是在缺乏Nhp 2 p或Nop 10 p的细胞中观察到的H/ACA snoRNA和Gar 1 p不稳定的直接结果。我们的结果表明，Nhp 2 p和Nop 10 p，以及Cbf 5 p，构成了H/ACA snoRNP的核心。
The small nucleolar ribonucleoprotein particles containing H/ACA-type snoRNAs (H/ACA snoRNPs) are crucial trans-acting factors intervening in eukaryotic ribosome biogenesis, Most of these particles generate the site-specific pseudouridylation of rRNAs while a subset are required for 18S rRNA synthesis, To understand in detail how these particles carry out these functions, all of their protein components have to be characterized. For that purpose, we have affinity-purified complexes containing epitope-tagged Gar1p protein, previously shown to be part of H/ACA snoRNPs, Under the conditions used, three polypeptides of 65, 22 and 10 kDa apparent molecular weight specifically copurify with epitope-tagged Gar1p, The 22 and 10 kDa polypeptides were identified as Nhp2p and a novel protein we termed Nop10p, respectively. Both proteins are conserved, essential and present in the dense fibrillar component of the nucleolus, Nhp2p and Nop10p are specifically associated with all H/ACA snoRNAs and are essential to the function of H/ACA snoRNPs. Cells lacking Nhp2p or Nop10p are impaired in global rRNA pseudouridylation and in the A1 and A2 cleavage steps of the pre-rRNA required for the synthesis of mature 18S rRNA, These phenotypes are probably a direct consequence of the instability of H/ACA snoRNAs and Gar1p observed in cells deprived of Nhp2p or Nop10p, Our results suggest that Nhp2p and Nop10p, together with Cbf5p, constitute the core of H/ACA snoRNPs.