Mpp10p, a U3 small nucleolar ribonucleoprotein component required for pre-18S rRNA processing in yeast
Mpp10p, a U3 small nucleolar ribonucleoprotein component required for pre-18S rRNA processing in yeast
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DOI：
10.1128/mcb.17.10.5803
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发表时间：
1997-10-01
影响因子：
5.3
通讯作者：
Baserga, SJ
中科院分区：
文献类型：
--
作者：
Dunbar, DA;Wormsley, S;Baserga, SJ
我们已经分离和其特征在于Mpp 10 p，一种新的蛋白质组分的U3小核仁核糖核蛋白（snoRNP）从酵母酿酒酵母。MPP 10蛋白首先在人类细胞中通过其与识别有丝分裂磷酸化的特定位点的抗体的反应性被鉴定。为了研究MPP 10在pre-rRNA加工中的功能作用，我们通过进行GenBank搜索来鉴定酵母蛋白。酵母Mpp 10 p同源物在其长度上与人类蛋白质有30%相同。纯化的酵母蛋白的抗体识别酵母提取物中的110-kDa多肽并免疫沉淀U3 snoRNA，表明Mpp 10 p是酵母中U3 snoRNP的特异性蛋白组分。作为Mpp 10 p功能遗传分析的第一步，二倍体S.用无效等位基因转化酿酒酵母细胞。孢子形成和四分体分析表明，MPP 10是一个必需基因。构建了一种菌株，其中Mpp 10 p从半乳糖诱导型葡萄糖阻遏型启动子表达。在葡萄糖中生长耗尽Mpp 10 p后，细胞生长被阻止，18 S及其20 S前体的水平降低或不存在，而23 S和35 S前体积累。rRNA前体的这种积累模式表明，Mpp 10 p是在位点A0、A1和A2处切割所必需的。在Mpp 10 p缺失的酵母中新合成的前体rRNA的脉冲追踪分析证实了几乎没有成熟的18 S rRNA形成。这些结果揭示了核糖体生物合成所必需的新蛋白质，并进一步阐明了U3 snoRNP的组成。
We have isolated and characterized Mpp10p, a novel protein component of the U3 small nucleolar ribonucleoprotein (snoRNP) from the yeast Saccharomyces cerevisiae. The MPP10 protein was first identified in human cells by its reactivity with an antibody that recognizes specific sites of mitotic phosphorylation. To study the functional role of MPP10 in pre-rRNA processing, we identified the yeast protein by performing a GenBank search. The yeast Mpp10p homolog is 30% identical to the human protein over its length. Antibodies to the purified yeast protein recognize a 110-kDa polypeptide in yeast extracts and immunoprecipitate the U3 snoRNA, indicating that Mpp10p is a specific protein component of the U3 snoRNP in yeast. As a first step in the genetic analysis of Mpp10p function, diploid S. cerevisiae cells were transformed with a null allele. Sporulation and tetrad analysis indicate that MPP10 is an essential gene. A strain was constructed where Mpp10p is expressed from a galactose-inducible, glucose-repressible promoter. After depletion of Mpp10p by growth in glucose, cell growth is arrested and levels of 18S and its 20S precursor are reduced or absent while the 23S and 35S precursors accumulate. This pattern of accumulation of rRNA precursors suggests that Mpp10p is required for cleavage at sites A0, A1, and A2. Pulse-chase analysis of newly synthesized pre-rRNAs in Mpp10p-depleted yeast confirms that little mature 18S rRNA formed. These results reveal a novel protein essential for ribosome biogenesis and further elucidate the composition of the U3 snoRNP.