Proteins P1, P2, and P0, components of the eukaryotic ribosome stalk. New structural and functional aspects
Proteins P1, P2, and P0, components of the eukaryotic ribosome stalk. New structural and functional aspects
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DOI：
10.1139/o95-103
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发表时间：
1995-11-01
影响因子：
2.9
通讯作者：
Ballesta, JPG
中科院分区：
文献类型：
--
作者：
Remacha, M;JimenezDiaz, A;Ballesta, JPG
真核核糖体柄被认为由磷酸化蛋白P1和P2组成，它们与蛋白P0形成复合体。该复合物在大亚基rRNA的GTPase结构域相互作用，重叠了真核生物中l11样蛋白（酿酒酵母蛋白L15和哺乳动物蛋白L12）的结合位点。在真核细胞质中检测到一种不寻常的蛋白质P1和P2的去磷酸化形式，并且在翻译过程中，池中的蛋白质和核糖体上的蛋白质之间发生交换。四重破坏的酵母菌株携带四个无活性的酸性蛋白质基因，因此含有完全耗尽酸性蛋白质的核糖体，是有活力的，但生长时间是野生型细胞的两倍，高出三倍。来自这些染色的体外翻译系统是有活性的，但体内和体外表达的蛋白质的二维凝胶电泳模式部分不同。这些结果表明P1和P2蛋白不是核糖体活性所必需的，但能够影响一些特定mrna的翻译。蛋白P0类似于细菌核糖体蛋白L10，但携带一个额外的羧基结构域，与酸性蛋白P1和P2具有高度的序列同源性，包括末端肽DDDMGFGLFD。P0羧基结构域的连续缺失表明，在野生型遗传背景下，从P0羧基结构域去除最后21个氨基酸仅轻微影响核糖体活性；然而，在酸性P1/P2蛋白被剥夺的四重干扰物中，同样的缺失是致命的。额外的缺失影响P0与P1和P2蛋白以及与rRNA的相互作用。现有的实验数据支持真核胞柄组分在某些调节核糖体活性的调控过程中的作用。
The eukaryoic ribosomal stalk is thought to consist of the phosphoproteins P1 and P2, which form a complex with protein P0. This complex interacts at the GTPase domain in the large subunit rRNA, overlapping the binding site of the protein L11-like eukaryotic counterpart (Saccharomyces cerevisiae protein L15 and mammalian protein L12). An unusual pool of the dephosphorylated forms of proteins P1 and P2 is detected in eukaryotic cytoplasm, and an exchange between the proteins in the pool and on the ribosome takes place during translation. Quadruply disrupted yeast strains, carrying four inactive acidic protein genes and, therefore, containing ribosomes totally depleted of acidic proteins, are viable but grow with a doubling time threefold higher than wild-type cells. The in vitro translation systems derived from these stains are active but the two-dimensional gel electrophoresis pattern of proteins expressed in vivo and in vitro is partially different. These results indicate that the P1 and P2 proteins are not essential for ribosome activity but are able to affect the translation of some specific mRNAs. Protein P0 is analogous to bacterial ribosomal protein L10 but carries an additional carboxyl domain showing a high sequence homology to the acidic proteins P1 and P2, including the terminal peptide DDDMGFGLFD. Successive deletions of the P0 carboxyl domain show that removal of the last 21 amino acids from the P0 carboxyl domain only slightly affects the ribosome activity in a wild-type genetic background; however, the same deletion is lethal in a quadruple disruptant deprived of acidic P1/P2 proteins. Additional deletions affect the interaction of P0 with the P1 and P2 proteins and with the rRNA. The experimental data available support the implication of the eukaryotic stalk components in some regulatory process that modulates the ribosomal activity.