Structural Basis for Translation Factor Recruitment to the Eukaryotic/Archaeal Ribosomes
Structural Basis for Translation Factor Recruitment to the Eukaryotic/Archaeal Ribosomes
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DOI：
10.1074/jbc.m109.068098
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发表时间：
2010-02-12
影响因子：
4.8
通讯作者：
Tanaka, Isao
中科院分区：
文献类型：
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作者：
Naganuma, Takao;Nomura, Naoko;Tanaka, Isao
古细菌核糖体茎复合物已被证明具有与真核五聚体茎复合物明显保守的功能结构;它提供了与真核茎相当的水平的真核延伸因子的通路。古细菌七聚体（P0（P1）（2）（P1）（2）（P1）（2））茎复合物的晶体结构表明，rRNA锚蛋白P0由N-末端rRNA锚定结构域和三个分离的脊螺旋组成，三个P1二聚体结合在脊螺旋上。基于该结构，我们已经产生了耗尽P1二聚体的任何结合位点的P0突变体。因子依赖性GTdR分析表明，第一个P1二聚体比其他突变体具有更高的活性。此外，我们通过将P0的rRNA锚定结构域叠加在古菌50 S上，构建了一个具有柄复合物的古菌50 S模型。该模型表明，翻译因子结合的P1二聚体的C末端都定位于50 S和P0脊柱螺旋的茎基部之间的区域。结合突变实验，我们推断多拷贝P1的功能意义在于在核糖体茎基附近的有限空间内创建因子库。
The archaeal ribosomal stalk complex has been shown to have an apparently conserved functional structure with eukaryotic pentameric stalk complex; it provides access to eukaryotic elongation factors at levels comparable to that of the eukaryotic stalk. The crystal structure of the archaeal heptameric (P0(P1)(2)(P1)(2)(P1)(2)) stalk complex shows that the rRNA anchor protein P0 consists of an N-terminal rRNA-anchoring domain followed by three separated spine helices on which three P1 dimers bind. Based on the structure, we have generated P0 mutants depleted of any binding site(s) for P1 dimer(s). Factor-dependent GTPase assay of such mutants suggested that the first P1 dimer has higher activity than the others. Furthermore, we constructed a model of the archaeal 50 S with stalk complex by superposing the rRNA-anchoring domain of P0 on the archaeal 50 S. This model indicates that the C termini of P1 dimers where translation factors bind are all localized to the region between the stalk base of the 50 S and P0 spine helices. Together with the mutational experiments we infer that the functional significance of multiple copies of P1 is in creating a factor pool within a limited space near the stalk base of the ribosome.