The Yeast Ski Complex: Crystal Structure and RNA Channeling to the Exosome Complex
The Yeast Ski Complex: Crystal Structure and RNA Channeling to the Exosome Complex
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DOI：
10.1016/j.cell.2013.07.017
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发表时间：
2013-08-15
期刊：
影响因子：
64.5
通讯作者：
Conti, Elena
中科院分区：
文献类型：
--
作者：
Halbach, Felix;Reichelt, Peter;Conti, Elena
Ski复合物是外泌体的细胞质功能所需的保守的多蛋白组装体，包括RNA周转、监视和干扰。Ski 2、Ski 3和Ski 8以1：1：2化学计量组装成四聚体。S.酿酒酵母370 kDa核心复合物显示，Ski 3形成在N-末端和C-末端臂中组织的33个TPR基序的阵列。Ski 3的C-末端臂和两个Ski 8亚基将Ski 2的解旋酶核心定位在复合物的中心，增强RNA结合。Ski 3 N-末端臂和Ski 2插入结构域变构调节复合物的ATP酶和解旋酶活性。生物化学数据表明，Ski复合物可以将RNA直接连接到外泌体，通过连续的RNA通道偶联解旋酶和核糖核酸外切酶。最后，我们确定了一个Ski 8结合基序共同Ski 3和Spo 11，合理化的兼职性质的Ski 8在mRNA衰变和减数分裂。
The Ski complex is a conserved multiprotein assembly required for the cytoplasmic functions of the exosome, including RNA turnover, surveillance, and interference. Ski2, Ski3, and Ski8 assemble in a tetramer with 1: 1: 2 stoichiometry. The crystal structure of an S. cerevisiae 370 kDa core complex shows that Ski3 forms an array of 33 TPR motifs organized in N-terminal and C-terminal arms. The C-terminal arm of Ski3 and the two Ski8 subunits position the helicase core of Ski2 centrally within the complex, enhancing RNA binding. The Ski3 N-terminal arm and the Ski2 insertion domain allosterically modulate the ATPase and helicase activities of the complex. Biochemical data suggest that the Ski complex can thread RNAs directly to the exosome, coupling the helicase and the exoribonuclease through a continuous RNA channel. Finally, we identify a Ski8-binding motif common to Ski3 and Spo11, rationalizing the moonlighting properties of Ski8 in mRNA decay and meiosis.