Structural insights into the interaction of the ribosomal P stalk protein P2 with a type II ribosome-inactivating protein ricin.
Structural insights into the interaction of the ribosomal P stalk protein P2 with a type II ribosome-inactivating protein ricin.
复制标题
核糖体 P 茎蛋白 P2 与 II 型核糖体失活蛋白蓖麻毒素相互作用的结构见解
DOI：
10.1038/srep37803
复制
发表时间：
2016-11-25
影响因子：
4.6
通讯作者：
Li X
中科院分区：
文献类型：
--
作者：
Fan X;Zhu Y;Wang C;Niu L;Teng M;Li X
蓖麻毒素是一种II型核糖体失活蛋白，它在28 S核糖体核糖核酸的sarcin-ricin环上去纯化A4324，从而通过阻止延伸因子与GTP酶激活中心结合来灭活核糖体。最近的研究表明，真核细胞核糖体P茎蛋白保守的C末端结构域(CTD)参与了核糖体的转录过程。然而，蓖麻毒素和P秸秆蛋白之间的分子相互作用的细节仍不清楚。在这里，我们报告了与人核糖体蛋白P2的CTD形成的复合体中的蓖麻毒素A链(RTA)的结构。结构分析表明，P2的Phe111、Leu113和Phe114残基插入到RTA的Tyr183、Arg235、Phe240和Ile251残基形成的疏水口袋中，而P2的Asp115与RTA的Arg235形成氢键。RTA和P2中形成复合体的关键残基发生了突变，并通过下拉分析确定了它们的重要性。无细胞翻译实验的结果进一步证实了与P茎蛋白的相互作用是RTA抑制蛋白质合成所必需的。综上所述，我们的结果提供了一个结构基础，将提高我们对蓖麻毒素靶向核糖体的过程的理解，这将有助于开发用于治疗的有效小分子抑制剂。
Ricin is a type II ribosome-inactivating protein (RIP) that depurinates A4324at the sarcin-ricin loop of 28 S ribosomal RNA (rRNA), thus inactivating the ribosome by preventing elongation factors from binding to the GTPase activation centre. Recent studies have disclosed that the conserved C-terminal domain (CTD) of eukaryotic ribosomal P stalk proteins is involved in the process that RIPs target ribosome. However, the details of the molecular interaction between ricin and P stalk proteins remain unknown. Here, we report the structure of ricin-A chain (RTA) in a complex with the CTD of the human ribosomal protein P2. The structure shows that the Phe111, Leu113and Phe114residues of P2 insert into a hydrophobic pocket formed by the Tyr183, Arg235, Phe240and Ile251residues of RTA, while Asp115of P2 forms hydrogen bonds with Arg235of RTA. The key residues in RTA and P2 for complex formation were mutated, and their importance was determined by pull-down assays. The results from cell-free translation assays further confirmed that the interaction with P stalk proteins is essential for the inhibition of protein synthesis by RTA. Taken together, our results provide a structural basis that will improve our understanding of the process by which ricin targets the ribosome, which will benefit the development of effective small-molecule inhibitors for use as therapeutic agents.