Blasticidin S inhibits translation by trapping deformed tRNA on the ribosome
Blasticidin S inhibits translation by trapping deformed tRNA on the ribosome
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DOI：
10.1073/pnas.1304922110
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发表时间：
2013-07-23
影响因子：
11.1
通讯作者：
Korostelev, Andrei A.
中科院分区：
文献类型：
--
作者：
Svidritskiy, Egor;Ling, Clarence;Korostelev, Andrei A.
抗生素杀稻瘟菌素 S (BlaS) 是细菌和真核生物中蛋白质合成的有效抑制剂。我们确定了与 70S-tRNA 核糖体复合物结合的 BlaS 的 3.4 埃晶体结构，并进行了生化和单分子 FRET 实验，以确定抗生素的作用机制。我们发现 BlaS 增强了 tRNA 与大核糖体亚基 P 位点的结合，并减慢了易位前核糖体中自发的亚基间旋转。然而，抗生素对延伸因子 G 催化的 tRNA 和 mRNA 易位的影响可以忽略不计。抗生素-核糖体复合物的晶体结构表明，BlaS 通过将 P 位 tRNA 的 3' 末端弯曲到大核糖体亚基的 A 位点，通过独特的机制阻碍蛋白质合成。生化实验表明，BlaS 对 P 位 tRNA 变形构象的稳定可通过释放因子强烈抑制肽基-tRNA 水解，并在较小程度上抑制肽键形成。
The antibiotic blasticidin S (BlaS) is a potent inhibitor of protein synthesis in bacteria and eukaryotes. We have determined a 3.4-angstrom crystal structure of BlaS bound to a 70S-tRNA ribosome complex and performed biochemical and single-molecule FRET experiments to determine the mechanism of action of the antibiotic. We find that BlaS enhances tRNA binding to the P site of the large ribosomal subunit and slows down spontaneous intersubunit rotation in pretranslocation ribosomes. However, the antibiotic has negligible effect on elongation factor G catalyzed translocation of tRNA and mRNA. The crystal structure of the antibiotic-ribosome complex reveals that BlaS impedes protein synthesis through a unique mechanism by bending the 3' terminus of the P-site tRNA toward the A site of the large ribosomal subunit. Biochemical experiments demonstrate that stabilization of the deformed conformation of the P-site tRNA by BlaS strongly inhibits peptidyl-tRNA hydrolysis by release factors and, to a lesser extent, peptide bond formation.