Zavacki Ann Marie, Mansell John B, Chung Mirra, Klimovitsky Boris, Harney John W, Berry Marla J
Thyroid Division, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
Mol Cell. 2003 Mar;11(3):773-81. doi: 10.1016/s1097-2765(03)00064-9.
SECIS elements recode UGA codons from "stop" to "sense." These RNA secondary structures, present in eukaryotic selenoprotein mRNA 3' untranslated regions, recruit a SECIS binding protein, which recruits a selenocysteine-specific elongation factor-tRNA complex. Elucidation of the assembly of this multicomponent complex is crucial to understanding the mechanism of selenocysteine incorporation. Coprecipitation studies identified the C-terminal 64 amino acids of the elongation factor as sufficient for interaction with the SECIS binding protein. Selenocysteyl-tRNA is required for this interaction; the two factors do not coprecipitate in its absence. Finally, through promoting this interaction, selenocysteyl-tRNA stabilizes the C-terminal domain of the elongation factor. We suggest that the coupling effect is critical to preventing nonproductive decoding attempts and hence forms a basis for effective selenoprotein synthesis.
硒代半胱氨酸插入序列（SECIS）元件将UGA密码子从“终止”重新编码为“有义”。这些存在于真核生物硒蛋白mRNA 3'非翻译区的RNA二级结构会招募一种SECIS结合蛋白，该蛋白进而招募一个硒代半胱氨酸特异性延伸因子-tRNA复合物。阐明这种多组分复合物的组装对于理解硒代半胱氨酸掺入机制至关重要。共沉淀研究表明，延伸因子的C末端64个氨基酸足以与SECIS结合蛋白相互作用。这种相互作用需要硒代半胱氨酰-tRNA；在没有它的情况下，这两个因子不会共沉淀。最后，通过促进这种相互作用，硒代半胱氨酰-tRNA稳定了延伸因子的C末端结构域。我们认为这种偶联效应对于防止无效的解码尝试至关重要，因此构成了有效合成硒蛋白的基础。
