Characterization of mSelB, a novel mammalian elongation factor for selenoprotein translation
Characterization of mSelB, a novel mammalian elongation factor for selenoprotein translation
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DOI：
10.1093/emboj/19.17.4796
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发表时间：
2000-09-01
期刊：
影响因子：
11.4
通讯作者：
Krol, A
中科院分区：
文献类型：
--
作者：
Fagegaltier, D;Hubert, N;Krol, A
真细菌中UGA硒代半胱氨酸密码子的解码由特异性延伸因子SelB介导，SelB通过结合SECIS mRNA发夹将带电荷的tRNA（Sec）传递到核糖体的A位点。为了分离SelB的真核同源物，在这项工作中的数据库搜索鉴定了小鼠表达的序列标签，其含有编码583个氨基酸的新蛋白质的完整cDNA，我们称之为mSelB。几条证据使我们能够确定mSelB是真正的哺乳动物硒蛋白翻译延伸因子：它结合GTP，在体外和体内识别Sec-tRNA（Sec），并且是体内有效硒蛋白翻译所需的。与真细菌SelB相反，单独的重组mSelB不能特异性结合真核SECIS RNA发夹。然而，与HeLa细胞提取物的互补导致含有mSelB和至少另一种因子的SECIS依赖性复合物的形成。因此，在真核生物中，单个延伸因子在真细菌硒蛋白翻译中的作用致力于两个或更多个专门的蛋白质。
Decoding of UGA selenocysteine codons in eubacteria is mediated by the specialized elongation factor SelB, which conveys the charged tRNA(Sec) to the A site of the ribosome, through binding to the SECIS mRNA hairpin. In an attempt to isolate the eukaryotic homolog of SelB, a database search in this work identified a mouse expressed sequence tag containing the complete cDNA encoding a novel protein of 583 amino acids, which we called mSelB, Several lines of evidence enabled us to establish that mSelB is the bona fide mammalian elongation factor for selenoprotein translation: it binds GTP, recognizes the Sec-tRNA(Sec) in vitro and in vivo, and is required for efficient selenoprotein translation in vivo. In contrast to the eubacterial SelB, the recombinant mSelB alone is unable to bind specifically the eukaryotic SECIS RNA hairpin. However, complementation with HeLa cell extracts led to the formation of a SECIS-dependent complex containing mSelB and at least another factor. Therefore, the role carried out by a single elongation factor in eubacterial selenoprotein translation is devoted to two or more specialized proteins in eukaryotes.