Crystal structure of human selenocysteine tRNA
Crystal structure of human selenocysteine tRNA
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DOI：
10.1093/nar/gkp648
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发表时间：
2009-10-01
影响因子：
14.9
通讯作者：
Yokoyama, Shigeyuki
中科院分区：
文献类型：
--
作者：
Itoh, Yuzuru;Chiba, Shiho;Yokoyama, Shigeyuki
硒半胱氨酸（Sec）是翻译中的第21个氨基酸。Sec tRNA（tRNA(Sec)）具有一个与UGA密码子互补的反密码子。我们解决了人类tRNA的晶体结构（Sec）。tRNA（Sec）有一个9-bp的受体干和一个4-bp的T干，而典型tRNA只有7-bp的受体干和5-bp的T干。受体柄在U6:U67和G7:C66碱基对之间扭结，形成弯曲的受体- t茎螺旋。tRNA（Sec）有一个6 bp的D干和一个4 nt的D环。长D杆包含独特的A14:U21和G15:C20a对。d环：t环相互作用包括碱基对G18:U55和U16:U59，以及独特的碱基对U20:G19:C56。额外的臂包括一个6-bp干和一个4-nt环。值得注意的是，D柄和额外的臂不会在tRNA中形成三级相互作用（Sec）。相反，tRNA（Sec）有一个开放的空腔，而不是典型tRNA的三级核心。连接受体和D基的连接体残基A8和U9不参与三级碱基配对。相反，U9被堆积在额外手臂的第一个碱基对上。这些特征可能使tRNA（Sec）成为Sec合成/掺入机制的目标。
Selenocysteine (Sec) is the 21st amino acid in translation. Sec tRNA (tRNA(Sec)) has an anticodon complementary to the UGA codon. We solved the crystal structure of human tRNA(Sec). tRNA(Sec) has a 9-bp acceptor stem and a 4-bp T stem, in contrast with the 7-bp acceptor stem and the 5-bp T stem in the canonical tRNAs. The acceptor stem is kinked between the U6:U67 and G7:C66 base pairs, leading to a bent acceptor-T stem helix. tRNA(Sec) has a 6-bp D stem and a 4-nt D loop. The long D stem includes unique A14:U21 and G15:C20a pairs. The D-loop: T-loop interactions include the base pairs G18:U55 and U16:U59, and a unique base triple, U20:G19:C56. The extra arm comprises of a 6-bp stem and a 4-nt loop. Remarkably, the D stem and the extra arm do not form tertiary interactions in tRNA(Sec). Instead, tRNA(Sec) has an open cavity, in place of the tertiary core of a canonical tRNA. The linker residues, A8 and U9, connecting the acceptor and D stems, are not involved in tertiary base pairing. Instead, U9 is stacked on the first base pair of the extra arm. These features might allow tRNA(Sec) to be the target of the Sec synthesis/incorporation machineries.