The role of exportin-t in selective nuclear export of mature tRNAs
The role of exportin-t in selective nuclear export of mature tRNAs
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DOI：
10.1093/emboj/17.24.7430
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发表时间：
1998-12-15
期刊：
影响因子：
11.4
通讯作者：
Mattaj, IW
中科院分区：
文献类型：
--
作者：
Arts, GJ;Kuersten, S;Mattaj, IW
Exportin-t(XPO-t)是脊椎动物tRNAs的核输出受体，它与携带GTP的RAN协同结合tRNA，XPO-t抗体被证明能有效地阻止非洲爪哇卵母核的tRNA输出，这表明它至少负责这些细胞中大部分tRNA的输出。我们研究了XPO-t-RanGTP特异性输出成熟tRNAs而不是其他形式的核RNA，包括tRNA前体的机制。化学和酶足迹以及磷酸修饰干扰揭示了T Psi C的骨架与tRNA(Phe)和XPO-t-RanGTP的受体臂之间的广泛相互作用。对突变体或前体tRNA形式的分析表明，除了这些识别元件外，tRNA的准确5‘和3’末端处理影响XPO-t-RanGTP相互作用和核输出，而氨基酰化不是必需的。含有内含子、末端加工的前tRNA可以与XPO-t-RanGTP结合，如果XPO-t存在过量，则可以迅速从核中输出，这些结果表明，在核输出之前，至少有两种机制参与了对前tRNA和成熟tRNA的区分。
Exportin-t (Xpo-t) is a vertebrate nuclear export receptor for tRNAs that binds tRNA cooperatively with GTP-loaded Ran, Xpo-t antibodies are shown to efficiently block tRNA export from Xenopus oocyte nuclei suggesting that it is responsible for at least the majority of tRNA export in these cells, We examine the mechanism by which Xpo-t-RanGTP specifically exports mature tRNAs rather than other forms of nuclear RNA, including tRNA precursors. Chemical and enzymatic footprinting together with phosphate modification interference reveals an extensive interaction between the backbone of the T Psi C and acceptor arms of tRNA(Phe) and Xpo-t-RanGTP. Analysis of mutant or precursor tRNA forms demonstrates that, aside from these recognition elements, accurate 5' and 3' end-processing of tRNA affects Xpo-t-RanGTP interaction and nuclear export, while aminoacylation is not essential. Intron-containing, end-processed, pre-tRNAs can be bound by Xpo-t-RanGTP and are rapidly exported from the nucleus if Xpo-t is present in excess, These results suggest that at least two mechanisms are involved in discrimination of pre-tRNAs and mature tRNAs prior to nuclear export.