The yeast rapid tRNA decay pathway primarily monitors the structural integrity of the acceptor and T-stems of mature tRNA
The yeast rapid tRNA decay pathway primarily monitors the structural integrity of the acceptor and T-stems of mature tRNA
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DOI：
10.1101/gad.2050711
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发表时间：
2011-06-01
影响因子：
10.5
通讯作者：
Phizicky, Eric M.
中科院分区：
文献类型：
--
作者：
Whipple, Joseph M.;Lane, Elizabeth A.;Phizicky, Eric M.
与其他RNA一样，tRNAs在生物合成期间和之后经历质量控制步骤。我们先前描述了一种快速tRNA降解（RTD）途径，其中5 '-3'核酸外切酶Rat 1和Xrn 1降解缺乏m（7）G和m（5）C的酵母突变体中的成熟tRNA（瓦尔（AAC）），以及缺乏Um和ac（4）C的突变体中的成熟tRNA（Ser（CGA））。为了了解RTD途径如何在缺乏相同修饰的不同tRNA中选择底物tRNA，我们使用遗传筛选来检查tRNA（Ser（CGA））变体。我们的研究结果表明，RTD底物在体内的识别主要取决于受体和T-茎的稳定性，而不是反密码子茎，并不一定取决于修改，因为完全修饰的tRNA受到RTD，如果适当地去稳定化。我们发现，较弱的预期稳定性的受体和T-茎的tRNA是强烈相关的RTD敏感性，增加RNase T2敏感性的这一区域的tRNA在体外，和增加的5'端暴露于磷酸酶。我们还发现，纯化的Xrn 1选择性降解RTD底物tRNA在体外条件下，其中nonsubstrates免疫。这些结果表明，tRNA不仅进化为精确翻译，而且还能抵抗RTD的攻击。
tRNAs, like other RNAs, are subject to quality control steps during and after biosynthesis. We previously described a rapid tRNA degradation (RTD) pathway in which the 5'-3' exonucleases Rat1 and Xrn1 degrade mature tRNA(Val(AAC)) in yeast mutants lacking m(7)G and m(5)C, and mature tRNA(Ser(CGA)) in mutants lacking Um and ac(4)C. To understand how the RTD pathway selects substrate tRNAs among different tRNAs lacking the same modifications, we used a genetic screen to examine tRNA(Ser(CGA)) variants. Our results suggest that RTD substrate recognition in vivo depends primarily on the stability of the acceptor and T-stems, and not the anti-codon stem, and does not necessarily depend on modifications, since fully modified tRNAs are subject to RTD if appropriately destabilized. We found that weaker predicted stability of the acceptor and T-stems of tRNAs is strongly correlated with RTD sensitivity, increased RNase T2 sensitivity of this region of the tRNA in vitro, and increased exposure of the 5' end to phosphatase. We also found that purified Xrn1 selectively degrades RTD substrate tRNAs in vitro under conditions in which nonsubstrates are immune. These results suggest that tRNAs have evolved not only for accurate translation, but for resistance to attack by RTD.