The Trypanosoma brucei La protein is a candidate poly(U) shield that impacts spliced leader RNA maturation and tRNA intron removal
The Trypanosoma brucei La protein is a candidate poly(U) shield that impacts spliced leader RNA maturation and tRNA intron removal
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DOI：
10.1016/j.ijpara.2004.12.012
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发表时间：
2005-04-01
影响因子：
4
通讯作者：
Lukes, J
中科院分区：
文献类型：
--
作者：
Foldynová-Trantírková, S;Paris, Z;Lukes, J
由于其优先结合到小RNA前体和核定位基序上的聚（U）尾，La蛋白已被认为在真核细胞中稳定和保留各种小RNA的加工中间体的核中起作用。作为反式剪接的通用底物，剪接的前导RNA被转录为具有这样一个尾部的前体。La蛋白的靶向选择性敲低诱导RNA干扰在Topanosoina布氏。在所采用的三种RNA干扰策略中，p2 T7 -177载体在减少来自诱导细胞的La mRNA以及蛋白质本身方面最有效。在La蛋白T相对缺乏的情况下。与酵母中的La基因敲除相反，布鲁氏菌细胞不能存活。在诱导下检查了各种潜在的小RNA底物，包括剪接前导RNA、剪接前导相关RNA、U1、U2、U4和U6小核RNA、5S核糖体RNA、U3小核仁RNA和tRNA（Tyr）。这些分子中没有一个在其成熟形式的大小或丰度上显示出显著的变化，尽管在La耗尽条件下剪接的前导RNA和tRNA（Tyr）、内含子剪接出现了中间体的离散子集。5-剪接的前导RNA和U1小核RNA的末端甲基化不受影响。布氏锥虫致死的直接原因并不明显，但可能代表了多种缺陷的累积效应，包括剪接前导RNA、tRNA（Tyr）和其他未鉴定的RNA底物的加工。这项研究表明，La蛋白的结合是不是必不可少的成熟的剪接前导RNA，但不排除存在的替代加工途径，可以弥补正常相关的La蛋白的情况下。(c)2005年由Elsevier Ltd代表Australian Society for Parasitology Inc.出版。
By virtue of its preferential binding to poly(U) tails on small RNA precursors and nuclear localisation motif, the La protein has been implicated for a role in the stabilisation and nuclear retention of processing intermediates for a variety of small RNAs in eukaryotic cells. As the universal substrate for trans-splicing, the spliced leader RNA is transcribed as a precursor with just such a tail. La protein was targeted for selective knockdown by inducible RNA interference in Topanosoina brucei. Of three RNA interference strategies employed, a p2T7-177 vector was the most effective in reducing both the La mRNA as well as the protein itself from induced cells. In the relative absence of La protein T. brucei cells were not viable, in contrast to La gene knockouts in yeast. A variety of potential small RNA substrates were examined under induction, including spliced leader RNA, spliced leader associated RNA, the U1, U2, U4, and U6 small nuclear RNAs, 5S ribosomal RNA, U3 small nucleolar RNA, and tRNA(Tyr). None of these molecules showed significant variance in size or abundance in their mature forms, although a discrete subset of intermediates appear for spliced leader RNA and tRNA(Tyr), intron splicing under La depletion conditions. 5-end methylation in the spliced leader RNA and U1 small nuclear RNA was unaffected. The immediate cause of lethality in T brucei was not apparent, but may represent a cumulative effect of multiple defects including processing of spliced leader RNA, tRNA(Tyr) and other unidentified RNA substrates. This study indicates that La protein binding is not essential for maturation of the spliced leader RNA, but does not rule out the presence of an alternative processing pathway that could compensate for the absence of normally-associated La protein. (c) 2005 Published by Elsevier Ltd on behalf of Australian Society for Parasitology Inc.