Most mRNAs in the nematode Ascaris lumbricoides are trans-spliced: a role for spliced leader addition in translational efficiency.
Most mRNAs in the nematode Ascaris lumbricoides are trans-spliced: a role for spliced leader addition in translational efficiency.
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发表时间：
1995-09
期刊：
影响因子：
4.5
通讯作者：
P. Maroney;J. Denker;E. Darżynkiewicz;Ronald Laneve;Timothy W. Nilsen
中科院分区：
文献类型：
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作者：
P. Maroney;J. Denker;E. Darżynkiewicz;Ronald Laneve;Timothy W. Nilsen
线虫中的一些前体mRNA通过反式剪接加工。在该反应中，从专门的Sm snRNP（SL RNP）获得22-nt 5'末端外显子（剪接前导序列，SL）及其相关的2，2，7-三甲基鸟苷帽。虽然多年来已经证明并非所有线虫的mRNA都含有SL序列，但除了秀丽隐杆线虫外，反式剪接mRNA的流行率尚未确定。为了解决这个问题，在一个生物体服从生化分析，我们已经准备了一个信息依赖的蛋白质合成系统从发育中的胚胎的寄生线虫，蛔虫。利用这一系统，我们使用了杂交捕获和杂交选择方法，表明绝大多数（80-90%）的A。蚯蚓mRNA含有SL序列，因此通过反式剪接进行加工。此外，为了检查SL添加对翻译的影响，我们测量了用各种合成mRNA编程的提取物中的蛋白质合成水平。我们发现，SL序列本身及其相关的高甲基化帽功能合作，以提高翻译效率，大概在蛋白质合成的起始水平。这些结果表明反式剪接在线虫基因表达中起着比以前怀疑的更大的作用。
Some pre-mRNAs in nematodes are processed by trans-splicing. In this reaction, a 22-nt 5' terminal exon (the spliced leader, SL) and its associated 2,2,7-trimethylguanosine cap are acquired from a specialized Sm snRNP, the SL RNP. Although it has been evident for many years that not all nematode mRNAs contain the SL sequence, the prevalence of trans-spliced mRNAs has, with the exception of Caenorhabditis elegans, not been determined. To address this question in an organism amenable to biochemical analysis, we have prepared a message-dependent protein synthesis system from developing embryos of the parasitic nematode, Ascaris lumbricoides. Using this system, we have used both hybrid-arrest and hybrid-selection approaches to show that the vast majority (80-90%) of A. lumbricoides mRNAs contain the SL sequence and therefore are processed by trans-splicing. Furthermore, to examine the effect of SL addition on translation, we have measured levels of protein synthesis in extracts programmed with a variety of synthetic mRNAs. We find that the SL sequence itself and its associated hypermethylated cap functionally collaborate to enhance translational efficiency, presumably at the level of initiation of protein synthesis. These results indicate that trans-splicing plays a larger role in nematode gene expression than previously suspected.