cis-acting signals involved in termination of vesicular stomatitis virus mRNA synthesis include the conserved AUAC and the U7 signal for polyadenylation
cis-acting signals involved in termination of vesicular stomatitis virus mRNA synthesis include the conserved AUAC and the U7 signal for polyadenylation
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DOI：
10.1128/jvi.71.11.8718-8725.1997
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发表时间：
1997-11-01
影响因子：
5.4
通讯作者：
Wertz, GW
中科院分区：
文献类型：
--
作者：
Barr, JN;Whelan, SPJ;Wertz, GW
我们通过使用双顺反子基因组类似物研究了参与终止水泡性口病毒mRNA合成的顺式作用序列，终止所需的所有顺式作用信号都位于23核苷酸保守基因连接的前13个核苷酸内，上游基因末端的该13个核苷酸终止序列包含四核苷酸AUAC， 包含七个尿苷（U7 区域）和基因间二核苷酸 (GA) 的区域，但不包括下游基因起始序列，此处提供的数据显示上游 mRNA 终止独立于下游 mRNA 起始，13 核苷酸序列中任何核苷酸的改变都会降低基因连接的终止活性，并导致双顺反子通读的合成增加 核糖核酸。这一发现表明野生型基因连接已经进化到达到最大终止效率，AUAC序列最关键的位置是C，在不完全丧失mRNA终止的情况下不能改变C，将野生型U7段的长度减少到零、五个或六个U残基也完全废除了mRNA终止，导致双顺反子通读mRNA的排他合成。将野生型 U7 束缩短至 5 个或 6 个 U 残基，在通读 RNA 合成过程中消除了 VSV 聚合酶滑移，由于 U5 和 U6 模板都无法指导 mRNA 终止，这些数据意味着聚合酶滑移是终止的先决条件。还提供的证据表明，除了导致聚合酶滑移之外，U7 束本身或其 Poly(A) 产物 构成 mRNA 终止的重要信号。
We investigated the cis-acting sequences involved in termination of vesicular stomatis virus mRNA synthesis by using bicistronic genomic analogs, All of the cis-acting signals necessary for termination reside within the first 13 nucleotides of the 23-nucleotide conserved gene junction, This 13-nucleotide termination sequence at the end of the upstream gene comprises the tetranucleotide AUAC, the tract containing seven uridines (U7 tract), and the intergenic dinucleotide (GA), but it does not include the downstream gene start sequence, Data presented here show that upstream mRNA termination is independent of downstream mRNA initiation, Alteration of any nucleotide in the 13-nucleotide sequence decreased the termination activity of the gene junction and resulted in increased synthesis of a bicistronic readthrough RNA. This finding indicated that the wild-type gene junction has evolved to achieve the maximum termination efficiency, The most critical position of the AUAC sequence was the C, which could not be altered without complete loss of mRNA termination, Reducing the length of the wild-type U7 tract to zero, five, or six U residues also totally abolished mRNA termination, resulting in exclusive synthesis of the bicistronic readthrough mRNA. Shortening the wild-type U7 tract to either five or six U residues abolished VSV polymerase slippage during readthrough RNA synthesis, Since neither the U5 nor U6 template was able to direct mRNA termination, these data imply that polymerase slippage is a prerequisite for termination, Evidence is also presented to show that in addition to causing polymerase slippage, the U7 tract itself or its poly(A) product constitutes an essential signal for mRNA termination.