Stent-loop 1 of the U1 snRNP plays a critical role in the suppression of HIV-1 polyadenylation
Stent-loop 1 of the U1 snRNP plays a critical role in the suppression of HIV-1 polyadenylation
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DOI：
10.1017/s1355838200991957
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发表时间：
2000-02-01
期刊：
影响因子：
4.5
通讯作者：
Proudfoot, NJ
中科院分区：
文献类型：
--
作者：
Ashe, MP;Furger, A;Proudfoot, NJ
HIV-1 poly（A）信号在5'长末端重复序列（LTR）中的失活或闭塞已被机械地研究。首先，我们表明，无论是同源的HIV-1启动子，也不是这个RNA加工信号的转录起始位点的紧密接近所需的闭塞效应。相反，我们证明，主要剪接供体（MSD）网站定位约200 bp的下游保持聚（A）位点处于非活性状态。尽管MSD的突变导致5' LTR poly（A）信号的激活，但这种效应可以通过碱基配对靶向突变的MSD附近的U1 snRNA来抑制。我们表明，杂合U 7-U1 snRNA也可以抑制poly（A）信号，并且这种抑制依赖于U1茎环1，特别是与茎环1的环结构结合的U1 snRNP蛋白70 K的结合位点与poly（A）位点闭塞相关。这些实验是用HIV-1前病毒构建体进行的，因此强调了这种剪接供体-多聚腺苷酸位点相互作用的生理重要性。
The inactivity or occlusion of the HIV-1 poly(A) signal when in the 5' long terminal repeat (LTR) has been mechanistically investigated. First we show that neither the homologous HIV-1 promoter nor the close proximity of this RNA processing signal to the transcript initiation site is required for the occlusion effect. Instead we demonstrate that the major splice donor (MSD) site positioned about 200 bp downstream maintains the poly(A) site in an inactive state. Although mutation of MSD results in activation of the 5' LTR poly(A) signal, this effect can be suppressed by targeting U1 snRNAs near to the mutated MSD by base pairing. We show that hybrid U7-U1 snRNAs can also suppress the poly(A) signal and that this suppression is dependent on the U1 stem-loop 1, In particular the binding site for the U1 snRNP protein 70K that binds to the loop structure of stem-loop 1 is associated with poly(A) site occlusion. These experiments were carried out with an HIV-1 proviral construct and as such emphasize the physiological importance of this splice donor-poly(A) site interaction.