STRUCTURE, SEQUENCE, AND POSITION OF THE STEM LOOP IN TAR DETERMINE TRANSCRIPTIONAL ELONGATION BY TAT THROUGH THE HIV-1 LONG TERMINAL REPEAT
STRUCTURE, SEQUENCE, AND POSITION OF THE STEM LOOP IN TAR DETERMINE TRANSCRIPTIONAL ELONGATION BY TAT THROUGH THE HIV-1 LONG TERMINAL REPEAT
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DOI：
10.1101/gad.3.4.547
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发表时间：
1989-04-01
影响因子：
10.5
通讯作者：
PETERLIN, BM
中科院分区：
文献类型：
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作者：
SELBY, MJ;BAIN, ES;PETERLIN, BM
人类免疫缺陷病毒(HIV-1)编码的反式激活剂(TAT)增加了HIV基因的表达和复制。在此之前，我们证明了TAT通过HIV-1的长末端重复序列(LTR)促进转录的延长，并且在没有TAT的情况下，与过早终止的RNA相对应的短转录产物被释放和积累。在这里，使用瞬时表达分析，我们测试了反式作用反应区域(TAR)的簇状和补偿性突变以及3‘’缺失，并观察到TAT需要TAT反式激活TAR中的茎环的一级序列和茎的二级结构。在TAR的5‘’区域的插入表明，TAR必须位于HIV-1启动TAT反式激活的转录物的位置附近。缺失(3‘’)和在TAR中的插入表明，恢复过早终止的转录本需要完整的茎环。在没有TAT和存在TAT的情况下，也观察到了HIV 2型(HIV-2)的短转录本和全长转录本。我们得出的结论是，TAT中完整的茎环对于TAT的反式激活是必不可少的，并且HIV-1启动子因子的转录启动和TAT的转录延伸是耦合的。
The human immunodeficiency virus (HIV-1)-encoded trans-activator (tat) increases HIV gene expression and replication. Previously, we demonstrated that tat facilitates elongation of transcription through the HIV-1 long terminal repeat (LTR) and that short transcripts corresponding to prematurely terminated RNA are released and accumulate in the absence of tat. Here, using a transient expression assay, we tested clustered and compensatory mutations, as well as 3'' deletions, in the trans-acting responsive region (tar) and observed that the primary sequence in the loop and secondary structure in the stem of the stem-loop in tar are required for trans-activation by tat. Insertions in the 5'' region of tar revealed that tar must be near the site of HIV-1 initiations of transcritpion for trans-activation by tat. Deletions (3'') and an insertion in tar demonstrated that an intact stem-loop is required for the recovery of prematurely terminated transcripts. Short and full-length transcripts were observed also with HIV type 2 (HIV-2) in the absence and presence of tat, respectively. We conclude that an intact stem-loop in tar is essential for trans-activation by tat and that initiation of transcription by HIV-1 promoter factors and elongation of transcription by tat are coupled.