Architecture of an HIV-1 reverse transcriptase initiation complex
Architecture of an HIV-1 reverse transcriptase initiation complex
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DOI：
10.1038/s41586-018-0055-9
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发表时间：
2018-05-03
期刊：
影响因子：
64.8
通讯作者：
Puglisi, Elisabetta Viani
中科院分区：
文献类型：
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作者：
Larsen, Kevin P.;Mathiharan, Yamuna Kalyani;Puglisi, Elisabetta Viani
将HIV-1 RNA基因组逆转录为双链DNA是病毒感染的核心步骤1，也是抗逆转录病毒药物的常见靶点（2）。该反应由病毒逆转录酶（RT）催化（3，4），病毒逆转录酶包装在感染性病毒粒子中，病毒基因组RNA（5）的两个拷贝各与宿主赖氨酸3转移RNA（tRNA（3）（Lys））结合，作为逆转录起始的引物（6，7）。在病毒进入细胞后，与延伸相比，启动是缓慢的且非进行性的（8，9）。尽管广泛的努力，RT功能的结构基础在启动过程中仍然是一个谜。在这里，我们使用冷冻电子显微镜来确定一个HIV-1 RT起始复合物的三维结构。在我们的结构中，RT处于无活性的聚合酶构象，具有开放的手指和拇指，并且核酸引物-模板复合物远离活性位点移动。tRNA（3）（Lys）和HIV-1 RNA之间形成的引物结合位点（PBS）螺旋位于RT的裂缝中，并通过额外的配对相互作用延伸。tRNA的5'端在PBS上重折叠并堆叠以产生长螺旋结构，而剩余的病毒RNA形成位于RT活性位点上方的两个螺旋茎，具有将这些螺旋连接到PBS的RNA酶H区的接头。我们的研究结果说明了起始复合物中的RNA结构如何改变RT构象以降低活性，突出了药物作用的潜在靶点。
Reverse transcription of the HIV-1 RNA genome into doublestranded DNA is a central step in viral infection1 and a common target of antiretroviral drugs(2). The reaction is catalysed by viral reverse transcriptase (RT)(3,4) that is packaged in an infectious virion with two copies of viral genomic RNA(5) each bound to host lysine 3 transfer RNA (tRNA(3)(Lys)), which acts as a primer for initiation of reverse transcription(6,7). Upon viral entry into cells, initiation is slow and non-processive compared to elongation(8,9). Despite extensive efforts, the structural basis of RT function during initiation has remained a mystery. Here we use cryo-electron microscopy to determine a three-dimensional structure of an HIV-1 RT initiation complex. In our structure, RT is in an inactive polymerase conformation with open fingers and thumb and with the nucleic acid primer-template complex shifted away from the active site. The primer binding site (PBS) helix formed between tRNA(3)(Lys) and HIV-1 RNA lies in the cleft of RT and is extended by additional pairing interactions. The 5' end of the tRNA refolds and stacks on the PBS to create a long helical structure, while the remaining viral RNA forms two helical stems positioned above the RT active site, with a linker that connects these helices to the RNase H region of the PBS. Our results illustrate how RNA structure in the initiation complex alters RT conformation to decrease activity, highlighting a potential target for drug action.