Department of Biochemistry and Molecular Biology, Molecular Epigenetics, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, B.C. Canada.
Virology. 2011 Sep 15;418(1):57-66. doi: 10.1016/j.virol.2011.07.002. Epub 2011 Aug 2.
Transcription from the HIV-1 long terminal repeat (LTR) is mediated by numerous host transcription factors. In this study we characterized an E-box motif (RBE1) within the core promoter that was previously implicated in both transcriptional activation and repression. We show that RBE1 is a binding site for the RBF-2 transcription factor complex (USF1, USF2, and TFII-I), previously shown to bind an upstream viral element, RBE3. The RBE1 and RBE3 elements formed complexes of identical mobility and protein constituents in gel shift assays, both with Jurkat T-cell nuclear extracts and recombinant USF/TFII-I. Furthermore, both elements are regulators of HIV-1 expression; mutations in LTR-luciferase reporters and in HIV-1 molecular clones resulted in decreased transcription, virion production, and proviral expression in infected cells. Collectively, our data indicate that RBE1 is a bona fide RBF-2 binding site and that the RBE1 and RBE3 elements are necessary for mediating proper transcription from the HIV-1 LTR.
HIV-1 长末端重复序列（LTR）的转录由许多宿主转录因子介导。在这项研究中，我们描述了核心启动子内的一个 E 盒基序（RBE1），该基序先前与转录激活和抑制都有关。我们表明，RBE1 是 RBF-2 转录因子复合物（USF1、USF2 和 TFII-I）的结合位点，该复合物先前已被证明与上游病毒元件 RBE3 结合。凝胶迁移分析显示，RBE1 和 RBE3 元件形成了相同迁移率和蛋白成分的复合物，无论是在 Jurkat T 细胞核提取物还是重组 USF/TFII-I 中。此外，这两个元件都是 HIV-1 表达的调节剂；LTR-荧光素酶报告基因和 HIV-1 分子克隆中的突变导致转录、病毒粒子产生和感染细胞中的前病毒表达减少。总之，我们的数据表明，RBE1 是 RBF-2 的真正结合位点，并且 RBE1 和 RBE3 元件是介导 HIV-1 LTR 正确转录所必需的。
