Suzuki T, Yamamoto T, Kurabayashi M, Nagai R, Yazaki Y, Horikoshi M
Departments of Developmental Biology and Cellular Biology, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0032, Japan.
J Biochem. 1998 Aug;124(2):389-95. doi: 10.1093/oxfordjournals.jbchem.a022124.
Human immunodeficiency virus (HIV) and its clinical syndrome, acquired immune deficiency syndrome (AIDS), are one of the world's most prominent health problems. To understand the mechanisms underlying HIV transcription and thereby its propagation, we have focused on the molecular interactions at the GC-rich binding sites of the HIV-1 core promoter, a region important for HIV-1 transcription. Previous biochemical studies have shown that Sp1, a zinc finger transcription factor initially isolated as a cellular factor binding that binds to the SV40 early promoter GC-rich sequence, binds to the HIV-1 GC-rich binding sites due to sequence similarities. However, the HIV-1 GC-rich binding sites are considerably different from the Sp1 consensus binding sequence, and recent genetic studies have shown the lack of regulation by Sp1 in numerous genes thought to be regulated by that factor in the past. We reasoned that other factors may bind to the HIV-1 GC-rich binding sites. Using the native HIV-1 GC-rich binding sequence as the bait, genetic screening for interacting factors was performed by the yeast one-hybrid method. A cDNA encoding a novel zinc finger protein named GBF, GC-rich sites binding factor, was isolated from a human peripheral blood leukocyte library. Primary structure analysis of GBF revealed a C2H2 Krüppel-type zinc finger at its C-terminus, and putative acidic and proline-rich domains at its N-terminus. We also show that GBF belongs to a subgroup of Krüppel-type zinc fingers distinct from Sp1. By directly addressing interactions at the HIV-1 GC-rich binding sites, our present study sheds new light on molecular interactions at the HIV-1 promoter.
人类免疫缺陷病毒（HIV）及其临床综合征——获得性免疫缺陷综合征（AIDS），是全球最突出的健康问题之一。为了解HIV转录及其传播的潜在机制，我们聚焦于HIV-1核心启动子富含GC的结合位点处的分子相互作用，该区域对HIV-1转录至关重要。先前的生化研究表明，Sp1是一种最初作为与SV40早期启动子富含GC序列结合的细胞因子而分离出的锌指转录因子，因其序列相似性而与HIV-1富含GC的结合位点结合。然而，HIV-1富含GC的结合位点与Sp1共有结合序列有很大不同，并且最近的遗传学研究表明，过去认为受该因子调控的众多基因中缺乏Sp1的调控作用。我们推测可能有其他因子与HIV-1富含GC的结合位点结合。以天然的HIV-1富含GC的结合序列为诱饵，采用酵母单杂交方法对相互作用因子进行了遗传筛选。从人外周血白细胞文库中分离出一个编码新型锌指蛋白GBF（富含GC位点结合因子）的cDNA。GBF的一级结构分析显示其C端有一个C2H2型克鲁ppel锌指，N端有推定的酸性和富含脯氨酸结构域。我们还表明，GBF属于不同于Sp1的克鲁ppel型锌指亚组。通过直接研究HIV-1富含GC的结合位点处的相互作用，我们目前的研究为HIV-1启动子处的分子相互作用提供了新的线索。
