BOVINE PAPILLOMAVIRUS E2 TRANS-ACTIVATING GENE-PRODUCT BINDS TO SPECIFIC SITES IN PAPILLOMAVIRUS DNA
BOVINE PAPILLOMAVIRUS E2 TRANS-ACTIVATING GENE-PRODUCT BINDS TO SPECIFIC SITES IN PAPILLOMAVIRUS DNA
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DOI：
10.1038/325070a0
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发表时间：
1987-01-01
期刊：
影响因子：
64.8
通讯作者：
SCHILLER, JT
中科院分区：
文献类型：
--
作者：
ANDROPHY, EJ;LOWY, DR;SCHILLER, JT
增强子是高级真核生物中激活转录的作用元件，与它们所激活的启动子的位置或取向无关。增强子激活转录的机制尚不清楚，部分原因是，除了糖皮质激素受体外，与增强子直接相互作用的蛋白质还没有被纯化，编码它们的基因也没有被克隆。位于牛乳头瘤病毒1型基因组（BPV）早期基因之前的上游调控区（URR）被BPV E2开放阅读框（ORF）的反式作用基因产物激活时具有增强子活性（图1）6。目前尚不清楚这种增强是否代表E2对URR的直接或间接影响。我们利用细菌中表达的E2肽和dna -蛋白复合物免疫沉淀法研究了URR对E2介导的转录增强作用。我们在这里表明，这种肽直接结合到BPV URR中的四个特定位点，以及人乳头瘤病毒(H)PV16 URR中的一个位点。所有的结合位点都包含一个相关的核苷酸序列；含有该序列的23个碱基对（bp）片段可以特异性地阻止E2蛋白与BPV URR的结合。因此，BPV E2-URR增强子相互作用可能为研究转录增强机制提供了一个有用的模型系统，因为效应蛋白及其靶增强子都可以被纯化和基因操纵。
Enhancers arecis-act ing elements that activate transcription in higher eukaryotes independently of their position or orientation relative to the promoter that they activate1. The mechanisms by which enhancers activate transcription are poorly understood, in part because, with the exception of the glucocorticoid receptor2, the proteins that directly interact with enhancers have not been purified, nor have the genes encoding them been cloned3–5. The upstream regulatory region (URR) that immediately precedes the early genes of the bovine papillomavirus type 1 genome (BPV) has enhancer activity when it is activated by atrans-acting gene product of the BPV E2 open reading frame (ORF) (Fig. 1)6. It is not known whether this enhancement represents a direct or indirect effect of E2 on the URR. We have used an E2 peptide expressed in bacteria and a DNA-protein complex immunoprecipitation assay to study E2-mediated enhancement of transcription by the URR. We show here that this peptide directly binds to four specific sites in the BPV URR, and to one site in the human papillomavirus (H)PV16 URR. All the binding sites contain a related sequence of nucleotides; a 23 base pair (bp) fragment containing this sequence can specifically prevent binding of the E2 protein to the BPV URR. The BPV E2–URR enhancer interaction may therefore represent a useful model system for studying the mechanism of transcriptional enhancement, as both an effector protein and its target enhancer can be purified and genetically manipulated.