Chon S K, Rim B M, Im D S
College of Veterinary Medicine, Chonbuk National University, Chonju, Korea.
IUBMB Life. 1999 Oct;48(4):397-404. doi: 10.1080/713803543.
Adeno-associated virus type-2 (AAV-2) is a helper-dependent parvovirus that has been implicated in the inhibition of replication and oncogenic transformation of bovine papillomavirus type-1 (BPV-1) and other transforming DNA viruses. Previous studies have suggested that the Rep78 protein of AAV-2 is a key player mediating this effect. In this report we have analyzed the effect of AAV-2 Rep78 protein on the regulation of gene expression of a reporter gene under the control of the long control region (LCR) of BPV-1. Our results show that Rep78 is capable of down-regulating the promoter activity of the LCR in vivo in tissue culture cells. Inhibition of LCR activity in vivo suggested the need for Rep78 to bind to a region of the LCR promoter spanning the E2-responsive elements of BPV-1. This observation was further confirmed in vitro with gel shift assays showing specific binding of Rep78 to DNA oligonucleotides containing E2-responsive element 1 (E2RE1) sequences of BPV-1 LCR. Our results expand the understanding of the mechanism of trans-regulation mediated by Rep78 and involving this protein and DNA sequences with complex secondary structure.
2型腺相关病毒（AAV-2）是一种依赖辅助病毒的细小病毒，它与抑制1型牛乳头瘤病毒（BPV-1）及其他转化性DNA病毒的复制和致癌转化有关。先前的研究表明，AAV-2的Rep78蛋白是介导这种效应的关键因子。在本报告中，我们分析了AAV-2 Rep78蛋白对BPV-1长控制区（LCR）控制下的报告基因的基因表达调控的影响。我们的结果表明，Rep78能够在组织培养细胞中体内下调LCR的启动子活性。体内LCR活性的抑制表明Rep78需要与跨越BPV-1 E2反应元件的LCR启动子区域结合。凝胶迁移试验在体外进一步证实了这一观察结果，显示Rep78与含有BPV-1 LCR的E2反应元件1（E2RE1）序列的DNA寡核苷酸特异性结合。我们的结果扩展了对由Rep78介导的反式调控机制的理解，该机制涉及这种蛋白质和具有复杂二级结构的DNA序列。
