Kamens J, Brent R
Department of Molecular Biology, Massachusetts General Hospital, Boston 02114.
New Biol. 1991 Oct;3(10):1005-13.
Recent data have demonstrated that vRel, cRel, Dorsal, and NF-kappa B are members of a larger family of DNA-binding regulatory proteins. Rel proteins interact to form homo- and heterodimers that recognize specific sites on DNA, and it is likely that such protein-protein and protein-DNA interactions contribute to proper regulation of target gene expression by these proteins. Here we describe the use of a yeast transcription activation assay to study binding of three Rel family proteins to their native binding sites. These results show that the vRel and cRel proteins recognize two known NF-kappa B binding sites; the Dorsal protein does not recognize NF-kappa B sites, but does recognize related sites upstream of the Drosophila zerknüllt gene. Our experiments demonstrate that the members of this protein family recognize similar, but not identical, sites in the promoters of target genes, and we are able to identify a particular nucleotide that is apparently involved in the DNA-protein interaction. We exploit the properties of LexA fusion proteins to study the dimerization and DNA-contacting domains of cRel. Our results suggest that the cRel protein forms homodimers and that dimer formation may be necessary for cRel to bind DNA. Finally, our results show that transcription activation by these proteins is cooperative; such cooperativity may be important for correct temporal and spatial regulation of target gene expression.
最近的数据表明，vRel、cRel、Dorsal和核因子-κB是一个更大的DNA结合调节蛋白家族的成员。Rel蛋白相互作用形成同源二聚体和异源二聚体，识别DNA上的特定位点，并且这种蛋白质-蛋白质和蛋白质-DNA相互作用可能有助于这些蛋白质对靶基因表达的正确调节。在这里，我们描述了使用酵母转录激活试验来研究三种Rel家族蛋白与其天然结合位点的结合。这些结果表明，vRel和cRel蛋白识别两个已知的核因子-κB结合位点；Dorsal蛋白不识别核因子-κB位点，但能识别果蝇zerknüllt基因上游的相关位点。我们的实验表明，这个蛋白家族的成员在靶基因启动子中识别相似但不相同的位点，并且我们能够鉴定出一个明显参与DNA-蛋白质相互作用的特定核苷酸。我们利用LexA融合蛋白的特性来研究cRel的二聚化和DNA接触结构域。我们的结果表明，cRel蛋白形成同源二聚体，并且二聚体形成可能是cRel结合DNA所必需的。最后，我们的结果表明，这些蛋白的转录激活是协同的；这种协同作用可能对靶基因表达的正确时空调节很重要。
