Arkhipova I R, Ilyin Y V
V.A. Engelhardt Institute of Molecular Biology, Academy of Sciences of the USSR, Moscow.
EMBO J. 1991 May;10(5):1169-77. doi: 10.1002/j.1460-2075.1991.tb08057.x.
A sequence 30 bp downstream from the start site of the Drosophila melanogaster retrotransposon mdg1 is shown to be responsible for correct and precise initiation of mdg1 RNA synthesis in combination with the RNA start-site sequence TCAGTT. A sequence-specific DNA binding protein is demonstrated to interact with the +30 sequence, and the efficient binding of this factor is necessary for in vivo transcriptional activity of the plasmid constructs containing mdg1 promoter fragments. The nucleotides -8/+34 of mdg1 represent a minimal promoter which is able to provide correct initiation of transcription by RNA polymerase II at basal levels. A comparison with properties of some other retrotransposable elements and several developmentally regulated cellular genes allows us to conclude that together they form a specific class of RNA polymerase II promoter. This promoter class characteristically lacks upstream sequences necessary for transcription initiation, such as TATA boxes, but requires a specific downstream promoter element within 40 bp downstream of the RNA start site. The level of transcription can, however, be modulated by upstream regulatory elements. The identified sequence-specific downstream initiation factor may be responsible for transcription initiation on promoters of some genes which belong to this class.
果蝇黑腹逆转录转座子mdg1起始位点下游30个碱基对的序列，与RNA起始位点序列TCAGTT共同作用时，被证明负责mdg1 RNA合成的正确精确起始。一种序列特异性DNA结合蛋白被证明可与 +30序列相互作用，并且该因子的有效结合对于含有mdg1启动子片段的质粒构建体的体内转录活性是必需的。mdg1的核苷酸-8 / +34代表一个最小启动子，它能够在基础水平上通过RNA聚合酶II提供正确的转录起始。与其他一些逆转座元件和几个发育调控的细胞基因的特性进行比较，使我们能够得出结论，它们共同形成了一类特定的RNA聚合酶II启动子。这类启动子的特征是缺乏转录起始所需的上游序列，如TATA框，但需要在RNA起始位点下游40个碱基对内有一个特定的下游启动子元件。然而，转录水平可以由上游调控元件调节。已鉴定的序列特异性下游起始因子可能负责属于此类的一些基因启动子上的转录起始。
