Baumgärtner B, Heiland S, Kunze N, Richter A, Knippers R
Division of Biology, Universität Konstanz, Germany.
Biochim Biophys Acta. 1994 May 17;1218(1):123-7. doi: 10.1016/0167-4781(94)90114-7.
The gene for mammalian type I DNA topoisomerase is constitutively expressed, but also regulated by a number of external stimuli. We compared the nucleotide sequences of the human and the mouse topoisomerase I gene promoters because promoter elements, essential for basic as well as regulated gene expression, should be conserved during evolution. We found that proximal upstream sequences are highly conserved and include potential binding sites for ubiquitous transcription factors, a regulatory CRE site as well as two novel promoter elements that have been shown to be important for the expression of the human gene. The more distal parts of the upstream sequences are less well conserved but include two regions that are almost identical in the human and the mouse gene. One of these regions contains a binding site for a basic-helix-loop-helix/leucine-zipper protein, and the other contains an AT-rich element with the potential for DNA bending.
哺乳动物I型DNA拓扑异构酶基因持续表达，但也受多种外部刺激调控。我们比较了人类和小鼠拓扑异构酶I基因启动子的核苷酸序列，因为对于基础基因表达以及受调控基因表达至关重要的启动子元件在进化过程中应该是保守的。我们发现近端上游序列高度保守，包括普遍存在的转录因子的潜在结合位点、一个调控性CRE位点以及两个已被证明对人类基因表达很重要的新型启动子元件。上游序列较远的部分保守性较差，但包括人类和小鼠基因中几乎相同的两个区域。其中一个区域包含一个碱性螺旋-环-螺旋/亮氨酸拉链蛋白的结合位点，另一个区域包含一个具有DNA弯曲潜力的富含AT的元件。
