Schlapp T, Rödel G
Institut für Genetik und Mikrobiologie der Universität München, Federal Republic of Germany.
Mol Gen Genet. 1990 Sep;223(3):438-42. doi: 10.1007/BF00264451.
Oligo(dA-dT) tracts are frequently found in the intergenic regions of the yeast Saccharomyces cerevisiae and have been proposed to act as upstream promoter elements for constitutive transcription. An oligo(dA-dT) tract of 23 bp is also found as a characteristic sequence motif in the centre of the 230 bp segment which separates the open reading frames of the CBS2 gene and its 5'-flanking gene on chromosome IV. Recently we have reported that transcription of CBS2 is initiated immediately adjacent to this oligo(dA-dT) tract (michaelis et al. 1988). Here we report that the flanking gene of unknown function is divergently transcribed into an RNA with heterogeneous 5' ends. Two of these 5' ends map within the oligo(dA-dT) stretch, while the third is located upstream, leading to an RNA species which is partially complementary to the CBS2 transcript. Gel shift assays show that the oligo(dA-dT) stretch is specifically recognized by (a) binding factor(s) in nuclear extracts. We discuss these results with respect to the role of oligo(dA-dT) stretches in gene expression in yeast.
寡聚（dA-dT）序列常见于酿酒酵母的基因间区域，并被认为可作为组成型转录的上游启动子元件。在第IV号染色体上，一个23 bp的寡聚（dA-dT）序列也作为特征性序列基序，存在于分隔CBS2基因及其5'侧翼基因开放阅读框的230 bp片段的中心位置。最近我们报道，CBS2的转录起始于紧邻该寡聚（dA-dT）序列处（米夏埃利斯等人，1988年）。在此我们报道，这个功能未知的侧翼基因以相反方向转录成一种5'端异质性的RNA。其中两个5'端位于寡聚（dA-dT）序列内，而第三个位于其上游，产生一种与CBS2转录本部分互补的RNA分子。凝胶迁移实验表明，寡聚（dA-dT）序列能被核提取物中的（一种或多种）结合因子特异性识别。我们结合寡聚（dA-dT）序列在酵母基因表达中的作用来讨论这些结果。
