Osborne B I, Guarente L
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Proc Natl Acad Sci U S A. 1989 Jun;86(11):4097-101. doi: 10.1073/pnas.86.11.4097.
We have isolated and mutagenized a DNA fragment from Saccharomyces cerevisiae that specifies mRNA 3' end formation for the convergently transcribed CYC1 and UTR1 genes. An in vivo plasmid supercoiling assay previously showed that this fragment is a transcriptional terminator, and "run-on" assays shown here are consistent with this interpretation. The poly(A) sites in the mRNAs formed by the fragment are the same whether the fragment resides at the native location or at a heterologous location. No single linker substitution abolishes the fragment's activity, whereas certain large, nonoverlapping deletions have strong, deleterious effects. Therefore, the yeast terminator behaves more like rho-dependent bacterial terminators than terminators of higher eukaryotes. That a number of deletions or substitutions have different effects in the two orientations suggests that the fragment contains the sequences of two, unidirectional terminator elements.
我们从酿酒酵母中分离并诱变了一个DNA片段，该片段决定了反向转录的CYC1和UTR1基因的mRNA 3'末端形成。先前的体内质粒超螺旋分析表明，该片段是一个转录终止子，此处所示的“连续转录”分析结果与这一解释一致。无论该片段位于天然位置还是异源位置，由其形成的mRNA中的聚腺苷酸化位点都是相同的。没有单个接头取代会消除该片段的活性，而某些大的、不重叠的缺失则有强烈的有害影响。因此，酵母终止子的行为更类似于依赖ρ因子的细菌终止子，而不是高等真核生物的终止子。许多缺失或取代在两个方向上有不同的影响，这表明该片段包含两个单向终止子元件的序列。
