Challice J M, Segall J
Department of Biochemistry, University of Toronto, Ontario, Canada.
J Biol Chem. 1989 Nov 25;264(33):20060-7.
In vitro transcription of templates containing deletion-substitution mutations has localized two essential promoter elements of the 5 S rRNA gene of Saccharomyces cerevisiae. A promoter element spanning the start site of transcription extends from -14 to +8, and a short internal control region (ICR) extends from +81 to +94. Changes in spacing between these elements by more than a few base pairs significantly reduce transcription. The site of RNA polymerase III transcription factor A (TFIIIA) binding, mapped by determination of the G residues that are protected from methylation on exposure of the TFIIIA.5 S DNA complex to dimethyl sulfate, is coincident with the ICR. Incorporation of TFIIIC into the TFIIIA.5 S rRNA gene complex protects additional G residues 5' and 3' of the ICR from methylation.
对含有缺失-替换突变的模板进行体外转录，已定位出酿酒酵母5S rRNA基因的两个必需启动子元件。一个跨越转录起始位点的启动子元件从-14延伸至+8，一个短的内部控制区（ICR）从+81延伸至+94。这些元件之间的间距变化超过几个碱基对会显著降低转录。通过测定在TFIIIA-5S DNA复合物暴露于硫酸二甲酯时受到甲基化保护的G残基来定位RNA聚合酶III转录因子A（TFIIIA）的结合位点，该位点与ICR重合。将TFIIIC掺入TFIIIA-5S rRNA基因复合物可保护ICR 5'和3'端的其他G残基不被甲基化。
