Properties of an intergenic terminator and start site switch that regulate IMD2 transcription in yeast
Properties of an intergenic terminator and start site switch that regulate IMD2 transcription in yeast
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DOI：
10.1128/mcb.00380-08
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发表时间：
2008-06-01
影响因子：
5.3
通讯作者：
Reines, Daniel
中科院分区：
文献类型：
--
作者：
Jenks, M. Harley;O'Rourke, Thomas W.;Reines, Daniel
酿酒酵母中的IMD2基因受胞内鸟嘌呤核苷酸的调控。调控是通过选择可选的转录起始点来实施的，这会导致合成终止于起始密码子上游的不稳定的短转录本或合成全长的生产性IMD2 mRNA。起始点的选择由细胞内鸟嘌呤核苷酸水平决定。在这里，我们已经绘制了上游不稳定的短转录本的多聚腺苷酸化位点，这些转录本形成了大约200个核苷酸的异质RNA家族。从上游起始点到下游起始点的切换需要RNA聚合酶II的Rpb9亚基。随着起始点从TATA盒向下游移动，该酶定位下游起始点的能力呈指数下降。这表明，当RNA聚合酶II在DNA上滑动寻找起点时，它的钳形抓地力是重要的。上游转录产物的外切体降解高度依赖于终止子和启动子之间的距离。同样，当靠近启动子时，终止依赖于Sen1解旋酶。这些发现扩展了新兴的概念，即RNA聚合酶II存在不同的终止模式，终止子与启动子的距离及其序列对所选择的途径很重要。
The IMD2 gene in Saccharomyces cerevisiae is regulated by intracellular guanine nucleotides. Regulation is exerted through the choice of alternative transcription start sites that results in synthesis of either an unstable short transcript terminating upstream of the start codon or a full-length productive IMD2 mRNA. Start site selection is dictated by the intracellular guanine nucleotide levels. Here we have mapped the polyadenylation sites of the upstream, unstable short transcripts that form a heterogeneous family of RNAs of approximate to 200 nucleotides. The switch from the upstream to downstream start sites required the Rpb9 subunit of RNA polymerase II. The enzyme's ability to locate the downstream initiation site decreased exponentially as the start was moved downstream from the TATA box. This suggests that RNA polymerase II's pincer grip is important as it slides on DNA in search of a start site. Exosome degradation of the upstream transcripts was highly dependent upon the distance between the terminator and promoter. Similarly, termination was dependent upon the Sen1 helicase when close to the promoter. These findings extend the emerging concept that distinct modes of termination by RNA polymerase II exist and that the distance of the terminator from the promoter, as well as its sequence, is important for the pathway chosen.