CHARACTERIZATION OF VSG GENE-EXPRESSION SITE PROMOTERS AND PROMOTER-ASSOCIATED DNA REARRANGEMENT EVENTS
CHARACTERIZATION OF VSG GENE-EXPRESSION SITE PROMOTERS AND PROMOTER-ASSOCIATED DNA REARRANGEMENT EVENTS
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DOI：
10.1128/mcb.11.5.2467
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发表时间：
1991-05-01
影响因子：
5.3
通讯作者：
VANDERPLOEG, LHT
中科院分区：
文献类型：
--
作者：
GOTTESDIENER, K;CHUNG, HM;VANDERPLOEG, LHT
布氏锥虫表达的变异细胞表面糖蛋白 (VSG) 基因位于大型端粒多顺反子转录单元或表达位点的 3' 端。 我们发现，VSG 基因上游 45 kb 的区域，位于 1.5 Mb 染色体上的表达位点，包含至少两个串联排列的启动子，指导表达位点的转录。 DNA 重排事件专门发生在表达位点失活时，这些事件删除了最上游的转录区域，并用大量简单序列 DNA 取代它，使下游启动子保持完整。 由于简单序列 DNA 的放置，剩余的下游启动子现在在结构上与先前描述的 VSG 启动子相同。 下游启动子在基因组中是重复的，因为它存在于几个不同的表达位点。 限制性片段长度多态性作图允许将表达位点分为两个家族，即具有和不具有上游转录单元的家族，并且DNA重排事件将表达位点从一种类型转换为另一种类型。 上游转录单元的删除也会导致一些稳态 RNA 的丢失。 这些发现可能表明启动子相关的 DNA 重排事件和/或串联排列的启动子之间的相互作用在表达位点转录控制中的作用。
The expressed variant cell surface glycoprotein (VSG) gene of Trypanosoma brucei is located at the 3' end of a large, telomeric, polycistronic transcription unit or expression site. We show that the region 45 kb upstream of the VSG gene, in the expression site on a 1.5-Mb chromosome, contains at least two promoters that are arranged in tandem, directing the transcription of the expression site. DNA rearrangement events occur specifically, at inactivation of the expression site, and these events delete the most upstream transcribed region and replace it with a large array of simple-sequence DNA, leaving the downstream promoter intact. Because of the placement of simple-sequence DNA, the remaining downstream promoter now becomes structurally identical to previously described VSG promoters. The downstream promoter is repetitive in the genome, since it is present at several different expression sites. Restriction fragment length polymorphism mapping allows grouping of the expression sites into two families, those with and those without an upstream transcription unit, and the DNA rearrangement events convert the expression sites from one type to the other. Deletion of the upstream transcription unit also leads to the loss of several steady-state RNAs. The findings may indicate a role for promoter-associated DNA rearrangement events, and/or interactions between tandemly arranged promoters, in expression site transcriptional control.