GENETIC-EVIDENCE FOR PROMOTER COMPETITION IN SACCHAROMYCES-CEREVISIAE
GENETIC-EVIDENCE FOR PROMOTER COMPETITION IN SACCHAROMYCES-CEREVISIAE
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DOI：
10.1128/mcb.8.11.4608
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发表时间：
1988-11-01
影响因子：
5.3
通讯作者：
WINSTON, F
中科院分区：
文献类型：
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作者：
HIRSCHMAN, JE;DURBIN, KJ;WINSTON, F
his4-912.delta。突变是长末端重复序列（δ）的插入。将酵母逆转录转座子Ty插入HIS 4启动子区，使得δ是位于HIS 4转录起始位点上游97个碱基对。携带his 4 - 912.delta的菌株。等位基因是His-23 °。这种表型可以通过在37 ℃下生长而逆转。C或通过反式作用SPT基因突变。在他的4 - 912.赋予His-表型时，HIS 4转录起始于δ。起始位点，而不是在HIS 4起始位点，产生更长的非功能性转录物。在菌株为His+的条件下，转录起始于野生型HIS 4起始位点。为了理解转录如何在.和HIS 4启动子，我们选择了his 4 - 912 δ的顺式作用抑制子。由六个独立突变定义的两类恢复功能性HIS 4转录物的合成。第一类是所提出的δ上游的1个碱基的A到G碱基变化。TATA序列。这些突变体不合成δ-启动的转录物;相反，它们仅合成野生型HIS 4转录物。第二类突变改变了功能性HIS 4 TATA序列周围的碱基对。这类最强的两个His+突变体以与它们的His+表型一致的水平合成野生型HIS 4转录物。令人惊讶的是，这两种突变体也具有降低水平的δ-相对于his 4 - 912. δ的起始转录物。家长对这些突变体的分析表明，来自一个启动子的转录水平可以影响来自另一个启动子的转录水平，并表明δ和HIS 4转录信号竞争从每个位点开始转录。
The his4-912.delta. mutation is an insertion of the long terminal repeat (.delta.) of the yeast retrotransposon Ty into the HIS4 promoter region, such that the .delta. is 97 base pairs upstream of the HIS4 transcription initiation site. Strains carrying the his4-912.delta. allele are His- at 23.degree. C; this phenotype can be reversed either by growth at 37.degree. C or by mutations in trans-acting SPT genes. Under conditions in which his4-912.delta. confers a His- phenotype, HIS4 transcription initiates at the .delta. initiation site, rather than at the HIS4 initiation site, producing a longer, nonfunctional transcript. Under conditions in which the strain is His+, transcription initiates at the wild-type HIS4 initiation site. To understand how transcription is balanced between the .delta. and HIS4 promoters, we have selected for cis-acting suppressors of his4-912.delta.. Two classes defined by six independent mutations restore synthesis of a functional HIS4 transcript. The first class is an A-to-G base change 1 base upstream of the proposed .delta. TATA sequence. These mutants do not synthesize the .delta.-initiated transcript; instead, they synthesize only the wild-type HIS4 transcript. The second class of mutations alters base pairs surrounding the functional HIS4 TATA sequence. The two strongest His+ mutants of this class synthesize the wild-type HIS4 transcript at levels consistent with their His+ phenotype. Surprisingly, these two mutants also have a reduced level of the .delta.-initiated transcript relative to the his4-912.delta. parent. Analysis of these mutants indicates that the level of transcription from one promoter can affect the level of transcription from the other promoter and suggests that .delta. and HIS4 transcription signals compete for initiation of transcription from each site.