Nucleosome structure of the yeast CHA1 promoter:: analysis of activation-dependent chromatin remodeling of an RNA-polymerase-II-transcribed gene in TBP and RNA pol II mutants defective in vivo in response to acidic activators
Nucleosome structure of the yeast CHA1 promoter:: analysis of activation-dependent chromatin remodeling of an RNA-polymerase-II-transcribed gene in TBP and RNA pol II mutants defective in vivo in response to acidic activators
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DOI：
10.1093/emboj/17.20.6028
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发表时间：
1998-10-15
期刊：
影响因子：
11.4
通讯作者：
Holmberg, S
中科院分区：
文献类型：
--
作者：
Moreira, JMA;Holmberg, S
酿酒酵母cha1基因编码分解代谢的L-丝氨酸(L-苏氨酸)脱水酶。我们先前已经证明，转录激活蛋白Cha4p介导丝氨酸/苏氨酸诱导CHA1的表达。我们使用对微球菌核酸酶和DNase I的可及性来确定CHA1染色体基因座在体内的染色质结构，无论是在非诱导状态下还是在诱导状态下。激活后，封闭TATA盒和转录起始点的精确定位的核小体(nuc-1)被移除。不含CHA4P的菌株在诱导条件下未见染色质改变。5个酵母TBP突变体在激活转录过程中存在不同步骤的缺陷，使CHA1的表达消失，但不影响启动子区域诱导依赖的染色质重排。RNA聚合酶II C末端结构域的逐渐截断导致CHA1转录的逐渐减少，但在染色质重塑方面没有差异。对Swi1、Swi3、Snf5和Snf6以及gcn5、ada2和ada3突变体的分析表明，SWI/SnF和ADA/GCN5复合体都不参与CHA1启动子的有效激活和/或重塑。有趣的是，在sir4缺失株中，CHA1的抑制部分丧失，并观察到nuc-1的非激活剂依赖的重塑。我们提出了一个基于启动子重塑的CHA1激活模型，该模型通过Cha4p与染色质成分的相互作用，而不是基础因子和相关蛋白。
The Saccharomyces cerevisiae CHA1 gene encodes the catabolic L-serine (L-threonine) dehydratase. We have previously shown that the transcriptional activator protein Cha4p mediates serine/threonine induction of CHA1 expression. We used accessibility to micrococcal nuclease and DNase I to determine the in vivo chromatin structure of the CHA1 chromosomal locus, both in the non-induced state and upon induction. Upon activation, a precisely positioned nucleosome (nuc-1) occluding the TATA box and the transcription start site is removed. A strain devoid of Cha4p showed no chromatin alteration under inducing conditions. Five yeast TBP mutants defective in different steps in activated transcription abolished CHA1 expression, but failed to affect induction-dependent chromatin rearrangement of the promoter region. Progressive truncations of the RNA polymerase II C-terminal domain caused a progressive reduction in CHA1 transcription, but no difference in chromatin remodeling. Analysis of swi1, swi3, snf5 and snf6, as well as gcn5, ada2 and ada3 mutants, suggested that neither the SWI/SNF complex nor the ADA/GCN5 complex is involved in efficient activation and/or remodeling of the CHA1 promoter. Interestingly, in a sir4 deletion strain, repression of CHA1 is partly lost and activator-independent remodeling of nuc-1 is observed. We propose a model for CHA1 activation based on promoter remodeling through interactions of Cha4p with chromatin components other than basal factors and associated proteins.