The minimal transactivation region of Saccharomyces cerevisiae Gln3p is localized to 13 amino acids.
The minimal transactivation region of Saccharomyces cerevisiae Gln3p is localized to 13 amino acids.
复制标题
酿酒酵母 Gln3p 的最小反式激活区域位于 13 个氨基酸。
DOI：
10.1128/jb.179.24.7644-7652.1997
复制
发表时间：
1997
影响因子：
3.2
通讯作者：
Cooper,TG
中科院分区：
文献类型：
--
作者：
Svetlov,V;Cooper,TG
在酿酒酵母中，调控的氮分解代谢基因转录是由4个相互对立的正调控因子（Gln3p和Gat1p/Nil1p）和负调控因子（Dal80p/Uga43p和Deh1p/Nil2p/GZF3p）介导的。这四种蛋白都含有GATA型锌指结构域，其中三个（Gln3p， Dal80p和Deh1p）已被证明与位于氮分解代谢抑制（NCR）敏感基因上游的GATA序列结合。阳性调节因子Gln3p和Gat1p，当被LexAp连接到报告基因的启动子上时，能够支持转录激活，而报告基因的上游激活序列已被一个或多个lexA操作符位点取代。现有数据表明，这四种蛋白通过相互竞争结合介导ncr敏感基因表达的GATA序列来调节转录。我们发现介导转录激活的最小Gln3p结构域由13个氨基酸组成，预测倾向于形成α -螺旋。该区域（Gln3p残基126 ~ 138，QQNGEIAQLWDFN）的遗传分析表明，丙氨酸可以取代芳香和酸性氨基酸，而不会破坏转录激活电位。然而，用丙氨酸替代异亮氨酸和亮氨酸这两种疏水氨基酸会破坏激活，用碱性氨基酸代替酸性残基或将脯氨酸引入序列中心也会破坏激活。Gln3p激活区的一个点突变破坏了它在体内支持ncr敏感的DAL5表达的能力。我们没有发现令人信服的证据表明NCR通过调节其激活区的功能来调节Gln3p的功能。
Regulated nitrogen catabolic gene transcription in Saccharomyces cerevisiae is mediated by four positive (Gln3p and Gat1p/Nil1p) and negative (Dal80p/Uga43p and Deh1p/Nil2p/GZF3p) regulators which function in opposition to one another. All four proteins contain GATA-type zinc finger domains, and three of them (Gln3p, Dal80p, and Deh1p) have been shown to bind to GATA sequences situated upstream of genes whose expression is sensitive to nitrogen catabolite repression (NCR). The positive regulators, Gln3p and Gat1p, are able to support transcriptional activation when tethered by LexAp to the promoter of a reporter gene whose upstream activation sequences have been replaced with one or more lexA operator sites. Existing data suggest that these four proteins regulate transcription by competing with one another for binding to the GATA sequences which mediate NCR-sensitive gene expression. We show that the minimal Gln3p domain mediating transcriptional activation consists of 13 amino acids with a predicted propensity to form an alpha-helix. Genetic analysis of this region (Gln3p residues 126 to 138, QQNGEIAQLWDFN) demonstrated that alanine may be substituted for the aromatic and acidic amino acids without destroying transcriptional activation potential. Similar substitution of alanine for the two hydrophobic amino acids, isoleucine and leucine, however, destroys activation, as does introduction of basic amino acids in place of the acidic residues or introduction of proline into the center of the sequence. A point mutation in the Gln3p activation region destroys its in vivo ability to support NCR-sensitive DAL5 expression. We find no convincing evidence that NCR regulates Gln3p function by modulating the functioning of its activation region.