Transcriptional activation domains stimulate initiation and elongation at different times and via different residues
Transcriptional activation domains stimulate initiation and elongation at different times and via different residues
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DOI：
10.1093/emboj/17.11.3146
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发表时间：
1998-06-01
期刊：
影响因子：
11.4
通讯作者：
Kingston, RE
中科院分区：
文献类型：
--
作者：
Brown, SA;Weirich, CS;Kingston, RE
转录激活因子可以刺激转录过程中的多个步骤。我们已经使用GAL 4融合蛋白来表征不同转录激活结构域在体外刺激热休克蛋白70基因转录延伸的能力。延长的刺激显然是通过一种与刺激起始不同的机制途径发生的：单纯疱疹病毒VP 16、热休克因子1（HSF 1）和两亲性螺旋（AH）激活结构域都刺激起始，但只有VP 16和HSF 1刺激延长;并且HSF 1激活结构域的疏水残基中的突变削弱了对延伸的刺激而不是对起始的刺激，而相邻酸性残基中的突变损害起始刺激多于延伸刺激。在起始和延伸之间交换激活剂的实验表明，HSF 1的延伸功能将刺激已经启动并转录参与的RNA聚合酶。因此，转录激活因子似乎具有至少两种不同的功能，它们位于同一结构域中，并且在不同的时间起作用以刺激起始和延伸。
Transcriptional activators can stimulate multiple steps in the transcription process. We have used GAL4 fusion proteins to characterize the ability of different transcriptional activation domains to stimulate transcriptional elongation on the hsp70 gene irt vitro. Stimulation of elongation apparently occurs via a mechanistic pathway different from that of stimulation of initiation: the herpes simplex virus VP16, heat shock factor 1 (HSF1) and amphipathic helix (AH) activation domains all stimulate initiation, but only VP16 and HSF1 stimulate elongation; and mutations in hydrophobic residues of the HSF1 activation domains impair stimulation of elongation but not of initiation, while mutations in adjacent acidic residues impair stimulation of initiation more than of elongation. Experiments in which activators were exchanged between initiation and elongation demonstrate that the elongation function of HSF1 will stimulate RNA polymerase that has initiated and is transcriptionally engaged. Transcriptional activators thus appear to have at least two distinct functions that reside in the same domain, and that act at different times to stimulate initiation and elongation.