Piskacek Martin, Havelka Marek, Rezacova Martina, Knight Andrea
Laboratory of Cancer Biology and Genetics, Department of Pathological Physiology, Masaryk University Brno, Czech Republic.
Gamma Delta T Cell Laboratory, Department of Pathological Physiology, Faculty of Medicine, Masaryk University Brno, Czech Republic.
PLoS One. 2017 Jan 5;12(1):e0169261. doi: 10.1371/journal.pone.0169261. eCollection 2017.
The Gal4 protein is a well-known prototypic acidic activator that has multiple activation domains. We have previously identified a new activation domain called the nine amino acid transactivation domain (9aaTAD) in Gal4 protein. The family of the 9aaTAD activators currently comprises over 40 members including p53, MLL, E2A and other members of the Gal4 family; Oaf1, Pip2, Pdr1 and Pdr3. In this study, we revised function of all reported Gal4 activation domains. Surprisingly, we found that beside of the activation domain 9aaTAD none of the previously reported activation domains had considerable transactivation potential and were not involved in the activation of transcription. Our results demonstrated that the 9aaTAD domain is the only decisive activation domain in the Gal4 protein. We found that the artificial peptides included in the original Gal4 constructs were results of an unintended consequence of cloning that were responsible for the artificial transcriptional activity. Importantly, the activation domain 9aaTAD, which is the exclusive activation domain in Gal4, is also the central part of a conserved sequence recognized by the inhibitory protein Gal80. We propose a revision of the Gal4 regulation, in which the activation domain 9aaTAD is directly linked to both activation function and Gal80 mediated inhibition.
Gal4蛋白是一种著名的典型酸性激活剂，具有多个激活结构域。我们之前在Gal4蛋白中鉴定出一个新的激活结构域，称为九氨基酸反式激活结构域（9aaTAD）。9aaTAD激活剂家族目前包含40多个成员，包括p53、MLL、E2A以及Gal4家族的其他成员；Oaf1、Pip2、Pdr1和Pdr3。在本研究中，我们修正了所有已报道的Gal4激活结构域的功能。令人惊讶的是，我们发现除了9aaTAD激活结构域之外，之前报道的激活结构域均没有可观的反式激活潜力，且不参与转录激活。我们的结果表明，9aaTAD结构域是Gal4蛋白中唯一决定性的激活结构域。我们发现原始Gal4构建体中包含的人工肽是克隆意外产生的结果，这些人工肽导致了人工转录活性。重要的是，9aaTAD激活结构域作为Gal4中唯一的激活结构域，也是抑制蛋白Gal80识别的保守序列的中心部分。我们提出了对Gal4调控的修正，其中9aaTAD激活结构域与激活功能和Gal80介导的抑制直接相关。
