Effects of different osmolytes on the induced folding of the N-terminal activation domain (AF1) of the glucocorticoid receptor.
Effects of different osmolytes on the induced folding of the N-terminal activation domain (AF1) of the glucocorticoid receptor.
复制标题
不同渗透剂对糖皮质激素受体 N 端激活域 (AF1) 诱导折叠的影响。
DOI：
10.1016/j.abb.2007.06.019
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发表时间：
2007
影响因子：
3.9
通讯作者：
Thompson,EB
中科院分区：
文献类型：
--
作者：
Kumar,R;Serrette,JM;Khan,SH;Miller,AL;Thompson,EB
为了了解糖皮质激素对基因的调控，了解糖皮质激素受体（GR）的主要反式激活结构域AF 1的功能是关键。AF 1位于GR的N-末端区域，对转录调控具有重要的定量意义，但直到最近几年，我们才开始了解AF 1的工作原理。这部分是由于重组AF 1（rAF 1）肽作为构象异构体的随机集合存在的事实。预测结构的算法支持这样的观点，即AF 1在全息GR中也不是很有序，AF 1中氨基酸的性质表明它本质上是无序的。然而，一般认为GR AF 1的内在无序序列必须实现一个或多个有序构象以进行反式激活活性。基于我们以前发表的工作和现有的文献，我们假设在生理条件下操作的影响的汇合导致功能活性构象（S）在AF 1中形成。我们已经证明，当rAF 1在增加浓度的天然存在的渗透剂三甲基胺-N-氧化物（TMAO）中孵育时，肽折叠成功能活性构象，选择性地结合几种关键的共调节蛋白。由于细胞含有各种有机渗透剂，其作用可能是累积的，并且鉴于GR AF 1作用的细胞特异性作用，我们测试了它是否可以被代表三种类型的其他天然有机渗透剂折叠：某些氨基酸（脯氨酸），甲胺（肌氨酸）和多元醇（山梨醇）。渗透剂诱导的rAF 1折叠显示出对特异性结合蛋白的亲和力大大增加，包括TATA盒结合蛋白（TBP）、CREB结合蛋白（CBP）和类固醇受体共激活因子-1（SRC-1）。与其他蛋白质的理论和已发表的数据一致，我们的研究结果表明，不同的渗透剂对rAF 1折叠有不同的影响。GR AF 1的细胞特异性功能，以及其他核激素受体的AF 1，可能部分受到特定细胞环境中特定渗透剂的存在和浓度的影响。
In order to understand gene regulation by glucocorticoids, it is pivotal to know how the major transactivation domain AF1 of the glucocorticoid receptor (GR) functions. Located in the N-terminal region of the GR, AF1 is quantitatively important for transcriptional regulation, but only in recent years have we begun to understand how AF1 works. This is in part due to the fact that the recombinant AF1 (rAF1) peptide exists as a random ensemble of conformers. Algorithms that predict structure support the view that AF1 is also not well ordered in the holo-GR, and the properties of the amino acids in AF1 suggest that it is intrinsically disordered. However, it is generally believed that intrinsically disordered sequences of the GR AF1 must achieve one or more ordered conformation(s) to carry out transactivation activity. Based on our previous published work and available literature, we hypothesize that a confluence of effects that operate under physiological conditions cause functionally active conformation(s) to form in AF1. We have shown that when rAF1 is incubated in increasing concentrations of a naturally occurring osmolyte trimethylamine-N-oxide (TMAO), the peptide folds into functionally active conformation(s) that selectively binds several critical coregulatory proteins. Because cells contain various organic osmolytes whose effects may be cumulative, and in light of cell-specific effects of GR AF1 action, we tested whether it can be folded by other natural organic osmolytes representative of three classes: certain amino acids (proline), methylamines (sarcosine), and polyols (sorbitol). The osmolyte-induced folding of rAF1 shows greatly increased affinity for specific binding proteins, including TATA box-binding protein (TBP), CREB-binding protein (CBP), and steroid receptor coactivator-1 (SRC-1). Consistent with theory and published data with other proteins, our results show that different osmolytes have differential effects on rAF1 folding. The cell-specific functions of the GR AF1—and by extension the AF1s of other nuclear hormone receptors—may in part be affected by the presence and concentrations of particular osmolytes within a particular cellular environment.