NMR OF TRANSITION BETWEEN DIMER & TETRAMER OF EK18, MUTANT OF TRP REPRESSOR

EK 18是trp阻遏蛋白的突变体，被称为“超阻遏蛋白”。 因为它抑制了基因的转录 色氨酸合成在较低水平的色氨酸分子在 cell. 其分子量为约12.5千道尔顿/单体， 主要以二聚体形式存在。 然而，当盐浓度为 寡聚化降低或蛋白质浓度增加 发生在二聚体之间。 蛋白质之间的相互作用似乎 在压抑机制中的作用。 除了辅阻遏物 浓度，这种寡聚化可以起到微调基因的作用。 调控 已经有几项研究使用荧光 光谱来研究低聚反应，但没有结构 到目前为止已经进行了研究。 核磁共振研究这种低聚反应 将告诉两个二聚体如何相互作用（即，是否 四聚体是特异性的还是非特异性的，或者它是对称的， 或不对称）。

EK18 is a mutant of trp repressor and is cal a "super-repressor" since it represses the transcription of genes responsible for typtophan synthesis at a lower level of tryptophan molecules in the cell. Its molecular weight is about 12.5 kDaltons per monomer and it exists primarily as a dimer. However, when the salt concentration is lowered, or the protein concentration is increased, oligomerization occurs between dimers. The protein-protein interaction seems to play a role in the mechanism of repression. In addition to the corepressor concentration, this oligomerization may act to fine tune the gene regulation. Several studies have been done using fluorescence spectroscopy to investigate the oligomerization, but no structural studies have been done to date. NMR studies of this oligomerization will tell how the two dimers interact (i.e., whether the tetramerization is specific or nonspecific, or whether is it symmetric or unsymmetric).