Crystal structure of the λ repressor C-terminal domain octamer
Crystal structure of the λ repressor C-terminal domain octamer
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DOI：
10.1006/jmbi.2000.5196
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发表时间：
2001-12-14
影响因子：
5.6
通讯作者：
Lewis, M
中科院分区：
文献类型：
--
作者：
Bell, CE;Lewis, M
抑制因子c端结构域（CTD）的三维结构在原子分辨率上被确定。在晶体中，CTD形成一个2重对称的四聚体，介导两个阻遏物二聚体与对操作位点的合作结合。基于这种结构，提出了在存在和不存在DNA的情况下形成的八聚体抑制因子的结构模型。在这里，我们已经确定了三种新的晶体形式的λ阻遏物CTD的结构，在各种各样的条件下。所有的晶体基本上都有相同的四聚体，证实了早期研究的结果。一种晶体形式有两个四聚体结合形成一个八聚体，这与先前提出的模型具有相同的总体结构。该八聚体在晶体结构中的一个意想不到的特征是在四聚体-四聚体界面上具有独特的相互作用，由残基Gln209、Tyr210和Pro211组成，这些残基与来自该八聚体其他亚基的对称等效残基接触。有趣的是，这些残基也位于二聚体-二聚体界面，在那里的具体相互作用是不同的。因此，结构表明特定的氨基酸残基，至少在原则上，当改变时可以导致形成四聚体而不是八聚体的抑制物。(C) 2001学术出版社。
The three-dimensional structure of the lambda repressor C-terminal domain (CTD) has been determined at atomic resolution. In the crystal, the CTD forms a 2-fold symmetric tetramer that mediates cooperative binding of two repressor dimers to pairs of operator sites. Based upon this structure, a model was proposed for the structure of an octameric repressor that forms both in the presence and absence of DNA. Here, we have determined the structure of the lambda repressor CTD in three new crystal forms, under a wide variety of conditions. All crystals have essentially the same tetramer, confirming the results of the earlier study. One crystal form has two tetramers bound to form an octamer, which has the same overall architecture as the previously proposed model. An unexpected feature of the octamer in the crystal structure is a unique interaction at the tetramer-tetramer interface, formed by residues Gln209, Tyr210 and Pro211, which contact symmetry-equivalent residues from other subunits of the octamer. Interestingly, these residues are also located at the dimer-dimer interface, where the specific interactions are different. The structures thus indicate specific amino acid residues that, at least in principle, when altered could result in repressors that form tetramers but not octamers. (C) 2001 Academic Press.