Appropriation of the MinD protein-interaction motif by the dimeric interface of the bacterial cell division regulator MinE
Appropriation of the MinD protein-interaction motif by the dimeric interface of the bacterial cell division regulator MinE
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DOI：
10.1073/pnas.1007141107
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发表时间：
2010-10-26
影响因子：
11.1
通讯作者：
Goto, Natalie K.
中科院分区：
文献类型：
--
作者：
Ghasriani, Houman;Ducat, Thierry;Goto, Natalie K.
MinE是Min蛋白动态振荡所必需的，Min蛋白将细胞动力学隔膜的形成限制在革兰氏阴性菌中细胞的中点。这种振荡的关键是MinE与MinD的结合，以刺激MinD ATP水解，这是MinE中第一个类似于30个残基的功能。以前的模型的基础上的自主折叠的二聚体C-末端片段的结构表明，N-末端结构域是自由访问与MinD的相互作用。在这里，我们报告的解决方案NMR结构的全长MinE二聚体淋病奈瑟氏球菌，与两个部分的N-末端结构域形成的二聚化界面的一个组成部分。出乎意料的是，溶剂的可及性是高度限制的残基，以前假设直接与MinD相互作用。为了描绘真正的MinD结合区域，进行MinE刺激的MinD活性的体外测定。从MinE获得的全长和N-末端肽的相对MinD结合亲和力表明，埋在二聚体界面中的残基仍然参与与MinD的直接相互作用。根据NMR自旋弛豫实验的结果，访问这些掩埋的残基可能会促进构象交换的存在。我们认为，这种隐藏的MinD结合残基的MinE二聚体接口提供了一种机制，用于预防非特异性相互作用，特别是与脂质膜，允许MinE的自由扩散，这是至关重要的Min蛋白振荡。
MinE is required for the dynamic oscillation of Min proteins that restricts formation of the cytokinetic septum to the midpoint of the cell in gram negative bacteria. Critical for this oscillation is MinD-binding by MinE to stimulate MinD ATP hydrolysis, a function that had been assigned to the first similar to 30 residues in MinE. Previous models based on the structure of an autonomously folded dimeric C-terminal fragment suggested that the N-terminal domain is freely accessible for interactions with MinD. We report here the solution NMR structure of the full-length MinE dimer from Neisseria gonorrhoeae, with two parts of the N-terminal domain forming an integral part of the dimerization interface. Unexpectedly, solvent accessibility is highly restricted for residues that were previously hypothesized to directly interact with MinD. To delineate the true MinD-binding region, in vitro assays for MinE-stimulated MinD activity were performed. The relative MinD-binding affinities obtained for full-length and N-terminal peptides from MinE demonstrated that residues that are buried in the dimeric interface nonetheless participate in direct interactions with MinD. According to results from NMR spin relaxation experiments, access to these buried residues may be facilitated by the presence of conformational exchange. We suggest that this concealment of MinD-binding residues by the MinE dimeric interface provides a mechanism for prevention of nonspecific interactions, particularly with the lipid membrane, to allow the free diffusion of MinE that is critical for Min protein oscillation.