The crystal structure of glutamine-binding protein from Escherichia coli
The crystal structure of glutamine-binding protein from Escherichia coli
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DOI：
10.1006/jmbi.1996.0509
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发表时间：
1996-09-20
影响因子：
5.6
通讯作者：
Wang, BC
中科院分区：
文献类型：
--
作者：
Hsiao, CD;Sun, YJ;Wang, BC
来自大肠杆菌的处于无配体“开放”构象状态的谷氨酰胺结合蛋白 (GlnBP) 的晶体结构已通过同晶置换方法确定，并在 2.3 埃分辨率下精修至 R 值 21.4%。不对称单元中有两个分子，通过伪四重螺旋对称相关。精炼后的模型由来自 440 个残基（两个单体）的 3587 个非氢原子和 159 个水分子组成。该结构与“理想”键长的均方根偏差为 0.013 埃，与“理想”键角的均方根偏差为 1.5 度。GlnBP 分子的总体尺寸约为 60 埃 x 40 埃 x 35 埃，由两个域（称为大和小）组成，这两个域表现出类似的超二级结构，由两个反平行结构连接 β链。小结构域包含三个 α 螺旋和 4 个平行和 1 个反平行 β 链。大结构域与小结构域相似，但包含两个额外的 α 螺旋和三个更短的反平行 β 链。讨论了 GlnBP 与其他周质结合蛋白二级结构基序的比较。基于组氨酸结合蛋白-His 复合物和“开放形式”GlnBP 的晶体结构，提出了“封闭形式”GlnBP-Gln 复合物的模型。该模型已成功用作通过分子置换方法确定“闭合形式”GlnBP-Gln 复合物晶体结构的搜索模型。该模型与 Gln-GlnBP 复合物的晶体结构非常吻合，均方根偏差为 1.29 埃。我们的研究表明，至少在我们的例子中，可以从周质结合蛋白的另一种构象状态预测该蛋白的一种构象状态。比较模型的谷氨酰胺结合袋和晶体结构并描述建模技术。 (C) 1996 学术出版社有限公司
The crystal structure of the glutamine-binding protein (GlnBP) from Escherichia coli in a ligand-free ''open'' conformational state has been determined by isomorphous replacement methods and refined to an R-value of 21.4% at 2.3 Angstrom resolution. There are two molecules in the asymmetric unit, related by pseudo 4-fold screw symmetry. The refined model consists of 3587 non-hydrogen atoms from 440 residues (two monomers), and 159 water molecules. The structure has root-mean-square deviations of 0.013 Angstrom from ''ideal'' bond lengths and 1.5 degrees from ''ideal'' bond angles.The GlnBP molecule has overall dimensions of approximately 60 Angstrom x 40 Angstrom x 35 Angstrom and is made up of two domains (termed large and small), which exhibit a similar supersecondary structure, linked by two antiparallel beta-strands. The small domain contains three alpha-helices and four parallel and one antiparallel beta-strands. The large domain is similar to the small domain but contains two additional alpha-helices and three more short antiparallel beta-strands. A comparison of the secondary structural motifs of GlnBP with those of other periplasmic binding proteins is discussed.A model of the ''closed form'' GlnBP-Gln complex has been proposed based on the crystal structures of the histidine-binding protein-His complex and ''open form'' GlnBP. This model has been successfully used as a search model in the crystal structure determination of the ''closed form'' GlnBP-Gln complex by molecular replacement methods. The model agrees remarkably well with the crystal structure of the Gln-GlnBP complex with root-mean-square deviation of 1.29 Angstrom. Our study shows that, at least in our case, it is possible to predict-one conformational state of a periplasmic binding protein from another conformational state of the protein. The glutamine-binding pockets of the model and the crystal structure are compared and the modeling technique is described. (C) 1996 Academic Press Limited