The 1.30 Å resolution structure of the Bacillus subtilis chorismate mutase catalytic homotrimer
The 1.30 Å resolution structure of the Bacillus subtilis chorismate mutase catalytic homotrimer
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DOI：
10.1107/s0907444900004625
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发表时间：
2000-06-01
影响因子：
2.2
通讯作者：
Gilliland, GL
中科院分区：
文献类型：
--
作者：
Ladner, JE;Reddy, P;Gilliland, GL
对芳香氨基酸生物合成途径中的一种酶--枯草芽孢杆菌分支酸变位酶的晶体结构进行了测定，其分辨率为1.30埃。用晶胞参数为a=52.2，b=83.8，c=86.0埃的空间群P2(1)2(1)2(1)的正交晶进行分子置换，确定了该三聚体的结构。单斜晶系结构的ABC三聚体[Chook et al.(1994)，J.Mol.比奥尔。240,476-500]作为起始模型。最终的坐标由127个氨基酸残基组成的三个完整的多肽链组成。此外，结构中还有9个硫酸盐离子、5个甘油分子和424个水分子清晰可见。该结构通过各向异性温度因子进行了优化，具有良好的几何构型，晶体学R因子为0.169，无R因子为0.236。大分子的三个活性部位在亚基界面，每个部位有两个亚基的残基贡献。这种正交晶型晶体是以硫酸铵为沉淀剂生长的，在数据采集过程中使用甘油作为冷冻保护剂。在每个活性中心都发现了甘油分子和硫酸盐离子，它们模仿过渡态类似物。在这种结构中，三聚体亚基的C-末端末端与晶体中相邻三聚体活性中心的残基氢键，从而使晶格中的分子发生交联。
The crystal structure of the Bacillus subtilis chorismate mutase, an enzyme of the aromatic amino acids biosynthetic pathway, was determined to 1.30 Angstrom resolution. The structure of the homotrimer was determined by molecular replacement using orthorhombic crystals of space group P2(1)2(1)2(1) with unit-cell parameters a = 52.2, b = 83.8, c = 86.0 Angstrom. The ABC trimer of the monoclinic crystal structure [Chook et al. (1994), J. Mol. Biol. 240, 476-500] was used as the starting model. The final coordinates are composed of three complete polypeptide chains of 127 amino-acid residues. In addition, there are nine sulfate ions, five glycerol molecules and 424 water molecules clearly visible in the structure. This structure was refined with aniosotropic temperature factors, has excellent geometry and a crystallographic R factor of 0.169 with an R-free of 0.236. The three active sites of the macromolecule are at the subunit interfaces, with residues from two subunits contributing to each site. This orthorhombic crystal form was grown using ammonium sulfate as the precipitant; glycerol was used as a cryoprotectant during data collection. A glycerol molecule and sulfate ion in each of the active sites was found mimicking a transition-state analog. In this structure, the C-terminal tails of the subunits of the trimer are hydrogen bonded to residues of the active site of neighboring trimers in the crystal and thus cross-link the molecules in the crystal lattice.