Duée E D, Fanchon E, Vicat J, Sieker L C, Meyer J, Moulis J M
Laboratoire de Cristallographie Macromoléculaire, Institut de Biologie Structurale, Grenoble, France.
J Mol Biol. 1994 Nov 4;243(4):683-95. doi: 10.1016/0022-2836(94)90041-8.
The crystal structure of the 2[4Fe-4S] ferredoxin from Clostridium acidurici has been determined at a resolution of 1.84 A and refined to an R-factor of 0.169. Crystals belong to space group P4(3)2(1)2 with unit cell dimensions a = b = 34.44 A and c = 74.78 A. The structure was determined by molecular replacement using the previously published model of an homologous ferredoxin and refined by molecular dynamics techniques. The model contains the protein and 46 water molecules. Only two amino acid residues, Asp27 and Asp28, are poorly defined in the electron density maps. The molecule has an overall chain fold similar to that of other [4Fe-4S] bacterial ferredoxins of known structure. The two [4Fe-4S] clusters display similar bond distances and angles. In both of them the co-ordination of one iron atom (bound to Cys11 and Cys40) is slightly distorted as compared with that of the other iron atoms. A core of hydrophobic residues and a few water molecules contribute to the stability of the structure. The [4Fe-4S] clusters interact with the polypeptide chain through eight hydrogen bonds each, in addition to the covalent Fe-Scys bonds. The ferredoxin from Clostridium acidurici is the most typical clostridial ferredoxin crystallized so far and the biological implications of the newly determined structure are discussed.
已确定来自嗜酸梭菌的2[4Fe-4S]铁氧化还原蛋白的晶体结构，分辨率为1.84 Å，并将其精修至R因子为0.169。晶体属于空间群P4(3)2(1)2，晶胞参数a = b = 34.44 Å，c = 74.78 Å。该结构通过分子置换法确定，使用先前发表的同源铁氧化还原蛋白模型，并通过分子动力学技术进行精修。模型包含蛋白质和46个水分子。在电子密度图中，只有两个氨基酸残基（Asp27和Asp28）的定义不清晰。该分子的整体链折叠与其他已知结构的[4Fe-4S]细菌铁氧化还原蛋白相似。两个[4Fe-4S]簇显示出相似的键距和键角。与其他铁原子相比，其中一个铁原子（与Cys11和Cys40结合）的配位略有扭曲。一个疏水残基核心和一些水分子有助于结构的稳定性。除了共价的Fe-S半胱氨酸键外，[4Fe-4S]簇与多肽链各通过八个氢键相互作用。嗜酸梭菌的铁氧化还原蛋白是迄今为止结晶的最典型的梭菌铁氧化还原蛋白，并讨论了新确定结构的生物学意义。
