Aono S, Bentrop D, Bertini I, Donaire A, Luchinat C, Niikura Y, Rosato A
School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa, Japan.
Biochemistry. 1998 Jul 7;37(27):9812-26. doi: 10.1021/bi972818b.
The solution structure of the paramagnetic seven-iron ferredoxin from Bacillus schlegelii in its oxidized form has been determined by 1H NMR. The protein, which contains 77 amino acids, is thermostable. Seventy-two residues and 79% of all theoretically expected proton resonances have been assigned. The structure has been determined through torsion angle dynamics calculations with the program DYANA, using 966 meaningful NOEs (from a total of 1305), hydrogen bond constraints, and NMR derived dihedral angle constraints for the cluster ligating cysteines, and by using crystallographic information to build up the two clusters. Afterwards, restrained energy minimization and restrained molecular dynamics were applied to each conformer of the family. The final family of 20 structures has RMSD values from the mean structure of 0.68 A for the backbone atoms and of 1.16 A for all heavy atoms. The contributions to the thermal stability of the B. schlegelii ferredoxin are discussed by comparing the present structure to that of the less stable Azotobacter vinelandii ferredoxin I which is the only other available structure of a bacterial seven-iron ferredoxin. It is proposed that the hydrophobic interactions and the hydrogen bond network linking the N-terminus and the C-terminus together and a high number of salt bridges contribute to the stability.
通过1H NMR已确定了来自施氏芽孢杆菌的顺磁性七铁铁氧化还原蛋白氧化形式的溶液结构。该蛋白质含有77个氨基酸，具有热稳定性。已对72个残基以及所有理论上预期的质子共振的79%进行了归属。该结构是通过使用程序DYANA进行扭转角动力学计算确定的，使用了966个有意义的NOE（总共1305个）、氢键约束以及对簇连接半胱氨酸的NMR衍生二面角约束，并利用晶体学信息构建两个簇。之后，对该家族的每个构象异构体应用了受限能量最小化和受限分子动力学。最终的20个结构家族对于主链原子而言，与平均结构的RMSD值为0.68 Å，对于所有重原子而言为1.16 Å。通过将当前结构与稳定性较差的棕色固氮菌铁氧化还原蛋白I（它是细菌七铁铁氧化还原蛋白的唯一其他可用结构）的结构进行比较，讨论了施氏芽孢杆菌铁氧化还原蛋白对热稳定性的贡献。有人提出，疏水相互作用以及将N端和C端连接在一起的氢键网络和大量盐桥有助于稳定性。
