Hough Michael A, Grossmann J Günter, Antonyuk Svetlana V, Strange Richard W, Doucette Peter A, Rodriguez Jorge A, Whitson Lisa J, Hart P John, Hayward Lawrence J, Valentine Joan Selverstone, Hasnain S Samar
Molecular Biophysics Group, Council for the Central Laboratory of the Research Councils, Daresbury Laboratory, Warrington, Cheshire WA4 4AD, United Kingdom.
Proc Natl Acad Sci U S A. 2004 Apr 20;101(16):5976-81. doi: 10.1073/pnas.0305143101. Epub 2004 Mar 31.
More than 90 point mutations in human CuZn superoxide dismutase lead to the development of familial amyotrophic lateral sclerosis, known also as motor neuron disease. A growing body of evidence suggests that a subset of mutations located close to the dimeric interface can lead to a major destabilization of the mutant enzymes. We have determined the crystal structures of the Ala4Val (A4V) and Ile113Thr (I113T) mutants to 1.9 and 1.6 A, respectively. In the A4V structure, small changes at the dimer interface result in a substantial reorientation of the two monomers. This effect is also seen in the case of the I113T crystal structure, but to a smaller extent. X-ray solution scattering data show that in the solution state, both of the mutants undergo a more pronounced conformational change compared with wild-type superoxide dismutase (SOD) than that observed in the A4V crystal structure. Shape reconstructions from the x-ray scattering data illustrate the nature of this destabilization. Comparison of these scattering data with those for bovine CuZn SOD measured at different temperatures shows that an analogous change in the scattering profile occurs for the bovine enzyme in the temperature range of 70-80 degrees C. These results demonstrate that the A4V and I113T mutants are substantially destabilized in comparison with wild-type SOD1, and it is possible that the pathogenic properties of this subset of familial amyotrophic lateral sclerosis mutants are at least in part due to this destabilization.
人类铜锌超氧化物歧化酶中90多个点突变会导致家族性肌萎缩侧索硬化症（也称为运动神经元病）的发生。越来越多的证据表明，位于二聚体界面附近的一部分突变会导致突变酶的严重失稳。我们分别测定了Ala4Val（A4V）和Ile113Thr（I113T）突变体的晶体结构，分辨率分别为1.9 Å和1.6 Å。在A4V结构中，二聚体界面处的微小变化导致两个单体发生了显著的重新定向。在I113T晶体结构中也观察到了这种效应，但程度较小。X射线溶液散射数据表明，在溶液状态下，与野生型超氧化物歧化酶（SOD）相比，这两种突变体都经历了比在A4V晶体结构中观察到的更为明显的构象变化。根据X射线散射数据进行的形状重建说明了这种失稳的本质。将这些散射数据与在不同温度下测量的牛铜锌SOD的散射数据进行比较表明，在70 - 80摄氏度的温度范围内，牛酶的散射图谱发生了类似的变化。这些结果表明，与野生型SOD1相比，A4V和I113T突变体严重失稳，并且这种家族性肌萎缩侧索硬化症突变体子集的致病特性可能至少部分归因于这种失稳。
