Structural and dynamic aspects related to oligomerization of apo SOD1 and its mutants
Structural and dynamic aspects related to oligomerization of apo SOD1 and its mutants
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DOI：
10.1073/pnas.0809845106
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发表时间：
2009-04-28
影响因子：
11.1
通讯作者：
Vieru, Miguela
中科院分区：
文献类型：
--
作者：
Banci, Lucia;Bertini, Ivano;Vieru, Miguela
WT人超氧化物歧化酶1（SOD 1）及其家族性肌萎缩侧索硬化症（fALS）相关突变体T54 R和I113 T的无金属形式的结构和动力学性质在溶液中通过NMR进行表征，在晶体中通过X射线衍射进行表征。我们发现，所有3个X射线结构在2个环区域中显示出显著的结构紊乱，这些环区域在完全金属化的结构中定义良好。有趣的是，载脂蛋白状态仅在低温下结晶，而金属化形式的所有3种蛋白质在任何温度下结晶，这表明结晶选择了载脂蛋白形式在溶液中所采用的多种构象中最稳定的构象之一。事实上，核磁共振实验表明，溶液中的蛋白质是高度无序的，采样了大范围的构象。载脂蛋白状态的大的构象可变性允许游离的还原半胱氨酸Cys-6在溶液中变得高度溶剂可及，而它基本上被掩埋在金属化状态和晶体结构中。这样的溶剂可及性，连同Cys-111的溶剂可及性，解释了无金属状态的低聚化倾向。目前的结果表明，调查的溶液状态加上晶体状态，可以提供主要的见解SOD 1途径向低聚化有关fALS。
The structural and dynamical properties of the metal-free form of WT human superoxide dismutase 1 (SOD1) and its familial amyotrophic lateral sclerosis (fALS)-related mutants, T54R and I113T, were characterized both in solution, through NMR, and in the crystal, through X-ray diffraction. We found that all 3 X-ray structures show significant structural disorder in 2 loop regions that are, at variance, well defined in the fully-metalated structures. Interestingly, the apo state crystallizes only at low temperatures, whereas all 3 proteins in the metalated form crystallize at any temperature, suggesting that crystallization selects one of the most stable conformations among the manifold adopted by the apo form in solution. Indeed, NMR experiments show that the protein in solution is highly disordered, sampling a large range of conformations. The large conformational variability of the apo state allows the free reduced cysteine Cys-6 to become highly solvent accessible in solution, whereas it is essentially buried in the metalated state and the crystal structures. Such solvent accessibility, together with that of Cys-111, accounts for the tendency to oligomerization of the metal-free state. The present results suggest that the investigation of the solution state coupled with that of the crystal state can provide major insights into SOD1 pathway toward oligomerization in relation to fALS.