Amyotrophic lateral sclerosis mutations have the greatest destabilizing effect on the Apo- and reduced form of SOD1, leading to unfolding and oxidative aggregation
Amyotrophic lateral sclerosis mutations have the greatest destabilizing effect on the Apo- and reduced form of SOD1, leading to unfolding and oxidative aggregation
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DOI：
10.1074/jbc.m500482200
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发表时间：
2005-04-29
影响因子：
4.8
通讯作者：
O'Halloran, TV
中科院分区：
文献类型：
--
作者：
Furukawa, Y;O'Halloran, TV
导致家族性肌萎缩侧索硬化症（ALS）的铜锌超氧化物歧化酶（SOD 1）突变形式表现出促进运动神经元死亡的毒性。毒性特性的建议通常涉及异常催化活性或蛋白质聚集。ALS突变体SOD 1成熟形式的惊人热力学稳定性（T-m > 70摄氏度）并不是涉及解折叠的蛋白质聚集模型的典型特征。根据金属占有率、二硫键状态和寡聚状态，多肽可能有超过44种状态;然而，尚不清楚哪种形式可能导致毒性。最近的分子内二硫键已被证明是必需的SOD 1活性，导致我们检查这些状态的几个致病的SOD 1突变体。我们发现ALS突变对最不成熟形式的SOD 1具有最大的影响，使无金属和二硫键还原的多肽不稳定，以至于它在生理温度（T-m < 37摄氏度）下展开。我们还发现，不成熟状态的ALS突变体（而不是野生型）蛋白很容易形成低聚物在生理浓度。此外，这些寡聚体对温和的氧化应激更敏感，这促进保守半胱氨酸之间的不正确的二硫键交联并驱动聚集。因此，它是SOD 1装配途径中最早的二硫键还原多肽，其在解折叠和氧化聚集方面最不稳定，这是由ALS引起的突变造成的。
Mutant forms of Cu, Zn-superoxide dismutase (SOD1) that cause familial amyotrophic lateral sclerosis (ALS) exhibit toxicity that promotes the death of motor neurons. Proposals for the toxic properties typically involve aberrant catalytic activities or protein aggregation. The striking thermodynamic stability of mature forms of the ALS mutant SOD1 (T-m > 70 degrees C) is not typical of protein aggregation models that involve unfolding. Over 44 states of the polypeptide are possible, depending upon metal occupancy, disulfide status, and oligomeric state; however, it is not clear which forms might be responsible for toxicity. Recently the intramolecular disulfide has been shown to be required for SOD1 activity, leading us to examine these states of several disease-causing SOD1 mutants. We find that ALS mutations have the greatest effect on the most immature form of SOD1, destabilizing the metal-free and disulfide-reduced polypeptide to the point that it is unfolded at physiological temperatures (T-m < 37 degrees C). We also find that immature states of ALS mutant ( but not wild type) proteins readily form oligomers at physiological concentrations. Furthermore, these oligomers are more susceptible to mild oxidative stress, which promotes incorrect disulfide cross-links between conserved cysteines and drives aggregation. Thus it is the earliest disulfide-reduced polypeptides in the SOD1 assembly pathway that are most destabilized with respect to unfolding and oxidative aggregation by ALS-causing mutations.