Oxidation of Dueling Cysteine Promotes Subunit Exchange in SOD1
Oxidation of Dueling Cysteine Promotes Subunit Exchange in SOD1
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DOI：
10.1021/acschemneuro.3c00174
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发表时间：
2023-04-06
影响因子：
5
通讯作者：
Shaw，Bryan F.
中科院分区：
文献类型：
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作者：
Zhang，Ao Yun;Dashnaw，Chad M.;Shaw，Bryan F.
野生型 (WT) 铜、锌超氧化物歧化酶-1 (SOD1) 和突变型 SOD1 的异二聚化可能是 SOD1 相关肌萎缩侧索硬化症 (ALS) 发病机制中的关键步骤。加速 SOD1 异二聚化的翻译后修饰仍未确定。在这里，我们使用毛细管电泳来量化半胱氨酸 111 氧化对 ALS 突变体/WT SOD1 异二聚化的速率和自由能的影响。 Cys111-β-SH 氧化为亚磺酸和磺酸（通过过氧化氢）使异二聚化（与未氧化的蛋白质）的速率增加了约 3 倍。半胱氨酸氧化将 SOD1 异二聚化的平衡自由能驱动高达 ΔΔG= -5.11 ± 0.36 kJ mol–1。分子动力学模拟表明，氧化同型二聚体和未氧化同型二聚体之间的这种增强的异二聚化是由两个“决斗”Cys111-SO2–/SO3–之间的静电排斥促进的，这两个Cys111-SO2–/SO3–在同型二聚体状态下彼此指向对方。总之，这些结果表明 Cys-111 的氧化促进氧化同型二聚体和未氧化同型二聚体之间的亚基交换，无论它们是突变体还是 WT 二聚体。
The heterodimerization of wild-type (WT) Cu, Zn superoxide dismutase-1 (SOD1) and mutant SOD1 might be a critical step in the pathogenesis of SOD1-linked amyotrophic lateral sclerosis (ALS). Post-translational modifications that accelerate SOD1 heterodimerization remain unidentified. Here, we used capillary electrophoresis to quantify the effect of cysteine-111 oxidation on the rate and free energy of ALS mutant/WT SOD1 heterodimerization. The oxidation of Cys111-β-SH to sulfinic and sulfonic acid (by hydrogen peroxide) increased rates of heterodimerization (with unoxidized protein) by ∼3-fold. Cysteine oxidation drove the equilibrium free energy of SOD1 heterodimerization by up to ΔΔG= −5.11 ± 0.36 kJ mol–1. Molecular dynamics simulations suggested that this enhanced heterodimerization, between oxidized homodimers and unoxidized homodimers, was promoted by electrostatic repulsion between the two “dueling” Cys111-SO2–/SO3–, which point toward one another in the homodimeric state. Together, these results suggest that oxidation of Cys-111 promotes subunit exchange between oxidized homodimers and unoxidized homodimers, regardless of whether they are mutant or WT dimers.