Redox sensor properties of human cytoglobin allosterically regulate heme pocket reactivity.
Redox sensor properties of human cytoglobin allosterically regulate heme pocket reactivity.
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DOI：
10.1016/j.freeradbiomed.2020.10.321
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发表时间：
2021-01
影响因子：
7.4
通讯作者：
Gladwin MT
中科院分区：
文献类型：
--
作者：
DeMartino AW;Amdahl MB;Bocian K;Rose JJ;Tejero J;Gladwin MT
细胞球蛋白是一种在哺乳动物组织中广泛表达的保守的血红蛋白，它在一氧化氮(NO)和脂类代谢中进行电子传递反应，具有已知的信号功能。细胞球蛋白有一个E7远端组氨酸(His81)，与肌红蛋白和血红蛋白等相关球蛋白不同，它在结合的六坐标状态和非结合的五坐标状态之间处于平衡状态。His81的结合平衡似乎受到两个半胱氨酸(Cys38和Cys83)之间分子内二硫键的变构调节。这种二硫键的形成调节亚硝酸还原酶的活性和脂质结合。在这里，我们试图阐明定义的硫醇氧化态对细胞球蛋白血红素小分子结合的影响，使用氰化物结合来探测铁的状态。氰化物与野生型细胞球蛋白的结合动力学揭示了至少两个动力学上不同的亚群，这取决于硫醇的氧化状态。用NEM、谷胱甘肽和氨基酸取代(C38S、C83S和H81A)修饰共价硫醇的实验表明，从完全还原的硫醇、单一的硫醇氧化和分子内二硫键形成等不同的亚群决定了血红素的结合性质，这是通过调节组氨酸-血红素亲和力和配体结合来实现的。配体结合的氧化还原调节对过氧化氢的生理水平很敏感，天然细胞珠蛋白分子内二硫键的功能中点氧化还原电位为−189±4 mV，在细胞内氧化还原电位的边界内。这些结果支持细胞球蛋白上的Cys38和Cys83作为敏感的氧化还原感受器调节细胞球蛋白远端血红素口袋反应性和配体结合的假设。
Cytoglobin is a conserved hemoprotein ubiquitously expressed in mammalian tissues, which conducts electron transfer reactions with proposed signaling functions in nitric oxide (NO) and lipid metabolism. Cytoglobin has an E7 distal histidine (His81), which unlike related globins such as myoglobin and hemoglobin, is in equilibrium between a bound, hexacoordinate state and an unbound, pentacoordinate state. The His81 binding equilibrium appears to be allosterically modulated by the presence of an intramolecular disulfide between two cysteines (Cys38 and Cys83). The formation of this disulfide bridge regulates nitrite reductase activity and lipid binding. Herein, we attempt to clarify the effects of defined thiol oxidation states on small molecule binding of cytoglobin heme, using cyanide binding to probe the ferric state. Cyanide binding kinetics to wild-type cytoglobin reveal at least two kinetically distinct subpopulations, depending on thiol oxidation states. Experiments with covalent thiol modification by NEM, glutathione, and amino acid substitutions (C38S, C83S and H81A), indicate that subpopulations ranging from fully reduced thiols, single thiol oxidation, and intramolecular disulfide formation determine heme binding properties by modulating the histidine-heme affinity and ligand binding. The redox modulation of ligand binding is sensitive to physiological levels of hydrogen peroxide, with a functional midpoint redox potential for the native cytoglobin intramolecular disulfide bond of −189 ± 4 mV, a value within the boundaries of intracellular redox potentials. These results support the hypothesis that Cys38 and Cys83 on cytoglobin serve as sensitive redox sensors that modulate the cytoglobin distal heme pocket reactivity and ligand binding.
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影响因子：
2.9
作者：
Dou, Y;Olson, JS;IkedaSaito, M
通讯作者：
IkedaSaito, M
影响因子：
3.5
作者：
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影响因子：
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作者：
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Tejero, Jesus
DOI：
10.1073/pnas.172398899
发表时间：
2002-09-03
影响因子：
11.1
作者：
Dinkova-Kostova, AT;Holtzclaw, WD;Talalay, P
通讯作者：
Talalay, P
影响因子：
4.8
作者：
Fago, A;Hundahl, C;Weber, RE
通讯作者：
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