Effects of ligand binding on the stability of aldo-keto reductases: Implications for stabilizer or destabilizer chaperones.
Effects of ligand binding on the stability of aldo-keto reductases: Implications for stabilizer or destabilizer chaperones.
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DOI：
10.1002/pro.3036
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发表时间：
2016-12
期刊：
影响因子：
8
通讯作者：
Kuwata, Kazuo
中科院分区：
文献类型：
--
作者：
Kabir, Aurangazeb;Honda, Ryo P.;Kamatari, Yuji O.;Endo, Satoshi;Fukuoka, Mayuko;Kuwata, Kazuo
关键词：
配体如酶抑制剂在与天然状态结合时稳定蛋白质的天然构象，但一些化合物在与非天然状态结合时使天然构象不稳定。前一种配体被称为“稳定剂分子伴侣”，后一种配体被称为“去稳定剂分子伴侣”。由于稳定作用对于医学伴侣（MC）假说是必不可少的，在这里，我们已经制定了一个热力学系统，由配体和蛋白质在其天然和非天然状态。使用差示扫描荧光法和改变尿素浓度和温度的圆二色性，我们发现当辅酶NADP+不存在时，抑制剂如异石胆酸在结合时稳定醛酮还原酶AKR1A1，这实际上显示了三态折叠，但使AKR1B10不稳定。相反，在NADP+存在下，它们使AKR1A1不稳定并使AKR1B10稳定。为了解释这些现象，我们将稳定化自由能（ΔΔG）分解为焓（ΔΔH）和熵（ΔΔS）分量。然后我们发现，在一个相对不稳定的三态折叠蛋白质中，天然构象被负ΔΔH和负ΔΔS稳定，这表明稳定剂伴侣减少了靶蛋白的构象波动或增加了其水合作用。然而，在其他情况下，ΔΔG基本上由ΔΔH和ΔΔS之间的微妙平衡决定。所提出的热力学形式适用于具有变构相互作用的多配体体系。这些发现将促进MCs筛选策略的发展，以调节目标构象。
Ligands such as enzyme inhibitors stabilize the native conformation of a protein upon binding to the native state, but some compounds destabilize the native conformation upon binding to the non‐native state. The former ligands are termed “stabilizer chaperones” and the latter ones “destabilizer chaperones.” Because the stabilization effects are essential for the medical chaperone (MC) hypothesis, here we have formulated a thermodynamic system consisting of a ligand and a protein in its native‐ and non‐native state. Using the differential scanning fluorimetry and the circular dichroism varying the urea concentration and temperature, we found that when the coenzyme NADP+ was absent, inhibitors such as isolithocholic acid stabilized the aldo–keto reductase AKR1A1 upon binding, which showed actually the three‐state folding, but destabilized AKR1B10. In contrast, in the presence of NADP+, they destabilized AKR1A1 and stabilized AKR1B10. To explain these phenomena, we decomposed the free energy of stabilization (ΔΔG) into its enthalpy (ΔΔH) and entropy (ΔΔS) components. Then we found that in a relatively unstable protein showing the three‐state folding, native conformation was stabilized by the negative ΔΔH in association with the negative ΔΔS, suggesting that the stabilizer chaperon decreases the conformational fluctuation of the target protein or increase its hydration. However, in other cases, ΔΔG was essentially determined by the delicate balance between ΔΔH and ΔΔS. The proposed thermodynamic formalism is applicable to the system including multiple ligands with allosteric interactions. These findings would promote the development of screening strategies for MCs to regulate the target conformations.
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影响因子：
3.7
作者：
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