Remote Perturbations in Tertiary Contacts Trigger Ligation of Lysine to the Heme Iron in Cytochrome c.
Remote Perturbations in Tertiary Contacts Trigger Ligation of Lysine to the Heme Iron in Cytochrome c.
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DOI：
10.1021/acs.biochem.6b01187
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发表时间：
2017-06-13
期刊：
影响因子：
2.9
通讯作者：
Pletneva EV
中科院分区：
文献类型：
--
作者：
Gu J;Shin DW;Pletneva EV
蛋白质结构的扰动定义了变构调节和生物信息传递的机制。在细胞色素 c (cyt c) 中，Met80 与血红素铁的连接对于该蛋白在氧化磷酸化中的电子转移 (ET) 功能以及在细胞凋亡中抑制其过氧化物酶活性至关重要。硬碱 Lys 比软碱 Met 更适合硬三价铁，这表明蛋白质支架在有利于 Met 连接中发挥着关键作用。为了探究蛋白质结构在维持 Met 连接中的作用，设计突变 T49V 和 Y67R/M80A 分别破坏氢键和血红素配位环的堆积。电子吸收、NMR 和 EPR 光谱表明，两种变体的三价铁形式在中性 pH 下均以 Lys 连接。 T49V 中远离血红素协调环的三级接触的微小变化似乎足以执行连接的变化，表明蛋白质结构的不同区域之间存在串扰以及细胞色素 c 中内置构象开关的可能性。对热力学稳定性、Lys 结合和解离动力学以及连接中 pH 依赖性变化的分析提供了这些变体中 Lys 配位的详细表征，并将这些特性与结构扰动的程度联系起来。这些发现强调了氢键网络在控制天然 Met80 与血红素铁连接方面的重要性。
Perturbations in protein structure define the mechanism of allosteric regulation and biological information transfer. In cytochrome c (cyt c), Met80 ligation to the heme iron is critical for the protein’s electron-transfer (ET) function in oxidative phosphorylation and for suppressing its peroxidase activity in apoptosis. The hard base Lys is a better match for the hard ferric iron than the soft base Met, suggesting the key role of the protein scaffold in favoring Met ligation. To probe the role of the protein structure in maintenance of Met ligation, mutations T49V and Y67R/M80A were designed to disrupt hydrogen bonding and packing of the heme coordination loop, respectively. Electronic absorption, NMR, and EPR spectra reveal that ferric forms of both variants are Lys-ligated at neutral pH. A minor change in the tertiary contacts in T49V, away from the heme coordination loop, appears to be sufficient to execute a change in ligation, suggesting a cross-talk between the different regions of the protein structure and a possibility of built-in conformational switches in cyt c. Analyses of thermodynamic stability, kinetics of Lys binding and dissociation and the pH-dependent changes in ligation provide detailed characterization of the Lys coordination in these variants and relate these properties to the extent of structural perturbations. The findings emphasize the importance of the hydrogen-bonding network in controlling the native Met80 ligation to the heme iron.
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影响因子：
15
作者：
Assfalg, M;Bertini, I;Gray, HB
通讯作者：
Gray, HB
影响因子：
2.9
作者：
ELOVE, GA;BHUYAN, AK;RODER, H
通讯作者：
RODER, H
影响因子：
15
作者：
BARKER, PD;MAUK, AG
通讯作者：
MAUK, AG
DOI：
10.1046/j.1432-1327.1999.00249.x
发表时间：
1999-04-01
期刊：
EUROPEAN JOURNAL OF BIOCHEMISTRY
影响因子：
--
作者：
Döpner, S;Hildebrandt, P;Soulimane, T
通讯作者：
Soulimane, T
影响因子：
2.9
作者：
BERRY, EA;TRUMPOWER, BL
通讯作者：
TRUMPOWER, BL