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Electron transfer and conformational transitions of cytochrome c are modulated by the same dynamical features.
Archives of Biochemistry and Biophysics ( IF 3.8 ) Pub Date : 2019-12-30 , DOI: 10.1016/j.abb.2019.108243 Santiago Oviedo-Rouco 1 , Juan Manuel Perez-Bertoldi 1 , Celicia Spedalieri 1 , María A Castro 1 , Florencia Tomasina 2 , Verónica Tortora 2 , Rafael Radi 2 , Daniel H Murgida 1
Archives of Biochemistry and Biophysics ( IF 3.8 ) Pub Date : 2019-12-30 , DOI: 10.1016/j.abb.2019.108243 Santiago Oviedo-Rouco 1 , Juan Manuel Perez-Bertoldi 1 , Celicia Spedalieri 1 , María A Castro 1 , Florencia Tomasina 2 , Verónica Tortora 2 , Rafael Radi 2 , Daniel H Murgida 1
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Cytochrome c is a prototypical multifunctional protein that is implicated in a variety of processes that are essential both for sustaining and for terminating cellular life. Typically, alternative functions other than canonical electron transport in the respiratory chain are associated to alternative conformations. In this work we apply a combined experimental and computational study of Cyt c variants to assess whether the parameters that regulate the canonical electron transport function of Cyt c are correlated with those that determine the transition to alternative conformations, using the alkaline transition as a model conformational change. The results show that pKa values of the alkaline transition correlate with the activation energies of the frictionally-controlled electron transfer reaction, and that both parameters are mainly modulated by the flexibility of the Ω-loop 70-85. Reduction potentials and non-adiabatic ET reorganization energies, on the other hand, are both modulated by the flexibilities of the Ω-loops 40-57 and 70-85. Finally, all the measured thermodynamic and kinetic parameters that characterize both types of processes exhibit systematic variations with the dynamics of the hydrogen bond between the axial ligand Met80 and the second sphere ligand Tyr67, thus highlighting the critical role of Tyr67 in controlling canonical and alternative functions of Cyt c.
中文翻译：
细胞色素c的电子转移和构象转变受相同的动力学特征调节。
细胞色素c是一种典型的多功能蛋白，涉及多种过程，这些过程对于维持和终止细胞生命都是必不可少的。通常，呼吸链中除了规范电子传输以外的替代功能与替代构象相关。在这项工作中，我们使用Cyt c变体的组合实验和计算研究来评估调节Cyt c规范电子传输功能的参数是否与确定过渡到替代构象的参数相关联，并使用碱性转变作为模型构象改变。结果表明，碱性跃迁的pKa值与摩擦控制的电子转移反应的活化能相关，并且这两个参数主要是由Ω回路70-85的灵活性来调制的。另一方面，还原电势和非绝热ET重组能量均由Ω回路40-57和70-85的柔韧性调节。最后，表征两种过程的所有热力学和动力学参数均表现出随着轴向配体Met80和第二个球形配体Tyr67之间氢键动力学的变化而系统地变化，从而突显了Tyr67在控制规范和替代功能中的关键作用Cyt的。
更新日期：2019-12-30
中文翻译：
细胞色素c的电子转移和构象转变受相同的动力学特征调节。
细胞色素c是一种典型的多功能蛋白，涉及多种过程，这些过程对于维持和终止细胞生命都是必不可少的。通常，呼吸链中除了规范电子传输以外的替代功能与替代构象相关。在这项工作中，我们使用Cyt c变体的组合实验和计算研究来评估调节Cyt c规范电子传输功能的参数是否与确定过渡到替代构象的参数相关联，并使用碱性转变作为模型构象改变。结果表明，碱性跃迁的pKa值与摩擦控制的电子转移反应的活化能相关，并且这两个参数主要是由Ω回路70-85的灵活性来调制的。另一方面，还原电势和非绝热ET重组能量均由Ω回路40-57和70-85的柔韧性调节。最后，表征两种过程的所有热力学和动力学参数均表现出随着轴向配体Met80和第二个球形配体Tyr67之间氢键动力学的变化而系统地变化，从而突显了Tyr67在控制规范和替代功能中的关键作用Cyt的。
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