Pulsed Multifrequency Electron Paramagnetic Resonance Spectroscopy Reveals Key Branch Points for One- vs Two-Electron Reactivity in Mn/Fe Proteins.
Pulsed Multifrequency Electron Paramagnetic Resonance Spectroscopy Reveals Key Branch Points for One- vs Two-Electron Reactivity in Mn/Fe Proteins.
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脉冲多频电子顺磁共振光谱揭示了MN/Fe蛋白中的一单电子反应性的关键分支点。
DOI：
10.1021/jacs.1c13738
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发表时间：
2022-07-13
影响因子：
15
通讯作者：
Shafaat, Hannah S.
中科院分区：
文献类型：
--
作者：
Kisgeropoulos, Effie C.;Gan, Yunqiao J.;Greer, Samuel M.;Hazei, Joseph M.;Shafaat, Hannah S.
传统上，类似铁蛋白的超家族蛋白被认为只使用双铁活性位点来催化多种依赖氧的反应。近年来，在Ic类（R2c）核糖核苷酸还原酶（RNRs）的自由基生成R2亚基和相关的R2类配体结合氧化酶（R2lox）中发现了具有异金属Mn/Fe活性位点的新型氧化还原活性辅助因子。然而，区分R2c自由基活性与R2lox C-H活化反应的蛋白特异性因子仍然未知。在这项工作中，多频脉冲EPR光谱和配体超精细技术结合破对称密度泛函理论计算，用于表征在R2lox Mn/Fe辅因子的有氧组装过程中捕获的两个EPR活性中间体的分子和电子结构。MnIII(μ-O)(μ-OH)FeIII是第一个epr活性物种，代表了两类氧化还原活性Mn/Fe蛋白之间的共同状态。MnIII(μ-O)(μ-OH)FeIII态下游的物种表现出独特的EPR特性，包括前所未有的光谱宽度和同位素依赖的g张量，这归因于弱耦合的氢键MnIII(μ-OH)FeIII。这一最终中间体先于MnIII/FeIII静息状态的形成，被认为与了解R2lox的内源性反应性有关。
Traditionally, the ferritin-like superfamily of proteins was thought to exclusively use a diiron active site in catalyzing a diverse array of oxygen-dependent reactions. In recent years, novel redox-active cofactors featuring heterobimetallic Mn/Fe active sites have been discovered in both the radical-generating R2 subunit of class Ic (R2c) ribonucleotide reductases (RNRs) and the related R2-like ligand-binding oxidases (R2lox). However, the protein-specific factors that differentiate the radical reactivity of R2c from the C-H activation reactions of R2lox remain unknown. In this work, multifrequency pulsed EPR spectroscopy and ligand hyperfine techniques in conjunction with broken-symmetry density functional theory calculations are used to characterize the molecular and electronic structures of two EPR-active intermediates trapped during aerobic assembly of the R2lox Mn/Fe cofactor. A MnIII(μ-O)(μ-OH)FeIII species is identified as the first EPR-active species and represents a common state between the two classes of redox-active Mn/Fe proteins. The species downstream from the MnIII(μ-O)(μ-OH)FeIII state exhibits unique EPR properties, including unprecedented spectral breadth and isotope-dependent g-tensors, which are attributed to a weakly coupled, hydrogen-bonded MnIII(μ-OH)FeIII species. This final intermediate precedes formation of the MnIII/FeIII resting state and is suggested to be relevant to understanding the endogenous reactivity of R2lox.
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影响因子：
15
作者：
Dassama, Laura M. K.;Jiang, Wei;Varano, Paul T.;Pandelia, Maria-Eirini;Conner, Denise A.;Xie, Jiajia;Bollinger, J. Martin, Jr.;Krebs, Carsten
通讯作者：
Krebs, Carsten
影响因子：
15
作者：
Campbell, KA;Force, DA;Britt, RD
通讯作者：
Britt, RD
DOI：
10.1073/pnas.1817526116
发表时间：
2019-08-20
影响因子：
11.1
作者：
Chrysina, Maria;Heyno, Eiri;Cox, Nicholas
通讯作者：
Cox, Nicholas
DOI：
10.1073/pnas.0812971106
发表时间：
2009-04-07
影响因子：
11.1
作者：
Andersson, Charlotta S.;Hoegbom, Martin
通讯作者：
Hoegbom, Martin
影响因子：
3.3
作者：
Beal, Nathan J.;Corry, Thomas A.;O'Malley, Patrick J.
通讯作者：
O'Malley, Patrick J.