NRVS studies of the peroxide shunt intermediate in a Rieske dioxygenase and its relation to the native FeII O2 reaction,Journal of the American Chemical Society

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NRVS studies of the peroxide shunt intermediate in a Rieske dioxygenase and its relation to the native FeII O2 reaction
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2018-04-04 , DOI: 10.1021/jacs.8b01822
Kyle D Sutherlin ₁ , Brent S Rivard ₂ , Lars H Böttger ₁ , Lei V Liu ₁ , Melanie S Rogers ₂ , Martin Srnec _{1,

3} , Kiyoung Park _{1,

4} , Yoshitaka Yoda ₅ , Shinji Kitao ₆ , Yasuhiro Kobayashi ₆ , Makina Saito ₆ , Makoto Seto ₆ , Michael Hu ₇ , Jiyong Zhao ₇ , John D Lipscomb ₂ , Edward I Solomon _{1,

8}

Affiliation

The Rieske dioxygenases are a major subclass of mononuclear nonheme iron enzymes that play an important role in bioremediation. Recently, a high-spin FeIII-(hydro)peroxy intermediate (BZDOp) has been trapped in the peroxide shunt reaction of benzoate 1,2-dioxygenase. Defining the structure of this intermediate is essential to understanding the reactivity of these enzymes. Nuclear resonance vibrational spectroscopy (NRVS) is a recently developed synchrotron technique that is ideal for obtaining vibrational, and thus structural, information on Fe sites, as it gives complete information on all vibrational normal modes containing Fe displacement. In this study, we present NRVS data on BZDOp and assign its structure using these data coupled to experimentally calibrated density functional theory calculations. From this NRVS structure, we define the mechanism for the peroxide shunt reaction. The relevance of the peroxide shunt to the native FeII/O2 reaction is evaluated. For the native FeII/O2 reaction, an FeIII-superoxo intermediate is found to react directly with substrate. This process, while uphill thermodynamically, is found to be driven by the highly favorable thermodynamics of proton-coupled electron transfer with an electron provided by the Rieske [2Fe-2S] center at a later step in the reaction. These results offer important insight into the relative reactivities of FeIII-superoxo and FeIII-hydroperoxo species in nonheme Fe biochemistry.

中文翻译：

Rieske 双加氧酶中过氧化物分流中间体的 NRVS 研究及其与天然 FeII O2 反应的关系

Rieske 双加氧酶是单核非血红素铁酶的主要亚类，在生物修复中发挥重要作用。最近，高自旋 FeIII-(氢)过氧中间体 (BZDOp) 被捕获在苯甲酸 1,2-双加氧酶的过氧化物分流反应中。定义这种中间体的结构对于理解这些酶的反应性至关重要。核共振振动光谱 (NRVS) 是一种最近开发的同步加速器技术，非常适合获取 Fe 位点的振动信息和结构信息，因为它提供了包含 Fe 位移的所有振动简正模式的完整信息。在这项研究中，我们展示了 BZDOp 的 NRVS 数据，并使用这些数据与实验校准的密度泛函理论计算相结合来分配其结构。从这个 NRVS 结构中，我们定义了过氧化物分流反应的机制。评估了过氧化物分流与天然 FeII/O2 反应的相关性。对于天然 FeII/O2 反应，发现 FeIII-超氧中间体直接与底物反应。这个过程虽然在热力学上是艰难的，但被发现是由质子耦合电子转移的非常有利的热力学驱动的，其中电子由 Rieske [2Fe-2S] 中心在反应的后续步骤中提供。这些结果为非血红素铁生物化学中 FeIII-超氧和 FeIII-氢过氧物种的相对反应性提供了重要的见解。

更新日期：2018-04-04

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