Reactive oxygen species production by forward and reverse electron fluxes in the mitochondrial respiratory chain.
Reactive oxygen species production by forward and reverse electron fluxes in the mitochondrial respiratory chain.
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DOI：
10.1371/journal.pcbi.1001115
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发表时间：
2011-03
影响因子：
4.3
通讯作者：
Cascante M
中科院分区：
文献类型：
--
作者：
Selivanov VA;Votyakova TV;Pivtoraiko VN;Zeak J;Sukhomlin T;Trucco M;Roca J;Cascante M
线粒体呼吸链（RC）中产生的活性氧（ROS）是调节细胞适应环境的主要信号，也是与各种全身性疾病或移植相关的缺氧/复氧条件下损害细胞的破坏性因素。 ROS 在细胞存活中的重要作用需要详细研究 ROS 产生的机制和决定因素。为了进行这样的研究，我们扩展了基于规则的复合物 III 模型，以便考虑整个 RC 中的电子传输与质子易位、跨膜电化学势生成、TCA 循环反应和底物传输到线粒体的耦合。它符合在琥珀酸或丙酮酸和苹果酸为燃料的大鼠脑线粒体中测量的呼吸电子通量，以及通过从琥珀酸到复合物 I 的反向电子传输来还原 NAD+ 的动力学。测量特征的拟合可以深入了解控制自由基形成的潜在过程的机制，自由基可以将不成对的电子转移到产氧超氧化物，从而启动 ROS 的生成。我们的分析揭示了 ROS 产生与单个电子转运蛋白的特定自由基水平及其在复合物 I 和 III 中的组合之间的关联。结果发现，先前作为复合体 III 的特性揭示的双稳态现象对于整个 RC 仍然有效。基于理论分析预测了配合物III中转变为高含量自由基状态的条件，并通过实验证实。这些发现为 RC 中 ROS 产生机制提供了新的见解。线粒体水平的呼吸被认为是通过一组构成呼吸链（RC）的转运蛋白将电子和质子从 NADH 或琥珀酸传递到氧气。线粒体呼吸涉及不成对电子的转移，可能会产生活性氧 (ROS)，例如 O2 - 以及随后产生的副产物 H2O2。 ROS 的化学性质非常活跃，会对细胞成分造成氧化损伤。 ROS 的产生通常较低，但在压力下会增加到与细胞生存不相容的水平；因此，了解 RC 中 ROS 产生的方式是研究中的一项重要任务。我们使用数学模型来分析分离脑线粒体的实验，旨在研究电子传输和 ROS 产生之间的关系。在其他地方，我们报道了线粒体复合物 III 可以在相同的微环境条件下以两种不同的稳态运行，产生低水平或高水平的 ROS。在这里，整个 RC 的双稳态特性得到了证实。建立了复合物 I 和 III 中测量的 ROS 产生与计算的个体自由基水平之间的关联。所发现的双稳态现象对于器官移植和治疗新策略的基础具有重要意义。
Reactive oxygen species (ROS) produced in the mitochondrial respiratory chain (RC) are primary signals that modulate cellular adaptation to environment, and are also destructive factors that damage cells under the conditions of hypoxia/reoxygenation relevant for various systemic diseases or transplantation. The important role of ROS in cell survival requires detailed investigation of mechanism and determinants of ROS production. To perform such an investigation we extended our rule-based model of complex III in order to account for electron transport in the whole RC coupled to proton translocation, transmembrane electrochemical potential generation, TCA cycle reactions, and substrate transport to mitochondria. It fits respiratory electron fluxes measured in rat brain mitochondria fueled by succinate or pyruvate and malate, and the dynamics of NAD+ reduction by reverse electron transport from succinate through complex I. The fitting of measured characteristics gave an insight into the mechanism of underlying processes governing the formation of free radicals that can transfer an unpaired electron to oxygen-producing superoxide and thus can initiate the generation of ROS. Our analysis revealed an association of ROS production with levels of specific radicals of individual electron transporters and their combinations in species of complexes I and III. It was found that the phenomenon of bistability, revealed previously as a property of complex III, remains valid for the whole RC. The conditions for switching to a state with a high content of free radicals in complex III were predicted based on theoretical analysis and were confirmed experimentally. These findings provide a new insight into the mechanisms of ROS production in RC. Respiration at the level of mitochondria is considered as delivery of electrons and protons from NADH or succinate to oxygen through a set of transporters constituting the respiratory chain (RC). Mitochondrial respiration, dealing with transfer of unpaired electrons, may produce reactive oxygen species (ROS) such as O2 − and subsequently H2O2 as side products. ROS are chemically very active and can cause oxidative damage to cellular components. The production of ROS, normally low, can increase under stress to the levels incompatible with cell survival; thus, understanding the ways of ROS production in the RC represents a vital task in research. We used mathematical modeling to analyze experiments with isolated brain mitochondria aimed to study relations between electron transport and ROS production. Elsewhere we reported that mitochondrial complex III can operate in two distinct steady states at the same microenvironmental conditions, producing either low or high levels of ROS. Here, this property of bistability was confirmed for the whole RC. The associations between measured ROS production and computed individual free radical levels in complexes I and III were established. The discovered phenomenon of bistability is important as a basis for new strategies in organ transplantation and therapy.
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影响因子：
3.5
作者：
Ohnishi, T;Salerno, JC
通讯作者：
Salerno, JC
影响因子：
3.9
作者：
CADENAS, E;BOVERIS, A;STOPPANI, AOM
通讯作者：
STOPPANI, AOM
DOI：
10.1126/stke.3442006re6
发表时间：
2006-07-18
期刊：
Science's STKE : signal transduction knowledge environment
影响因子：
--
作者：
Hlavacek, William S;Faeder, James R;Fontana, Walter
通讯作者：
Fontana, Walter
影响因子：
4.8
作者：
Kim, Ha Won;Haider, Husnain K.;Ashraf, Muhammad
通讯作者：
Ashraf, Muhammad
影响因子：
4.3
作者：
Dutton, PL;Moser, CC;Ohnishi, T
通讯作者：
Ohnishi, T