Reactive oxygen species are generated by the respiratory complex II - evidence for lack of contribution of the reverse electron flow in complex I
Reactive oxygen species are generated by the respiratory complex II - evidence for lack of contribution of the reverse electron flow in complex I
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DOI：
10.1111/febs.12086
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发表时间：
2013-02-01
期刊：
影响因子：
5.4
通讯作者：
Rodriguez-Enriquez, Sara
中科院分区：
文献类型：
--
作者：
Moreno-Sanchez, Rafael;Hernandez-Esquivel, Luz;Rodriguez-Enriquez, Sara
通过复合物II（CII）的琥珀酸盐驱动的氧化可能对线粒体产生活性氧（ROS）的高速率具有显著贡献。在这里，我们表明，CII Q位点抑制剂thenoyltrifluoroacetone（TTFA）块琥珀酸+鱼藤酮驱动的ROS生产，而复合物III（CIII）Qo抑制剂stigmatellin没有影响，表明CII，而不是CIII，是ROS生产网站。复合物I（Cl）抑制剂鱼藤酮部分地减少由高琥珀酸水平（5 mM）驱动的ROS产生，这通常被解释为是由于抑制了从CII到Cl的反向电子流。然而，这里提出的实验证据与反向电子流的模型相矛盾。首先，使用琥珀酸+鱼藤酮产生的ROS水平显著高于使用谷氨酸+苹果酸+鱼藤酮产生的ROS水平。第二，在肿瘤线粒体中，琥珀酸驱动的ROS产生显着增加（而不是减少）鱼藤酮。第三，在肝线粒体中，鱼藤酮对琥珀酸驱动的ROS产生没有影响。第四，使用分离的心脏或肝癌（AS-30 D）线粒体，CII Qp抗癌药物血管靶向维生素E琥珀酸酯（MitoVES）在低水平琥珀酸酯（0.5 mm）存在下诱导ROS产生升高，但鱼藤酮没有影响。使用亚线粒体颗粒，铜基抗癌药物Casiopeina II-gly增强了琥珀酸驱动的ROS产生。因此，目前的结果是不一致的，并质疑从CII到CI的反向电子流的解释和鱼藤酮对活性氧产生的影响，支持琥珀酸氧化。相反，一个在化学上更有利的解释是，在没有CIII或复合物IV（CIV）抑制剂的情况下（当加入时，通过诱导泛醇（CI产物）的积累来促进反向电子流），CII氧化还原中心是琥珀酸盐驱动的ROS产生的主要来源。
Succinate-driven oxidation via complex II (CII) may have a significant contribution towards the high rates of production of reactive oxygen species (ROS) by mitochondria. Here, we show that the CII Q site inhibitor thenoyltrifluoroacetone (TTFA) blocks succinate + rotenone-driven ROS production, whereas the complex III (CIII) Qo inhibitor stigmatellin has no effect, indicating that CII, not CIII, is the ROS-producing site. The complex I (CI) inhibitor rotenone partially reduces the ROS production driven by high succinate levels (5 mm), which is commonly interpreted as being due to inhibition of a reverse electron flow from CII to CI. However, experimental evidence presented here contradicts the model of reverse electron flow. First, ROS levels produced using succinate + rotenone were significantly higher than those produced using glutamate + malate + rotenone. Second, in tumor mitochondria, succinate-driven ROS production was significantly increased (not decreased) by rotenone. Third, in liver mitochondria, rotenone had no effects on succinate-driven ROS production. Fourth, using isolated heart or hepatoma (AS-30D) mitochondria, the CII Qp anti-cancer drug mitochondrially targeted vitamin E succinate (MitoVES) induced elevated ROS production in the presence of low levels of succinate(0.5 mm), but rotenone had no effect. Using sub-mitochondrial particles, the Cu-based anti-cancer drug Casiopeina II-gly enhanced succinate-driven ROS production. Thus, the present results are inconsistent with and question the interpretation of reverse electron flow from CII to CI and the rotenone effect on ROS production supported by succinate oxidation. Instead, a thermodynamically more favorable explanation is that, in the absence of CIII or complex IV (CIV) inhibitors (which, when added, facilitate reverse electron flow by inducing accumulation of ubiquinol, the CI product), the CII redox centers are the major source of succinate-driven ROS production.