Reactive oxygen species production induced by pore opening in cardiac mitochondria: The role of complex II

• Published in: The Journal of biological chemistry 2017-06, Vol.292 (24), p.9896-9905
• Main Authors: Korge, Paavo, John, Scott A., Calmettes, Guillaume, Weiss, James N.
• Format: Article
• Language: English
• Subjects: Alamethicin - pharmacology; Animals; Binding Sites; Binding, Competitive; Biocatalysis - drug effects; Bioenergetics; Calcium Signaling - drug effects; complex II; electron transfer complex; Electron Transport - drug effects; Electron Transport Complex II - antagonists & inhibitors; Electron Transport Complex II - chemistry; Electron Transport Complex II - metabolism; electron transport system; Enzyme Inhibitors - pharmacology; Fumarates - metabolism; Ionophores - pharmacology; Membrane Potential, Mitochondrial - drug effects; mitochondria; Mitochondria, Heart - chemistry; Mitochondria, Heart - drug effects; Mitochondria, Heart - metabolism; mitochondrial membrane potential; mitochondrial respiratory chain complex; Models, Molecular; nicotinamide adenine dinucleotide (NADH); Oxidation-Reduction; Permeability - drug effects; Polyenes - pharmacology; Porosity; Pyridones - pharmacology; Rabbits; reactive oxygen species (ROS); Reactive Oxygen Species - agonists; Reactive Oxygen Species - metabolism; Succinic Acid - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M116.768325

Succinate-driven reverse electron transport (RET) through complex I is hypothesized to be a major source of reactive oxygen species (ROS) that induces permeability transition pore (PTP) opening and damages the heart during ischemia/reperfusion. Because RET can only generate ROS when mitochondria are fully polarized, this mechanism is self-limiting once PTP opens during reperfusion. In the accompanying article (Korge, P., Calmettes, G., John, S. A., and Weiss, J. N. (2017) J. Biol. Chem. 292, 9882–9895), we showed that ROS production after PTP opening can be sustained when complex III is damaged (simulated by antimycin). Here we show that complex II can also contribute to sustained ROS production in isolated rabbit cardiac mitochondria following inner membrane pore formation induced by either alamethicin or calcium-induced PTP opening. Two conditions are required to maximize malonate-sensitive ROS production by complex II in isolated mitochondria: (a) complex II inhibition by atpenin A5 or complex III inhibition by stigmatellin that results in succinate-dependent reduction of the dicarboxylate-binding site of complex II (site IIf); (b) pore opening in the inner membrane resulting in rapid efflux of succinate/fumarate and other dicarboxylates capable of competitively binding to site IIf. The decrease in matrix [dicarboxylate] allows O2 access to reduced site IIf, thereby making electron donation to O2 possible, explaining the rapid increase in ROS production provided that site IIf is reduced. Because ischemia is known to inhibit complexes II and III and increase matrix succinate/fumarate levels, we hypothesize that by allowing dicarboxylate efflux from the matrix, PTP opening during reperfusion may activate sustained ROS production by this mechanism after RET-driven ROS production has ceased.