TY - JOUR
T1 - Can All Major ROS Forming Sites of the Respiratory Chain Be Activated By High FADH2/NADH Ratios?
T2 - Ancient evolutionary constraints determine mitochondrial ROS formation
AU - Speijer, Dave
N1 - Funding Information: The author thanks Jan van Maarseveen and Bas de Bruin for enlightening him regarding (the chelating capacities of) carnitine and Andrew Moore as well as several anonymous reviewers for helping him to improve the overall presentation of the concepts described here. Publisher Copyright: © 2018 The Authors. BioEssays Published by Wiley Periodicals, Inc.
PY - 2019/1
Y1 - 2019/1
N2 - Aspects of peroxisome evolution, uncoupling, carnitine shuttles, supercomplex formation, and missing neuronal fatty acid oxidation (FAO) are linked to reactive oxygen species (ROS) formation in respiratory chains. Oxidation of substrates with high FADH2/NADH (F/N) ratios (e.g., FAs) initiate ROS formation in Complex I due to insufficient availability of its electron acceptor (Q) and reverse electron transport from QH2, e.g., during FAO or glycerol-3-phosphate shuttle use. Here it is proposed that the Q-cycle of Complex III contributes to enhanced ROS formation going from low F/N ratio substrates (glucose) to high F/N substrates. This contribution is twofold: 1) Complex III uses Q as substrate, thus also competing with Complex I; 2) Complex III itself will produce more ROS under these conditions. I link this scenario to the universally observed Complex III dimerization. The Q-cycle of Complex III thus again illustrates the tension between efficient ATP generation and endogenous ROS formation. This model can explain recent findings concerning succinate and ROS-induced uncoupling.
AB - Aspects of peroxisome evolution, uncoupling, carnitine shuttles, supercomplex formation, and missing neuronal fatty acid oxidation (FAO) are linked to reactive oxygen species (ROS) formation in respiratory chains. Oxidation of substrates with high FADH2/NADH (F/N) ratios (e.g., FAs) initiate ROS formation in Complex I due to insufficient availability of its electron acceptor (Q) and reverse electron transport from QH2, e.g., during FAO or glycerol-3-phosphate shuttle use. Here it is proposed that the Q-cycle of Complex III contributes to enhanced ROS formation going from low F/N ratio substrates (glucose) to high F/N substrates. This contribution is twofold: 1) Complex III uses Q as substrate, thus also competing with Complex I; 2) Complex III itself will produce more ROS under these conditions. I link this scenario to the universally observed Complex III dimerization. The Q-cycle of Complex III thus again illustrates the tension between efficient ATP generation and endogenous ROS formation. This model can explain recent findings concerning succinate and ROS-induced uncoupling.
KW - FADH/NADH ratio
KW - Q-cycle
KW - beta-oxidation
KW - carnitine
KW - peroxisomes
KW - reverse electron transport (RET)
KW - symbiogenesis
UR - http://www.scopus.com/inward/record.url?scp=85058049836&partnerID=8YFLogxK
UR - https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85058049836&origin=inward
UR - https://www.ncbi.nlm.nih.gov/pubmed/30512221
U2 - https://doi.org/10.1002/bies.201800180
DO - https://doi.org/10.1002/bies.201800180
M3 - Article
C2 - 30512221
SN - 0265-9247
VL - 41
SP - e1800180
JO - BioEssays
JF - BioEssays
IS - 1
M1 - 1800180
ER -