Fumarate is a terminal electron acceptor in the mammalian electron transport chain
A circuit of electron flow in the mammalian ETC that maintains mitochondrial functions under oxygen limitation is delineated, finding that complex I and dihydroorotate dehydrogenase can still deposit electrons into the ETC when oxygen reduction is impeded.
Abstract
<jats:title>Reversing the chain</jats:title> <jats:p> The mitochondrial electron transport chain is a major part of cellular metabolism and plays key roles in both cellular respiration and the synthesis of critical metabolites. Typically, electrons flow through the electron transport chain in a specific direction, ending up with oxygen as the terminal electron acceptor. Spinelli <jats:italic>et al</jats:italic> . characterized an alternative path of electron flow through the transport chain, ending with fumarate as the electron acceptor (see the Perspective by Baksh and Finley). This pathway operates under conditions of limited oxygen availability, and the authors have confirmed its activity in vivo in a mouse model, observing that the propensity to use this pathway varied between organs. —YN </jats:p>