Two distinct, membrane-bound, FAD-containing enzymes are responsible for the catalysis of fumarate and succinate interconversion; the fumarate reductase is used in anaerobic growth, and the succinate dehydrogenase is used in aerobic growth. a quinone + succinate = a quinol + fumarate a menaquinone + succinate = a menaquinol + fumarate Binds 1 [2Fe-2S] cluster. Binds 1 [3Fe-4S] cluster. Binds 1 [4Fe-4S] cluster. Fumarate dehydrogenase forms part of an enzyme complex containing four subunits: a flavoprotein, an iron-sulfur, and two hydrophobic anchor proteins. Belongs to the succinate dehydrogenase/fumarate reductase iron-sulfur protein family.