Membrane-anchoring subunit of succinate dehydrogenase 2 (Sdh2). Sdh2 may catalyze the two-electron oxidation of succinate to fumarate with a corresponding reduction of quinone to quinol under low oxygen conditions, when the primary aerobic succinate dehydrogenase (Sdh1) is inhibited. Sdh2 seems to be the generator of the proton motive force (PMF) under hypoxia. The heme is bound between the two transmembrane subunits. Part of an enzyme complex containing four subunits: a flavoprotein (SdhA), an iron-sulfur protein (SdhB), plus two membrane-anchoring proteins (SdhC and SdhD). Cells lacking the sdh2 operon (sdhCDAB) display a stationary phase exit defect after 60 days in culture. They show only slight difference in intracellular succinate and malate concentrations during aerobic growth or hypoxia when compared to wild-type. The mutant strain is more susceptible to proton motive force (PMF) inhibition than the parental strain, and it was impossible to recover colonies from mutant cultures after 21 days. Cells harboring a deletion of sdh2 consume oxygen at a reduced rate and are able to modulate respiration as dissolved oxygen (DO) is depleted to about 6%. Belongs to the cytochrome b560 family. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus.