Component of KG oxidoreductase (KOR) that catalyzes the CoA-dependent oxidative decarboxylation of 2-oxoglutarate (alpha-ketoglutarate, KG) to succinyl-CoA. Methyl viologen can act as electron acceptor in vitro; the physiologic electron acceptor is unknown. Is involved in the alternative TCA pathway that functions concurrently with fatty acid beta-oxidation. Since a growing body of evidence indicates that lipids (for example cholesterol and fatty acids) are a predominant growth substrate for M.tuberculosis during infection, flux through KOR likely represents an important step in intermediary metabolism in vivo. KOR-dependent decarboxylation of KG also appears to be an important source of CO(2) in M.tuberculosis metabolism. 2-oxoglutarate + CoA + 2 oxidized [2Fe-2S]-[ferredoxin] = CO2 + H(+) + 2 reduced [2Fe-2S]-[ferredoxin] + succinyl-CoA Carbohydrate metabolism; tricarboxylic acid cycle. KG oxidoreductase (KOR) is composed of KorA and KorB subunits. CoA-dependent KG oxidoreductase activity is absent in a mutant strain deleted for both genes korA and korB, and this strain is impaired for aerobic growth in the absence of sufficient amounts of CO(2). Inhibition of the glyoxylate shunt or exclusion of exogenous fatty acids alleviates this growth defect. Simultaneous disruption of korAB and kgd results in strict dependence upon the glyoxylate shunt for growth. Is extremely stable under aerobic conditions.