Catalyzes the coenzyme A-dependent oxidative decarboxylation of different 2-oxoacids such as 2-oxoglutarate, pyruvate and 2-oxobutyrate to form their CoA derivatives. a 2-oxocarboxylate + CoA + 2 oxidized [2Fe-2S]-[ferredoxin] = an acyl-CoA + CO2 + H(+) + 2 reduced [2Fe-2S]-[ferredoxin] Inhibited by low concentration of 4-fluoro-7-nitrobenzofurazan (NBD-F). Heterodimer composed of an alpha and a beta subunit. The Tyr-Pro-Ile-Thr-Pro (YPITP) motif is important for the turnover of the reaction, presumably through its flexibility and mobility.