Catalyzes the coenzyme A-dependent oxidative decarboxylation of different 2-oxoacids such as pyruvate, 2-oxobutyrate, glyoxylate and 2-oxoglutarate to form their CoA derivatives. a 2-oxocarboxylate + CoA + 2 oxidized [2Fe-2S]-[ferredoxin] = an acyl-CoA + CO2 + H(+) + 2 reduced [2Fe-2S]-[ferredoxin] Optimum pH is 8.5. Optimum temperature is over 110 degrees Celsius. 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.