CoA + 2 oxidized [2Fe-2S]-[ferredoxin] + pyruvate = acetyl-CoA + CO2 + H(+) + 2 reduced [2Fe-2S]-[ferredoxin] Binds 1 [4Fe-4S] cluster per subunit. Heterotetramer of one alpha, one beta, one delta and one gamma chain. It also catalyzes the oxidation of 2-oxobutyrate.