Converts carnitine to trimethylamine and malic semialdehyde. Can also use gamma-butyrobetaine, choline and betaine as substrates. (R)-carnitine + H(+) + NADH + O2 = (3R)-3-hydroxy-4-oxobutanoate + H2O + NAD(+) + trimethylamine (R)-carnitine + H(+) + NADPH + O2 = (3R)-3-hydroxy-4-oxobutanoate + H2O + NADP(+) + trimethylamine Binds 1 [2Fe-2S] cluster per subunit. Binds 1 Fe cation per subunit. Amine and polyamine metabolism; carnitine metabolism. Composed of an oxygenase subunit (yeaW) and a reductase subunit (yeaX). Belongs to the bacterial ring-hydroxylating dioxygenase alpha subunit family. CntA subfamily.