Converts carnitine to trimethylamine and malic semialdehyde. (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. Amine and polyamine metabolism; carnitine metabolism. Composed of an oxygenase subunit (cntA) and a reductase subunit (cntB). Mutant cannot grow on carnitine as a sole carbon and energy source, whereas the growth on succinate is not affected. Mutation abolishes trimethylamine formation from carnitine. Belongs to the PDR/VanB family. CntB subfamily.