Reduces trimethylamine-N-oxide (TMAO) into trimethylamine; an anaerobic reaction coupled to energy-yielding reactions. Can also reduce other N- and S-oxide compounds such as 4-methylmorpholine-N-oxide and biotin sulfoxide (BSO), but with a lower catalytic efficiency. 2 Fe(III)-[cytochrome c] + H2O + trimethylamine = 2 Fe(II)-[cytochrome c] + 3 H(+) + trimethylamine N-oxide Binds 1 molybdenum-bis(molybdopterin guanine dinucleotide) (Mo-bis-MGD) cofactor per subunit. Exported by the Tat system. The position of the signal peptide cleavage has been experimentally proven. Can also be exported by the Sec system. Expression of torYZ allows E.coli to grow anaerobically on a wider range of substrates than does expression of torCAD. Belongs to the prokaryotic molybdopterin-containing oxidoreductase family. Was originally thought to be a biotin sulfoxide reductase.