Catalyzes the reduction of dimethyl sulfoxide (DMSO) to dimethyl sulfide (DMS). DMSO reductase serves as the terminal reductase under anaerobic conditions, with DMSO being the terminal electron acceptor. Terminal reductase during anaerobic growth on various sulfoxides and N-oxide compounds. Allows E.coli to grow anaerobically on DMSO as respiratory oxidant. a menaquinone + dimethyl sulfide + H2O = a menaquinol + dimethyl sulfoxide Binds 1 [4Fe-4S] cluster. Binds 1 molybdenum-bis(molybdopterin guanine dinucleotide) (Mo-bis-MGD) cofactor per subunit. Inhibited by dithionite, sodium hydrogensulfite and tungstate. Heterotrimeric enzyme composed of a catalytic heterodimer (DmsAB) and a membrane anchor protein (DmsC). Exported by the Tat system. The position of the signal peptide cleavage has been experimentally proven. Can also be exported by the Sec system. The Tat signal sequence is essential for the expression of dmsA, the stability of the DmsAB dimer and membrane targeting. Despite the presence of a signal sequence, DmsA is not exported to the periplasm. Belongs to the prokaryotic molybdopterin-containing oxidoreductase family. Truncated N-terminus.