Catalyzes the reduction of dimethyl sulfoxide (DMSO) to dimethyl sulfide (DMS). The terminal DMSO reductase can also use various sulfoxides and N-oxide compounds as terminal electron acceptor in addition to DMSO (By similarity). 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. Heterotrimeric enzyme composed of a catalytic heterodimer (DmsAB) and a membrane anchor protein (DmsC). Predicted to be exported by the Tat system. The position of the signal peptide cleavage has not been experimentally proven. 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 (By similarity). Belongs to the prokaryotic molybdopterin-containing oxidoreductase family.