Dimethyl sulfoxide (DMSO) reductase catalyzes the reduction of dimethyl sulfoxide (DMSO) to dimethyl sulfide (DMS) during anaerobic respiration; it can also use trimethylamine N-oxide (TMAO) as terminal electron acceptor. Subunit B is proposed to be involved in electron transfer. Binds 4 [4Fe-4S] clusters. Probable multiprotein complex that likely consists of DmsA, DmsB and DmsC. By anaerobic conditions. Its expression is under the control of DmsR.