dmsA (Escherichia coli K12): Dimethyl sulfoxide reductase, anaerobic, subunit A; 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.