Terminal reductase that allows anaerobic growth on selenate as the sole respiratory oxidant. A + H2O + selenite = AH2 + selenate Binds 1 [4Fe-4S] cluster. Binds 1 molybdenum-bis(molybdopterin guanine dinucleotide) (Mo-bis-MGD) cofactor per subunit. Inhibited by O(2). Heterotrimer of alpha, beta and gamma subunits. Predicted to be exported by the Tat system. The position of the signal peptide cleavage has been experimentally proven. Has potential use in bioremediation of waste sites contaminated with selenate, such as agricultural drainage waters. Belongs to the prokaryotic molybdopterin-containing oxidoreductase family.