A variant conferring cofactor-dependent assembly of Escherichia coli dimethylsulfoxide reductase

► DmsABC maturation depends on [Fe-S] cluster (FS0) assembly and cofactor availability. ► The molybdenum cofactor can function as a chemical chaperone. ► ApoDmsAB is translocated to the periplasm by the Tat translocon. ► Serine is an acceptable ligand for the FS0 cluster, but alters its EPR properties. ► The dual insults of replacing cystine with serine and lack of cofactor cause enzyme degradation.