Binds 3 [4Fe-4S] clusters (By similarity). The first cluster is coordinated with 3 cysteines and an exchangeable S-adenosyl-L-methionine (By similarity). Belongs to the radical SAM superfamily. Anaerobic sulfatase-maturating enzyme family. Despite its homology to the anaerobic sulfatase-maturating enzymes, it is not involved in Cys-type sulfatase maturation in vivo.