Fig. 1.

Maturation of gut microbial sulfatases by the radical SAM anSMEs. (a) Sulfate removal from an N-acetyl-glucosamine-6-sulfate substrate by sulfatases harboring an formylglycine (fGly) cofactor. (b) Post-translational modification of a sulfatase L-serine or L-cysteine residue to an fGly residue that is hydrated to the gem-diol active form. (c) Depiction of the anaerobic sulfatase maturating enzyme (PDB accession code: 4K38) with SAM coordinating the radical SAM cluster and a peptide substrate analogue (dark grey sticks) bound in the active site. (d) Reductive cleavage of S-adenosylmethionine (SAM) by the radical SAM [4Fe–4S]1+ cluster to generate 50 -deoxyadenosine radical (50 dAc) and L-methionine. (e) Proposed mechanism for fGly generation by anSMEs.