The formylglycine-generating enzyme (FGE) is a unique copper protein that catalyzes oxygen-dependent C-H activation. We describe 1.66 Å- and 1.28 Å-resolution crystal structures of FGE from Thermomonospora curvata in complex with either AgI or CdII providing definitive evidence for a high-affinity metal-binding site in this enzyme. The structures reveal a bis-cysteine linear coordination of the monovalent metal, and tetrahedral coordination of the bivalent metal. Similar coordination changes may occur in the active enzyme as a result of CuI/II redox cycling. Complexation of copper atoms by two cysteine residues is common among copper-trafficking proteins, but is unprecedented for redox-active copper enzymes or synthetic copper catalysts.
Keywords: C−H activation; copper chaperone; copper enzyme; enzyme catalysis; formylglycine.
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