Biochemical Characterization of the FEZ-1 Metallo-β-Lactamase of Legionella gormanii ATCC 33297(T) Produced in Escherichia coli

The bla(FEZ-1) gene coding for the metallo-β-lactamase of Legionella (Fluoribacter) gormanii ATCC 33297(T) was overexpressed via a T7 expression system in Escherichia coli BL21(DE3)(pLysS). The product was purified to homogeneity in two steps with a yield of 53%. The FEZ-1 metallo-β-lactamase exhibited a broad-spectrum activity profile, with a preference for cephalosporins such as cephalothin, cefuroxime, and cefotaxime. Monobactams were not hydrolyzed. The β-lactamase was inhibited by metal chelators. FEZ-1 is a monomeric enzyme with a molecular mass of 29,440 Da which possesses two zinc-binding sites. Its zinc content did not vary in the pH range of 5 to 9, but the presence of zinc ions modified the catalytic efficiency of the enzyme. A model of the FEZ-1 three-dimensional structure was built.