Biochemical Characterization of Sfh-I, a Subclass B2 Metallo-β-Lactamase from Serratia fonticola UTAD54

The subclass B2 metallo-beta-lactamase (MBL) Sfh-I from Serratia fonticola UTAD54 was cloned and overexpressed in Escherichia coli. The recombinant protein binds one equivalent of zinc, as shown by mass spectrometry, and preferentially hydrolyzes carbapenem substrates. However, compared to other B2 MBLs, Sfh-I also shows limited hydrolytic activity against some additional substrates and is not inhibited by a second equivalent of zinc. These data confirm Sfh-I to be a subclass B2 metallo-beta-lactamase with some distinctive properties.