The metallo-β-lactamase GOB is a Mono-Zn(II) enzyme with a novel active site

Abstract

Metallo-β-lactamases (MβLs) are zinc-dependent enzymes able to hydrolyze and inactivate most β-lactam antibiotics. The large diversity of active site structures and metal content among MβLs from different sources has limited the design of a pan-MβL inhibitor. Here we report the biochemical and biophysical characterization of a novel MβL, GOB-18, from a clinical isolate of a Gram-negative opportunistic pathogen, Elizabethkingia meningoseptica. Different spectroscopic techniques, three-dimensional modeling, and mutagenesis experiments, reveal that the Zn(II) ion is bound to Asp 120, His121, His263, and a solvent molecule, i.e. in the canonical Zn2 site of dinuclear MβLs. Contrasting all other related MβLs, GOB-18 is fully active against a broad range of β-lactam substrates using a single Zn(II) ion in this site. These data further enlarge the structural diversity of MβLs. © 2007 by The American Society for Biochemistry and Molecular Biology, Inc.