In Vivo Impact of Met221 Substitution in GOB Metallo-B-Lactamase

MORAN BARRIO, J; LISA MN; VILA AJ

ANTIMICROBIAL AGENTS AND CHEMOTHERAPY

AMER SOC MICROBIOLOGY

Lugar: Washington DC 20036; Año: 2012 vol. 56 p. 1769 - 1773

0066-4804

Metallo-beta-lactamases (MBLs) represent one of the main mechanisms of bacterial resistance against b-lactam antibiotics. Elucidation of their mechanism has been mostly limited by the structural diversity among their active sites. All MBLs structurally characterized so far present a Cys or a Ser residue in position 221, which is critical for catalysis. GOB lactamases stand as an exception within this picture, possessing a Met residue in this location. We studied different mutants in this position, and we show that Met221 is essential for protein stability, most likely due to its involvement in a hydrophobic core. In contrast to other known MBLs, residue 221 is not involved in metal binding or in catalysis in GOB enzymes, further highlighting the structural diversity of MBLs. We also demonstrate the usefulness of protein periplasmic profiles to assess the contribution of protein stability to antibiotic resistance.