Mono- and binuclear Zn-β-lactamase from Bacteroides fragilis: catalytic and structural roles of the zinc ions

• Published in: FEBS letters Vol. 438; no. 1; pp. 137 - 140
• Main Authors: Paul-Soto, Raquel, Hernandez-Valladares, Maria, Galleni, Moreno, Bauer, Rogert, Zeppezauer, Michael, Frère, Jean-Marie, Adolph, Hans-Werner
• Format: Journal Article Web Resource
• Language: English
• Published: England Elsevier B.V 30.10.1998; Wiley-Blackwell
• Subjects: AAS, atomic absorption spectroscopy; Anti-Bacterial Agents - metabolism; Apoenzymes - metabolism; Bacteroides fragilis; Bacteroides fragilis - enzymology; beta-Lactamases - metabolism; beta-Lactams; Binding Sites; Biochemistry, biophysics & molecular biology; Biochimie, biophysique & biologie moléculaire; Cadmium - metabolism; Cadmium - pharmacology; Cadmium/metabolism/pharmacology; Calorimetry, Differential Scanning; Chelating Agents - pharmacology; Coenzymes - chemistry; Coenzymes - pharmacology; Coenzymes/chemistry/pharmacology; Dialysis; Dithiothreitol - pharmacology; DSC, differential scanning calorimetry; DTT, dithiothreitol; IDA, iminodiacetic acid; Kinetics; Life sciences; Metal exchange; Nbs2, 5,5′-dithio-bis(2-nitrobenzoate); Picolinic Acids - pharmacology; Protein Denaturation; Sciences du vivant; Spectrometry, Fluorescence; Substrate Specificity; Thermal denaturation; Thermodynamics; Titrimetry; Zinc - chemistry; Zinc - metabolism; Zinc removal; Zinc β-lactamase; Zinc/chemistry/metabolism; Zinc removal; DSC, differential scanning calorimetry; Zinc β-lactamase; Bacteroides fragilis; Thermal denaturation; Nbs 2, 5,5′-dithio-bis(2-nitrobenzoate); AAS, atomic absorption spectroscopy; IDA, iminodiacetic acid; Metal exchange; DTT, dithiothreitol
• ISSN: 0014-5793; 1873-3468; 1873-3468
• DOI: 10.1016/S0014-5793(98)01289-7

The Bacteroides fragilis Zn-β-lactamase is active with a mono- and a binuclear zinc site. The apoenzyme produced by removal of both Zn ions does not recover full activity upon readdition of Zn 2+ in contrast to an active mono-Zn form prepared at pH 6.0. Differences in k cat values observed are substrate-dependent implying distinct mechanisms for the mono- and binuclear species. The substrate profile of a Zn,Cd hybrid obtained by selective exchange of one zinc ion is different from that of the Zn 2 enzyme with a remarkable 15-fold increased activity with cefoxitin as substrate.