Reference : Mono- and binuclear Zn2+-beta-lactamase. Role of the conserved cysteine in the cataly...
Scientific journals : Article
Life sciences : Biochemistry, biophysics & molecular biology
Mono- and binuclear Zn2+-beta-lactamase. Role of the conserved cysteine in the catalytic mechanism.
Paul-Soto, R. [> >]
Bauer, R. [> >]
Frère, Jean-Marie mailto [Université de Liège - ULiège > > Centre d'ingénierie des protéines >]
Galleni, Moreno mailto [Université de Liège - ULiège > Département des sciences de la vie > Macromolécules biologiques >]
Meyer-Klaucke, W. [> >]
Nolting, H. [> >]
Rossolini, G. M. [> >]
DE SENY, Dominique mailto [Centre Hospitalier Universitaire de Liège - CHU > > Rhumatologie >]
Hernandez-Valladares, M. [> >]
Zeppezauer, M. [> >]
Adolph, H. W. [> >]
Journal of Biological Chemistry
Yes (verified by ORBi)
[en] Bacillus cereus/enzymology ; Base Sequence ; Binding Sites ; Catalysis ; Cephalosporins/metabolism ; Cysteine/chemistry/metabolism ; DNA Primers ; Hydrolysis ; Kinetics ; Mutagenesis, Site-Directed ; Penicillin G/metabolism ; Protein Binding ; Protein Conformation ; Spectrometry, X-Ray Emission ; Zinc/chemistry/metabolism ; beta-Lactamases/chemistry/genetics/metabolism
[en] When expressed by pathogenic bacteria, Zn2+-beta-lactamases induce resistance to most beta-lactam antibiotics. A possible strategy to fight these bacteria would be a combined therapy with non-toxic inhibitors of Zn2+-beta-lactamases together with standard antibiotics. For this purpose, it is important to verify that the inhibitor is effective under all clinical conditions. We have investigated the correlation between the number of zinc ions bound to the Zn2+-beta-lactamase from Bacillus cereus and hydrolysis of benzylpenicillin and nitrocefin for the wild type and a mutant where cysteine 168 is replaced by alanine. It is shown that both the mono-Zn2+ (mononuclear) and di-Zn2+ (binuclear) Zn2+-beta-lactamases are catalytically active but with different kinetic properties. The mono-Zn2+-beta-lactamase requires the conserved cysteine residue for hydrolysis of the beta-lactam ring in contrast to the binuclear enzyme where the cysteine residue is not essential. Substrate affinity is not significantly affected by the mutation for the mononuclear enzyme but is decreased for the binuclear enzyme. These results were derived from kinetic studies on two wild types and the mutant enzyme with benzylpenicillin and nitrocefin as substrates. Thus, targeting drug design to modify this residue might represent an efficient strategy, the more so if it also interferes with the formation of the binuclear enzyme.

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