Mono- and binuclear Zn2+-β-lactamase. Role of the conserved cysteine in the catalytic mechanism

Raquel Paul-Soto, Rogert Bauer, Jean Marie Frère, Moreno Galleni, Wolfram Meyer-Klaucke, Hans Nolting, Gian Maria Rossolini, Dominique De Seny, Maria Hernandez-Valladares, Michael Zeppezauer, Hans Werner Adolph

Research output: Contribution to journalArticlepeer-review

Abstract

When expressed by pathogenic bacteria, Zn2+-β-lactamases induce resistance to most β-lactam antibiotics. A possible strategy to fight these bacteria would be a combined therapy with non-toxic inhibitors of Zn2+-β- 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+-β-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+-β-lactamases are catalytically active but with different kinetic properties. The mono-Zn2+- β-lactamase requires the conserved cysteine residue for hydrolysis of the β-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.

Original languageEnglish
Pages (from-to)13242-13249
Number of pages8
JournalJournal of Biological Chemistry
Volume274
Issue number19
DOIs
Publication statusPublished - May 7 1999

ASJC Scopus subject areas

  • Biochemistry

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