Identification and characterization of an unusual metallo-β-lactamase from Serratia proteamaculans

Peter Vella, Manfredi Miraula, Emer Phelan, Eleanor W.W. Leung, Fernanda Ely, David L. Ollis, Ross P. McGeary, Gerhard Schenk*, Nataša Mitić

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    31 Citations (Scopus)


    Metallo-β-lactamases (MBLs) are a family of metalloenzymes that are capable of hydrolyzing β-lactam antibiotics and are an important means by which bacterial pathogens use to inactivate antibiotics. A database search of the available amino acid sequences from Serratia proteamaculans indicates the presence of an unusual MBL. A full length amino acid sequence alignment indicates overall homology to B3-type MBLs, but also suggests considerable variations in the active site, notably among residues that are relevant to metal ion binding. Steady-state kinetic measurements further indicate functional differences and identify two relevant pK a values for catalysis (3.8 for the enzyme-substrate complex and 7.8 for the free enzyme) and a preference for penams with modest reactivity towards some cephalosporins. An analysis of the metal ion content indicates the presence of only one zinc ion per active site in the resting enzyme. In contrast, kinetic data suggest that the enzyme may operate as a binuclear enzyme, and it is thus proposed that a catalytically active di-Zn2+ center is formed only once the substrate is present.

    Original languageEnglish
    Pages (from-to)855-863
    Number of pages9
    JournalJournal of Biological Inorganic Chemistry
    Issue number7
    Publication statusPublished - Oct 2013


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