A general reaction mechanism for mono-and binuclear metallo beta lactamses

MARÍA-NATALIA LISA ; ANTONELA R. PALACIOS; MARIANO M. GONZÁLEZ ; DIEGO M. MORENO ; LETICIA I. LLARRULL ; VILA AJ

Encuentro; 13th Beta Lactamase Meeting, L?Aquila, Italia, 2017.; 2017

Carbapenem-resistantEnterobacteriaceae (CRE) represent an increasing threat to human health, sincecarbapenems are last resort drugs for infections by such organisms.Metallo-β-lactamases (MβLs) are the main mechanisms of resistance againstcarbapenems in CRE. Inhibitors of MβLs are currently unavailable as design hasbeen limited by the structural diversity of their active sites and byincomplete knowledge of their catalytic mechanism. Methods We usedstopped-flow techniques, X-ray absorption spectroscopy, NMR and theoreticalapproaches to study the mechanism of carbapenem hydrolysis by thebroad-spectrum subclass B1 enzymes NDM-1 and BcII in the bi-Zn(II) form, themono-Zn(II) B2 carbapenemase Sfh-I and the B3 enzyme GOB-18 in the mononuclearform.  Results We demonstratethat MβLs with different active sites and metal contents hydrolyse carbapenemsvia a similar mechanism, with accumulation of the same anionic intermediatespecies. We characterized the Michaelis complex in the mechanism of mono-Zn(II)enzymes, and we further identified all intermediate species, enabling us topropose a detailed chemical mechanism for mono and binuclear MβLs. Conclusion The finding of acommon mechanism suggests strategies for the rational design of inhibitorseffective against the full range of MβLs, notwithstanding the profounddifferences between these enzymes? active site structure, β-lactam specificityand metal content.