Molecular traits improving fitness in zinc-dependent carbapenemases: Mind the gap!

DELMONTI, JULIANA; LÓPEZ, CAROLINA; BAHR, GUILLERMO; PALACIOS, ANTONELA R.; ROSSI, AGUSTINA; GIANNINI, ESTEFANÍA; GONZÁLEZ, LISANDRO

Durango

Congreso; 6° Congreso de la Rama de Fisicoquímica, Estructura y Diseño de Proteínas; 2017

Sociedad Mexicana de Bioquímica, A.C. (SMB)

Metallo-beta-lactamases (MBLs) are the latest resistance mechanism of pathogenic and opportunistic bacteria against carbapenems, considered as last resort drugs. The worldwide spread of genes coding for these enzymes, together with the lack of a clinically useful inhibitor, have raised a sign of alarm. Inhibitor design has been mostly impeded by the structural diversity of these enzymes. We have designed a series of inhibitors based on a common mechanism despite this diversity. Zn(II) binding is critical in the bacterial periplasm, not only to activate these enzymes and provide resistance, but also to stabilize the protein scaffold. This phenomenon is not paralleled by in vitro studies. We have developed a strategy aimed to correlate the biochemical and biophysical features in purified enzymes with those in the bacterial periplasm, ultimately leading tothe selected phenotype, i.e., resistance to antibiotics. Optimization of the Zn(II) binding affinity is key in MBL evolution. Finally, we have found that in NDM, the New Delhi Metallo-beta-lactamase, one of the most potent and widespread lactamases, membrane anchoring provides a stabilizing effect upon zinc starvation conditions, as those present during bacterial infection. This cellular localization claims for new drug discovery strategies, complementing enzyme inhibition.