7rpd: Difference between revisions

The evolution of multidrug resistance in Acinetobacter spp. increases the risk of our best antibiotics losing their efficacy. From a clinical perspective, the carbapenem-hydrolyzing class D beta-lactamase subfamily present in Acinetobacter spp. is particularly concerning because of its ability to confer resistance to carbapenems. The kinetic profiles of class D beta-lactamases exhibit variability in carbapenem hydrolysis, suggesting functional differences. To better understand the structure-function relationship between the carbapenem-hydrolyzing class D beta-lactamase OXA-24/40 found in Acinetobacter baumannii and carbapenem substrates, we analyzed steady-state kinetics with the carbapenem antibiotics meropenem and ertapenem and determined the structures of complexes of OXA-24/40 bound to imipenem, meropenem, doripenem, and ertapenem, as well as the expanded-spectrum cephalosporin cefotaxime, using X-ray crystallography. We show that OXA-24/40 exhibits a preference for ertapenem compared with meropenem, imipenem, and doripenem, with an increase in catalytic efficiency of up to fourfold. We suggest that superposition of the nine OXA-24/40 complexes will better inform future inhibitor design efforts by providing insight into the complicated and varying ways in which carbapenems are selected and bound by class D beta-lactamases.

Conformational flexibility in carbapenem hydrolysis drives substrate specificity of the class D carbapenemase OXA-24/40.,Mitchell JM, June CM, Baggett VL, Lowe BC, Ruble JF, Bonomo RA, Leonard DA, Powers RA J Biol Chem. 2022 Jul;298(7):102127. doi: 10.1016/j.jbc.2022.102127. Epub 2022 , Jun 14. PMID:35709986<ref>PMID:35709986</ref>