title: Covalent inhibition of New Delhi metallo-β-lactamase-1 (NDM-1) by cefaclor.
abstract: Covalent irreversible inhibitors can successfully treat antibiotic-resistant infections by targeting serine β-lactamases. However, this strategy is useless for New Delhi metallo-β-lactamase (NDM), which uses a non-covalent catalytic mechanism and lacks an active-site serine. Here, NDM-1 was irreversibly inactivated by three β-lactam substrates: cephalothin, moxalactam, and cefaclor, albeit at supratherapeutic doses (e.g., cefaclor KI =2.3 ± 0.1 mM; k(inact) =0.024 ± 0.001 min(-1)). Inactivation by cephalothin and moxalactam was mediated through Cys208. Inactivation by cefaclor proceeded through multiple pathways, in part mediated by Lys211. Use of a cefaclor metabolite enabled mass spectrometric identification of a +346.0735 Da covalent adduct on Lys211, and an inactivation mechanism is proposed. Lys211 was identified as a promising "handhold" for developing covalent NDM-1 inhibitors and serves as a conceptual example for creating covalent inhibitors for enzymes with non-covalent mechanisms.
authors.affiliation: College of Pharmacy, Medicinal Chemistry Division, University of Texas, 1 University Station, C0850, Austin TX 78712 (USA).
authors.forename: Pei W
authors.initials: PW
authors.lastname: Thomas
authors.forename: Michael
authors.initials: M
authors.lastname: Cammarata
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Brodbelt
authors.forename: Walter
authors.initials: W
authors.lastname: Fast
mesh_terms: D002433:Cefaclor / Q000737:chemistry / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D015394:Molecular Structure; D013329:Structure-Activity Relationship; D013997:Time Factors; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D002433:Cefaclor; D001618:beta-Lactamases; C552864:beta-lactamase NDM-1
keywords: antibiotic resistance; covalent inhibition; inactivation mechanisms; metallo-beta-lactamase