title: Structural and biochemical characterization of VIM-26 shows that Leu224 has implications for the substrate specificity of VIM metallo-β-lactamases.
abstract: During the last decades antimicrobial resistance has become a global health problem. Metallo-β-lactamases (MBLs) which are broad-spectrum β-lactamases that inactivate virtually all β-lactams including carbapenems, are contributing to this health problem. In this study a novel MBL variant, termed VIM-26, identified in a Klebsiella pneumoniae isolate was studied. VIM-26 belongs to the Verona integron-encoded metallo-β-lactamase (VIM) family of MBLs and is a His224Leu variant of the well-characterized VIM-1 variant. In this study, we report the kinetic parameters, minimum inhibitory concentrations and crystal structures of a recombinant VIM-26 protein, and compare them to previously published data on VIM-1, VIM-2 and VIM-7. The kinetic parameters and minimum inhibitory concentration determinations show that VIM-26, like VIM-7, has higher penicillinase activity but lower cephalosporinase activity than VIM-1 and VIM-2. The four determined VIM-26 crystal structures revealed mono- and di-zinc forms, where the Zn1 ion has distorted tetrahedral coordination geometry with an additional water molecule (W2) at a distance of 2.6-3.7 Å, which could be important during catalysis. The R2 drug binding site in VIM-26 is more open compared to VIM-2 and VIM-7 and neutrally charged due to Leu224 and Ser228. Thus, the VIM-26 drug binding properties are different from the VIM-2 (Tyr224/Arg228) and VIM-7 (His224/Arg228) structures, indicating a role of these residues in the substrate specificity.
authors.affiliation: Norwegian Structural Biology Centre, Department of Chemistry, UiT The Arctic University of Norway, Tromsø, Norway.
authors.forename: Hanna-Kirsti S
authors.initials: HK
authors.lastname: Leiros
authors.forename: Kine Susann Waade
authors.initials: KS
authors.lastname: Edvardsen
authors.forename: Gro Elin Kjaereng
authors.initials: GE
authors.lastname: Bjerga
authors.forename: Ørjan
authors.initials: Ø
authors.lastname: Samuelsen
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D015780:Carbapenems / Q000737:chemistry; D002384:Catalysis; D002511:Cephalosporins / Q000737:chemistry; D018360:Crystallography, X-Ray; D024881:Drug Resistance, Bacterial; D007477:Ions; D007711:Klebsiella pneumoniae / Q000201:enzymology; D007930:Leucine / Q000737:chemistry*; D010406:Penicillins / Q000737:chemistry; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D012694:Serine / Q000737:chemistry; D013379:Substrate Specificity; D001618:beta-Lactamases / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; D002511:Cephalosporins; D007477:Ions; D010406:Penicillins; D011994:Recombinant Proteins; D012694:Serine; D001618:beta-Lactamases; C000598202:beta-lactamase VIM-26, Klebsiella pneumoniae; D007930:Leucine
keywords: Klebsiella pneumoniae; antibiotic resistance; drug binding site; metallo-β-lactamase; minimum inhibitory concentrations