Dataset Information

Exploring the Landscape of Diazabicyclooctane (DBO) Inhibition: Avibactam Inactivation of PER-2 ?-Lactamase.

ABSTRACT: PER ?-lactamases are an emerging family of extended-spectrum ?-lactamases (ESBL) found in Gram-negative bacteria. PER ?-lactamases are unique among class A enzymes as they possess an inverted omega (?) loop and extended B3 ?-strand. These singular structural features are hypothesized to contribute to their hydrolytic profile against oxyimino-cephalosporins (e.g., cefotaxime and ceftazidime). Here, we tested the ability of avibactam (AVI), a novel non-?-lactam ?-lactamase inhibitor to inactivate PER-2. Interestingly, the PER-2 inhibition constants (i.e., k2/K = 2 × 103 ± 0.1 × 103 M-1 s-1, where k2 is the rate constant for acylation (carbamylation) and K is the equilibrium constant) that were obtained when AVI was tested were reminiscent of values observed testing the inhibition by AVI of class C and D ?-lactamases (i.e., k2/K range of ?103 M-1 s-1) and not class A ?-lactamases (i.e., k2/K range, 104 to 105 M-1 s-1). Once AVI was bound, a stable complex with PER-2 was observed via mass spectrometry (e.g., 31,389 ± 3 atomic mass units [amu] ? 31,604 ± 3 amu for 24 h). Molecular modeling of PER-2 with AVI showed that the carbonyl of AVI was located in the oxyanion hole of the ?-lactamase and that the sulfate of AVI formed interactions with the ?-lactam carboxylate binding site of the PER-2 ?-lactamase (R220 and T237). However, hydrophobic patches near the PER-2 active site (by Ser70 and B3-B4 ?-strands) were observed and may affect the binding of necessary catalytic water molecules, thus slowing acylation (k2/K) of AVI onto PER-2. Similar electrostatics and hydrophobicity of the active site were also observed between OXA-48 and PER-2, while CTX-M-15 was more hydrophilic. To demonstrate the ability of AVI to overcome the enhanced cephalosporinase activity of PER-2 ?-lactamase, we tested different ?-lactam-AVI combinations. By lowering MICs to ?2 mg/liter, the ceftaroline-AVI combination could represent a favorable therapeutic option against Enterobacteriaceae expressing blaPER-2 Our studies define the inactivation of the PER-2 ESBL by AVI and suggest that the biophysical properties of the active site contribute to determining the efficiency of inactivation.

SUBMITTER: Ruggiero M

PROVIDER: S-EPMC5444126 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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Publications

Exploring the Landscape of Diazabicyclooctane (DBO) Inhibition: Avibactam Inactivation of PER-2 β-Lactamase.

Ruggiero Melina M Papp-Wallace Krisztina M KM Taracila Magdalena A MA Mojica Maria F MF Bethel Christopher R CR Rudin Susan D SD Zeiser Elise T ET Gutkind Gabriel G Bonomo Robert A RA Power Pablo P

Antimicrobial agents and chemotherapy 20170524 6

PER β-lactamases are an emerging family of extended-spectrum β-lactamases (ESBL) found in Gram-negative bacteria. PER β-lactamases are unique among class A enzymes as they possess an inverted omega (Ω) loop and extended B3 β-strand. These singular structural features are hypothesized to contribute to their hydrolytic profile against oxyimino-cephalosporins (e.g., cefotaxime and ceftazidime). Here, we tested the ability of avibactam (AVI), a novel non-β-lactam β-lactamase inhibitor to inactivate ...[more]

PMID: 28348157

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Project description:KPC-2 is the most prevalent class A carbapenemase in the world. Previously, KPC-2 was shown to hydrolyze the β-lactamase inhibitors clavulanic acid, sulbactam, and tazobactam. In addition, substitutions at amino acid position R220 in the KPC-2 β-lactamase increased resistance to clavulanic acid. A novel bridged diazabicyclooctane (DBO) non-β-lactam β-lactamase inhibitor, avibactam, was shown to inactivate the KPC-2 β-lactamase. To better understand the mechanistic basis for inhibition of KPC-2 by avibactam, we tested the potency of ampicillin-avibactam and ceftazidime-avibactam against engineered variants of the KPC-2 β-lactamase that possessed single amino acid substitutions at important sites (i.e., Ambler positions 69, 130, 234, 220, and 276) that were previously shown to confer inhibitor resistance in TEM and SHV β-lactamases. To this end, we performed susceptibility testing, biochemical assays, and molecular modeling. Escherichia coli DH10B carrying KPC-2 β-lactamase variants with the substitutions S130G, K234R, and R220M demonstrated elevated MICs for only the ampicillin-avibactam combinations (e.g., 512, 64, and 32 mg/liter, respectively, versus the MICs for wild-type KPC-2 at 2 to 8 mg/liter). Steady-state kinetics revealed that the S130G variant of KPC-2 resisted inactivation by avibactam; the k2/K ratio was significantly lowered 4 logs for the S130G variant from the ratio for the wild-type enzyme (21,580 M(-1) s(-1) to 1.2 M(-1) s(-1)). Molecular modeling and molecular dynamics simulations suggested that the mobility of K73 and its ability to activate S70 (i.e., function as a general base) may be impaired in the S130G variant of KPC-2, thereby explaining the slowed acylation. Moreover, we also advance the idea that the protonation of the sulfate nitrogen of avibactam may be slowed in the S130G variant, as S130 is the likely proton donor and another residue, possibly K234, must compensate. Our findings show that residues S130 as well as K234 and R220 contribute significantly to the mechanism of avibactam inactivation of KPC-2. Fortunately, the emergence of S130G, K234R, and R220M variants of KPC in the clinic should not result in failure of ceftazidime-avibactam, as the ceftazidime partner is potent against E. coli DH10B strains possessing all of these variants.

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Dataset Information

Exploring the Landscape of Diazabicyclooctane (DBO) Inhibition: Avibactam Inactivation of PER-2 ?-Lactamase.

Publications

Exploring the Landscape of Diazabicyclooctane (DBO) Inhibition: Avibactam Inactivation of PER-2 β-Lactamase.

Similar Datasets

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