1
|
Sakhrani VV, Ghosh RK, Hilario E, Weiss KL, Coates L, Mueller LJ. Toho-1 β-lactamase: backbone chemical shift assignments and changes in dynamics upon binding with avibactam. JOURNAL OF BIOMOLECULAR NMR 2021; 75:303-318. [PMID: 34218390 PMCID: PMC9122098 DOI: 10.1007/s10858-021-00375-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 06/23/2021] [Indexed: 06/13/2023]
Abstract
Backbone chemical shift assignments for the Toho-1 β-lactamase (263 amino acids, 28.9 kDa) are reported based on triple resonance solution-state NMR experiments performed on a uniformly 2H,13C,15N-labeled sample. These assignments allow for subsequent site-specific characterization at the chemical, structural, and dynamical levels. At the chemical level, titration with the non-β-lactam β-lactamase inhibitor avibactam is found to give chemical shift perturbations indicative of tight covalent binding that allow for mapping of the inhibitor binding site. At the structural level, protein secondary structure is predicted based on the backbone chemical shifts and protein residue sequence using TALOS-N and found to agree well with structural characterization from X-ray crystallography. At the dynamical level, model-free analysis of 15N relaxation data at a single field of 16.4 T reveals well-ordered structures for the ligand-free and avibactam-bound enzymes with generalized order parameters of ~ 0.85. Complementary relaxation dispersion experiments indicate that there is an escalation in motions on the millisecond timescale in the vicinity of the active site upon substrate binding. The combination of high rigidity on short timescales and active site flexibility on longer timescales is consistent with hypotheses for achieving both high catalytic efficiency and broad substrate specificity: the induced active site dynamics allows variously sized substrates to be accommodated and increases the probability that the optimal conformation for catalysis will be sampled.
Collapse
Affiliation(s)
- Varun V Sakhrani
- Department of Chemistry, University of California Riverside, Riverside, CA, 92521, USA
| | - Rittik K Ghosh
- Department of Biochemistry, University of California Riverside, Riverside, CA, 92521, USA
| | - Eduardo Hilario
- Department of Chemistry, University of California Riverside, Riverside, CA, 92521, USA
| | - Kevin L Weiss
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37831, USA
| | - Leighton Coates
- Second Target Station, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37831, USA.
| | - Leonard J Mueller
- Department of Chemistry, University of California Riverside, Riverside, CA, 92521, USA.
| |
Collapse
|
2
|
Lizana I, Uribe EA, Delgado EJ. A theoretical approach for the acylation/deacylation mechanisms of avibactam in the reversible inhibition of KPC-2. J Comput Aided Mol Des 2021; 35:943-952. [PMID: 34236545 PMCID: PMC8264174 DOI: 10.1007/s10822-021-00408-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 06/30/2021] [Indexed: 11/28/2022]
Abstract
Klebsiella pneumoniae carbapenemase (KPC-2) is the most commonly encountered class A β-lactamase variant worldwide, which confer high-level resistance to most available antibiotics. In this article we address the issue by a combined approach involving molecular dynamics simulations and hybrid quantum mechanics/molecular mechanics calculations. The study contributes to improve the understanding, at molecular level, of the acylation and deacylation stages of avibactam involved in the inhibition of KPC-2. The results show that both mechanisms, acylation and deacylation, the reaction occur via the formation of a tetrahedral intermediate. The formation of this intermediate corresponds to the rate limiting stage. The activation barriers are 19.5 kcal/mol and 23.0 kcal/mol for the acylation and deacylation stages, respectively. The associated rate constants calculated, using the Eyring equation, are 1.2 × 10−1 and 3.9 × 10−4 (s−1). These values allow estimating a value of 3.3 × 10−3 for the inhibition constant, in good agreement with the experimental value.
Collapse
Affiliation(s)
- Ignacio Lizana
- Grupo QTC, Departamento de Físico-Química, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile.,Millennium Nucleus on Catalytic Processes Towards Sustainable Chemistry, 4070386, Santiago, Chile
| | - Elena A Uribe
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Eduardo J Delgado
- Grupo QTC, Departamento de Físico-Química, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile. .,Millennium Nucleus on Catalytic Processes Towards Sustainable Chemistry, 4070386, Santiago, Chile.
| |
Collapse
|
3
|
Das CK, Nair NN. Elucidating the Molecular Basis of Avibactam‐Mediated Inhibition of Class A β‐Lactamases. Chemistry 2020; 26:9639-9651. [DOI: 10.1002/chem.202001261] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 04/10/2020] [Indexed: 12/25/2022]
Affiliation(s)
- Chandan Kumar Das
- Department of ChemistryIndian Institute of Technology Kanpur Kanpur 208016 India
- Current Address: Lehrstuhl für Theoretische ChemieRuhr Universität Bochum 44780 Bochum Germany
| | - Nisanth N. Nair
- Department of ChemistryIndian Institute of Technology Kanpur Kanpur 208016 India
| |
Collapse
|
4
|
Lizana I, Ortiz-López D, Delgado-Hurtado A, Delgado EJ. Theoretical Evidence for the Nonoccurrence of Tetrahedral Intermediates in the Deacylation Pathway of the Oxacillinase-24/Avibactam Complex. ACS OMEGA 2019; 4:21954-21961. [PMID: 31891074 PMCID: PMC6933777 DOI: 10.1021/acsomega.9b03022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 11/27/2019] [Indexed: 05/10/2023]
Abstract
Oxacillinases (OXAs) β-lactamases are of special interest because of their capacity to hydrolyze antibacterial drugs such as cephalosporins and carbapenems, which are frequently used as the last option for the treatment of multidrug-resistant bacteria. Although the comprehension of the involved mechanisms at the atomic level is crucial for the rational design of new inhibitors and antibiotics, currently there is no study on the acylation/deacylation mechanisms of the OXA-24/avibactam complex from first principles; therefore, mechanistic details such as activation barriers, characterization of intermediates, and transition states are still uncertain. In this article, we address the deacylation of the OXA-24/avibactam complex by molecular dynamics simulations and hybrid quantum mechanics/molecular mechanics computations. The study supplies mechanistic details not available so far, namely, topology of the potential energy surfaces, characterization of transition states and intermediates, and calculation of the respective activation barriers. The results show that the deacylation occurs via a mechanism of two stages; the first one involves the formation of a dianionic intermediate with a computed activation barrier of 24 kcal/mol. The second stage corresponds to the cleavage of the OS81-C bond promoted by the protonation of the OS81 atom by the carboxylated Lys84 and the concomitant formation of the C7-N6 bond, allowing the liberation of avibactam and recovery of the enzyme. The calculated activation barrier for the second stage is 13 kcal/mol. The structure of the intermediate, formed in the first stage, does not fulfill the characteristics of a tetrahedral intermediate. These results suggest that the recyclization of avibactam from the OXA-24/avibactam complex may occur without the emergence of tetrahedral intermediates, unlike that observed in the class A CTX-M-15.
Collapse
Affiliation(s)
- Ignacio Lizana
- QTC
Group, Department of Physical-Chemistry, Faculty of Chemical
Sciences and Department of Biochemistry and Molecular Biology, Faculty of Biological
Sciences, Universidad de Concepción, Concepción 4070386, Chile
| | - Diego Ortiz-López
- QTC
Group, Department of Physical-Chemistry, Faculty of Chemical
Sciences and Department of Biochemistry and Molecular Biology, Faculty of Biological
Sciences, Universidad de Concepción, Concepción 4070386, Chile
| | - Aleksei Delgado-Hurtado
- QTC
Group, Department of Physical-Chemistry, Faculty of Chemical
Sciences and Department of Biochemistry and Molecular Biology, Faculty of Biological
Sciences, Universidad de Concepción, Concepción 4070386, Chile
| | - Eduardo J. Delgado
- QTC
Group, Department of Physical-Chemistry, Faculty of Chemical
Sciences and Department of Biochemistry and Molecular Biology, Faculty of Biological
Sciences, Universidad de Concepción, Concepción 4070386, Chile
- Millenium
Nucleus on Catalytic Processes Toward Sustainable Chemistry, Santiago 4070386, Chile
- E-mail:
| |
Collapse
|
5
|
Structural Insights into the Inhibition of the Extended-Spectrum β-Lactamase PER-2 by Avibactam. Antimicrob Agents Chemother 2019; 63:AAC.00487-19. [PMID: 31235626 DOI: 10.1128/aac.00487-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 06/17/2019] [Indexed: 02/07/2023] Open
Abstract
The diazabicyclooctane (DBO) avibactam (AVI) reversibly inactivates most serine-β-lactamases. Previous investigations showed that inhibition constants of AVI toward class A PER-2 are reminiscent of values observed for class C and D β-lactamases (i.e., k 2/K of ≈103 M-1 s-1) but lower than other class A β-lactamases (i.e., k 2/K = 104 to 105 M-1 s-1). Herein, biochemical and structural studies were conducted with PER-2 and AVI to explore these differences. Furthermore, biochemical studies on Arg220 and Thr237 variants with AVI were conducted to gain deeper insight into the mechanism of PER-2 inactivation. The main biochemical and structural observations revealed the following: (i) both amino-acid substitutions in Arg220 and the rich hydrophobic content in the active site hinder the binding of catalytic waters and acylation, impairing AVI inhibition; (ii) movement of Ser130 upon binding of AVI favors the formation of a hydrogen bond with the sulfate group of AVI; and (iii) the Thr237Ala substitution alters the AVI inhibition constants. The acylation constant (k 2/K) of PER-2 by AVI is primarily influenced by stabilizing hydrogen bonds involving AVI and important residues such as Thr237 and Arg220. (Variants in Arg220 demonstrate a dramatic reduction in k 2/K) We also observed that displacement of Ser130 side chain impairs AVI acylation, an observation not made in other extended-spectrum β-lactamases (ESBLs). Comparatively, relebactam combined with a β-lactam is more potent against Escherichia coli producing PER-2 variants than β-lactam-AVI combinations. Our findings provide a rationale for evaluating the utility of the currently available DBO inhibitors against unique ESBLs like PER-2 and anticipate the effectiveness of these inhibitors toward variants that may eventually be selected upon AVI usage.
Collapse
|
6
|
Lizana I, Delgado EJ. Molecular Insights on the Release of Avibactam from the Acyl-Enzyme Complex. Biophys J 2019; 116:1650-1657. [PMID: 31010666 DOI: 10.1016/j.bpj.2019.03.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 02/13/2019] [Accepted: 03/06/2019] [Indexed: 02/06/2023] Open
Abstract
Avibactam is a non-β-lactam β-lactamase inhibitor for treating complicated urinary tract and respiratory infections caused by multidrug-resistant bacterial pathogens, a serious public health threat. Despite its importance, the release mechanism of avibactam from the enzyme-inhibitor complex has been scarcely studied from first principles, considering the total protein environment. This information at the molecular level is essential for the rational design of new antibiotics and inhibitors. In this article, we addressed the release of avibactam from the complex CTX-M-15 by means of molecular dynamics simulations and quantum mechanics/molecular mechanics calculations. This study provides molecular information not available earlier, including exploration of the potential energy surfaces, characterization of the observed intermediate, and their critical points, as well. Our results show that unlike that observed in the acylation reaction, the residues Glu166 and Lys73 would be in their neutral forms. Release of avibactam follows a stepwise mechanism in which the first stage corresponds to the formation of a tetrahedral intermediate, whereas the second stage corresponds to the cleavage of the Ser70-C7 bond, mediated by Lys73, either directly or through Ser130.
Collapse
Affiliation(s)
- Ignacio Lizana
- Departament of Physical Chemistry, Universidad de Concepción, Concepción, Chile
| | - Eduardo J Delgado
- Departament of Physical Chemistry, Universidad de Concepción, Concepción, Chile; Millenium Nucleus on Catalytic Processes toward Sustainable Chemistry, Santiago, Chile.
| |
Collapse
|