1
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Fröhlich C, Bunzel HA, Buda K, Mulholland AJ, van der Kamp MW, Johnsen PJ, Leiros HKS, Tokuriki N. Epistasis arises from shifting the rate-limiting step during enzyme evolution of a β-lactamase. Nat Catal 2024; 7:499-509. [PMID: 38828429 PMCID: PMC11136654 DOI: 10.1038/s41929-024-01117-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 01/25/2024] [Indexed: 06/05/2024]
Abstract
Epistasis, the non-additive effect of mutations, can provide combinatorial improvements to enzyme activity that substantially exceed the gains from individual mutations. Yet the molecular mechanisms of epistasis remain elusive, undermining our ability to predict pathogen evolution and engineer biocatalysts. Here we reveal how directed evolution of a β-lactamase yielded highly epistatic activity enhancements. Evolution selected four mutations that increase antibiotic resistance 40-fold, despite their marginal individual effects (≤2-fold). Synergistic improvements coincided with the introduction of super-stochiometric burst kinetics, indicating that epistasis is rooted in the enzyme's conformational dynamics. Our analysis reveals that epistasis stemmed from distinct effects of each mutation on the catalytic cycle. The initial mutation increased protein flexibility and accelerated substrate binding, which is rate-limiting in the wild-type enzyme. Subsequent mutations predominantly boosted the chemical steps by fine-tuning substrate interactions. Our work identifies an overlooked cause for epistasis: changing the rate-limiting step can result in substantial synergy that boosts enzyme activity.
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Affiliation(s)
| | - H. Adrian Bunzel
- Department of Biosystem Science and Engineering, ETH Zurich, Basel, Switzerland
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, UK
- School of Biochemistry, University of Bristol, Bristol, UK
| | - Karol Buda
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia Canada
| | - Adrian J. Mulholland
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, UK
| | - Marc W. van der Kamp
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, UK
- School of Biochemistry, University of Bristol, Bristol, UK
| | - Pål J. Johnsen
- Department of Pharmacy, UiT The Arctic University of Norway, Tromsø, Norway
| | | | - Nobuhiko Tokuriki
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia Canada
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2
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Zhou Q, Catalán P, Bell H, Baumann P, Cooke R, Evans R, Yang J, Zhang Z, Zappalà D, Zhang Y, Blackburn GM, He Y, Jin Y. An Ion-Pair Induced Intermediate Complex Captured in Class D Carbapenemase Reveals Chloride Ion as a Janus Effector Modulating Activity. ACS CENTRAL SCIENCE 2023; 9:2339-2349. [PMID: 38161376 PMCID: PMC10755735 DOI: 10.1021/acscentsci.3c00609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 11/17/2023] [Accepted: 11/17/2023] [Indexed: 01/03/2024]
Abstract
Antibiotic-resistant Enterobacterales that produce oxacillinase (OXA)-48-like Class D β-lactamases are often linked to increased clinical mortality. Though the catalytic mechanism of OXA-48 is known, the molecular origin of its biphasic kinetics has been elusive. We here identify selective chloride binding rather than decarbamylation of the carbamylated lysine as the source of biphasic kinetics, utilizing isothermal titration calorimetry (ITC) to monitor the complete reaction course with the OXA-48 variant having a chemically stable N-acetyl lysine. Further structural investigation enables us to capture an unprecedented inactive acyl intermediate wedged in place by a halide ion paired with a conserved active site arginine. Supported by mutagenesis and mathematical simulation, we identify chloride as a "Janus effector" that operates by allosteric activation of the burst phase and by inhibition of the steady state in kinetic assays of β-lactams. We show that chloride-induced biphasic kinetics directly affects antibiotic efficacy and facilitates the differentiation of clinical isolates encoding Class D from Class A and B carbapenemases. As chloride is present in laboratory and clinical procedures, our discovery greatly expands the roles of chloride in modulating enzyme catalysis and highlights its potential impact on the pharmacokinetics and efficacy of antibiotics during in vivo treatment.
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Affiliation(s)
- Qi Zhou
- Key
Laboratory of Synthetic and Natural Functional Molecule, College of
Chemistry and Materials Science, Northwest
University, Xi’an 710127, P. R. China
| | - Pablo Catalán
- Grupo
Interdisciplinar de Sistemas Complejos, Departamento de Matemáticas, Universidad Carlos III de Madrid, 28911 Leganés, Spain
| | - Helen Bell
- School
of Chemistry, Cardiff University, Cardiff, CF10 3AT, United Kingdom
| | - Patrick Baumann
- School
of Chemistry, Cardiff University, Cardiff, CF10 3AT, United Kingdom
- Manchester
Institute of Biotechnology, University of
Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Rebekah Cooke
- School
of Chemistry, Cardiff University, Cardiff, CF10 3AT, United Kingdom
| | - Rhodri Evans
- School
of Chemistry, Cardiff University, Cardiff, CF10 3AT, United Kingdom
- Manchester
Institute of Biotechnology, University of
Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Jianhua Yang
- Key
Laboratory of Synthetic and Natural Functional Molecule, College of
Chemistry and Materials Science, Northwest
University, Xi’an 710127, P. R. China
| | - Zhen Zhang
- Key
Laboratory of Synthetic and Natural Functional Molecule, College of
Chemistry and Materials Science, Northwest
University, Xi’an 710127, P. R. China
- School
of Chemistry, Cardiff University, Cardiff, CF10 3AT, United Kingdom
| | - Davide Zappalà
- School
of Chemistry, Cardiff University, Cardiff, CF10 3AT, United Kingdom
| | - Ye Zhang
- Key
Laboratory of Synthetic and Natural Functional Molecule, College of
Chemistry and Materials Science, Northwest
University, Xi’an 710127, P. R. China
| | - George Michael Blackburn
- School
of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, United Kingdom
| | - Yuan He
- Key
Laboratory of Synthetic and Natural Functional Molecule, College of
Chemistry and Materials Science, Northwest
University, Xi’an 710127, P. R. China
| | - Yi Jin
- School
of Chemistry, Cardiff University, Cardiff, CF10 3AT, United Kingdom
- Manchester
Institute of Biotechnology, University of
Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
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3
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Yin C, Song Z, Tian H, Palzkill T, Tao P. Unveiling the structural features that regulate carbapenem deacylation in KPC-2 through QM/MM and interpretable machine learning. Phys Chem Chem Phys 2023; 25:1349-1362. [PMID: 36537692 PMCID: PMC11162551 DOI: 10.1039/d2cp03724f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Resistance to carbapenem β-lactams presents major clinical and economical challenges for the treatment of pathogen infections. The fast hydrolysis of carbapenems by carbapenemase-producing bacterial strains enables the effective deactivation of carbapenem antibiotics. In this study, we aim to unravel the structural features that distinguish the notable deacylation activity of carbapenemases. The deacylation reactions between imipenem (IPM) and the KPC-2 class A serine-based β-lactamases (ASβLs) are modeled with combined quantum mechanical/molecular mechanical (QM/MM) minimum energy pathway (MEP) calculations and interpretable machine-learning (ML) methods. We first applied a dual-level computational protocol to achieve fast sampling of QM/MM MEPs. A tree-based ensemble ML model was employed to learn the MEP activation barriers from the conformational features of the KPC-2/IPM active site. The barrier-predicting model was then unboxed using the Shapley additive explanation (SHAP) importance attribution methods to derive mechanistic insights, which were also verified by additional QM/MM wavefunction analysis. Essentially, we show that potential hydrogen bonding interactions of the general base and the tautomerization states of the carbapenem pyrroline ring could concertedly regulate the activation barrier of KPC-2/IPM deacylation. Nonetheless, we demonstrate the efficacy of interpretable ML to assist the analysis of QM/MM simulation data for robust extraction of human-interpretable mechanistic insights.
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Affiliation(s)
- Chao Yin
- Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, Texas, 75205, USA.
| | - Zilin Song
- Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, Texas, 75205, USA.
| | - Hao Tian
- Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, Texas, 75205, USA.
| | - Timothy Palzkill
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Peng Tao
- Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, Texas, 75205, USA.
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4
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OXA-48-Like β-Lactamases: Global Epidemiology, Treatment Options, and Development Pipeline. Antimicrob Agents Chemother 2022; 66:e0021622. [PMID: 35856662 PMCID: PMC9380527 DOI: 10.1128/aac.00216-22] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Modern medicine is threatened by the rising tide of antimicrobial resistance, especially among Gram-negative bacteria, where resistance to β-lactams is most often mediated by β-lactamases. The penicillin and cephalosporin ascendancies were, in their turn, ended by the proliferation of TEM penicillinases and CTX-M extended-spectrum β-lactamases. These class A β-lactamases have long been considered the most important. For carbapenems, however, the threat is increasingly from the insidious rise of a class D carbapenemase, OXA-48, and its close relatives. Over the past 20 years, OXA-48 and "OXA-48-like" enzymes have proliferated to become the most prevalent enterobacterial carbapenemases across much of Europe, Northern Africa, and the Middle East. OXA-48-like enzymes are notoriously difficult to detect because they often cause only low-level in vitro resistance to carbapenems, meaning that the true burden is likely underestimated. Despite this, they are associated with carbapenem treatment failures. A highly conserved incompatibility complex IncL plasmid scaffold often carries blaOXA-48 and may carry other antimicrobial resistance genes, leaving limited treatment options. High conjugation efficiency means that this plasmid is sometimes carried by multiple Enterobacterales in a single patient. Producers evade most β-lactam-β-lactamase inhibitor combinations, though promising agents have recently been licensed, notably ceftazidime-avibactam and cefiderocol. The molecular machinery enabling global spread, current treatment options, and the development pipeline of potential new therapies for Enterobacterales that produce OXA-48-like β-lactamases form the focus of this review.
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5
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Chudyk EI, Beer M, Limb MAL, Jones CA, Spencer J, van der Kamp MW, Mulholland AJ. QM/MM Simulations Reveal the Determinants of Carbapenemase Activity in Class A β-Lactamases. ACS Infect Dis 2022; 8:1521-1532. [PMID: 35877936 PMCID: PMC9379904 DOI: 10.1021/acsinfecdis.2c00152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Indexed: 11/28/2022]
Abstract
β-lactam antibiotic resistance in Gram-negative bacteria, primarily caused by β-lactamase enzymes that hydrolyze the β-lactam ring, has become a serious clinical problem. Carbapenems were formerly considered "last resort" antibiotics because they escaped breakdown by most β-lactamases, due to slow deacylation of the acyl-enzyme intermediate. However, an increasing number of Gram-negative bacteria now produce β-lactamases with carbapenemase activity: these efficiently hydrolyze the carbapenem β-lactam ring, severely limiting the treatment of some bacterial infections. Here, we use quantum mechanics/molecular mechanics (QM/MM) simulations of the deacylation reactions of acyl-enzyme complexes of eight β-lactamases of class A (the most widely distributed β-lactamase group) with the carbapenem meropenem to investigate differences between those inhibited by carbapenems (TEM-1, SHV-1, BlaC, and CTX-M-16) and those that hydrolyze them (SFC-1, KPC-2, NMC-A, and SME-1). QM/MM molecular dynamics simulations confirm the two enzyme groups to differ in the preferred acyl-enzyme orientation: carbapenem-inhibited enzymes favor hydrogen bonding of the carbapenem hydroxyethyl group to deacylating water (DW). QM/MM simulations of deacylation give activation free energies in good agreement with experimental hydrolysis rates, correctly distinguishing carbapenemases. For the carbapenem-inhibited enzymes, free energies for deacylation are significantly higher than for the carbapenemases, even when the hydroxyethyl group was restrained to prevent interaction with the DW. Analysis of these simulations, and additional simulations of mutant enzymes, shows how factors including the hydroxyethyl orientation, the active site volume, and architecture (conformations of Asn170 and Asn132; organization of the oxyanion hole; and the Cys69-Cys238 disulfide bond) collectively determine catalytic efficiency toward carbapenems.
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Affiliation(s)
- Ewa I. Chudyk
- Centre
for Computational Chemistry, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Michael Beer
- Centre
for Computational Chemistry, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
- School
of Cellular and Molecular Medicine, University
of Bristol Medical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - Michael A. L. Limb
- Centre
for Computational Chemistry, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Charlotte A. Jones
- Centre
for Computational Chemistry, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - James Spencer
- School
of Cellular and Molecular Medicine, University
of Bristol Medical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - Marc W. van der Kamp
- Centre
for Computational Chemistry, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
- School
of Biochemistry, University of Bristol Medical
Sciences Building, University Walk, Bristol BS8 1TD, United
Kingdom
| | - Adrian J. Mulholland
- Centre
for Computational Chemistry, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
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6
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Affiliation(s)
- Vaishali Thakkur
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Chandan Kumar Das
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Nisanth N. Nair
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
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7
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Avci FG, Tastekil I, Jaisi A, Ozbek Sarica P, Sariyar Akbulut B. A review on the mechanistic details of OXA enzymes of ESKAPE pathogens. Pathog Glob Health 2022; 117:219-234. [PMID: 35758005 PMCID: PMC10081068 DOI: 10.1080/20477724.2022.2088496] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
Abstract
The production of β-lactamases is a prevalent mechanism that poses serious pressure on the control of bacterial resistance. Furthermore, the unavoidable and alarming increase in the transmission of bacteria producing extended-spectrum β-lactamases complicates treatment alternatives with existing drugs and/or approaches. Class D β-lactamases, designated as OXA enzymes, are characterized by their activity specifically towards oxacillins. They are widely distributed among the ESKAPE bugs that are associated with antibiotic resistance and life-threatening hospital infections. The inadequacy of current β-lactamase inhibitors for conventional treatments of 'OXA' mediated infections confirms the necessity of new approaches. Here, the focus is on the mechanistic details of OXA-10, OXA-23, and OXA-48, commonly found in highly virulent and antibiotic-resistant pathogens Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Enterobacter spp. to describe their similarities and differences. Furthermore, this review contains a specific emphasis on structural and computational perspectives, which will be valuable to guide efforts in the design/discovery of a common single-molecule drug against ESKAPE pathogens.
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Affiliation(s)
- Fatma Gizem Avci
- Bioengineering Department, Uskudar University, Uskudar, 34662, Turkey
| | - Ilgaz Tastekil
- Bioengineering Department, Marmara University, Kadikoy, 34722, Turkey
| | - Amit Jaisi
- Drug and Cosmetics Excellence Center, School of Pharmacy, Walailak University, 80160, Nakhon Si Thammarat, Thailand
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8
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Galvani F, Scalvini L, Rivara S, Lodola A, Mor M. Mechanistic Modeling of Monoglyceride Lipase Covalent Modification Elucidates the Role of Leaving Group Expulsion and Discriminates Inhibitors with High and Low Potency. J Chem Inf Model 2022; 62:2771-2787. [PMID: 35580195 PMCID: PMC9198976 DOI: 10.1021/acs.jcim.2c00140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Inhibition of monoglyceride
lipase (MGL), also known as monoacylglycerol
lipase (MAGL), has emerged as a promising approach for treating neurological
diseases. To gain useful insights in the design of agents with balanced
potency and reactivity, we investigated the mechanism of MGL carbamoylation
by the reference triazole urea SAR629 (IC50 = 0.2 nM) and
two recently described inhibitors featuring a pyrazole (IC50 = 1800 nM) or a 4-cyanopyrazole (IC50 = 8 nM) leaving
group (LG), using a hybrid quantum mechanics/molecular mechanics (QM/MM)
approach. Opposite to what was found for substrate 2-arachidonoyl-sn-glycerol (2-AG), covalent modification of MGL by azole
ureas is controlled by LG expulsion. Simulations indicated that changes
in the electronic structure of the LG greatly affect reaction energetics
with triazole and 4-cyanopyrazole inhibitors following a more accessible
carbamoylation path compared to the unsubstituted pyrazole derivative.
The computational protocol provided reaction barriers able to discriminate
between MGL inhibitors with different potencies. These results highlight
how QM/MM simulations can contribute to elucidating structure–activity
relationships and provide insights for the design of covalent inhibitors.
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Affiliation(s)
- Francesca Galvani
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A, I-43124 Parma, Italy
| | - Laura Scalvini
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A, I-43124 Parma, Italy
| | - Silvia Rivara
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A, I-43124 Parma, Italy
| | - Alessio Lodola
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A, I-43124 Parma, Italy
| | - Marco Mor
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A, I-43124 Parma, Italy.,Microbiome Research Hub, University of Parma, Parco Area delle Scienze 11/A, I-43124 Parma, Italy
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9
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Hirvonen VA, Weizmann TM, Mulholland AJ, Spencer J, van der Kamp MW. Multiscale Simulations Identify Origins of Differential Carbapenem Hydrolysis by the OXA-48 β-Lactamase. ACS Catal 2022; 12:4534-4544. [PMID: 35571461 PMCID: PMC9097296 DOI: 10.1021/acscatal.1c05694] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 03/22/2022] [Indexed: 12/27/2022]
Abstract
OXA-48 β-lactamases are frequently encountered in bacterial infections caused by carbapenem-resistant Gram-negative bacteria. Due to the importance of carbapenems in the treatment of healthcare-associated infections and the increasingly wide dissemination of OXA-48-like enzymes on plasmids, these β-lactamases are of high clinical significance. Notably, OXA-48 hydrolyzes imipenem more efficiently than other commonly used carbapenems, such as meropenem. Here, we use extensive multiscale simulations of imipenem and meropenem hydrolysis by OXA-48 to dissect the dynamics and to explore differences in the reactivity of the possible conformational substates of the respective acylenzymes. Quantum mechanics/molecular mechanics (QM/MM) simulations of the deacylation reaction for both substrates demonstrate that deacylation is favored when the 6α-hydroxyethyl group is able to hydrogen bond to the water molecule responsible for deacylation but disfavored by the increasing hydration of either oxygen of the carboxylated Lys73 general base. Differences in free energy barriers calculated from the QM/MM simulations correlate well with the experimentally observed differences in hydrolytic efficiency between meropenem and imipenem. We conclude that the impaired breakdown of meropenem, compared to imipenem, which arises from a subtle change in the hydrogen bonding pattern between the deacylating water molecule and the antibiotic, is most likely induced by the meropenem 1β-methyl group. In addition to increased insights into carbapenem breakdown by OXA β-lactamases, which may aid in future efforts to design antibiotics or inhibitors, our approach exemplifies the combined use of atomistic simulations in determining the possible different enzyme-substrate substates and their influence on enzyme reaction kinetics.
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Affiliation(s)
- Viivi
H. A. Hirvonen
- School
of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, U.K.
- Centre
for Computational Chemistry, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
| | - Tal Moshe Weizmann
- School
of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, U.K.
| | - Adrian J. Mulholland
- Centre
for Computational Chemistry, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
| | - James Spencer
- School
of Cellular and Molecular Medicine, University
of Bristol, University
Walk, Bristol BS8 1TD, U.K.
| | - Marc W. van der Kamp
- School
of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, U.K.
- Centre
for Computational Chemistry, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
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10
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Mora-Ochomogo M, Lohans CT. β-Lactam antibiotic targets and resistance mechanisms: from covalent inhibitors to substrates. RSC Med Chem 2021; 12:1623-1639. [PMID: 34778765 PMCID: PMC8528271 DOI: 10.1039/d1md00200g] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 07/25/2021] [Indexed: 12/24/2022] Open
Abstract
The β-lactams are the most widely used antibacterial agents worldwide. These antibiotics, a group that includes the penicillins and cephalosporins, are covalent inhibitors that target bacterial penicillin-binding proteins and disrupt peptidoglycan synthesis. Bacteria can achieve resistance to β-lactams in several ways, including the production of serine β-lactamase enzymes. While β-lactams also covalently interact with serine β-lactamases, these enzymes are capable of deacylating this complex, treating the antibiotic as a substrate. In this tutorial-style review, we provide an overview of the β-lactam antibiotics, focusing on their covalent interactions with their target proteins and resistance mechanisms. We begin by describing the structurally diverse range of β-lactam antibiotics and β-lactamase inhibitors that are currently used as therapeutics. Then, we introduce the penicillin-binding proteins, describing their functions and structures, and highlighting their interactions with β-lactam antibiotics. We next describe the classes of serine β-lactamases, exploring some of the mechanisms by which they achieve the ability to degrade β-lactams. Finally, we introduce the l,d-transpeptidases, a group of bacterial enzymes involved in peptidoglycan synthesis which are also targeted by β-lactam antibiotics. Although resistance mechanisms are now prevalent for all antibiotics in this class, past successes in antibiotic development have at least delayed this onset of resistance. The β-lactams continue to be an essential tool for the treatment of infectious disease, and recent advances (e.g., β-lactamase inhibitor development) will continue to support their future use.
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Affiliation(s)
| | - Christopher T Lohans
- Department of Biomedical and Molecular Sciences, Queen's University Kingston ON K7L 3N6 Canada
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11
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Antimicrobial Resistance Conferred by OXA-48 β-Lactamases: Towards a Detailed Mechanistic Understanding. Antimicrob Agents Chemother 2021; 65:AAC.00184-21. [PMID: 33753332 DOI: 10.1128/aac.00184-21] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
OXA-48-type β-lactamases are now routinely encountered in bacterial infections caused by carbapenem-resistant Enterobacterales These enzymes are of high and growing clinical significance due to the importance of carbapenems in treatment of health care-associated infections by Gram-negative bacteria, the wide and increasing dissemination of OXA-48 enzymes on plasmids, and the challenges posed by their detection. OXA-48 confers resistance to penicillin (which is efficiently hydrolyzed) and carbapenem antibiotics (which is more slowly broken down). In addition to the parent enzyme, a growing array of variants of OXA-48 is now emerging. The spectrum of activity of these variants varies, with some hydrolyzing expanded-spectrum oxyimino-cephalosporins. The growth in importance and diversity of the OXA-48 group has motivated increasing numbers of studies that aim to elucidate the relationship between structure and specificity and establish the mechanistic basis for β-lactam turnover in this enzyme family. In this review, we collate recently published structural, kinetic, and mechanistic information on the interactions between clinically relevant β-lactam antibiotics and inhibitors and OXA-48 β-lactamases. Collectively, these studies are starting to form a detailed picture of the underlying bases for the differences in β-lactam specificity between OXA-48 variants and the consequent differences in resistance phenotype. We focus specifically on aspects of carbapenemase and cephalosporinase activities of OXA-48 β-lactamases and discuss β-lactamase inhibitor development in this context. Throughout the review, we also outline key open research questions for future investigation.
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12
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Abstract
Very low antibiotic concentrations have been shown to drive the evolution of antimicrobial resistance. While substantial progress has been made to understand the driving role of low concentrations during resistance development for different antimicrobial classes, the importance of β-lactams, the most commonly used antibiotics, is still poorly studied. Our current understanding of how low antibiotic concentrations shape the evolution of contemporary β-lactamases is limited. Using the widespread carbapenemase OXA-48, we tested the long-standing hypothesis that selective compartments with low antibiotic concentrations cause standing genetic diversity that could act as a gateway to developing clinical resistance. Here, we subjected Escherichia coli expressing blaOXA-48, on a clinical plasmid, to experimental evolution at sub-MICs of ceftazidime. We identified and characterized seven single variants of OXA-48. Susceptibility profiles and dose-response curves showed that they increased resistance only marginally. However, in competition experiments at sub-MICs of ceftazidime, they demonstrated strong selectable fitness benefits. Increased resistance was also reflected in elevated catalytic efficiencies toward ceftazidime. These changes are likely caused by enhanced flexibility of the Ω- and β5-β6 loops and fine-tuning of preexisting active site residues. In conclusion, low-level concentrations of β-lactams can drive the evolution of β-lactamases through cryptic phenotypes which may act as stepping-stones toward clinical resistance. IMPORTANCE Very low antibiotic concentrations have been shown to drive the evolution of antimicrobial resistance. While substantial progress has been made to understand the driving role of low concentrations during resistance development for different antimicrobial classes, the importance of β-lactams, the most commonly used antibiotics, is still poorly studied. Here, we shed light on the evolutionary impact of low β-lactam concentrations on the widespread β-lactamase OXA-48. Our data indicate that the exposure to β-lactams at very low concentrations enhances β-lactamase diversity and drives the evolution of β-lactamases by significantly influencing their substrate specificity. Thus, in contrast to high concentrations, low levels of these drugs may substantially contribute to the diversification and divergent evolution of these enzymes, providing a standing genetic diversity that can be selected and mobilized when antibiotic pressure increases.
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13
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Stojanoski V, Hu L, Sankaran B, Wang F, Tao P, Prasad BVV, Palzkill T. Mechanistic Basis of OXA-48-like β-Lactamases' Hydrolysis of Carbapenems. ACS Infect Dis 2021; 7:445-460. [PMID: 33492952 DOI: 10.1021/acsinfecdis.0c00798] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Carbapenem-hydrolyzing class D β-lactamases (CHDLs) are an important source of resistance to these last resort β-lactam antibiotics. OXA-48 is a member of a group of CHDLs named OXA-48-like enzymes. On the basis of sequence similarity, OXA-163 can be classified as an OXA-48-like enzyme, but it has altered substrate specificity. Compared to OXA-48, it shows impaired activity for carbapenems but displays an enhanced hydrolysis of oxyimino-cephalosporins. Here, we address the mechanistic and structural basis for carbapenem hydrolysis by OXA-48-like enzymes. Pre-steady-state kinetic analysis indicates that the rate-limiting step for OXA-48 and OXA-163 hydrolysis of carbapenems is deacylation and that the greatly reduced carbapenemase activity of OXA-163 compared to that of OXA-48 is due entirely to a slower deacylation reaction. Furthermore, our structural data indicate that the positioning of the β5-β6 loop is necessary for carbapenem hydrolysis by OXA-48. A major difference between the OXA-48 and OXA-163 complexes with carbapenems is that the 214-RIEP-217 deletion in OXA-163 creates a large opening in the active site that is absent in the OXA-48/carbapenem structures. We propose that the larger active site results in less constraint on the conformation of the 6α-hydroxyethyl group in the acyl-enzyme. The acyl-enzyme intermediate assumes multiple conformations, most of which are incompatible with rapid deacylation. Consistent with this hypothesis, molecular dynamics simulations indicate that the most stable complex is formed between OXA-48 and imipenem, which correlates with the OXA-48 hydrolysis of imipenem being the fastest observed. Furthermore, the OXA-163 complexes with imipenem and meropenem are the least stable and show significant conformational fluctuations, which correlates with the slow hydrolysis of these substrates.
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Affiliation(s)
| | | | - Banumathi Sankaran
- Department of Molecular Biophysics and Integrated Bioimaging, Berkeley Center for Structural Biology, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States,
| | - Feng Wang
- Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, Texas 75205, United States
| | - Peng Tao
- Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, Texas 75205, United States
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Scalvini L, Ghidini A, Lodola A, Callegari D, Rivara S, Piomelli D, Mor M. N-Acylethanolamine Acid Amidase (NAAA): Mechanism of Palmitoylethanolamide Hydrolysis Revealed by Mechanistic Simulations. ACS Catal 2020. [DOI: 10.1021/acscatal.0c02903] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Laura Scalvini
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle scienze 27/A, I-43124 Parma, Italy
| | - Andrea Ghidini
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle scienze 27/A, I-43124 Parma, Italy
| | - Alessio Lodola
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle scienze 27/A, I-43124 Parma, Italy
| | - Donatella Callegari
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle scienze 27/A, I-43124 Parma, Italy
| | - Silvia Rivara
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle scienze 27/A, I-43124 Parma, Italy
| | - Daniele Piomelli
- Department of Anatomy and Neurobiology, University of California, Irvine, California 92697-4625, United States
- Department of Pharmaceutical Sciences, University of California, Irvine, California 92697-4625, United States
- Department of Biological Chemistry and Molecular Biology, University of California, Irvine, California 92697-4625, United States
| | - Marco Mor
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle scienze 27/A, I-43124 Parma, Italy
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