1
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Tooke C, Hinchliffe P, Beer M, Zinovjev K, Colenso CK, Schofield CJ, Mulholland AJ, Spencer J. Tautomer-Specific Deacylation and Ω-Loop Flexibility Explain the Carbapenem-Hydrolyzing Broad-Spectrum Activity of the KPC-2 β-Lactamase. J Am Chem Soc 2023; 145:7166-7180. [PMID: 36972204 PMCID: PMC10080687 DOI: 10.1021/jacs.2c12123] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Indexed: 03/29/2023]
Abstract
KPC-2 (Klebsiella pneumoniae carbapenemase-2) is a globally disseminated serine-β-lactamase (SBL) responsible for extensive β-lactam antibiotic resistance in Gram-negative pathogens. SBLs inactivate β-lactams via a mechanism involving a hydrolytically labile covalent acyl-enzyme intermediate. Carbapenems, the most potent β-lactams, evade the activity of many SBLs by forming long-lived inhibitory acyl-enzymes; however, carbapenemases such as KPC-2 efficiently deacylate carbapenem acyl-enzymes. We present high-resolution (1.25-1.4 Å) crystal structures of KPC-2 acyl-enzymes with representative penicillins (ampicillin), cephalosporins (cefalothin), and carbapenems (imipenem, meropenem, and ertapenem) obtained utilizing an isosteric deacylation-deficient mutant (E166Q). The mobility of the Ω-loop (residues 165-170) negatively correlates with antibiotic turnover rates (kcat), highlighting the role of this region in positioning catalytic residues for efficient hydrolysis of different β-lactams. Carbapenem-derived acyl-enzyme structures reveal the predominance of the Δ1-(2R) imine rather than the Δ2 enamine tautomer. Quantum mechanics/molecular mechanics molecular dynamics simulations of KPC-2:meropenem acyl-enzyme deacylation used an adaptive string method to differentiate the reactivity of the two isomers. These identify the Δ1-(2R) isomer as having a significantly (7 kcal/mol) higher barrier than the Δ2 tautomer for the (rate-determining) formation of the tetrahedral deacylation intermediate. Deacylation is therefore likely to proceed predominantly from the Δ2, rather than the Δ1-(2R) acyl-enzyme, facilitated by tautomer-specific differences in hydrogen-bonding networks involving the carbapenem C-3 carboxylate and the deacylating water and stabilization by protonated N-4, accumulating a negative charge on the Δ2 enamine-derived oxyanion. Taken together, our data show how the flexible Ω-loop helps confer broad-spectrum activity upon KPC-2, while carbapenemase activity stems from efficient deacylation of the Δ2-enamine acyl-enzyme tautomer.
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Affiliation(s)
- Catherine
L. Tooke
- School
of Cellular and Molecular Medicine, Biomedical Sciences
Building, University Walk, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Philip Hinchliffe
- School
of Cellular and Molecular Medicine, Biomedical Sciences
Building, University Walk, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Michael Beer
- School
of Cellular and Molecular Medicine, Biomedical Sciences
Building, University Walk, University of Bristol, Bristol BS8 1TD, United Kingdom
- Centre
for Computational Chemistry, School of Chemistry, Cantock’s
Close, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Kirill Zinovjev
- School
of Biochemistry, Biomedical Sciences Building, University
Walk, University of Bristol, Bristol BS8 1TD, United Kingdom
- Departamento
de Química Física, Universitat
de València, Burjassot 46100, Comunitat Valenciana, Spain
| | - Charlotte K. Colenso
- School
of Cellular and Molecular Medicine, Biomedical Sciences
Building, University Walk, University of Bristol, Bristol BS8 1TD, United Kingdom
- Centre
for Computational Chemistry, School of Chemistry, Cantock’s
Close, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Christopher J. Schofield
- Chemistry
Research Laboratory, Department of Chemistry and the Ineos Oxford
Institute for Antimicrobial Research, Mansfield Road, University of Oxford, Oxford OX1 3TA United
Kingdom
| | - Adrian J. Mulholland
- Centre
for Computational Chemistry, School of Chemistry, Cantock’s
Close, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - James Spencer
- School
of Cellular and Molecular Medicine, Biomedical Sciences
Building, University Walk, University of Bristol, Bristol BS8 1TD, United Kingdom
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2
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Fisher JF, Mobashery S. β-Lactams from the Ocean. Mar Drugs 2023; 21:86. [PMID: 36827127 PMCID: PMC9963991 DOI: 10.3390/md21020086] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/21/2023] [Accepted: 01/24/2023] [Indexed: 01/27/2023] Open
Abstract
The title of this essay is as much a question as it is a statement. The discovery of the β-lactam antibiotics-including penicillins, cephalosporins, and carbapenems-as largely (if not exclusively) secondary metabolites of terrestrial fungi and bacteria, transformed modern medicine. The antibiotic β-lactams inactivate essential enzymes of bacterial cell-wall biosynthesis. Moreover, the ability of the β-lactams to function as enzyme inhibitors is of such great medical value, that inhibitors of the enzymes which degrade hydrolytically the β-lactams, the β-lactamases, have equal value. Given this privileged status for the β-lactam ring, it is therefore a disappointment that the exemplification of this ring in marine secondary metabolites is sparse. It may be that biologically active marine β-lactams are there, and simply have yet to be encountered. In this report, we posit a second explanation: that the value of the β-lactam to secure an ecological advantage in the marine environment might be compromised by its close structural similarity to the β-lactones of quorum sensing. The steric and reactivity similarities between the β-lactams and the β-lactones represent an outside-of-the-box opportunity for correlating new structures and new enzyme targets for the discovery of compelling biological activities.
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Affiliation(s)
- Jed F Fisher
- Department of Chemistry & Biochemistry, 354 McCourtney Hall, University of Note Dame, Notre Dame, IN 46656-5670, USA
| | - Shahriar Mobashery
- Department of Chemistry & Biochemistry, 354 McCourtney Hall, University of Note Dame, Notre Dame, IN 46656-5670, USA
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3
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Studentova V, Sudova V, Bitar I, Paskova V, Moravec J, Pompach P, Volny M, Novak P, Hrabak J. Preferred β-lactone synthesis can explain high rate of false-negative results in the detection of OXA-48-like carbapenemases. Sci Rep 2022; 12:22235. [PMID: 36564543 PMCID: PMC9789108 DOI: 10.1038/s41598-022-26735-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
The resistance to carbapenems is usually mediated by enzymes hydrolyzing β-lactam ring. Recently, an alternative way of the modification of the antibiotic, a β-lactone formation by OXA-48-like enzymes, in some carbapenems was identified. We focused our study on a deep analysis of OXA-48-like-producing Enterobacterales, especially strains showing poor hydrolytic activity. In this study, well characterized 74 isolates of Enterobacterales resistant to carbapenems were used. Carbapenemase activity was determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), liquid chromatography/mass spectrometry (LC-MS), Carba-NP test and modified Carbapenem Inactivation Method (mCIM). As meropenem-derived β-lactone possesses the same molecular weight as native meropenem (MW 383.46 g/mol), β-lactonization cannot be directly detected by MALDI-TOF MS. In the spectra, however, the peaks of m/z = 340.5 and 362.5 representing decarboxylated β-lactone and its sodium adduct were detected in 25 out of 35 OXA-48-like producers. In the rest 10 isolates, decarboxylated hydrolytic product (m/z = 358.5) and its sodium adduct (m/z = 380.5) have been detected. The peak of m/z = 362.5 was detected in 3 strains co-producing OXA-48-like and NDM-1 carbapenemases. The respective signal was identified in no strain producing class A or class B carbapenemase alone showing its specificity for OXA-48-like carbapenemases. Using LC-MS, we were able to identify meropenem-derived β-lactone directly according to the different retention time. All strains with a predominant β-lactone production showed negative results of Carba NP test. In this study, we have demonstrated that the strains producing OXA-48-like carbapenemases showing false-negative results using Carba NP test and MALDI-TOF MS preferentially produced meropenem-derived β-lactone. We also identified β-lactone-specific peak in MALDI-TOF MS spectra and demonstrated the ability of LC-MS to detect meropenem-derived β-lactone.
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Affiliation(s)
- Vendula Studentova
- grid.4491.80000 0004 1937 116XBiomedical Center, Faculty of Medicine in Pilsen, Charles University, Alej Svobody 76, 323 00 Pilsen, Czech Republic ,grid.4491.80000 0004 1937 116XDepartment of Microbiology, Faculty of Medicine in Pilsen, Charles University, Alej Svobody 80, 323 00 Pilsen, Czech Republic
| | - Vendula Sudova
- grid.4491.80000 0004 1937 116XBiomedical Center, Faculty of Medicine in Pilsen, Charles University, Alej Svobody 76, 323 00 Pilsen, Czech Republic ,grid.4491.80000 0004 1937 116XDepartment of Clinical Biochemistry and Haematology, Faculty of Medicine in Pilsen, Charles University, Alej Svobody 80, 323 00 Pilsen, Czech Republic
| | - Ibrahim Bitar
- grid.4491.80000 0004 1937 116XBiomedical Center, Faculty of Medicine in Pilsen, Charles University, Alej Svobody 76, 323 00 Pilsen, Czech Republic ,grid.4491.80000 0004 1937 116XDepartment of Microbiology, Faculty of Medicine in Pilsen, Charles University, Alej Svobody 80, 323 00 Pilsen, Czech Republic
| | - Veronika Paskova
- grid.4491.80000 0004 1937 116XBiomedical Center, Faculty of Medicine in Pilsen, Charles University, Alej Svobody 76, 323 00 Pilsen, Czech Republic ,grid.4491.80000 0004 1937 116XDepartment of Microbiology, Faculty of Medicine in Pilsen, Charles University, Alej Svobody 80, 323 00 Pilsen, Czech Republic
| | - Jiri Moravec
- grid.4491.80000 0004 1937 116XBiomedical Center, Faculty of Medicine in Pilsen, Charles University, Alej Svobody 76, 323 00 Pilsen, Czech Republic
| | - Petr Pompach
- grid.418800.50000 0004 0555 4846Institute of Microbiology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Michael Volny
- grid.418800.50000 0004 0555 4846Institute of Microbiology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Petr Novak
- grid.418800.50000 0004 0555 4846Institute of Microbiology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Jaroslav Hrabak
- grid.4491.80000 0004 1937 116XBiomedical Center, Faculty of Medicine in Pilsen, Charles University, Alej Svobody 76, 323 00 Pilsen, Czech Republic ,grid.4491.80000 0004 1937 116XDepartment of Microbiology, Faculty of Medicine in Pilsen, Charles University, Alej Svobody 80, 323 00 Pilsen, Czech Republic
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4
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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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5
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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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6
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C6 Hydroxymethyl-Substituted Carbapenem MA-1-206 Inhibits the Major Acinetobacter baumannii Carbapenemase OXA-23 by Impeding Deacylation. mBio 2022; 13:e0036722. [PMID: 35420470 PMCID: PMC9239083 DOI: 10.1128/mbio.00367-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Acinetobacter baumannii has become a major nosocomial pathogen, as it is often multidrug-resistant, which results in infections characterized by high mortality rates. The bacterium achieves high levels of resistance to β-lactam antibiotics by producing β-lactamases, enzymes which destroy these valuable agents. Historically, the carbapenem family of β-lactam antibiotics have been the drugs of choice for treating A. baumannii infections. However, their effectiveness has been significantly diminished due to the pathogen’s production of carbapenem-hydrolyzing class D β-lactamases (CHDLs); thus, new antibiotics and inhibitors of these enzymes are urgently needed. Here, we describe a new carbapenem antibiotic, MA-1-206, in which the canonical C6 hydroxyethyl group has been replaced with hydroxymethyl. The antimicrobial susceptibility studies presented here demonstrated that this compound is more potent than meropenem and imipenem against A. baumannii producing OXA-23, the most prevalent CHDL of this pathogen, and also against strains producing the CHDL OXA-24/40 and the class B metallo-β-lactamase VIM-2. Our kinetic and mass spectrometry studies revealed that this drug is a reversible inhibitor of OXA-23, where inhibition takes place through a branched pathway. X-ray crystallographic studies, molecular docking, and molecular dynamics simulations of the OXA-23-MA-1-206 complex show that the C6 hydroxymethyl group forms a hydrogen bond with the carboxylated catalytic lysine of OXA-23, effectively preventing deacylation. These results provide a promising strategy for designing a new generation of CHDL-resistant carbapenems to restore their efficacy against deadly A. baumannii infections.
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7
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Lucic A, Malla TR, Calvopiña K, Tooke CL, Brem J, McDonough MA, Spencer J, Schofield CJ. Studies on the Reactions of Biapenem with VIM Metallo β-Lactamases and the Serine β-Lactamase KPC-2. Antibiotics (Basel) 2022; 11:396. [PMID: 35326858 PMCID: PMC8944426 DOI: 10.3390/antibiotics11030396] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/08/2022] [Accepted: 03/09/2022] [Indexed: 02/06/2023] Open
Abstract
Carbapenems are important antibacterials and are both substrates and inhibitors of some β-lactamases. We report studies on the reaction of the unusual carbapenem biapenem, with the subclass B1 metallo-β-lactamases VIM-1 and VIM-2 and the class A serine-β-lactamase KPC-2. X-ray diffraction studies with VIM-2 crystals treated with biapenem reveal the opening of the β-lactam ring to form a mixture of the (2S)-imine and enamine complexed at the active site. NMR studies on the reactions of biapenem with VIM-1, VIM-2, and KPC-2 reveal the formation of hydrolysed enamine and (2R)- and (2S)-imine products. The combined results support the proposal that SBL/MBL-mediated carbapenem hydrolysis results in a mixture of tautomerizing enamine and (2R)- and (2S)-imine products, with the thermodynamically favoured (2S)-imine being the major observed species over a relatively long-time scale. The results suggest that prolonging the lifetimes of β-lactamase carbapenem complexes by optimising tautomerisation of the nascently formed enamine to the (2R)-imine and likely more stable (2S)-imine tautomer is of interest in developing improved carbapenems.
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Affiliation(s)
- Anka Lucic
- Chemistry Research Laboratory, The Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, Oxford OX1 3TA, UK; (A.L.); (T.R.M.); (K.C.); (J.B.); (M.A.M.)
| | - Tika R. Malla
- Chemistry Research Laboratory, The Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, Oxford OX1 3TA, UK; (A.L.); (T.R.M.); (K.C.); (J.B.); (M.A.M.)
| | - Karina Calvopiña
- Chemistry Research Laboratory, The Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, Oxford OX1 3TA, UK; (A.L.); (T.R.M.); (K.C.); (J.B.); (M.A.M.)
| | - Catherine L. Tooke
- Biomedical Sciences Building, School of Cellular and Molecular Medicine, Faculty of Life Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK; (C.L.T.); (J.S.)
| | - Jürgen Brem
- Chemistry Research Laboratory, The Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, Oxford OX1 3TA, UK; (A.L.); (T.R.M.); (K.C.); (J.B.); (M.A.M.)
| | - Michael A. McDonough
- Chemistry Research Laboratory, The Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, Oxford OX1 3TA, UK; (A.L.); (T.R.M.); (K.C.); (J.B.); (M.A.M.)
| | - James Spencer
- Biomedical Sciences Building, School of Cellular and Molecular Medicine, Faculty of Life Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK; (C.L.T.); (J.S.)
| | - Christopher J. Schofield
- Chemistry Research Laboratory, The Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, Oxford OX1 3TA, UK; (A.L.); (T.R.M.); (K.C.); (J.B.); (M.A.M.)
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8
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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: 41] [Impact Index Per Article: 13.7] [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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9
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VanPelt J, Stoffel S, Staude MW, Dempster K, Rose HA, Graney S, Graney E, Braynard S, Kovrigina E, Leonard DA, Peng JW. Arginine Modulates Carbapenem Deactivation by OXA-24/40 in Acinetobacter baumannii. J Mol Biol 2021; 433:167150. [PMID: 34271009 DOI: 10.1016/j.jmb.2021.167150] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Revised: 07/01/2021] [Accepted: 07/06/2021] [Indexed: 12/27/2022]
Abstract
The resistance of Gram-negative bacteria to β-lactam antibiotics stems mainly from β-lactamase proteins that hydrolytically deactivate the β-lactams. Of particular concern are the β-lactamases that can deactivate a class of β-lactams known as carbapenems. Carbapenems are among the few anti-infectives that can treat multi-drug resistant bacterial infections. Revealing the mechanisms of their deactivation by β-lactamases is a necessary step for preserving their therapeutic value. Here, we present NMR investigations of OXA-24/40, a carbapenem-hydrolyzing Class D β-lactamase (CHDL) expressed in the gram-negative pathogen, Acinetobacter baumannii. Using rapid data acquisition methods, we were able to study the "real-time" deactivation of the carbapenem known as doripenem by OXA-24/40. Our results indicate that OXA-24/40 has two deactivation mechanisms: canonical hydrolytic cleavage, and a distinct mechanism that produces a β-lactone product that has weak affinity for the OXA-24/40 active site. The mechanisms issue from distinct active site environments poised either for hydrolysis or β-lactone formation. Mutagenesis reveals that R261, a conserved active site arginine, stabilizes the active site environment enabling β-lactone formation. Our results have implications not only for OXA-24/40, but the larger family of CHDLs now challenging clinical settings on a global scale.
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Affiliation(s)
- Jamie VanPelt
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Shannon Stoffel
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Michael W Staude
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Kayla Dempster
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Heath A Rose
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Sarah Graney
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Erin Graney
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Sara Braynard
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Elizaveta Kovrigina
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - David A Leonard
- Department of Chemistry, Grand Valley State University, Allendale, MI 49401, USA
| | - Jeffrey W Peng
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA.
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10
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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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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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