Challenges in the Development of a Thiol-Based Broad-Spectrum Inhibitor for Metallo-β-Lactamases
TL;DR: The synthesis and biochemical characterization of thiol-based MBL inhibitors are reported and the challenges behind the development are highlighted, which exhibit good in vitro activity toward a broad spectrum of MBLs, selectivity against human off-targets, and reasonable activity against clinical isolates.
Abstract: Pathogens, expressing metallo-β-lactamases (MBLs), become resistant against most β-lactam antibiotics. Besides the dragging search for new antibiotics, development of MBL inhibitors would be an alternative weapon against resistant bacterial pathogens. Inhibition of resistance enzymes could restore the antibacterial activity of β-lactams. Various approaches to MBL inhibitors are described; among others, the promising motif of a zinc coordinating thiol moiety is very popular. Nevertheless, since the first report of a thiol-based MBL inhibitor (thiomandelic acid) in 2001, no steps in development of thiol based MBL inhibitors were reported that go beyond clinical isolate testing. In this study, we report on the synthesis and biochemical characterization of thiol-based MBL inhibitors and highlight the challenges behind the development of thiol-based compounds, which exhibit good in vitro activity toward a broad spectrum of MBLs, selectivity against human off-targets, and reasonable activity against clinical is...
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TL;DR: Owing to their unique structure and function and their diversity, MBLs pose a particular challenge for drug development, although several stable agents and inhibitor combinations are at various stages in the development pipeline.
Abstract: Modern medicine is threatened by the global rise of antibiotic resistance, especially among Gram-negative bacteria. Metallo-β-lactamase (MBL) enzymes are a particular concern and are increasingly disseminated worldwide, though particularly in Asia. Many MBL producers have multiple further drug resistances, leaving few obvious treatment options. Nonetheless, and more encouragingly, MBLs may be less effective agents of carbapenem resistance in vivo, under zinc limitation, than in vitro Owing to their unique structure and function and their diversity, MBLs pose a particular challenge for drug development. They evade all recently licensed β-lactam-β-lactamase inhibitor combinations, although several stable agents and inhibitor combinations are at various stages in the development pipeline. These potential therapies, along with the epidemiology of producers and current treatment options, are the focus of this review.
115 citations
Cites background from "Challenges in the Development of a ..."
...Thiol-containing compounds inhibit all MBL subtypes (B1, B2, and B3) (168), with strong competitive inhibition of IMP-1 by thioester derivatives first being reported in 1999 (169)....
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...Figure 1 illustrates the amino acid residues that bind zinc at the active sites of B1, B2, and B3 MBLs (8)....
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...Thiol-containing compounds inhibit all MBL subtypes (B1, B2, and B3) (168), with...
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...Accepted manuscript posted online 20 July 2020 Published October 2020 Volume 64 Issue 10 e00397-20 aac.asm.org 1Antimicrobial Agents and Chemotherapy 21 September 2020 Class B enzymes are further divided into three subclasses—B1, B2, and B3— based on differences in amino acid sequence at the active site, zinc ligands, zinc stoichiometry, loop architecture, and substrate profiles (8)....
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TL;DR: This review surveys the mechanisms of MBL inhibitors and describes methods that determine the mechanism of inhibition to guide development of future therapeutics.
102 citations
TL;DR: The studies dedicated to the design and development of effective NDM-1 inhibitors are reported: the discussion for each agent moves from the employed design strategy to the ability of the identified inhibitor to synergize β-lactam antibiotics.
Abstract: The worldwide emergence of New Delhi metallo-β-lactamase-1 (NDM-1) as a carbapenemase able to hydrolyze nearly all available β-lactam antibiotics has characterized the past decade, endangering efficacious antibacterial treatments. No inhibitors for NDM-1 are available in therapy, nor are promising compounds in the pipeline for future NDM-1 inhibitors. We report the studies dedicated to the design and development of effective NDM-1 inhibitors. The discussion for each agent moves from the employed design strategy to the ability of the identified inhibitor to synergize β-lactam antibiotics. A structural analysis of NDM-1 mechanism of action based on selected X-ray complexes is also reported: the intrinsic flexibility of the binding site and the comparison between penicillin/cephalosporin and carbapenem mechanisms of hydrolysis are evaluated. Despite the valuable progress in terms of structural and mechanistic information, the design of a potent NDM-1 inhibitor to be introduced in therapy remains challenging....
100 citations
TL;DR: An overview of recent FDA-approved β- lactam/β-lactamase inhibitor combinations as well as an update on research efforts aimed at the discovery and development of novel β-lacticamase inhibitors are provided.
Abstract: Antibiotic resistance caused by β-lactamase production continues to present a growing challenge to the efficacy of β-lactams and their role as the most important class of clinically used antibiotics. In response to this threat however, only a handful of β-lactamase inhibitors have been introduced to the market over the past thirty years. The first-generation β-lactamase inhibitors (clavulanic acid, sulbactam and tazobactam) are all β-lactam derivatives and work primarily by inactivating class A and some class C serine β-lactamases. The newer generations of β-lactamase inhibitors including avibactam and vaborbactam are based on non-β-lactam structures and their spectrum of inhibition is extended to KPC as an important class A carbapenemase. Despite these advances several class D and virtually all important class B β-lactamases are resistant to existing inhibitors. The present review provides an overview of recent FDA-approved β-lactam/β-lactamase inhibitor combinations as well as an update on research efforts aimed at the discovery and development of novel β-lactamase inhibitors.
97 citations
TL;DR: In this article, a review of the active site and catalytic mechanism of Metallo-β-lactamases (MBLs) is presented, and the success of MBLs in conferring resistance to carbapenems, penicillins, and cephalosporins.
Abstract: Antimicrobial resistance is one of the major problems in current practical medicine. The spread of genes coding for resistance determinants among bacteria challenges the use of approved antibiotics, narrowing the options for treatment. Resistance to carbapenems, last resort antibiotics, is a major concern. Metallo-β-lactamases (MBLs) hydrolyze carbapenems, penicillins, and cephalosporins, becoming central to this problem. These enzymes diverge with respect to serine-β-lactamases by exhibiting a different fold, active site, and catalytic features. Elucidating their catalytic mechanism has been a big challenge in the field that has limited the development of useful inhibitors. This review covers exhaustively the details of the active-site chemistries, the diversity of MBL alleles, the catalytic mechanism against different substrates, and how this information has helped developing inhibitors. We also discuss here different aspects critical to understand the success of MBLs in conferring resistance: the molecular determinants of their dissemination, their cell physiology, from the biogenesis to the processing involved in the transit to the periplasm, and the uptake of the Zn(II) ions upon metal starvation conditions, such as those encountered during an infection. In this regard, the chemical, biochemical and microbiological aspects provide an integrative view of the current knowledge of MBLs.
68 citations
References
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TL;DR: CCP4mg is a project that aims to provide a general-purpose tool for structural biologists, providing tools for X-ray structure solution, structure comparison and analysis, and publication-quality graphics.
Abstract: CCP4mg is a project that aims to provide a general-purpose tool for structural biologists, providing tools for X-ray structure solution, structure comparison and analysis, and publication-quality graphics. The map-fitting tools are available as a stand-alone package, distributed as `Coot'.
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TL;DR: The PHENIX software for macromolecular structure determination is described and its uses and benefits are described.
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TL;DR: MolProbity structure validation will diagnose most local errors in macromolecular crystal structures and help to guide their correction.
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TL;DR: This work provides a comprehensive overview of β-lactam antibiotics that are currently in use, as well as a look ahead to several new compounds that are in the development pipeline.
Abstract: β-Lactams are the most widely used class of antibiotics. Since the discovery of benzylpenicillin in the 1920s, thousands of new penicillin derivatives and related β-lactam classes of cephalosporins, cephamycins, monobactams, and carbapenems have been discovered. Each new class of β-lactam has been developed either to increase the spectrum of activity to include additional bacterial species or to address specific resistance mechanisms that have arisen in the targeted bacterial population. Resistance to β-lactams is primarily because of bacterially produced β-lactamase enzymes that hydrolyze the β-lactam ring, thereby inactivating the drug. The newest effort to circumvent resistance is the development of novel broad-spectrum β-lactamase inhibitors that work against many problematic β-lactamases, including cephalosporinases and serine-based carbapenemases, which severely limit therapeutic options. This work provides a comprehensive overview of β-lactam antibiotics that are currently in use, as well as a look ahead to several new compounds that are in the development pipeline.
560 citations
TL;DR: Findings from target-based and phenotypic screening efforts carried out at AstraZeneca over the past decade are described, some of the subsequent chemistry challenges are discussed and a description of new approaches comprising a combination of computational modelling and advanced biological tools which may pave the way towards the discovery of new antibacterial agents are described.
Abstract: Antimicrobial drug resistance is a growing threat to global public health. Multidrug resistance among the 'ESKAPE' organisms - encompassing Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp. - is of particular concern because they are responsible for many serious infections in hospitals. Although some promising agents are in the pipeline, there is an urgent need for new antibiotic scaffolds. However, antibacterial researchers have struggled to identify new small molecules with meaningful cellular activity, especially those effective against multidrug-resistant Gram-negative pathogens. This difficulty ultimately stems from an incomplete understanding of efflux systems and compound permeation through bacterial membranes. This Opinion article describes findings from target-based and phenotypic screening efforts carried out at AstraZeneca over the past decade, discusses some of the subsequent chemistry challenges and concludes with a description of new approaches comprising a combination of computational modelling and advanced biological tools which may pave the way towards the discovery of new antibacterial agents.
472 citations