1
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Batey SFD, Davie MJ, Hems ES, Liston JD, Scott TA, Alt S, Francklyn CS, Wilkinson B. The catechol moiety of obafluorin is essential for antibacterial activity. RSC Chem Biol 2023; 4:926-941. [PMID: 37920400 PMCID: PMC10619133 DOI: 10.1039/d3cb00127j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 08/11/2023] [Indexed: 11/04/2023] Open
Abstract
Obafluorin is a Pseudomonas fluorescens antibacterial natural product that inhibits threonyl-tRNA synthetase (ThrRS). It acts as a broad-spectrum antibiotic against a range of clinically relevant pathogens and comprises a strained β-lactone ring decorated with catechol and 4-nitro-benzyl moieties. The catechol moiety is widespread in nature and its role in the coordination of ferric iron has been well-characterised in siderophores and Trojan horse antibiotics. Here we use a combination of mutasynthesis, bioassays, enzyme assays and metal binding studies to delineate the role of the catechol moiety in the bioactivity of obafluorin. We use P. fluorescens biosynthetic mutants to generate obafluorin analogues with modified catechol moieties. We demonstrate that an intact catechol is required for both antibacterial activity and inhibition of the ThrRS molecular target. Although recent work showed that the obafluorin catechol coordinates Zn2+ in the ThrRS active site, we find that obafluorin is a weak Zn2+ binder in vitro, contrasting with a strong, specific 1 : 1 interaction with Fe3+. We use bioassays with siderophore transporter mutants to probe the role of the obafluorin catechol in Fe3+-mediated uptake. Surprisingly, obafluorin does not behave as a Trojan horse antibiotic but instead exhibits increased antibacterial activity in the presence of Fe3+. We further demonstrate that Fe3+ binding prevents the hydrolytic breakdown of the β-lactone ring, revealing a hitherto unreported function for the catechol moiety in natural product bioactivity.
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Affiliation(s)
- Sibyl F D Batey
- Department of Molecular Microbiology, John Innes Centre Norwich Research Park Norwich NR4 7UH UK
| | - Melissa J Davie
- Department of Molecular Microbiology, John Innes Centre Norwich Research Park Norwich NR4 7UH UK
| | - Edward S Hems
- Department of Molecular Microbiology, John Innes Centre Norwich Research Park Norwich NR4 7UH UK
| | - Jonathon D Liston
- Department of Molecular Microbiology, John Innes Centre Norwich Research Park Norwich NR4 7UH UK
| | - Thomas A Scott
- Department of Molecular Microbiology, John Innes Centre Norwich Research Park Norwich NR4 7UH UK
| | - Silke Alt
- Department of Molecular Microbiology, John Innes Centre Norwich Research Park Norwich NR4 7UH UK
| | - Christopher S Francklyn
- Department of Biochemistry, College of Medicine, University of Vermont, Burlington Vermont 05405 USA
| | - Barrie Wilkinson
- Department of Molecular Microbiology, John Innes Centre Norwich Research Park Norwich NR4 7UH UK
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2
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Comparative QM/MM study on the inhibition mechanism of β-Hydroxynorvaline to Threonyl-tRNA synthetase. J Mol Graph Model 2022; 115:108224. [DOI: 10.1016/j.jmgm.2022.108224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 03/26/2022] [Accepted: 05/13/2022] [Indexed: 11/18/2022]
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3
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Pang L, Weeks SD, Van Aerschot A. Aminoacyl-tRNA Synthetases as Valuable Targets for Antimicrobial Drug Discovery. Int J Mol Sci 2021; 22:1750. [PMID: 33578647 PMCID: PMC7916415 DOI: 10.3390/ijms22041750] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/04/2021] [Accepted: 02/06/2021] [Indexed: 12/20/2022] Open
Abstract
Aminoacyl-tRNA synthetases (aaRSs) catalyze the esterification of tRNA with a cognate amino acid and are essential enzymes in all three kingdoms of life. Due to their important role in the translation of the genetic code, aaRSs have been recognized as suitable targets for the development of small molecule anti-infectives. In this review, following a concise discussion of aaRS catalytic and proof-reading activities, the various inhibitory mechanisms of reported natural and synthetic aaRS inhibitors are discussed. Using the expanding repository of ligand-bound X-ray crystal structures, we classified these compounds based on their binding sites, focusing on their ability to compete with the association of one, or more of the canonical aaRS substrates. In parallel, we examined the determinants of species-selectivity and discuss potential resistance mechanisms of some of the inhibitor classes. Combined, this structural perspective highlights the opportunities for further exploration of the aaRS enzyme family as antimicrobial targets.
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Affiliation(s)
- Luping Pang
- KU Leuven, Rega Institute for Medical Research, Medicinal Chemistry, Herestraat 49–box 1041, 3000 Leuven, Belgium;
- KU Leuven, Biocrystallography, Department of Pharmaceutical and Pharmacological Sciences, Herestraat 49–box 822, 3000 Leuven, Belgium
| | | | - Arthur Van Aerschot
- KU Leuven, Rega Institute for Medical Research, Medicinal Chemistry, Herestraat 49–box 1041, 3000 Leuven, Belgium;
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4
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Abstract
Aminoacyl-tRNA synthetases (AARSs) have been considered very attractive drug-targets for decades. This interest probably emerged with the identification of differences in AARSs between prokaryotic and eukaryotic species, which provided a rationale for the development of antimicrobials targeting bacterial AARSs with minimal effect on the homologous human AARSs. Today we know that AARSs are not only attractive, but also valid drug targets as they are housekeeping proteins that: (i) play a fundamental role in protein translation by charging the corresponding amino acid to its cognate tRNA and preventing mistranslation mistakes [1], a critical process during fast growing conditions of microbes; and (ii) present significant differences between microbes and humans that can be used for drug development [2]. Together with the vast amount of available data on both pathogenic and mammalian AARSs, it is expected that, in the future, the numerous reported inhibitors of AARSs will provide the basis to develop new therapeutics for the treatment of human diseases. In this chapter, a detailed summary on the state-of-the-art in drug discovery and drug development for each aminoacyl-tRNA synthetase will be presented.
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Affiliation(s)
- Maria Lukarska
- Institute for Advanced Biosciences (IAB), Structural Biology of Novel Drug Targets in Human Diseases, INSERM U1209, CNRS UMR 5309, University Grenoble Alpes, Grenoble, France
| | - Andrés Palencia
- Institute for Advanced Biosciences (IAB), Structural Biology of Novel Drug Targets in Human Diseases, INSERM U1209, CNRS UMR 5309, University Grenoble Alpes, Grenoble, France.
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5
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Aminoacyl-tRNA synthetase inhibition activates a pathway that branches from the canonical amino acid response in mammalian cells. Proc Natl Acad Sci U S A 2020; 117:8900-8911. [PMID: 32253314 DOI: 10.1073/pnas.1913788117] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Signaling pathways that sense amino acid abundance are integral to tissue homeostasis and cellular defense. Our laboratory has previously shown that halofuginone (HF) inhibits the prolyl-tRNA synthetase catalytic activity of glutamyl-prolyl-tRNA synthetase (EPRS), thereby activating the amino acid response (AAR). We now show that HF treatment selectively inhibits inflammatory responses in diverse cell types and that these therapeutic benefits occur in cells that lack GCN2, the signature effector of the AAR. Depletion of arginine, histidine, or lysine from cultured fibroblast-like synoviocytes recapitulates key aspects of HF treatment, without utilizing GCN2 or mammalian target of rapamycin complex 1 pathway signaling. Like HF, the threonyl-tRNA synthetase inhibitor borrelidin suppresses the induction of tissue remodeling and inflammatory mediators in cytokine-stimulated fibroblast-like synoviocytes without GCN2, but both aminoacyl-tRNA synthetase (aaRS) inhibitors are sensitive to the removal of GCN1. GCN1, an upstream component of the AAR pathway, binds to ribosomes and is required for GCN2 activation. These observations indicate that aaRS inhibitors, like HF, can modulate inflammatory response without the AAR/GCN2 signaling cassette, and that GCN1 has a role that is distinct from its activation of GCN2. We propose that GCN1 participates in a previously unrecognized amino acid sensor pathway that branches from the canonical AAR.
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6
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Scott TA, Batey SFD, Wiencek P, Chandra G, Alt S, Francklyn CS, Wilkinson B. Immunity-Guided Identification of Threonyl-tRNA Synthetase as the Molecular Target of Obafluorin, a β-Lactone Antibiotic. ACS Chem Biol 2019; 14:2663-2671. [PMID: 31675206 DOI: 10.1021/acschembio.9b00590] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
To meet the ever-growing demands of antibiotic discovery, new chemical matter and antibiotic targets are urgently needed. Many potent natural product antibiotics which were previously discarded can also provide lead molecules and drug targets. One such example is the structurally unique β-lactone obafluorin, produced by Pseudomonas fluorescens ATCC 39502. Obafluorin is active against both Gram-positive and -negative pathogens; however, the biological target was unknown. We now report that obafluorin targets threonyl-tRNA synthetase, and we identify a homologue, ObaO, which confers immunity to the obafluorin producer. Disruption of obaO in P. fluorescens ATCC 39502 results in obafluorin sensitivity, whereas expression in sensitive E. coli strains confers resistance. Enzyme assays demonstrate that E. coli threonyl-tRNA synthetase is fully inhibited by obafluorin, whereas ObaO is only partly susceptible, exhibiting a very unusual partial inhibition mechanism. Altogether, our data highlight the utility of an immunity-guided approach for the identification of an antibiotic target de novo and will ultimately enable the generation of improved obafluorin variants.
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Affiliation(s)
- Thomas A. Scott
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, U.K
| | - Sibyl F. D. Batey
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, U.K
| | - Patrick Wiencek
- Department of Biochemistry, College of Medicine, University of Vermont, Burlington, Vermont 05405, United States
| | - Govind Chandra
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, U.K
| | - Silke Alt
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, U.K
| | - Christopher S. Francklyn
- Department of Biochemistry, College of Medicine, University of Vermont, Burlington, Vermont 05405, United States
| | - Barrie Wilkinson
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, U.K
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7
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Francklyn CS, Mullen P. Progress and challenges in aminoacyl-tRNA synthetase-based therapeutics. J Biol Chem 2019; 294:5365-5385. [PMID: 30670594 DOI: 10.1074/jbc.rev118.002956] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Aminoacyl-tRNA synthetases (ARSs) are universal enzymes that catalyze the attachment of amino acids to the 3' ends of their cognate tRNAs. The resulting aminoacylated tRNAs are escorted to the ribosome where they enter protein synthesis. By specifically matching amino acids to defined anticodon sequences in tRNAs, ARSs are essential to the physical interpretation of the genetic code. In addition to their canonical role in protein synthesis, ARSs are also involved in RNA splicing, transcriptional regulation, translation, and other aspects of cellular homeostasis. Likewise, aminoacylated tRNAs serve as amino acid donors for biosynthetic processes distinct from protein synthesis, including lipid modification and antibiotic biosynthesis. Thanks to the wealth of details on ARS structures and functions and the growing appreciation of their additional roles regulating cellular homeostasis, opportunities for the development of clinically useful ARS inhibitors are emerging to manage microbial and parasite infections. Exploitation of these opportunities has been stimulated by the discovery of new inhibitor frameworks, the use of semi-synthetic approaches combining chemistry and genome engineering, and more powerful techniques for identifying leads from the screening of large chemical libraries. Here, we review the inhibition of ARSs by small molecules, including the various families of natural products, as well as inhibitors developed by either rational design or high-throughput screening as antibiotics and anti-parasitic therapeutics.
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Affiliation(s)
- Christopher S Francklyn
- From the Department of Biochemistry, College of Medicine, University of Vermont, Burlington, Vermont 05405
| | - Patrick Mullen
- From the Department of Biochemistry, College of Medicine, University of Vermont, Burlington, Vermont 05405
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8
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Hu C, Su H, Luo J, Han L, Liu Q, Wu W, Mu Y, Guan P, Sun T, Huang X. Design, synthesis and antifungal evaluation of borrelidin derivatives. Bioorg Med Chem 2018; 26:6035-6049. [DOI: 10.1016/j.bmc.2018.11.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 10/24/2018] [Accepted: 11/04/2018] [Indexed: 10/27/2022]
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9
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Ancheeva E, Daletos G, Proksch P. Lead Compounds from Mangrove-Associated Microorganisms. Mar Drugs 2018; 16:md16090319. [PMID: 30205507 PMCID: PMC6165052 DOI: 10.3390/md16090319] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 08/22/2018] [Accepted: 08/29/2018] [Indexed: 01/30/2023] Open
Abstract
The mangrove ecosystem is considered as an attractive biodiversity hotspot that is intensively studied in the hope of discovering new useful chemical scaffolds, including those with potential medicinal application. In the past two decades, mangrove-derived microorganisms, along with mangrove plants, proved to be rich sources of bioactive secondary metabolites as exemplified by the constant rise in the number of publications, which suggests the great potential of this important ecological niche. The present review summarizes selected examples of bioactive compounds either from mangrove endophytes or from soil-derived mangrove fungi and bacteria, covering the literature from 2014 to March 2018. Accordingly, 163 natural products are described in this review, possessing a wide range of potent bioactivities, such as cytotoxic, antibacterial, antifungal, α-glucosidase inhibitory, protein tyrosine phosphatase B inhibitory, and antiviral activities, among others.
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Affiliation(s)
- Elena Ancheeva
- Institute of Pharmaceutical Biology and Biotechnology, Heinrich-Heine-University, Universitaetsstrasse 1, 40225 Düsseldorf, Germany.
| | - Georgios Daletos
- Institute of Pharmaceutical Biology and Biotechnology, Heinrich-Heine-University, Universitaetsstrasse 1, 40225 Düsseldorf, Germany.
| | - Peter Proksch
- Institute of Pharmaceutical Biology and Biotechnology, Heinrich-Heine-University, Universitaetsstrasse 1, 40225 Düsseldorf, Germany.
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10
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Genetic manipulation of Leishmania donovani threonyl tRNA synthetase facilitates its exploration as a potential therapeutic target. PLoS Negl Trop Dis 2018; 12:e0006575. [PMID: 29897900 PMCID: PMC6025875 DOI: 10.1371/journal.pntd.0006575] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 06/29/2018] [Accepted: 06/01/2018] [Indexed: 12/13/2022] Open
Abstract
Background Aminoacyl tRNA synthetases are central enzymes required for protein synthesis. These enzymes are the known drug targets in bacteria and fungi. Here, we for the first time report the functional characterization of threonyl tRNA synthetase (LdThrRS) of Leishmania donovani, a protozoan parasite, the primary causative agent of visceral leishmaniasis. Methodology Recombinant LdThrRS (rLdThrRS) was expressed in E. coli and purified. The kinetic parameters for rLdThrRS were determined. The subcellular localization of LdThrRS was done by immunofluorescence analysis. Heterozygous mutants of LdThrRS were generated in Leishmania promastigotes. These genetically manipulated parasites were checked for their proliferation, virulence, aminoacylation activity and sensitivity to the known ThrRS inhibitor, borrelidin. An in silico generated structural model of L. donovani ThrRS was compared to that of human. Conclusions Recombinant LdThrRS displayed aminoacylation activity, and the protein is possibly localized to both the cytosol and mitochondria. The comparison of the 3D-model of LdThrRS to human ThrRS displayed considerable similarity. Heterozygous parasites showed restrictive growth phenotype and had attenuated infectivity. These heterozygous parasites were more susceptible to inhibition by borrelidin. Several attempts to obtain ThrRS homozygous null mutants were not successful, indicating its essentiality for the Leishmania parasite. Borrelidin showed a strong affinity for LdThrRS (KD: 0.04 μM) and was effective in inhibiting the aminoacylation activity of the rLdThrRS (IC50: 0.06 μM). Borrelidin inhibited the promastigotes (IC50: 21 μM) stage of parasites. Our data shows that LdThrRS is essential for L. donovani survival and is likely to bind with small drug-like molecules with strong affinity, thus making it a potential target for drug discovery efforts. Aminoacyl tRNA synthetases (aaRSs) are ubiquitous enzymes required for protein translation. They play a vital role in helping an organism's survival. Therefore, they have been suggested as favourable targets for the development of antileishmanial drugs. Leishmania, a protozoan parasite that causes leishmaniasis is known to encode 26 aaRSs. In the present study, we have worked on the functional characterization of L. donovani threonyl tRNA synthetase (LdThrRS) protein. We report that the L. donovani encodes a functional copy of ThrRS. The protein is localized in the cytosol and possibly also in mitochondria. The LdThrRS seems to be an essential gene for the parasite since null mutants did not survive. The deletion of one allele of the gene caused reduced growth and attenuated virulence in the heterozygous parasites. These parasites showed increased sensitivity to the known ThrRS inhibitor, borrelidin. Furthermore, borrelidin was found to inhibit the aminoacylation activity of LdThrRS thus, indicating that parasitic ThrRS can be exploited as a drug target for antileishmanial chemotherapy.
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11
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Validation of Putative Apicoplast-Targeting Drugs Using a Chemical Supplementation Assay in Cultured Human Malaria Parasites. Antimicrob Agents Chemother 2017; 62:AAC.01161-17. [PMID: 29109165 DOI: 10.1128/aac.01161-17] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 10/18/2017] [Indexed: 11/20/2022] Open
Abstract
Malaria parasites contain a relict plastid, the apicoplast, which is considered an excellent drug target due to its bacterial-like ancestry. Numerous parasiticidals have been proposed to target the apicoplast, but few have had their actual targets substantiated. Isopentenyl pyrophosphate (IPP) production is the sole required function of the apicoplast in the blood stage of the parasite life cycle, and IPP supplementation rescues parasites from apicoplast-perturbing drugs. Hence, any drug that kills parasites when IPP is supplied in culture must have a nonapicoplast target. Here, we use IPP supplementation to discriminate whether 23 purported apicoplast-targeting drugs are on- or off-target. We demonstrate that a prokaryotic DNA replication inhibitor (ciprofloxacin), several prokaryotic translation inhibitors (chloramphenicol, doxycycline, tetracycline, clindamycin, azithromycin, erythromycin, and clarithromycin), a tRNA synthase inhibitor (mupirocin), and two IPP synthesis pathway inhibitors (fosmidomycin and FR900098) have apicoplast targets. Intriguingly, fosmidomycin and FR900098 leave the apicoplast intact, whereas the others eventually result in apicoplast loss. Actinonin, an inhibitor of bacterial posttranslational modification, does not produce a typical delayed-death response but is rescued with IPP, thereby confirming its apicoplast target. Parasites treated with putative apicoplast fatty acid pathway inhibitors could not be rescued, demonstrating that these drugs have their primary targets outside the apicoplast, which agrees with the dispensability of the apicoplast fatty acid synthesis pathways in the blood stage of malaria parasites. IPP supplementation provides a simple test of whether a compound has a target in the apicoplast and can be used to screen novel compounds for mode of action.
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12
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Moen SO, Edwards TE, Dranow DM, Clifton MC, Sankaran B, Van Voorhis WC, Sharma A, Manoil C, Staker BL, Myler PJ, Lorimer DD. Ligand co-crystallization of aminoacyl-tRNA synthetases from infectious disease organisms. Sci Rep 2017; 7:223. [PMID: 28303005 PMCID: PMC5428304 DOI: 10.1038/s41598-017-00367-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 02/20/2017] [Indexed: 12/15/2022] Open
Abstract
Aminoacyl-tRNA synthetases (aaRSs) charge tRNAs with their cognate amino acid, an essential precursor step to loading of charged tRNAs onto the ribosome and addition of the amino acid to the growing polypeptide chain during protein synthesis. Because of this important biological function, aminoacyl-tRNA synthetases have been the focus of anti-infective drug development efforts and two aaRS inhibitors have been approved as drugs. Several researchers in the scientific community requested aminoacyl-tRNA synthetases to be targeted in the Seattle Structural Genomics Center for Infectious Disease (SSGCID) structure determination pipeline. Here we investigate thirty-one aminoacyl-tRNA synthetases from infectious disease organisms by co-crystallization in the presence of their cognate amino acid, ATP, and/or inhibitors. Crystal structures were determined for a CysRS from Borrelia burgdorferi bound to AMP, GluRS from Borrelia burgdorferi and Burkholderia thailandensis bound to glutamic acid, a TrpRS from the eukaryotic pathogen Encephalitozoon cuniculi bound to tryptophan, a HisRS from Burkholderia thailandensis bound to histidine, and a LysRS from Burkholderia thailandensis bound to lysine. Thus, the presence of ligands may promote aaRS crystallization and structure determination. Comparison with homologous structures shows conformational flexibility that appears to be a recurring theme with this enzyme class.
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Affiliation(s)
- Spencer O Moen
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Bethesda, MD, USA.,Beryllium Discovery Corp, Bainbridge Island, WA, 98110, USA
| | - Thomas E Edwards
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Bethesda, MD, USA. .,Beryllium Discovery Corp, Bainbridge Island, WA, 98110, USA.
| | - David M Dranow
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Bethesda, MD, USA.,Beryllium Discovery Corp, Bainbridge Island, WA, 98110, USA
| | - Matthew C Clifton
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Bethesda, MD, USA.,Beryllium Discovery Corp, Bainbridge Island, WA, 98110, USA
| | - Banumathi Sankaran
- Berkeley Center for Structural Biology, Advanced Light Source, Berkeley, CA, 94720, USA
| | - Wesley C Van Voorhis
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Bethesda, MD, USA.,University of Washington, Seattle, WA, 98195-6423, USA
| | - Amit Sharma
- International Center for Genetic Engineering and Biotechnology, New Delhi, 110 067, India
| | - Colin Manoil
- University of Washington, Department of Genome Sciences, Seattle, WA, 98195-5065, USA
| | - Bart L Staker
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Bethesda, MD, USA.,Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), Seattle, WA, 98109, USA
| | - Peter J Myler
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Bethesda, MD, USA.,Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), Seattle, WA, 98109, USA.,University of Washington, Department of Medical Education and Biomedical Informatics & Department of Global Health, Seattle, WA, 98195, USA
| | - Donald D Lorimer
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Bethesda, MD, USA.,Beryllium Discovery Corp, Bainbridge Island, WA, 98110, USA
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13
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Abbott JA, Livingston NM, Egri SB, Guth E, Francklyn CS. Characterization of aminoacyl-tRNA synthetase stability and substrate interaction by differential scanning fluorimetry. Methods 2016; 113:64-71. [PMID: 27794454 DOI: 10.1016/j.ymeth.2016.10.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 10/22/2016] [Accepted: 10/25/2016] [Indexed: 11/30/2022] Open
Abstract
Differential scanning fluorimetry (DSF) is a fluorescence-based assay to evaluate protein stability by determining protein melting temperatures. Here, we describe the application of DSF to investigate aminoacyl-tRNA synthetase (AARS) stability and interaction with ligands. Employing three bacterial AARS enzymes as model systems, methods are presented here for the use of DSF to measure the apparent temperatures at which AARSs undergo melting transitions, and the effect of AARS substrates and inhibitors. One important observation is that the extent of temperature stability realized by an AARS in response to a particular bound ligand cannot be predicted a priori. The DSF method thus serves as a rapid and highly quantitative approach to measure AARS stability, and the ability of ligands to influence the temperature at which unfolding transitions occur.
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Affiliation(s)
- Jamie A Abbott
- Department of Biochemistry, University of Vermont, Burlington, VT 05405, USA.
| | - Nathan M Livingston
- Department of Biochemistry, University of Vermont, Burlington, VT 05405, USA
| | - Shawn B Egri
- Department of Biochemistry, University of Vermont, Burlington, VT 05405, USA
| | - Ethan Guth
- Chemistry & Biochemistry Department, Norwich University, Northfield, VT 05663, USA
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14
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Ahmad MJ, Hassan SF, Nisa RU, Ayub K, Nadeem MS, Nazir S, Ansari FL, Qureshi NA, Rashid U. Synthesis, in vitro potential and computational studies on 2-amino-1, 4-dihydropyrimidines as multitarget antibacterial ligands. Med Chem Res 2016. [DOI: 10.1007/s00044-016-1613-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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15
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Saint-Léger A, Sinadinos C, Ribas de Pouplana L. The growing pipeline of natural aminoacyl-tRNA synthetase inhibitors for malaria treatment. Bioengineered 2016; 7:60-4. [PMID: 26963157 DOI: 10.1080/21655979.2016.1149270] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
Malaria remains a major global health problem. Parasite resistance to existing drugs makes development of new antimalarials an urgency. The protein synthesis machinery is an excellent target for the development of new anti-infectives, and aminoacyl-tRNA synthetases (aaRS) have been validated as antimalarial drug targets. However, avoiding the emergence of drug resistance and improving selectivity to target aaRS in apicomplexan parasites, such as Plasmodium falciparum, remain crucial challenges. Here we discuss such issues using examples of known inhibitors of P. falciparum aaRS, namely halofuginone, cladosporin and borrelidin (inhibitors of ProRS, LysRS and ThrRS, respectively). Encouraging recent results provide useful guidelines to facilitate the development of novel drug candidates which are more potent and selective against these essential enzymes.
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Affiliation(s)
| | | | - Lluís Ribas de Pouplana
- a Omnia Molecular S.L. , Barcelona , Spain.,b Institute for Research in Biomedicine (IRB Barcelona) , Barcelona , Spain.,c Catalan Institution for Research and Advanced Studies (ICREA) , Barcelona , Spain
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16
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Cochrane RVK, Norquay AK, Vederas JC. Natural products and their derivatives as tRNA synthetase inhibitors and antimicrobial agents. MEDCHEMCOMM 2016. [DOI: 10.1039/c6md00274a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The tRNA synthetase enzymes are promising targets for development of therapeutic agents against infections by parasitic protozoans (e.g. malaria), fungi and yeast, as well as bacteria resistant to current antibiotics.
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Affiliation(s)
| | - A. K. Norquay
- Department of Chemistry
- University of Alberta
- Edmonton
- T6G 2G2 Canada
| | - J. C. Vederas
- Department of Chemistry
- University of Alberta
- Edmonton
- T6G 2G2 Canada
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17
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Trader DJ, Carlson EE. Chemoselective enrichment as a tool to increase access to bioactive natural products: Case study borrelidin. Bioorg Med Chem Lett 2015; 25:4767-4769. [DOI: 10.1016/j.bmcl.2015.07.062] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 07/17/2015] [Accepted: 07/21/2015] [Indexed: 01/19/2023]
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Mirando AC, Fang P, Williams TF, Baldor LC, Howe AK, Ebert AM, Wilkinson B, Lounsbury KM, Guo M, Francklyn CS. Aminoacyl-tRNA synthetase dependent angiogenesis revealed by a bioengineered macrolide inhibitor. Sci Rep 2015; 5:13160. [PMID: 26271225 PMCID: PMC4536658 DOI: 10.1038/srep13160] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 07/16/2015] [Indexed: 11/23/2022] Open
Abstract
Aminoacyl-tRNA synthetases (AARSs) catalyze an early step in protein synthesis, but also regulate diverse physiological processes in animal cells. These include angiogenesis, and human threonyl-tRNA synthetase (TARS) represents a potent pro-angiogenic AARS. Angiogenesis stimulation can be blocked by the macrolide antibiotic borrelidin (BN), which exhibits a broad spectrum toxicity that has discouraged deeper investigation. Recently, a less toxic variant (BC194) was identified that potently inhibits angiogenesis. Employing biochemical, cell biological, and biophysical approaches, we demonstrate that the toxicity of BN and its derivatives is linked to its competition with the threonine substrate at the molecular level, which stimulates amino acid starvation and apoptosis. By separating toxicity from the inhibition of angiogenesis, a direct role for TARS in vascular development in the zebrafish could be demonstrated. Bioengineered natural products are thus useful tools in unmasking the cryptic functions of conventional enzymes in the regulation of complex processes in higher metazoans.
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Affiliation(s)
| | - Pengfei Fang
- Department of Cancer Biology, The Scripps Research Institute, Scripps Florida
| | | | | | - Alan K Howe
- Department of Pharmacology, University of Vermont
| | | | - Barrie Wilkinson
- Isomerase Therapeutics Ltd, Science Village, Chesterford Research Park, Cambridge CB10 1XL, UK
| | | | - Min Guo
- Department of Cancer Biology, The Scripps Research Institute, Scripps Florida
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Cvetesic N, Bilus M, Gruic-Sovulj I. The tRNA A76 Hydroxyl Groups Control Partitioning of the tRNA-dependent Pre- and Post-transfer Editing Pathways in Class I tRNA Synthetase. J Biol Chem 2015; 290:13981-91. [PMID: 25873392 DOI: 10.1074/jbc.m115.648568] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Indexed: 11/06/2022] Open
Abstract
Aminoacyl-tRNA synthetases catalyze ATP-dependent covalent coupling of cognate amino acids and tRNAs for ribosomal protein synthesis. Escherichia coli isoleucyl-tRNA synthetase (IleRS) exploits both the tRNA-dependent pre- and post-transfer editing pathways to minimize errors in translation. However, the molecular mechanisms by which tRNA(Ile) organizes the synthetic site to enhance pre-transfer editing, an idiosyncratic feature of IleRS, remains elusive. Here we show that tRNA(Ile) affects both the synthetic and editing reactions localized within the IleRS synthetic site. In a complex with cognate tRNA, IleRS exhibits a 10-fold faster aminoacyl-AMP hydrolysis and a 10-fold drop in amino acid affinity relative to the free enzyme. Remarkably, the specificity against non-cognate valine was not improved by the presence of tRNA in either of these processes. Instead, amino acid specificity is determined by the protein component per se, whereas the tRNA promotes catalytic performance of the synthetic site, bringing about less error-prone and kinetically optimized isoleucyl-tRNA(Ile) synthesis under cellular conditions. Finally, the extent to which tRNA(Ile) modulates activation and pre-transfer editing is independent of the intactness of its 3'-end. This finding decouples aminoacylation and pre-transfer editing within the IleRS synthetic site and further demonstrates that the A76 hydroxyl groups participate in post-transfer editing only. The data are consistent with a model whereby the 3'-end of the tRNA remains free to sample different positions within the IleRS·tRNA complex, whereas the fine-tuning of the synthetic site is attained via conformational rearrangement of the enzyme through the interactions with the remaining parts of the tRNA body.
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Affiliation(s)
- Nevena Cvetesic
- From the Department of Chemistry, University of Zagreb, Faculty of Science, Horvatovac 102a, 10000 Zagreb, Croatia
| | - Mirna Bilus
- From the Department of Chemistry, University of Zagreb, Faculty of Science, Horvatovac 102a, 10000 Zagreb, Croatia
| | - Ita Gruic-Sovulj
- From the Department of Chemistry, University of Zagreb, Faculty of Science, Horvatovac 102a, 10000 Zagreb, Croatia
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Structural basis for full-spectrum inhibition of translational functions on a tRNA synthetase. Nat Commun 2015; 6:6402. [PMID: 25824639 PMCID: PMC4389257 DOI: 10.1038/ncomms7402] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 01/26/2015] [Indexed: 11/08/2022] Open
Abstract
The polyketide natural product borrelidin displays antibacterial, antifungal, antimalarial, anticancer, insecticidal and herbicidal activities through the selective inhibition of threonyl-tRNA synthetase (ThrRS). How borrelidin simultaneously attenuates bacterial growth and suppresses a variety of infections in plants and animals is not known. Here we show, using X-ray crystal structures and functional analyses, that a single molecule of borrelidin simultaneously occupies four distinct subsites within the catalytic domain of bacterial and human ThrRSs. These include the three substrate-binding sites for amino acid, ATP and tRNA associated with aminoacylation, and a fourth ‘orthogonal’ subsite created as a consequence of binding. Thus, borrelidin competes with all three aminoacylation substrates, providing a potent and redundant mechanism to inhibit ThrRS during protein synthesis. These results highlight a surprising natural design to achieve the quadrivalent inhibition of translation through a highly conserved family of enzymes. Borrelidin is an antibiotic with antimicrobial, antifungal, antimalarial and immunosuppressive activity that targets threonyl-tRNA synthetase. Here the authors show that borrelidin functions by preventing binding of all three ThrRS substrates and inducing a distinct, non-productive, conformation of the enzyme.
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21
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Regulation of angiogenesis by aminoacyl-tRNA synthetases. Int J Mol Sci 2014; 15:23725-48. [PMID: 25535072 PMCID: PMC4284789 DOI: 10.3390/ijms151223725] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 12/11/2014] [Accepted: 12/12/2014] [Indexed: 02/06/2023] Open
Abstract
In addition to their canonical roles in translation the aminoacyl-tRNA synthetases (ARSs) have developed secondary functions over the course of evolution. Many of these activities are associated with cellular survival and nutritional stress responses essential for homeostatic processes in higher eukaryotes. In particular, six ARSs and one associated factor have documented functions in angiogenesis. However, despite their connection to this process, the ARSs are mechanistically distinct and exhibit a range of positive or negative effects on aspects of endothelial cell migration, proliferation, and survival. This variability is achieved through the appearance of appended domains and interplay with inflammatory pathways not found in prokaryotic systems. Complete knowledge of the non-canonical functions of ARSs is necessary to understand the mechanisms underlying the physiological regulation of angiogenesis.
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Analogs of natural aminoacyl-tRNA synthetase inhibitors clear malaria in vivo. Proc Natl Acad Sci U S A 2014; 111:E5508-17. [PMID: 25489076 DOI: 10.1073/pnas.1405994111] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Malaria remains a major global health problem. Emerging resistance to existing antimalarial drugs drives the search for new antimalarials, and protein translation is a promising pathway to target. Here we explore the potential of the aminoacyl-tRNA synthetase (ARS) family as a source of antimalarial drug targets. First, a battery of known and novel ARS inhibitors was tested against Plasmodium falciparum cultures, and their activities were compared. Borrelidin, a natural inhibitor of threonyl-tRNA synthetase (ThrRS), stands out for its potent antimalarial effect. However, it also inhibits human ThrRS and is highly toxic to human cells. To circumvent this problem, we tested a library of bioengineered and semisynthetic borrelidin analogs for their antimalarial activity and toxicity. We found that some analogs effectively lose their toxicity against human cells while retaining a potent antiparasitic activity both in vitro and in vivo and cleared malaria from Plasmodium yoelii-infected mice, resulting in 100% mice survival rates. Our work identifies borrelidin analogs as potent, selective, and unexplored scaffolds that efficiently clear malaria both in vitro and in vivo.
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Rehman W, Haq S, Muhammad B, Hassan SF, Badshah A, Waseem M, Rahim F, Abid OUR, Ansari FL, Rashid U. Organotin (IV) based complexes as promiscuous antibacterials: Synthesis, in vitro, in silico pharmacokinetic and docking studies. J Organomet Chem 2014. [DOI: 10.1016/j.jorganchem.2014.05.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Identification of borrelidin binding site on threonyl-tRNA synthetase. Biochem Biophys Res Commun 2014; 451:485-90. [PMID: 25128830 DOI: 10.1016/j.bbrc.2014.07.100] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 07/22/2014] [Indexed: 01/06/2023]
Abstract
Borrelidin exhibits a wide spectrum of biological activities and has been considered as a non-competitive inhibitor of threonyl-tRNA synthetase (ThrRS). However, the detailed mechanisms of borrelidin against ThrRS, especially borrelidin binding site on ThrRS, are still unclear, which limits the development of novel borrelidin derivatives and rational design of structure-based ThrRS inhibitors. In this study, the binding site of borrelidin on Escherichia coli ThrRS was predicted by molecular docking. To validate our speculations, the ThrRS mutants of E. coli (P424K, E458Δ, and G459Δ) were constructed and their sensitivity to borrelidin was compared to that of the wild-type ThrRS by enzyme kinetics and stopped-flow fluorescence analysis. The docking results showed that borrelidin binds the pocket outside but adjacent to the active site of ThrRS, consisting of residue Y313, R363, R375, P424, E458, G459, and K465. Site-directed mutagenesis results showed that sensitivities of P424K, E458Δ, and G459Δ ThrRSs to borrelidin were reduced markedly. All the results showed that residue Y313, P424, E458, and G459 play vital roles in the binding of borrelidin to ThrRS. It indicated that borrelidin may induce the cleft closure, which blocks the release of Thr-AMP and PPi, to inhibit activity of ThrRS rather than inhibit the binding of ATP and threonine. This study provides new insight into inhibitory mechanisms of borrelidin against ThrRS.
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Genetic validation of aminoacyl-tRNA synthetases as drug targets in Trypanosoma brucei. EUKARYOTIC CELL 2014; 13:504-16. [PMID: 24562907 DOI: 10.1128/ec.00017-14] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Human African trypanosomiasis (HAT) is an important public health threat in sub-Saharan Africa. Current drugs are unsatisfactory, and new drugs are being sought. Few validated enzyme targets are available to support drug discovery efforts, so our goal was to obtain essentiality data on genes with proven utility as drug targets. Aminoacyl-tRNA synthetases (aaRSs) are known drug targets for bacterial and fungal pathogens and are required for protein synthesis. Here we survey the essentiality of eight Trypanosoma brucei aaRSs by RNA interference (RNAi) gene expression knockdown, covering an enzyme from each major aaRS class: valyl-tRNA synthetase (ValRS) (class Ia), tryptophanyl-tRNA synthetase (TrpRS-1) (class Ib), arginyl-tRNA synthetase (ArgRS) (class Ic), glutamyl-tRNA synthetase (GluRS) (class 1c), threonyl-tRNA synthetase (ThrRS) (class IIa), asparaginyl-tRNA synthetase (AsnRS) (class IIb), and phenylalanyl-tRNA synthetase (α and β) (PheRS) (class IIc). Knockdown of mRNA encoding these enzymes in T. brucei mammalian stage parasites showed that all were essential for parasite growth and survival in vitro. The reduced expression resulted in growth, morphological, cell cycle, and DNA content abnormalities. ThrRS was characterized in greater detail, showing that the purified recombinant enzyme displayed ThrRS activity and that the protein localized to both the cytosol and mitochondrion. Borrelidin, a known inhibitor of ThrRS, was an inhibitor of T. brucei ThrRS and showed antitrypanosomal activity. The data show that aaRSs are essential for T. brucei survival and are likely to be excellent targets for drug discovery efforts.
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Pham JS, Dawson KL, Jackson KE, Lim EE, Pasaje CFA, Turner KEC, Ralph SA. Aminoacyl-tRNA synthetases as drug targets in eukaryotic parasites. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2013; 4:1-13. [PMID: 24596663 PMCID: PMC3940080 DOI: 10.1016/j.ijpddr.2013.10.001] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 10/24/2013] [Accepted: 10/25/2013] [Indexed: 01/02/2023]
Abstract
Aminoacyl-tRNA synthetases are essential and many aaRS inhibitors kill parasites. We examine compound inhibitors tested experimentally against parasite aaRSs. Successful inhibitors were discovered by both phenotype and target-based approaches. Selectivity and resistance are ongoing challenges for development of parasite drugs.
Aminoacyl-tRNA synthetases are central enzymes in protein translation, providing the charged tRNAs needed for appropriate construction of peptide chains. These enzymes have long been pursued as drug targets in bacteria and fungi, but the past decade has seen considerable research on aminoacyl-tRNA synthetases in eukaryotic parasites. Existing inhibitors of bacterial tRNA synthetases have been adapted for parasite use, novel inhibitors have been developed against parasite enzymes, and tRNA synthetases have been identified as the targets for compounds in use or development as antiparasitic drugs. Crystal structures have now been solved for many parasite tRNA synthetases, and opportunities for selective inhibition are becoming apparent. For different biological reasons, tRNA synthetases appear to be promising drug targets against parasites as diverse as Plasmodium (causative agent of malaria), Brugia (causative agent of lymphatic filariasis), and Trypanosoma (causative agents of Chagas disease and human African trypanosomiasis). Here we review recent developments in drug discovery and target characterisation for parasite aminoacyl-tRNA synthetases.
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Affiliation(s)
- James S Pham
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
| | - Karen L Dawson
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
| | - Katherine E Jackson
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
| | - Erin E Lim
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
| | - Charisse Flerida A Pasaje
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
| | - Kelsey E C Turner
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
| | - Stuart A Ralph
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
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Gafiuc D, Weiß M, Mylonas I, Brüning A. Borrelidin has limited anti-cancer effects in bcl-2 overexpressing breast cancer and leukemia cells and reveals toxicity in non-malignant breast epithelial cells. J Appl Toxicol 2013; 34:1109-13. [PMID: 24155182 DOI: 10.1002/jat.2946] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 09/12/2013] [Accepted: 09/12/2013] [Indexed: 01/23/2023]
Abstract
Clinically effective anti-cancer drugs have to tread a narrow line between selective cytotoxicity on tumor cells and tolerable adverse effects against healthy tissues. This causes the failure of many potential cancer drugs in advanced clinical trials, hence signifying the importance of a comprehensive initial estimate of the cytotoxicity of prospective anti-cancer drugs in preclinical studies. In this study, the cytotoxicity of borrelidin, a macrolide antibiotic with a high cytotoxic selectivity for proliferating endothelial cells and leukemia cells, was tested on malignant and non-malignant breast cells. Highly metastatic breast cancer cell lines (MDA-MB-231 and MDA-MB-435) showed promising results and exhibited good sensitivity to borrelidin at low nanomolar concentrations, but borrelidin was cytotoxic to a non-malignant breast epithelial cell line (MCF10A) as well. Furthermore, although a high sensitivity of endothelial cells (human umbilical vein endothelial cells; HUVEC) and individual leukemia cell lines (Jurkat and IM9) to borrelidin was confirmed in this study, another leukemia cell line (HL60) and an immortalized endothelial cell line (EA.hy926) displayed a significantly decreased sensitivity. Reduced sensitivity to borrelidin was associated with elevated bcl-2 expression in these cell lines. In conclusion, the results presented show that borrelidin displays high and selective cytotoxicity against subgroups of cancer cells and endothelial cells, but, owing to its non-specific toxicity to non-malignant cells, its clinical application might be restricted because of likely adverse effects and limited efficacy in bcl2-overexpressing cancer cells.
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Affiliation(s)
- Diana Gafiuc
- Department of Obstetrics and Gynecology, Ludwig-Maximilians-University, Maistrasse 11, 80337, München, Germany
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Orelle C, Szal T, Klepacki D, Shaw KJ, Vázquez-Laslop N, Mankin AS. Identifying the targets of aminoacyl-tRNA synthetase inhibitors by primer extension inhibition. Nucleic Acids Res 2013; 41:e144. [PMID: 23761439 PMCID: PMC3737564 DOI: 10.1093/nar/gkt526] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Aminoacyl-transfer RNA (tRNA) synthetases (RS) are essential components of the cellular translation machinery and can be exploited for antibiotic discovery. Because cells have many different RS, usually one for each amino acid, identification of the specific enzyme targeted by a new natural or synthetic inhibitor can be cumbersome. We describe the use of the primer extension technique in conjunction with specifically designed synthetic genes to identify the RS targeted by an inhibitor. Suppression of a synthetase activity reduces the amount of the cognate aminoacyl-tRNA in a cell-free translation system resulting in arrest of translation when the corresponding codon enters the decoding center of the ribosome. The utility of the technique is demonstrated by identifying a switch in target specificity of some synthetic inhibitors of threonyl-tRNA synthetase.
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Affiliation(s)
- Cédric Orelle
- Center for Pharmaceutical Biotechnology, University of Illinois, Chicago, IL 60607, USA and Trius Therapeutics, Inc., San Diego, CA 92121, USA
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Dewan V, Reader J, Forsyth KM. Role of aminoacyl-tRNA synthetases in infectious diseases and targets for therapeutic development. Top Curr Chem (Cham) 2013; 344:293-329. [PMID: 23666077 DOI: 10.1007/128_2013_425] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Aminoacyl-tRNA synthetases (AARSs) play a pivotal role in protein synthesis and cell viability. These 22 "housekeeping" enzymes (1 for each standard amino acid plus pyrrolysine and o-phosphoserine) are specifically involved in recognizing and aminoacylating their cognate tRNAs in the cellular pool with the correct amino acid prior to delivery of the charged tRNA to the protein synthesis machinery. Besides serving this canonical function, higher eukaryotic AARSs, some of which are organized in the cytoplasm as a multisynthetase complex of nine enzymes plus additional cellular factors, have also been implicated in a variety of non-canonical roles. AARSs are involved in the regulation of transcription, translation, and various signaling pathways, thereby ensuring cell survival. Based in part on their versatility, AARSs have been recruited by viruses to perform essential functions. For example, host synthetases are packaged into some retroviruses and are required for their replication. Other viruses mimic tRNA-like structures in their genomes, and these motifs are aminoacylated by the host synthetase as part of the viral replication cycle. More recently, it has been shown that certain large DNA viruses infecting animals and other diverse unicellular eukaryotes encode tRNAs, AARSs, and additional components of the protein-synthesis machinery. This chapter will review our current understanding of the role of host AARSs and tRNA-like structures in viruses and discuss their potential as anti-viral drug targets. The identification and development of compounds that target bacterial AARSs, thereby serving as novel antibiotics, will also be discussed. Particular attention will be given to recent work on a number of tRNA-dependent AARS inhibitors and to advances in a new class of natural "pro-drug" antibiotics called Trojan Horse inhibitors. Finally, we will explore how bacteria that naturally produce AARS-targeting antibiotics must protect themselves against cell suicide using naturally antibiotic resistant AARSs, and how horizontal gene transfer of these AARS genes to pathogens may threaten the future use of this class of antibiotics.
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Affiliation(s)
- Varun Dewan
- Department of Chemistry and Biochemistry, Ohio State Biochemistry Program, Center for RNA Biology, and Center for Retroviral Research, The Ohio State University, Columbus, OH, 43210, USA
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Gadakh B, Van Aerschot A. Aminoacyl-tRNA synthetase inhibitors as antimicrobial agents: a patent review from 2006 till present. Expert Opin Ther Pat 2012; 22:1453-65. [PMID: 23062029 DOI: 10.1517/13543776.2012.732571] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Aminoacyl-tRNA synthetases (aaRSs) are one of the leading targets for development of antimicrobial agents. Although these enzymes are well conserved among prokaryotes, significant divergence has occurred between prokaryotic and eukaryotic aaRSs, which can be exploited in the discovery of broad-spectrum antibacterial agents. Although several aaRS inhibitors have been reported before, they failed as a result of poor selectivity and limited cell penetration. AREAS COVERED This review covers January 2006 to April 2012 wherein several new analogues were claimed as aaRS inhibitors. Anacor Pharmaceuticals patented several boron-containing derivatives inhibiting the function of the editing domain of aaRSs. Two patents describe the combination of aaRS inhibitors with other antibacterial agents. Patents disclosing aaRS inhibitors for indications other than antimicrobial agents are not considered for review here. EXPERT OPINION Several recently disclosed leads may form the foundation for development of potent and selective bacterial aaRS inhibitors. In comparison with, for example, terbinafine and itraconazole, compound C10 (AN2690) is a very promising candidate for treatment of ungual and periungual infections with improved nail penetration and low keratin binding. In addition, Raplidyne, Inc. reported bicyclic heteroaromatic compounds as potent and selective inhibitors of bacterial MetRS. These have proven to be particularly effective for treatment of Clostridium difficile-associated diarrhea. Finally, combination of aaRS inhibitors to attenuate resistance looks as a viable strategy to expand the lifespan of existing antibiotics.
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Affiliation(s)
- Bharat Gadakh
- KU Leuven, Rega Institute for Medical Research, Laboratory of Medicinal Chemistry, Minderbroedersstraat 10, 3000 Leuven, Belgium
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Gao YM, Wang XJ, Zhang J, Li M, Liu CX, An J, Jiang L, Xiang WS. Borrelidin, a potent antifungal agent: insight into the antifungal mechanism against Phytophthora sojae. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:9874-9881. [PMID: 22967236 DOI: 10.1021/jf302857x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Borrelidin has high and specific antifungal activity against Phytophthora sojae . To explore the antifungal mechanism of borrelidin against P. sojae , the relationship between the antifungal activity of borrelidin and the concentration of threonine was evaluated. The results demonstrated that the growth-inhibitory effect of borrelidin on the growth of P. sojae was antagonized by threonine in a dose-dependent manner, suggesting that threonyl-tRNA synthetase (ThrRS) may be the potential target of borrelidin. Subsequently, the inhibition of the enzymatic activity of ThrRS by borrelidin in vitro was confirmed. Furthermore, the detailed interaction between ThrRS and borrelidin was investigated using fluorescence spectroscopy and circular dichroism (CD), implying a tight binding of borrelidin to ThrRS. Taken together, these results suggest that the antifungal activity of borrelidin against P. sojae was mediated by inhibition of ThrRS via the formation of the ThrRS-borrelidin complex.
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Affiliation(s)
- Ya-Mei Gao
- School of Life Science, Northeast Agricultural University, Harbin 150030, People's Republic of China
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Keller TL, Zocco D, Sundrud MS, Hendrick M, Edenius M, Yum J, Kim YJ, Lee HK, Cortese JF, Wirth DF, Dignam JD, Rao A, Yeo CY, Mazitschek R, Whitman M. Halofuginone and other febrifugine derivatives inhibit prolyl-tRNA synthetase. Nat Chem Biol 2012; 8:311-7. [PMID: 22327401 PMCID: PMC3281520 DOI: 10.1038/nchembio.790] [Citation(s) in RCA: 276] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Accepted: 11/22/2011] [Indexed: 01/01/2023]
Abstract
Febrifugine, one of the fifty fundamental herbs of traditional Chinese medicine, has been characterized for its therapeutic activity whilst its molecular target has remained unknown. Febrifugine derivatives have been used to treat malaria, cancer, fibrosis, and inflammatory disease. We recently demonstrated that halofuginone (HF), a widely studied derivative of febrifugine, inhibits the development of Th17-driven autoimmunity in a mouse model of multiple sclerosis by activating the amino acid response pathway (AAR). Here we show that HF binds glutamyl-prolyl-tRNA synthetase (EPRS) inhibiting prolyl-tRNA synthetase activity; this inhibition is reversed by the addition of exogenous proline or EPRS. We further show that inhibition of EPRS underlies the broad bioactivities of this family of natural products. This work both explains the molecular mechanism of a promising family of therapeutics, and highlights the AAR pathway as an important drug target for promoting inflammatory resolution.
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Affiliation(s)
- Tracy L Keller
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Massachusetts, USA.
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Vondenhoff GHM, Van Aerschot A. Aminoacyl-tRNA synthetase inhibitors as potential antibiotics. Eur J Med Chem 2011; 46:5227-36. [PMID: 21968372 DOI: 10.1016/j.ejmech.2011.08.049] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Revised: 08/12/2011] [Accepted: 08/15/2011] [Indexed: 11/29/2022]
Abstract
Increasing resistance to antibiotics is a major problem worldwide and provides the stimulus for development of new bacterial inhibitors with preferably different modes of action. In search for new leads, several new bacterial targets are being exploited beside the use of traditional screening methods. Hereto, inhibition of bacterial protein synthesis is a long-standing validated target. Aminoacyl-tRNA synthetases (aaRSs) play an indispensable role in protein synthesis and their structures proved quite conserved in prokaryotes and eukaryotes. However, some divergence has occurred allowing the development of selective aaRS inhibitors. Following an outline on the action mechanism of aaRSs, an overview will be given of already existing aaRS inhibitors, which are largely based on mimics of the aminoacyl-adenylates, the natural reaction intermediates. This is followed by a discussion on more recent developments in the field and the bioavailability problem.
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Affiliation(s)
- Gaston H M Vondenhoff
- Rega Institute for Medical Research, Laboratory of Medicinal Chemistry, Katholieke Universiteit Leuven, Minderbroedersstraat 10, BE-3000 Leuven, Belgium
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Gutierrez-Lugo MT, Bewley CA. Susceptibility and mode of binding of the Mycobacterium tuberculosis cysteinyl transferase mycothiol ligase to tRNA synthetase inhibitors. Bioorg Med Chem Lett 2011; 21:2480-3. [PMID: 21392992 PMCID: PMC3109356 DOI: 10.1016/j.bmcl.2011.02.042] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 02/06/2011] [Accepted: 02/14/2011] [Indexed: 10/18/2022]
Abstract
The cysteinyl transferase mycothiol ligase, or MshC, catalyzes the fourth step in the biosynthesis of the small molecular weight thiol mycothiol. MshC is essential for growth of Mycobacterium tuberculosis. Two groups of known aminoacyl tRNA synthetase inhibitors were evaluated for inhibition of M. tuberculosis MshC including aminoacyl adenosine analogs and natural products. Using enzyme assays, isothermal titration calorimetry and NMR, we show that MshC is selectively inhibited by cysteinyl sulfamoyl adenosine, and that discrimination occurs at the amino acid moiety.
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Affiliation(s)
| | - Carole A. Bewley
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, United States
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Misacylation of specific nonmethionyl tRNAs by a bacterial methionyl-tRNA synthetase. Proc Natl Acad Sci U S A 2011; 108:6933-8. [PMID: 21482813 DOI: 10.1073/pnas.1019033108] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Aminoacyl-tRNA synthetases perform a critical step in translation by aminoacylating tRNAs with their cognate amino acids. Although high fidelity of aminoacyl-tRNA synthetases is often thought to be essential for cell biology, recent studies indicate that cells tolerate and may even benefit from tRNA misacylation under certain conditions. For example, mammalian cells selectively induce mismethionylation of nonmethionyl tRNAs, and this type of misacylation contributes to a cell's response to oxidative stress. However, the enzyme responsible for tRNA mismethionylation and the mechanism by which specific tRNAs are mismethionylated have not been elucidated. Here we show by tRNA microarrays and filter retention that the methionyl-tRNA synthetase enzyme from Escherichia coli (EcMRS) is sufficient to mismethionylate two tRNA species, and , indicating that tRNA mismethionylation is also present in the bacterial domain of life. We demonstrate that the anticodon nucleotides of these misacylated tRNAs play a critical role in conferring mismethionylation identity. We also show that a certain low level of mismethionylation is maintained for these tRNAs, suggesting that mismethionylation levels may have evolved to confer benefits to the cell while still preserving sufficient translational fidelity to ensure cell viability. EcMRS mutants show distinct effects on mismethionylation, indicating that many regions in this synthetase enzyme influence mismethionylation. Our results show that tRNA mismethionylation can be carried out by a single protein enzyme, mismethionylation also requires identity elements in the tRNA, and EcMRS has a defined structure-function relationship for tRNA mismethionylation.
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Borrelidin, a potent antimalarial: stage-specific inhibition profile of synchronized cultures of Plasmodium falciparum. J Antibiot (Tokyo) 2011; 64:381-4. [DOI: 10.1038/ja.2011.6] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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38
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Woolard J, Vousden W, Moss SJ, Krishnakumar A, Gammons MVR, Nowak DG, Dixon N, Micklefield J, Spannhoff A, Bedford MT, Gregory MA, Martin CJ, Leadlay PF, Zhang MQ, Harper SJ, Bates DO, Wilkinson B. Borrelidin modulates the alternative splicing of VEGF in favour of anti-angiogenic isoforms. Chem Sci 2011; 2011:273-278. [PMID: 22822423 PMCID: PMC3399765 DOI: 10.1039/c0sc00297f] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The polyketide natural product borrelidin 1 is a potent inhibitor of angiogenesis and spontaneous metastasis. Affinity biopanning of a phage display library of colon tumor cell cDNAs identified the tandem WW domains of spliceosome-associated protein formin binding protein 21 (FBP21) as a novel molecular target of borrelidin, suggesting that borrelidin may act as a modulator of alternative splicing. In support of this idea, 1, and its more selective analog 2, bound to purified recombinant WW domains of FBP21. They also altered the ratio of vascular endothelial growth factor (VEGF) isoforms in retinal pigmented endothelial (RPE) cells in favour of anti-angiogenic isoforms. Transfection of RPE cells with FBP21 altered the ratio in favour of pro-angiogenic VEGF isoforms, an effect inhibited by 2. These data implicate FBP21 in the regulation of alternative splicing and suggest the potential of borrelidin analogs as tools to deconvolute key steps of spliceosome function.
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Affiliation(s)
- Jeanette Woolard
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Southwell Street Bristol, BS2 8EJ, UK. Fax: +44 (0)117 9288151; Tel: +44 (0)117 9289818;
| | - William Vousden
- Biotica, Chesterford Research Park, Cambridge, CB10 1XL, UK. Fax: +44 (0)1799 532921; Tel: +44 (0)1799 532925;
| | - Steven J. Moss
- Biotica, Chesterford Research Park, Cambridge, CB10 1XL, UK. Fax: +44 (0)1799 532921; Tel: +44 (0)1799 532925;
| | - Arjun Krishnakumar
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Southwell Street Bristol, BS2 8EJ, UK. Fax: +44 (0)117 9288151; Tel: +44 (0)117 9289818;
| | - Melissa VR Gammons
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Southwell Street Bristol, BS2 8EJ, UK. Fax: +44 (0)117 9288151; Tel: +44 (0)117 9289818;
| | - David G Nowak
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Southwell Street Bristol, BS2 8EJ, UK. Fax: +44 (0)117 9288151; Tel: +44 (0)117 9289818;
| | - Neil Dixon
- School of Chemistry and Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Jason Micklefield
- School of Chemistry and Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Astrid Spannhoff
- The University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, Smithville, Texas 78957, USA
| | - Mark T. Bedford
- The University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, Smithville, Texas 78957, USA
| | - Matthew A. Gregory
- Biotica, Chesterford Research Park, Cambridge, CB10 1XL, UK. Fax: +44 (0)1799 532921; Tel: +44 (0)1799 532925;
| | - Christine J. Martin
- Biotica, Chesterford Research Park, Cambridge, CB10 1XL, UK. Fax: +44 (0)1799 532921; Tel: +44 (0)1799 532925;
| | - Peter F. Leadlay
- Department of Biochemistry, 80 Tennis Court Road, University of Cambridge, Cambridge CB2 1GA, UK
| | - Ming Q. Zhang
- Biotica, Chesterford Research Park, Cambridge, CB10 1XL, UK. Fax: +44 (0)1799 532921; Tel: +44 (0)1799 532925;
| | - Steven J. Harper
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Southwell Street Bristol, BS2 8EJ, UK. Fax: +44 (0)117 9288151; Tel: +44 (0)117 9289818;
| | - David O. Bates
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Southwell Street Bristol, BS2 8EJ, UK. Fax: +44 (0)117 9288151; Tel: +44 (0)117 9289818;
| | - Barrie Wilkinson
- Biotica, Chesterford Research Park, Cambridge, CB10 1XL, UK. Fax: +44 (0)1799 532921; Tel: +44 (0)1799 532925;
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Huthmacher C, Hoppe A, Bulik S, Holzhütter HG. Antimalarial drug targets in Plasmodium falciparum predicted by stage-specific metabolic network analysis. BMC SYSTEMS BIOLOGY 2010; 4:120. [PMID: 20807400 PMCID: PMC2941759 DOI: 10.1186/1752-0509-4-120] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Accepted: 08/31/2010] [Indexed: 12/20/2022]
Abstract
BACKGROUND Despite enormous efforts to combat malaria the disease still afflicts up to half a billion people each year of which more than one million die. Currently no approved vaccine is available and resistances to antimalarials are widely spread. Hence, new antimalarial drugs are urgently needed. RESULTS Here, we present a computational analysis of the metabolism of Plasmodium falciparum, the deadliest malaria pathogen. We assembled a compartmentalized metabolic model and predicted life cycle stage specific metabolism with the help of a flux balance approach that integrates gene expression data. Predicted metabolite exchanges between parasite and host were found to be in good accordance with experimental findings when the parasite's metabolic network was embedded into that of its host (erythrocyte). Knock-out simulations identified 307 indispensable metabolic reactions within the parasite. 35 out of 57 experimentally demonstrated essential enzymes were recovered and another 16 enzymes, if additionally the assumption was made that nutrient uptake from the host cell is limited and all reactions catalyzed by the inhibited enzyme are blocked. This predicted set of putative drug targets, shown to be enriched with true targets by a factor of at least 2.75, was further analyzed with respect to homology to human enzymes, functional similarity to therapeutic targets in other organisms and their predicted potency for prophylaxis and disease treatment. CONCLUSIONS The results suggest that the set of essential enzymes predicted by our flux balance approach represents a promising starting point for further drug development.
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Affiliation(s)
- Carola Huthmacher
- Institute of Biochemistry, Charité, Monbijoustraße 2, 10117 Berlin, Germany
| | - Andreas Hoppe
- Institute of Biochemistry, Charité, Monbijoustraße 2, 10117 Berlin, Germany
| | - Sascha Bulik
- Institute of Biochemistry, Charité, Monbijoustraße 2, 10117 Berlin, Germany
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Merritt EA, Arakaki TL, Larson ET, Kelley A, Mueller N, Napuli AJ, Zhang L, Deditta G, Luft J, Verlinde CLMJ, Fan E, Zucker F, Buckner FS, Van Voorhis WC, Hol WGJ. Crystal structure of the aspartyl-tRNA synthetase from Entamoeba histolytica. Mol Biochem Parasitol 2009; 169:95-100. [PMID: 19874856 DOI: 10.1016/j.molbiopara.2009.10.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Revised: 10/15/2009] [Accepted: 10/19/2009] [Indexed: 10/20/2022]
Abstract
The crystal structure of the aspartyl-tRNA synthetase from the eukaryotic parasite Entamoeba histolytica has been determined at 2.8Aresolution. Relative to homologous sequences, the E. histolytica protein contains a 43-residue insertion between the N-terminal anticodon binding domain and the C-terminal catalytic domain. The present structure reveals that this insertion extends an arm of the hinge region that has previously been shown to mediate interaction of aspartyl-tRNA synthetase with the cognate tRNA D-stem. Modeling indicates that this Entamoeba-specific insertion is likely to increase the interaction surface with the cognate tRNA(Asp). In doing so it may substitute functionally for an RNA-binding motif located in N-terminal extensions found in AspRS sequences from lower eukaryotes but absent in Entamoeba. The E. histolytica AspRS structure shows a well-ordered N-terminus that contributes to the AspRS dimer interface.
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Affiliation(s)
- Ethan A Merritt
- Department of Biochemistry, University of Washington, Mailstop 357742, Seattle, WA 98195, USA.
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Van de Vijver P, Ostrowski T, Sproat B, Goebels J, Rutgeerts O, Van Aerschot A, Waer M, Herdewijn P. Aminoacyl-tRNA synthetase inhibitors as potent and synergistic immunosuppressants. J Med Chem 2008; 51:3020-9. [PMID: 18438987 DOI: 10.1021/jm8000746] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The aminoacyl-tRNA synthetase family of enzymes is the target of many antibacterials and inhibitors of eukaryotic hyperproliferation. In screening analogues of 5'-O-(N-L-aminoacyl)-sulfamoyladenosine containing all 20 proteinogenic amino acids, we found these compounds to have potent immunosuppressive activity. Also, we found that combinations of these compounds inhibited the immune response synergistically. Based on these data, analogues with modifications at the aminoacyl and ribose moieties were designed and evaluated, and several of these showed high immunosuppressive potency, with one compound having an IC50 of 80 nM, when tested in a cellular mixed lymphocyte reaction assay. Apart from showing the potential of aminoacyl-tRNA synthetase inhibitors as immunosuppressants, the current study also provides arguments for careful evaluation of the immunosuppressive activity of developmental antibacterials that target these enzymes.
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Affiliation(s)
- Pieter Van de Vijver
- Laboratory for Medicinal Chemistry, Rega Institute for Medical Research, Catholic University of Leuven, Leuven, Belgium
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Fatumo S, Plaimas K, Mallm JP, Schramm G, Adebiyi E, Oswald M, Eils R, König R. Estimating novel potential drug targets of Plasmodium falciparum by analysing the metabolic network of knock-out strains in silico. INFECTION GENETICS AND EVOLUTION 2008; 9:351-8. [PMID: 18313365 DOI: 10.1016/j.meegid.2008.01.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2007] [Revised: 12/21/2007] [Accepted: 01/17/2008] [Indexed: 10/22/2022]
Abstract
Malaria is one of the world's most common and serious diseases causing death of about 3 million people each year. Its most severe occurrence is caused by the protozoan Plasmodium falciparum. Biomedical research could enable treating the disease by effectively and specifically targeting essential enzymes of this parasite. However, the parasite has developed resistance to existing drugs making it indispensable to discover new drugs. We have established a simple computational tool which analyses the topology of the metabolic network of P. falciparum to identify essential enzymes as possible drug targets. We investigated the essentiality of a reaction in the metabolic network by deleting (knocking-out) such a reaction in silico. The algorithm selected neighbouring compounds of the investigated reaction that had to be produced by alternative biochemical pathways. Using breadth first searches, we tested qualitatively if these products could be generated by reactions that serve as potential deviations of the metabolic flux. With this we identified 70 essential reactions. Our results were compared with a comprehensive list of 38 targets of approved malaria drugs. When combining our approach with an in silico analysis performed recently [Yeh, I., Hanekamp, T., Tsoka, S., Karp, P.D., Altman, R.B., 2004. Computational analysis of Plasmodium falciparum metabolism: organizing genomic information to facilitate drug discovery. Genome Res. 14, 917-924] we could improve the precision of the prediction results. Finally we present a refined list of 22 new potential candidate targets for P. falciparum, half of which have reasonable evidence to be valid targets against micro-organisms and cancer.
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Affiliation(s)
- Segun Fatumo
- Computer and Information Sciences Department, Covenant University, Ota, Nigeria
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43
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Ochsner UA, Sun X, Jarvis T, Critchley I, Janjic N. Aminoacyl-tRNA synthetases: essential and still promising targets for new anti-infective agents. Expert Opin Investig Drugs 2007; 16:573-93. [PMID: 17461733 DOI: 10.1517/13543784.16.5.573] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The emergence of resistance to existing antibiotics demands the development of novel antimicrobial agents directed against novel targets. Historically, bacterial cell wall synthesis, protein, and DNA and RNA synthesis have been major targets of very successful classes of antibiotics such as beta-lactams, glycopeptides, macrolides, aminoglycosides, tetracyclines, rifampicins and quinolones. Recently, efforts have been made to develop novel agents against validated targets in these pathways but also against new, previously unexploited targets. The era of genomics has provided insights into novel targets in microbial pathogens. Among the less exploited--but still promising--targets is the family of 20 aminoacyl-tRNA synthetases (aaRSs), which are essential for protein synthesis. These targets have been validated in nature as aaRS inhibition has been shown as the specific mode of action for many natural antimicrobial agents synthesized by bacteria and fungi. Therefore, aaRSs have the potential to be targeted by novel agents either from synthetic or natural sources to yield specific and selective anti-infectives. Numerous high-throughput screening programs aimed at identifying aaRS inhibitors have been performed over the last 20 years. A large number of promising lead compounds have been identified but only a few agents have moved forward into clinical development. This review provides an update on the present strategies to develop novel aaRS inhibitors as anti-infective drugs.
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Affiliation(s)
- Urs A Ochsner
- Replidyne, Inc., 1450 Infinite Dr, Louisville, CO 80027, USA.
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44
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Abstract
The aminoacyl-tRNA synthetases (aaRSs) are responsible for selecting specific amino acids for protein synthesis, and this essential role in translation has garnered them much attention as targets for novel antimicrobials. Understanding how the aaRSs evolved efficient substrate selection offers a potential route to develop useful inhibitors of microbial protein synthesis. Here, we discuss discrimination of small molecules by aaRSs, and how the evolutionary divergence of these mechanisms offers a means to target inhibitors against these essential microbial enzymes.
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Affiliation(s)
- Sandro F Ataide
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, USA
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Hurdle JG, O'Neill AJ, Chopra I. Prospects for aminoacyl-tRNA synthetase inhibitors as new antimicrobial agents. Antimicrob Agents Chemother 2005; 49:4821-33. [PMID: 16304142 PMCID: PMC1315952 DOI: 10.1128/aac.49.12.4821-4833.2005] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Julian Gregston Hurdle
- Antimicrobial Research Centre and School of Biochemistry and Microbiology, University of Leeds, Leeds LS2 9JT, United Kingdom
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46
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Ahel D, Slade D, Mocibob M, Söll D, Weygand-Durasevic I. Selective inhibition of divergent seryl-tRNA synthetases by serine analogues. FEBS Lett 2005; 579:4344-8. [PMID: 16054140 DOI: 10.1016/j.febslet.2005.06.073] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2005] [Revised: 06/23/2005] [Accepted: 06/29/2005] [Indexed: 10/25/2022]
Abstract
Seryl-tRNA synthetases (SerRSs) fall into two distinct evolutionary groups of enzymes, bacterial and methanogenic. These two types of SerRSs display only minimal sequence similarity, primarily within the class II conserved motifs, and possess distinct modes of tRNA(Ser) recognition. In order to determine whether the two types of SerRSs also differ in their recognition of the serine substrate, we compared the sensitivity of the representative methanogenic and bacterial-type SerRSs to serine hydroxamate and two previously unidentified inhibitors, serinamide and serine methyl ester. Our kinetic data showed selective inhibition of the methanogenic SerRS by serinamide, suggesting a lack of mechanistic uniformity in serine recognition between the evolutionarily distinct SerRSs.
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Affiliation(s)
- Dragana Ahel
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA
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