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Sangsuwan W, Taweesablamlert A, Boonkerd A, Isarangkool Na Ayutthaya C, Yoo S, Javid B, Faikhruea K, Vilaivan T, Aonbangkhen C, Chuawong P. A quest for novel antimicrobial targets: Inhibition of Asp-tRNA Asn/Glu-tRNA Gln amidotransferase (GatCAB) by synthetic analogs of aminoacyl-adenosine in vitro and live bacteria. Bioorg Chem 2024; 150:107530. [PMID: 38852310 DOI: 10.1016/j.bioorg.2024.107530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 04/25/2024] [Accepted: 06/03/2024] [Indexed: 06/11/2024]
Abstract
The Asp-tRNAAsn/Glu-tRNAGln amidotransferase (GatCAB) has been proposed as a novel antibacterial drug target due to its indispensability in prominent human pathogens. While several inhibitors with in vitro activity have been identified, none have been demonstrated to have potent activity against live bacteria. In this work, seven non-hydrolyzable transition state mimics of GatCAB were synthesized and tested as the transamidase inhibitors against GatCAB from the human pathogen Helicobacter pylori. Notably, the methyl sulfone analog of glutamyl-adenosine significantly reduced GatCAB's transamination rate. Additionally, four lipid-conjugates of these mimics displayed antibacterial activity against Bacillus subtilis, likely due to enhanced cell permeability. Inhibitory activity against GatCAB in live bacteria was confirmed using a sensitive gain-of-function dual luciferase reporter in Mycobacterium bovis-BCG. Only the lipid-conjugated methyl sulfone analog exhibited a significant increase in mistranslation rate, highlighting its cell permeability and inhibitory potential. This study provides insights for developing urgently needed novel antibacterial agents amidst emerging antimicrobial drug resistance.
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Affiliation(s)
- Withsakorn Sangsuwan
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Special Research Unit for Advanced Magnetic Resonance (AMR), Kasetsart University, Bangkok 10900, Thailand
| | - Amata Taweesablamlert
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Special Research Unit for Advanced Magnetic Resonance (AMR), Kasetsart University, Bangkok 10900, Thailand
| | - Anon Boonkerd
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Special Research Unit for Advanced Magnetic Resonance (AMR), Kasetsart University, Bangkok 10900, Thailand
| | - Chawarat Isarangkool Na Ayutthaya
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Special Research Unit for Advanced Magnetic Resonance (AMR), Kasetsart University, Bangkok 10900, Thailand
| | - Sion Yoo
- Division of Experimental Medicine, University of California, San Francisco, CA, USA
| | - Babak Javid
- Division of Experimental Medicine, University of California, San Francisco, CA, USA
| | - Kriangsak Faikhruea
- Organic Synthesis Research Unit (OSRU), Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Tirayut Vilaivan
- Organic Synthesis Research Unit (OSRU), Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Chanat Aonbangkhen
- Center of Excellence in Natural Products Chemistry (CENP), Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330 Thailand; Center of Excellence on Petrochemical and Materials Technology, Chulalongkorn University, Pathumwan, Bangkok 10330, Thailand
| | - Pitak Chuawong
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Special Research Unit for Advanced Magnetic Resonance (AMR), Kasetsart University, Bangkok 10900, Thailand.
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Lewis AM, Fallon T, Dittemore GA, Sheppard K. Evolution and variation in amide aminoacyl-tRNA synthesis. IUBMB Life 2024. [PMID: 38391119 DOI: 10.1002/iub.2811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 01/22/2024] [Indexed: 02/24/2024]
Abstract
The amide proteogenic amino acids, asparagine and glutamine, are two of the twenty amino acids used in translation by all known life. The aminoacyl-tRNA synthetases for asparagine and glutamine, asparaginyl-tRNA synthetase and glutaminyl tRNA synthetase, evolved after the split in the last universal common ancestor of modern organisms. Before that split, life used two-step indirect pathways to synthesize asparagine and glutamine on their cognate tRNAs to form the aminoacyl-tRNA used in translation. These two-step pathways were retained throughout much of the bacterial and archaeal domains of life and eukaryotic organelles. The indirect routes use non-discriminating aminoacyl-tRNA synthetases (non-discriminating aspartyl-tRNA synthetase and non-discriminating glutamyl-tRNA synthetase) to misaminoacylate the tRNA. The misaminoacylated tRNA formed is then transamidated into the amide aminoacyl-tRNA used in protein synthesis by tRNA-dependent amidotransferases (GatCAB and GatDE). The enzymes and tRNAs involved assemble into complexes known as transamidosomes to help maintain translational fidelity. These pathways have evolved to meet the varied cellular needs across a diverse set of organisms, leading to significant variation. In certain bacteria, the indirect pathways may provide a means to adapt to cellular stress by reducing the fidelity of protein synthesis. The retention of these indirect pathways versus acquisition of asparaginyl-tRNA synthetase and glutaminyl tRNA synthetase in lineages likely involves a complex interplay of the competing uses of glutamine and asparagine beyond translation, energetic costs, co-evolution between enzymes and tRNA, and involvement in stress response that await further investigation.
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Affiliation(s)
- Alexander M Lewis
- Chemistry Department, Skidmore College, Saratoga Springs, New York, USA
| | - Trevor Fallon
- Chemistry Department, Skidmore College, Saratoga Springs, New York, USA
| | | | - Kelly Sheppard
- Chemistry Department, Skidmore College, Saratoga Springs, New York, USA
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Abstract
Most bacteria employ a two-step indirect tRNA aminoacylation pathway for the synthesis of aminoacylated tRNAGln and tRNAAsn. The heterotrimeric enzyme GatCAB performs a critical amidotransferase reaction in the second step of this pathway. We have previously demonstrated in mycobacteria that this two-step pathway is error prone and translational errors contribute to adaptive phenotypes such as antibiotic tolerance. Furthermore, we identified clinical isolates of the globally important pathogen Mycobacterium tuberculosis with partial loss-of-function mutations in gatA, and demonstrated that these mutations result in high, specific rates of translational error and increased rifampin tolerance. However, the mechanisms by which these clinically derived mutations in gatA impact GatCAB function were unknown. Here, we describe biochemical and biophysical characterization of M. tuberculosis GatCAB, containing either wild-type gatA or one of two gatA mutants from clinical strains. We show that these mutations have minimal impact on enzymatic activity of GatCAB; however, they result in destabilization of the GatCAB complex as well as that of the ternary asparaginyl-transamidosome. Stabilizing complex formation with the solute trehalose increases specific translational fidelity of not only the mutant strains but also of wild-type mycobacteria. Therefore, our data suggest that alteration of GatCAB stability may be a mechanism for modulation of translational fidelity. IMPORTANCE Most bacteria use a two-step indirect pathway to aminoacylate tRNAGln and tRNAAsn, despite the fact that the indirect pathway consumes more energy and is error prone. We have previously shown that the higher protein synthesis errors from this indirect pathway in mycobacteria allow adaptation to hostile environments such as antibiotic treatment through generation of novel alternate proteins not coded by the genome. However, the precise mechanisms of how translational fidelity is tuned were not known. Here, we biochemically and biophysically characterize the critical enzyme of the Mycobacterium tuberculosis indirect pathway, GatCAB, as well as two mutant enzymes previously identified from clinical isolates that were associated with increased mistranslation. We show that the mutants dysregulate the pathway via destabilizing the enzyme complex. Importantly, increasing stability improves translational fidelity in both wild-type and mutant bacteria, demonstrating a mechanism by which mycobacteria may tune mistranslation rates.
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Chew BLA, Tanoto FR, Luo D. LC-MS assay targeting the mycobacterial indirect aminoacylation pathway uncovers glutaminase activities of the nondiscriminating aspartyl-synthetase. FEBS Lett 2020; 594:2159-2167. [PMID: 32279326 DOI: 10.1002/1873-3468.13786] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 02/28/2020] [Accepted: 03/26/2020] [Indexed: 11/08/2022]
Abstract
The synthesis of asparagine (Asn)-tRNAAsn in most prokaryotes uses an indirect aminoacylation pathway involving a nondiscriminating aspartyl synthetase (ND-AspRS) and a glutamine amidotransferase (GatCAB). This was recently implicated as an adaptive mistranslation mechanism for antimicrobial resistance in Mycobacterium tuberculosis, but it remains poorly understood. We report an accessible liquid chromatography-mass spectrometry method with unparalleled chemical specificity, sensitivity, and quantification over the current assays to enable the direct analysis and drug screening campaigns of this pathway. Through this method, we show that the mycobacterial ND-AspRS stimulates the glutaminase activity of GatCAB. We further uncover novel glutaminase activity of the synthetase. These biological insights help better understand the indirect aminoacylation biology and allude to new roles beyond protein translation.
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Affiliation(s)
- Bing Liang Alvin Chew
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore City, Singapore
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore City, Singapore
- NTU Institute of Health Technologies, Interdisciplinary Graduate Programme, Nanyang Technological University, Singapore City, Singapore
| | | | - Dahai Luo
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore City, Singapore
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore City, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore City, Singapore
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Rathnayake UM, Hendrickson TL. Bacterial Aspartyl-tRNA Synthetase Has Glutamyl-tRNA Synthetase Activity. Genes (Basel) 2019; 10:genes10040262. [PMID: 30939863 PMCID: PMC6523644 DOI: 10.3390/genes10040262] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 03/25/2019] [Accepted: 03/27/2019] [Indexed: 01/03/2023] Open
Abstract
The aminoacyl-tRNA synthetases (aaRSs) are well established as the translators of the genetic code, because their products, the aminoacyl-tRNAs, read codons to translate messenger RNAs into proteins. Consequently, deleterious errors by the aaRSs can be transferred into the proteome via misacylated tRNAs. Nevertheless, many microorganisms use an indirect pathway to produce Asn-tRNAAsn via Asp-tRNAAsn. This intermediate is produced by a non-discriminating aspartyl-tRNA synthetase (ND-AspRS) that has retained its ability to also generate Asp-tRNAAsp. Here we report the discovery that ND-AspRS and its discriminating counterpart, AspRS, are also capable of specifically producing Glu-tRNAGlu, without producing misacylated tRNAs like Glu-tRNAAsn, Glu-tRNAAsp, or Asp-tRNAGlu, thus maintaining the fidelity of the genetic code. Consequently, bacterial AspRSs have glutamyl-tRNA synthetase-like activity that does not contaminate the proteome via amino acid misincorporation.
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MESH Headings
- Amino Acid Sequence/genetics
- Asparagine/chemistry
- Asparagine/genetics
- Aspartate-tRNA Ligase/chemistry
- Aspartate-tRNA Ligase/genetics
- Genetic Code/genetics
- Glutamate-tRNA Ligase/chemistry
- Glutamate-tRNA Ligase/genetics
- Mycobacterium smegmatis/chemistry
- Mycobacterium smegmatis/genetics
- Protein Conformation
- Proteome/chemistry
- Proteome/genetics
- RNA, Transfer, Amino Acyl/genetics
- RNA, Transfer, Asn/chemistry
- RNA, Transfer, Asn/genetics
- RNA, Transfer, Asp/chemistry
- RNA, Transfer, Asp/genetics
- Sequence Homology, Amino Acid
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Affiliation(s)
- Udumbara M Rathnayake
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202, USA.
| | - Tamara L Hendrickson
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202, USA.
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McCluskey GD, Bearne SL. "Pinching" the ammonia tunnel of CTP synthase unveils coordinated catalytic and allosteric-dependent control of ammonia passage. Biochim Biophys Acta Gen Subj 2018; 1862:2714-2727. [PMID: 30251661 DOI: 10.1016/j.bbagen.2018.08.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 07/20/2018] [Accepted: 08/06/2018] [Indexed: 01/10/2023]
Abstract
Molecular gates within enzymes often play important roles in synchronizing catalytic events. We explored the role of a gate in cytidine-5'-triphosphate synthase (CTPS) from Escherichia coli. This glutamine amidotransferase catalyzes the biosynthesis of CTP from UTP using either l-glutamine or exogenous NH3 as a substrate. Glutamine is hydrolyzed in the glutaminase domain, with GTP acting as a positive allosteric effector, and the nascent NH3 passes through a gate located at the end of a ~25-Å tunnel before entering the synthase domain where CTP is generated. Substitution of the gate residue Val 60 by Ala, Cys, Asp, Trp, or Phe using site-directed mutagenesis and subsequent kinetic analyses revealed that V60-substitution impacts glutaminase activity, nucleotide binding, salt-dependent inhibition, and inter-domain NH3 transport. Surprisingly, the increase in steric bulk present in V60F perturbed the local structure consistent with "pinching" the tunnel, thereby revealing processes that synchronize the transfer of NH3 from the glutaminase domain to the synthase domain. V60F had a slightly reduced coupling efficiency at maximal glutaminase activity that was ameliorated by slowing down the glutamine hydrolysis reaction, consistent with a "bottleneck" effect. The inability of V60F to use exogenous NH3 was overcome in the presence of GTP, and more so if CTPS was covalently modified by 6-diazo-5-oxo-l-norleucine. Use of NH2OH by V60F as an alternative bulkier substrate occurred most efficiently when it was concomitant with the glutaminase reaction. Thus, the glutaminase activity and GTP-dependent activation act in concert to open the NH3 gate of CTPS to mediate inter-domain NH3 transport.
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Affiliation(s)
- Gregory D McCluskey
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Stephen L Bearne
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada; Department of Chemistry, Dalhousie University, Halifax, NS B3H 4R2, Canada.
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7
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Indirect tRNA aminoacylation during accurate translation and phenotypic mistranslation. Curr Opin Chem Biol 2017; 41:114-122. [DOI: 10.1016/j.cbpa.2017.10.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 10/03/2017] [Accepted: 10/08/2017] [Indexed: 11/18/2022]
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