1
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Evic V, Soic R, Mocibob M, Kekez M, Houser J, Wimmerová M, Matković-Čalogović D, Gruic-Sovulj I, Kekez I, Rokov-Plavec J. Evolutionarily conserved cysteines in plant cytosolic seryl-tRNA synthetase are important for its resistance to oxidation. FEBS Lett 2023; 597:2975-2992. [PMID: 37804069 DOI: 10.1002/1873-3468.14748] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 09/08/2023] [Accepted: 09/22/2023] [Indexed: 10/08/2023]
Abstract
We have previously identified a unique disulfide bond in the crystal structure of Arabidopsis cytosolic seryl-tRNA synthetase involving cysteines evolutionarily conserved in all green plants. Here, we discovered that both cysteines are important for protein stability, but with opposite effects, and that their microenvironment may promote disulfide bond formation in oxidizing conditions. The crystal structure of the C244S mutant exhibited higher rigidity and an extensive network of noncovalent interactions correlating with its higher thermal stability. The activity of the wild-type showed resistance to oxidation with H2 O2 , while the activities of cysteine-to-serine mutants were impaired, indicating that the disulfide link may enable the protein to function under oxidative stress conditions which can be beneficial for an efficient plant stress response.
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Affiliation(s)
- Valentina Evic
- Division of Biochemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Zagreb, Croatia
| | - Ruzica Soic
- Division of General and Inorganic Chemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Zagreb, Croatia
| | - Marko Mocibob
- Division of Biochemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Zagreb, Croatia
| | - Mario Kekez
- Division of Biochemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Zagreb, Croatia
| | - Josef Houser
- Central European Institute of Technology (CEITEC), Brno, Czech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Michaela Wimmerová
- Central European Institute of Technology (CEITEC), Brno, Czech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic
- Department of Biochemistry, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Dubravka Matković-Čalogović
- Division of General and Inorganic Chemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Zagreb, Croatia
| | - Ita Gruic-Sovulj
- Division of Biochemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Zagreb, Croatia
| | - Ivana Kekez
- Division of General and Inorganic Chemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Zagreb, Croatia
| | - Jasmina Rokov-Plavec
- Division of Biochemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Zagreb, Croatia
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2
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Kuhle B, Hirschi M, Doerfel LK, Lander GC, Schimmel P. Structural basis for shape-selective recognition and aminoacylation of a D-armless human mitochondrial tRNA. Nat Commun 2022; 13:5100. [PMID: 36042193 PMCID: PMC9427863 DOI: 10.1038/s41467-022-32544-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 08/04/2022] [Indexed: 02/05/2023] Open
Abstract
Human mitochondrial gene expression relies on the specific recognition and aminoacylation of mitochondrial tRNAs (mtRNAs) by nuclear-encoded mitochondrial aminoacyl-tRNA synthetases (mt-aaRSs). Despite their essential role in cellular energy homeostasis, strong mutation pressure and genetic drift have led to an unparalleled sequence erosion of animal mtRNAs. The structural and functional consequences of this erosion are not understood. Here, we present cryo-EM structures of the human mitochondrial seryl-tRNA synthetase (mSerRS) in complex with mtRNASer(GCU). These structures reveal a unique mechanism of substrate recognition and aminoacylation. The mtRNASer(GCU) is highly degenerated, having lost the entire D-arm, tertiary core, and stable L-shaped fold that define canonical tRNAs. Instead, mtRNASer(GCU) evolved unique structural innovations, including a radically altered T-arm topology that serves as critical identity determinant in an unusual shape-selective readout mechanism by mSerRS. Our results provide a molecular framework to understand the principles of mito-nuclear co-evolution and specialized mechanisms of tRNA recognition in mammalian mitochondrial gene expression.
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Affiliation(s)
- Bernhard Kuhle
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 92037, USA.
| | - Marscha Hirschi
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92121, USA
| | - Lili K Doerfel
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92121, USA
| | - Gabriel C Lander
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92121, USA
| | - Paul Schimmel
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 92037, USA
- The Scripps Florida Research Institute at the University of Florida, Jupiter, FL, 33458, USA
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3
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Noureldin NA, Richards J, Kothayer H, Baraka MM, Eladl SM, Wootton M, Simons C. Design, computational studies, synthesis and in vitro antimicrobial evaluation of benzimidazole based thio-oxadiazole and thio-thiadiazole analogues. BMC Chem 2021; 15:58. [PMID: 34711258 PMCID: PMC8555319 DOI: 10.1186/s13065-021-00785-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 10/20/2021] [Indexed: 01/16/2023] Open
Abstract
Background Two series of benzimidazole based thio-oxadiazole and thio-thiadiazole analogues were designed and synthesised as novel antimicrobial drugs through inhibition of phenylalanyl-tRNA synthetase (PheRS), which is a promising antimicrobial target. Compounds were designed to mimic the structural features of phenylalanyl adenylate (Phe-AMP) the PheRS natural substrate. Methods A 3D conformational alignment for the designed compounds and the PheRS natural substrate revealed a high level of conformational similarity, and a molecular docking study indicated the ability of the designed compounds to occupy both Phe-AMP binding pockets. A molecular dynamics (MD) simulation comparative study was performed to understand the binding interactions with PheRS from different bacterial microorganisms. The synthetic pathway of the designed compounds proceeded in five steps starting from benzimidazole. The fourteen synthesised compounds 5a-d, 6a-c, 8a-d and 9a-c were purified, fully characterised and obtained in high yield. Results In vitro antimicrobial evaluation against five bacterial strains showed a moderate activity of compound 8b with MIC value of 32 μg/mL against S. aureus, while all the synthesised compounds showed weak activity against both E. faecalis and P. aeruginosa (MIC 128 μg/mL). Conclusion Compound 8b provides a lead compound for further structural development to obtain high affinity PheRS inhibitors. Supplementary Information The online version contains supplementary material available at 10.1186/s13065-021-00785-8.
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Affiliation(s)
- Nada A Noureldin
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, CF10 3NB, UK. .,Department of Medicinal Chemistry, Faculty of Pharmacy, Zagazig University, Zagazig, P.C. 44519, Egypt.
| | - Jennifer Richards
- Specialist Antimicrobial Chemotherapy Unit, University Hospital of Wales, Heath Park, Cardiff, CF14 4XW, UK
| | - Hend Kothayer
- Department of Medicinal Chemistry, Faculty of Pharmacy, Zagazig University, Zagazig, P.C. 44519, Egypt
| | - Mohammed M Baraka
- Department of Medicinal Chemistry, Faculty of Pharmacy, Zagazig University, Zagazig, P.C. 44519, Egypt
| | - Sobhy M Eladl
- Department of Medicinal Chemistry, Faculty of Pharmacy, Zagazig University, Zagazig, P.C. 44519, Egypt
| | - Mandy Wootton
- Specialist Antimicrobial Chemotherapy Unit, University Hospital of Wales, Heath Park, Cardiff, CF14 4XW, UK
| | - Claire Simons
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, CF10 3NB, UK
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4
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An RNA-centric historical narrative around the Protein Data Bank. J Biol Chem 2021; 296:100555. [PMID: 33744291 PMCID: PMC8080527 DOI: 10.1016/j.jbc.2021.100555] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 02/17/2021] [Accepted: 03/16/2021] [Indexed: 01/06/2023] Open
Abstract
Some of the amazing contributions brought to the scientific community by the Protein Data Bank (PDB) are described. The focus is on nucleic acid structures with a bias toward RNA. The evolution and key roles in science of the PDB and other structural databases for nucleic acids illustrate how small initial ideas can become huge and indispensable resources with the unflinching willingness of scientists to cooperate globally. The progress in the understanding of the molecular interactions driving RNA architectures followed the rapid increase in RNA structures in the PDB. That increase was consecutive to improvements in chemical synthesis and purification of RNA molecules, as well as in biophysical methods for structure determination and computer technology. The RNA modeling efforts from the early beginnings are also described together with their links to the state of structural knowledge and technological development. Structures of RNA and of its assemblies are physical objects, which, together with genomic data, allow us to integrate present-day biological functions and the historical evolution in all living species on earth.
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5
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Bouz G, Zitko J. Inhibitors of aminoacyl-tRNA synthetases as antimycobacterial compounds: An up-to-date review. Bioorg Chem 2021; 110:104806. [PMID: 33799176 DOI: 10.1016/j.bioorg.2021.104806] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/25/2021] [Accepted: 03/02/2021] [Indexed: 11/26/2022]
Abstract
Aminoacyl-tRNA synthetases (aaRSs) are crucial for the correct assembly of amino acids to cognate tRNA to maintain the fidelity of proteosynthesis. AaRSs have become a hot target in antimicrobial research. Three aaRS inhibitors are already in clinical practice; antibacterial mupirocin inhibits the synthetic site of isoleucyl-tRNA synthetase, antifungal tavaborole inhibits the editing site of leucyl-tRNA synthetase, and antiprotozoal halofuginone inhibits proline-tRNA synthetase. According to the World Health Organization, tuberculosis globally remains the leading cause of death from a single infectious agent. The rising incidence of multidrug-resistant tuberculosis is alarming and urges the search for new antimycobacterial compounds, preferably with yet unexploited mechanism of action. In this literature review, we have covered the up-to-date state in the field of inhibitors of mycobacterial aaRSs. The most studied aaRS in mycobacteria is LeuRS with at least four structural types of inhibitors, followed by TyrRS and AspRS. Inhibitors of MetRS, LysRS, and PheRS were addressed in a single significant study each. In many cases, the enzyme inhibition activity translated into micromolar or submicromolar inhibition of growth of mycobacteria. The most promising aaRS inhibitor as an antimycobacterial compound is GSK656 (compound 8), the only aaRS inhibitor in clinical trials (Phase IIa) for systemic use against tuberculosis. GSK656 is orally available and shares the oxaborole tRNA-trapping mechanism of action with antifungal tavaborole.
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Affiliation(s)
- Ghada Bouz
- Department of Pharmaceutical Chemistry and Pharmaceutical Analysis, Faculty of Pharmacy, Charles University
| | - Jan Zitko
- Department of Pharmaceutical Chemistry and Pharmaceutical Analysis, Faculty of Pharmacy, Charles University.
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6
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Guo J, Chen B, Yu Y, Cheng B, Ju Y, Tang J, Cai Z, Gu Q, Xu J, Zhou H. Structure-guided optimization and mechanistic study of a class of quinazolinone-threonine hybrids as antibacterial ThrRS inhibitors. Eur J Med Chem 2020; 207:112848. [PMID: 32980741 DOI: 10.1016/j.ejmech.2020.112848] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 08/12/2020] [Accepted: 09/12/2020] [Indexed: 11/20/2022]
Abstract
Aminoacyl-tRNA synthetases (aaRSs) are an attractive class of antibacterial drug targets due to their essential roles in protein translation. While most traditional aaRS inhibitors target the binding pockets of substrate amino acids and/or ATP, we recently developed a class of novel tRNA-amino acid dual-site inhibitors including inhibitor 3 ((2S,3R)-2-amino-N-((E)-4-(6,7-dichloro-4-oxoquinazolin-3(4H)-yl)but-2-en-1-yl)-3-hydroxybutanamide) against threonyl-tRNA synthetase (ThrRS). Here, the binding modes and structure-activity relationships (SARs) of these inhibitors were analyzed by the crystal structures of Salmonella enterica ThrRS (SeThrRS) in complex with three of them. Based on the cocrystal structures, twelve quinazolinone-threonine hybrids were designed and synthesized, and their affinities, enzymatic inhibitory activities, and cellular potencies were evaluated. The best derivative 8g achieved a Kd value of 0.40 μM, an IC50 value of 0.50 μM against SeThrRS and MIC values of 16-32 μg/mL against the tested bacterial strains. The cocrystal structure of the SeThrRS-8g complex revealed that 8g induced a bended conformation for Met332 by forming hydrophobic interactions, which better mimicked the binding of tRNAThr to ThrRS. Moreover, the inhibitory potency of 8g was less impaired than a reported ATP competitive inhibitor at high concentrations of ATP, supporting our hypothesis that tRNA site inhibitors are likely superior to ATP site inhibitors in vivo, where ATP typically reaches millimolar concentrations.
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Affiliation(s)
- Junsong Guo
- Research Center for Drug Discovery and Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Bingyi Chen
- Research Center for Drug Discovery and Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Ying Yu
- Research Center for Drug Discovery and Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Bao Cheng
- Research Center for Drug Discovery and Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Yingchen Ju
- Research Center for Drug Discovery and Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Jieyu Tang
- Research Center for Drug Discovery and Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Zhengjun Cai
- Research Center for Drug Discovery and Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Qiong Gu
- Research Center for Drug Discovery and Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Jun Xu
- Research Center for Drug Discovery and Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Huihao Zhou
- Research Center for Drug Discovery and Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China.
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7
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An orthogonal seryl-tRNA synthetase/tRNA pair for noncanonical amino acid mutagenesis in Escherichia coli. Bioorg Med Chem 2020; 28:115662. [PMID: 33069069 DOI: 10.1016/j.bmc.2020.115662] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 07/18/2020] [Indexed: 11/24/2022]
Abstract
We report the development of the orthogonal amber-suppressor pair Archaeoglobus fulgidus seryl-tRNA (Af-tRNASer)/Methanosarcina mazei seryl-tRNA synthetase (MmSerRS) in Escherichia coli. Furthermore, the crystal structure of MmSerRS was solved at 1.45 Å resolution, which should enable structure-guided engineering of its active site to genetically encode small, polar noncanonical amino acids (ncAAs).
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8
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Tawfik DS, Gruic-Sovulj I. How evolution shapes enzyme selectivity - lessons from aminoacyl-tRNA synthetases and other amino acid utilizing enzymes. FEBS J 2020; 287:1284-1305. [PMID: 31891445 DOI: 10.1111/febs.15199] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Revised: 12/08/2019] [Accepted: 12/30/2019] [Indexed: 12/21/2022]
Abstract
Aminoacyl-tRNA synthetases (AARSs) charge tRNA with their cognate amino acids. Many other enzymes use amino acids as substrates, yet discrimination against noncognate amino acids that threaten the accuracy of protein translation is a hallmark of AARSs. Comparing AARSs to these other enzymes allowed us to recognize patterns in molecular recognition and strategies used by evolution for exercising selectivity. Overall, AARSs are 2-3 orders of magnitude more selective than most other amino acid utilizing enzymes. AARSs also reveal the physicochemical limits of molecular discrimination. For example, amino acids smaller by a single methyl moiety present a discrimination ceiling of ~200, while larger ones can be discriminated by up to 105 -fold. In contrast, substrates larger by a hydroxyl group challenge AARS selectivity, due to promiscuous H-bonding with polar active site groups. This 'hydroxyl paradox' is resolved by editing. Indeed, when the physicochemical discrimination limits are reached, post-transfer editing - hydrolysis of tRNAs charged with noncognate amino acids, evolved. The editing site often selectively recognizes the edited noncognate substrate using the very same feature that the synthetic site could not efficiently discriminate against. Finally, the comparison to other enzymes also reveals that the selectivity of AARSs is an explicitly evolved trait, showing some clear examples of how selection acted not only to optimize catalytic efficiency with the target substrate, but also to abolish activity with noncognate threat substrates ('negative selection').
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Affiliation(s)
- Dan S Tawfik
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Ita Gruic-Sovulj
- Department of Chemistry, Faculty of Science, University of Zagreb, Croatia
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9
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Cain R, Salimraj R, Punekar AS, Bellini D, Fishwick CWG, Czaplewski L, Scott DJ, Harris G, Dowson CG, Lloyd AJ, Roper DI. Structure-Guided Enhancement of Selectivity of Chemical Probe Inhibitors Targeting Bacterial Seryl-tRNA Synthetase. J Med Chem 2019; 62:9703-9717. [PMID: 31626547 DOI: 10.1021/acs.jmedchem.9b01131] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Aminoacyl-tRNA synthetases are ubiquitous and essential enzymes for protein synthesis and also a variety of other metabolic processes, especially in bacterial species. Bacterial aminoacyl-tRNA synthetases represent attractive and validated targets for antimicrobial drug discovery if issues of prokaryotic versus eukaryotic selectivity and antibiotic resistance generation can be addressed. We have determined high-resolution X-ray crystal structures of the Escherichia coli and Staphylococcus aureus seryl-tRNA synthetases in complex with aminoacyl adenylate analogues and applied a structure-based drug discovery approach to explore and identify a series of small molecule inhibitors that selectively inhibit bacterial seryl-tRNA synthetases with greater than 2 orders of magnitude compared to their human homologue, demonstrating a route to the selective chemical inhibition of these bacterial targets.
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Affiliation(s)
- Ricky Cain
- School of Life Sciences , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , United Kingdom
| | - Ramya Salimraj
- School of Life Sciences , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , United Kingdom
| | - Avinash S Punekar
- School of Life Sciences , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , United Kingdom
| | - Dom Bellini
- School of Life Sciences , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , United Kingdom
| | - Colin W G Fishwick
- School of Chemistry , University of Leeds , Leeds LS2 9JT , United Kingdom
| | - Lloyd Czaplewski
- Chemical Biology Ventures Limited , Abingdon OX14 1XD , United Kingdom
| | - David J Scott
- School of Biosciences , University of Nottingham , Nottingham LE12 5RD , United Kingdom.,ISIS Spallation Neutron and Muon Source and the Research Complex at Harwell , Rutherford Appleton Laboratory , Oxfordshire OX11 0FA , United Kingdom
| | - Gemma Harris
- ISIS Spallation Neutron and Muon Source and the Research Complex at Harwell , Rutherford Appleton Laboratory , Oxfordshire OX11 0FA , United Kingdom
| | - Christopher G Dowson
- School of Life Sciences , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , United Kingdom
| | - Adrian J Lloyd
- School of Life Sciences , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , United Kingdom
| | - David I Roper
- School of Life Sciences , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , United Kingdom
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10
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Saha A, Dutta S, Nandi N. Inhibition of seryl tRNA synthetase by seryl nucleoside moiety (SB-217452) of albomycin antibiotic. J Biomol Struct Dyn 2019; 38:2440-2454. [PMID: 31241419 DOI: 10.1080/07391102.2019.1635912] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Amrita Saha
- Department of Chemistry, University of Kalyani, Kalyani, West Bengal, India
| | - Saheb Dutta
- Department of Chemistry, University of Kalyani, Kalyani, West Bengal, India
| | - Nilashis Nandi
- Department of Chemistry, University of Kalyani, Kalyani, West Bengal, India
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11
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Lux MC, Standke LC, Tan DS. Targeting adenylate-forming enzymes with designed sulfonyladenosine inhibitors. J Antibiot (Tokyo) 2019; 72:325-349. [PMID: 30982830 PMCID: PMC6594144 DOI: 10.1038/s41429-019-0171-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 02/19/2019] [Accepted: 02/26/2019] [Indexed: 02/07/2023]
Abstract
Adenylate-forming enzymes are a mechanistic superfamily that are involved in diverse biochemical pathways. They catalyze ATP-dependent activation of carboxylic acid substrates as reactive acyl adenylate (acyl-AMP) intermediates and subsequent coupling to various nucleophiles to generate ester, thioester, and amide products. Inspired by natural products, acyl sulfonyladenosines (acyl-AMS) that mimic the tightly bound acyl-AMP reaction intermediates have been developed as potent inhibitors of adenylate-forming enzymes. This simple yet powerful inhibitor design platform has provided a wide range of biological probes as well as several therapeutic lead compounds. Herein, we provide an overview of the nine structural classes of adenylate-forming enzymes and examples of acyl-AMS inhibitors that have been developed for each.
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Affiliation(s)
- Michaelyn C Lux
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA
| | - Lisa C Standke
- Pharmacology Graduate Program, Weill Cornell Graduate School of Medical Sciences, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA
| | - Derek S Tan
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA. .,Pharmacology Graduate Program, Weill Cornell Graduate School of Medical Sciences, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA. .,Chemical Biology Program, Sloan Kettering Institute, and Tri-Institutional Research Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA.
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12
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Kekez M, Zanki V, Kekez I, Baranasic J, Hodnik V, Duchêne A, Anderluh G, Gruic‐Sovulj I, Matković‐Čalogović D, Weygand‐Durasevic I, Rokov‐Plavec J. Arabidopsis
seryl‐
tRNA
synthetase: the first crystal structure and novel protein interactor of plant aminoacyl‐
tRNA
synthetase. FEBS J 2019; 286:536-554. [DOI: 10.1111/febs.14735] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 12/01/2018] [Accepted: 12/17/2018] [Indexed: 12/14/2022]
Affiliation(s)
- Mario Kekez
- Division of Biochemistry Department of Chemistry Faculty of Science University of Zagreb Croatia
| | - Vladimir Zanki
- Division of Biochemistry Department of Chemistry Faculty of Science University of Zagreb Croatia
| | - Ivana Kekez
- Division of General and Inorganic Chemistry Department of Chemistry Faculty of Science University of Zagreb Croatia
| | - Jurica Baranasic
- Division of Biochemistry Department of Chemistry Faculty of Science University of Zagreb Croatia
| | - Vesna Hodnik
- National Institute of Chemistry Ljubljana Slovenia
- Biotechnical faculty University of Ljubljana Slovenia
| | - Anne‐Marie Duchêne
- Institut de biologie moléculaire des plantes CNRS, Université de Strasbourg Strasbourg Cedex France
| | | | - Ita Gruic‐Sovulj
- Division of Biochemistry Department of Chemistry Faculty of Science University of Zagreb Croatia
| | - Dubravka Matković‐Čalogović
- Division of General and Inorganic Chemistry Department of Chemistry Faculty of Science University of Zagreb Croatia
| | - Ivana Weygand‐Durasevic
- Division of Biochemistry Department of Chemistry Faculty of Science University of Zagreb Croatia
| | - Jasmina Rokov‐Plavec
- Division of Biochemistry Department of Chemistry Faculty of Science University of Zagreb Croatia
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13
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Berg MD, Genereaux J, Zhu Y, Mian S, Gloor GB, Brandl CJ. Acceptor Stem Differences Contribute to Species-Specific Use of Yeast and Human tRNA Ser. Genes (Basel) 2018; 9:E612. [PMID: 30544642 PMCID: PMC6316282 DOI: 10.3390/genes9120612] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 11/22/2018] [Accepted: 12/03/2018] [Indexed: 01/01/2023] Open
Abstract
The molecular mechanisms of translation are highly conserved in all organisms indicative of a single evolutionary origin. This includes the molecular interactions of tRNAs with their cognate aminoacyl-tRNA synthetase, which must be precise to ensure the specificity of the process. For many tRNAs, the anticodon is a major component of the specificity. This is not the case for the aminoacylation of alanine and serine to their cognate tRNAs. Rather, aminoacylation relies on other features of the tRNA. For tRNASer, a key specificity feature is the variable arm, which is positioned between the anticodon arm and the T-arm. The variable arm is conserved from yeast to human. This work was initiated to determine if the structure/function of tRNASer has been conserved from Saccharomyces cerevisiae to human. We did this by detecting mistranslation in yeast cells with tRNASer derivatives having the UGA anticodon converted to UGG for proline. Despite being nearly identical in everything except the acceptor stem, human tRNASer is less active than yeast tRNASer. A chimeric tRNA with the human acceptor stem and other sequences from the yeast molecule acts similarly to the human tRNASer. The 3:70 base pair in the acceptor stem (C:G in yeast and A:U in humans) is a prime determinant of the specificity. Consistent with the functional difference of yeast and human tRNASer resulting from subtle changes in the specificity of their respective SerRS enzymes, the functionality of the human and chimeric tRNASerUGG molecules was enhanced when human SerRS was introduced into yeast. Residues in motif 2 of the aminoacylation domain of SerRS likely participated in the species-specific differences. Trp290 in yeast SerRS (Arg313 in humans) found in motif 2 is proximal to base 70 in models of the tRNA-synthetase interaction. Altering this motif 2 sequence of hSerRS to the yeast sequence decreases the activity of the human enzyme with human tRNASer, supporting the coadaptation of motif 2 loop⁻acceptor stem interactions.
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Affiliation(s)
- Matthew D Berg
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada.
| | - Julie Genereaux
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada.
| | - Yanrui Zhu
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada.
| | - Safee Mian
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada.
| | - Gregory B Gloor
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada.
| | - Christopher J Brandl
- Department of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada.
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14
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Lee EY, Kim S, Kim MH. Aminoacyl-tRNA synthetases, therapeutic targets for infectious diseases. Biochem Pharmacol 2018; 154:424-434. [PMID: 29890143 PMCID: PMC7092877 DOI: 10.1016/j.bcp.2018.06.009] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 06/07/2018] [Indexed: 12/17/2022]
Abstract
Despite remarkable advances in medical science, infection-associated diseases remain among the leading causes of death worldwide. There is a great deal of interest and concern at the rate at which new pathogens are emerging and causing significant human health problems. Expanding our understanding of how cells regulate signaling networks to defend against invaders and retain cell homeostasis will reveal promising strategies against infection. It has taken scientists decades to appreciate that eukaryotic aminoacyl-tRNA synthetases (ARSs) play a role as global cell signaling mediators to regulate cell homeostasis, beyond their intrinsic function as protein synthesis enzymes. Recent discoveries revealed that ubiquitously expressed standby cytoplasmic ARSs sense and respond to danger signals and regulate immunity against infections, indicating their potential as therapeutic targets for infectious diseases. In this review, we discuss ARS-mediated anti-infectious signaling and the emerging role of ARSs in antimicrobial immunity. In contrast to their ability to defend against infection, host ARSs are inevitably co-opted by viruses for survival and propagation. We therefore provide a brief overview of the communication between viruses and the ARS system. Finally, we discuss encouraging new approaches to develop ARSs as therapeutics for infectious diseases.
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Affiliation(s)
- Eun-Young Lee
- Infection and Immunity Research Laboratory, Metabolic Regulation Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Republic of Korea
| | - Sunghoon Kim
- Medicinal Bioconvergence Research Center, Seoul National University, Suwon 16229, Republic of Korea; College of Pharmacy, Seoul National University, Seoul 08826, Republic of Korea
| | - Myung Hee Kim
- Infection and Immunity Research Laboratory, Metabolic Regulation Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Republic of Korea; KRIBB School of Bioscience, Korea University of Science and Technology, Daejeon 34141, Republic of Korea.
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15
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Serpi M, Ferrari V, Pertusati F. Nucleoside Derived Antibiotics to Fight Microbial Drug Resistance: New Utilities for an Established Class of Drugs? J Med Chem 2016; 59:10343-10382. [PMID: 27607900 DOI: 10.1021/acs.jmedchem.6b00325] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Novel antibiotics are urgently needed to combat the rise of infections due to drug-resistant microorganisms. Numerous natural nucleosides and their synthetically modified analogues have been reported to have moderate to good antibiotic activity against different bacterial and fungal strains. Nucleoside-based compounds target several crucial processes of bacterial and fungal cells such as nucleoside metabolism and cell wall, nucleic acid, and protein biosynthesis. Nucleoside analogues have also been shown to target many other bacterial and fungal cellular processes although these are not well characterized and may therefore represent opportunities to discover new drugs with unique mechanisms of action. In this Perspective, we demonstrate that nucleoside analogues, cornerstones of anticancer and antiviral treatments, also have great potential to be repurposed as antibiotics so that an old drug can learn new tricks.
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Affiliation(s)
- Michaela Serpi
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University , Redwood Building, King Edward VII Avenue, CF10 3NB Cardiff, United Kingdom
| | - Valentina Ferrari
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University , Redwood Building, King Edward VII Avenue, CF10 3NB Cardiff, United Kingdom
| | - Fabrizio Pertusati
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University , Redwood Building, King Edward VII Avenue, CF10 3NB Cardiff, United Kingdom
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16
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Fang P, Guo M. Evolutionary Limitation and Opportunities for Developing tRNA Synthetase Inhibitors with 5-Binding-Mode Classification. Life (Basel) 2015; 5:1703-25. [PMID: 26670257 PMCID: PMC4695845 DOI: 10.3390/life5041703] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Revised: 11/24/2015] [Accepted: 11/25/2015] [Indexed: 12/30/2022] Open
Abstract
Aminoacyl-tRNA synthetases (aaRSs) are enzymes that catalyze the transfer of amino acids to their cognate tRNAs as building blocks for translation. Each of the aaRS families plays a pivotal role in protein biosynthesis and is indispensable for cell growth and survival. In addition, aaRSs in higher species have evolved important non-translational functions. These translational and non-translational functions of aaRS are attractive for developing antibacterial, antifungal, and antiparasitic agents and for treating other human diseases. The interplay between amino acids, tRNA, ATP, EF-Tu and non-canonical binding partners, had shaped each family with distinct pattern of key sites for regulation, with characters varying among species across the path of evolution. These sporadic variations in the aaRSs offer great opportunity to target these essential enzymes for therapy. Up to this day, growing numbers of aaRS inhibitors have been discovered and developed. Here, we summarize the latest developments and structural studies of aaRS inhibitors, and classify them with distinct binding modes into five categories.
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Affiliation(s)
- Pengfei Fang
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
- Department of Cancer Biology, The Scripps Research Institute, Scripps Florida, 130 Scripps Way, Jupiter, FL 33458, USA.
| | - Min Guo
- Department of Cancer Biology, The Scripps Research Institute, Scripps Florida, 130 Scripps Way, Jupiter, FL 33458, USA.
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17
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Vanlander AV, Menten B, Smet J, De Meirleir L, Sante T, De Paepe B, Seneca S, Pearce SF, Powell CA, Vergult S, Michotte A, De Latter E, Vantomme L, Minczuk M, Van Coster R. Two siblings with homozygous pathogenic splice-site variant in mitochondrial asparaginyl-tRNA synthetase (NARS2). Hum Mutat 2015; 36:222-31. [PMID: 25385316 DOI: 10.1002/humu.22728] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 10/28/2014] [Indexed: 12/13/2022]
Abstract
A homozygous missense mutation (c.822G>C) was found in the gene encoding the mitochondrial asparaginyl-tRNA synthetase (NARS2) in two siblings born to consanguineous parents. These siblings presented with different phenotypes: one had mild intellectual disability and epilepsy in childhood, whereas the other had severe myopathy. Biochemical analysis of the oxidative phosphorylation (OXPHOS) complexes in both siblings revealed a combined complex I and IV deficiency in skeletal muscle. In-gel activity staining after blue native-polyacrylamide gel electrophoresis confirmed the decreased activity of complex I and IV, and, in addition, showed the presence of complex V subcomplexes. Considering the consanguineous descent, homozygosity mapping and whole-exome sequencing were combined revealing the presence of one single missense mutation in the shared homozygous region. The c.822G>C variant affects the 3' splice site of exon 7, leading to skipping of the whole exon 7 and a part of exon 8 in the NARS2 mRNA. In EBV-transformed lymphoblasts, a specific decrease in the amount of charged mt-tRNA(Asn) was demonstrated as compared with controls. This confirmed the pathogenic nature of the variant. To conclude, the reported variant in NARS2 results in a combined OXPHOS complex deficiency involving complex I and IV, making NARS2 a new member of disease-associated aaRS2.
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Affiliation(s)
- Arnaud V Vanlander
- Department of Pediatric Neurology and Metabolism, Ghent University Hospital, Belgium
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18
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Ishikawa F, Konno S, Suzuki T, Dohmae N, Kakeya H. Profiling Nonribosomal Peptide Synthetase Activities Using Chemical Proteomic Probes for Adenylation Domains. ACS Chem Biol 2015; 10:1989-97. [PMID: 26038981 DOI: 10.1021/acschembio.5b00097] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Nonribosomal peptide synthetases (NRPSs) and polyketide synthases are large diverse families of biosynthetic enzymes that catalyze the synthesis of natural products that display biologically important activities. Genetic investigations have greatly contributed to our understanding of these biosynthetic enzymes; however, proteomic studies are limited. Here we describe the application of active site-directed proteomic probes for adenylation (A) domains to profile the activity of NRPSs directly in native proteomic environments. Derivatization of a 5'-O-N-(aminoacyl)sulfamoyladenosine appended clickable benzophenone functionality enabled activity-based protein profiling of the A-domains in NRPSs in proteomic extracts. These probes were used to identify natural product producing microorganisms, optimize culture conditions, and profile the activity dynamics of NRPSs. Our proteomic approach offers a simple and versatile method to monitor NRPS expression at the protein level and will facilitate the identification of orphan enzymatic pathways involved in secondary metabolite production.
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Affiliation(s)
- Fumihiro Ishikawa
- Department
of System Chemotherapy and Molecular Sciences, Division of Bioinformatics
and Chemical Genomics, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo, Kyoto 606-8501, Japan
| | - Sho Konno
- Department
of System Chemotherapy and Molecular Sciences, Division of Bioinformatics
and Chemical Genomics, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo, Kyoto 606-8501, Japan
| | - Takehiro Suzuki
- Biomolecular
Characterization Unit, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Naoshi Dohmae
- Biomolecular
Characterization Unit, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Hideaki Kakeya
- Department
of System Chemotherapy and Molecular Sciences, Division of Bioinformatics
and Chemical Genomics, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo, Kyoto 606-8501, Japan
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19
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Fang P, Han H, Wang J, Chen K, Chen X, Guo M. Structural Basis for Specific Inhibition of tRNA Synthetase by an ATP Competitive Inhibitor. ACTA ACUST UNITED AC 2015; 22:734-44. [PMID: 26074468 DOI: 10.1016/j.chembiol.2015.05.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 05/03/2015] [Accepted: 05/09/2015] [Indexed: 01/26/2023]
Abstract
Pharmaceutical inhibitors of aminoacyl-tRNA synthetases demand high species and family specificity. The antimalarial ATP-mimetic cladosporin selectively inhibits Plasmodium falciparum LysRS (PfLysRS). How the binding to a universal ATP site achieves the specificity is unknown. Here we report three crystal structures of cladosporin with human LysRS, PfLysRS, and a Pf-like human LysRS mutant. In all three structures, cladosporin occupies the class defining ATP-binding pocket, replacing the adenosine portion of ATP. Three residues holding the methyltetrahydropyran moiety of cladosporin are critical for the specificity of cladosporin against LysRS over other class II tRNA synthetase families. The species-exclusive inhibition of PfLysRS is linked to a structural divergence beyond the active site that mounts a lysine-specific stabilizing response to binding cladosporin. These analyses reveal that inherent divergence of tRNA synthetase structural assembly may allow for highly specific inhibition even through the otherwise universal substrate binding pocket and highlight the potential for structure-driven drug development.
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Affiliation(s)
- Pengfei Fang
- Department of Cancer Biology, The Scripps Research Institute, Scripps Florida, 130 Scripps Way, Jupiter, FL 33458, USA.
| | - Hongyan Han
- Department of Cancer Biology, The Scripps Research Institute, Scripps Florida, 130 Scripps Way, Jupiter, FL 33458, USA; School of Biology and Basic Medical Sciences, Soochow University, Suzhou 215123, People's Republic of China
| | - Jing Wang
- Department of Cancer Biology, The Scripps Research Institute, Scripps Florida, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Kaige Chen
- Department of Cancer Biology, The Scripps Research Institute, Scripps Florida, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Xin Chen
- Department of Cancer Biology, The Scripps Research Institute, Scripps Florida, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Min Guo
- Department of Cancer Biology, The Scripps Research Institute, Scripps Florida, 130 Scripps Way, Jupiter, FL 33458, USA; Department of Cell and Molecular Biology, The Scripps Research Institute, Scripps Florida, 130 Scripps Way, Jupiter, FL 33458, USA.
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20
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Dutta S, Nandi N. Dynamics of the Active Sites of Dimeric Seryl tRNA Synthetase from Methanopyrus kandleri. J Phys Chem B 2015; 119:10832-48. [PMID: 25794108 DOI: 10.1021/jp511585w] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Saheb Dutta
- Department
of Chemistry, University of Kalyani, Kalyani, Nadia, West Bengal 741235, India
| | - Nilashis Nandi
- Department
of Chemistry, University of Kalyani, Kalyani, Nadia, West Bengal 741235, India
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21
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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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22
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Gadakh B, Smaers S, Rozenski J, Froeyen M, Van Aerschot A. 5'-(N-aminoacyl)-sulfonamido-5'-deoxyadenosine: attempts for a stable alternative for aminoacyl-sulfamoyl adenosines as aaRS inhibitors. Eur J Med Chem 2015; 93:227-36. [PMID: 25686591 DOI: 10.1016/j.ejmech.2015.02.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 02/04/2015] [Accepted: 02/07/2015] [Indexed: 10/24/2022]
Abstract
Synthesis of aminoacyl-sulfamoyl adenosines (aaSAs) and their peptidyl conjugates as aminoacyl tRNA synthetase (aaRS) inhibitors remains problematic due to the low yield of the aminoacylation and the subsequent conjugation reaction causing concomitant formation of a cyclic adenosine derivative. In an effort to reduce this undesirable side reaction, we aimed to prepare the corresponding aminoacyl sulfonamide (aaSoA) analogues as more stable alternatives for aaSA derivatives. Deletion of the 5'-oxygen in aaSA analogues should render the C-5' less electrophilic and therefore improve the stability of the aminoacyl sulfamate analogues. We therefore synthesized six sulfonamides and compared their activity against the respective aaSA analogues. However, except for the aspartyl derivative, the new compounds are not able to inhibit the corresponding aaRS. Possible reasons for this loss of activity are discussed by modeling and comparison of the newly synthesized aaSoA derivatives with their parent aaSA analogues.
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Affiliation(s)
- Bharat Gadakh
- Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Minderbroedersstraat 10, 3000 Leuven, Belgium
| | - Simon Smaers
- Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Minderbroedersstraat 10, 3000 Leuven, Belgium
| | - Jef Rozenski
- Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Minderbroedersstraat 10, 3000 Leuven, Belgium
| | - Mathy Froeyen
- Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Minderbroedersstraat 10, 3000 Leuven, Belgium
| | - Arthur Van Aerschot
- Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Minderbroedersstraat 10, 3000 Leuven, Belgium.
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23
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Chiwata R, Kohori A, Kawakami T, Shiroguchi K, Furuike S, Adachi K, Sutoh K, Yoshida M, Kinosita K. None of the rotor residues of F1-ATPase are essential for torque generation. Biophys J 2014; 106:2166-74. [PMID: 24853745 PMCID: PMC4052266 DOI: 10.1016/j.bpj.2014.04.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 04/04/2014] [Accepted: 04/07/2014] [Indexed: 11/28/2022] Open
Abstract
F1-ATPase is a powerful rotary molecular motor that can rotate an object several hundred times as large as the motor itself against the viscous friction of water. Forced reverse rotation has been shown to lead to ATP synthesis, implying that the mechanical work against the motor’s high torque can be converted into the chemical energy of ATP. The minimal composition of the motor protein is α3β3γ subunits, where the central rotor subunit γ turns inside a stator cylinder made of alternately arranged α3β3 subunits using the energy derived from ATP hydrolysis. The rotor consists of an axle, a coiled coil of the amino- and carboxyl-terminal α-helices of γ, which deeply penetrates the stator cylinder, and a globular protrusion that juts out from the stator. Previous work has shown that, for a thermophilic F1, significant portions of the axle can be truncated and the motor still rotates a submicron sized bead duplex, indicating generation of up to half the wild-type (WT) torque. Here, we inquire if any specific interactions between the stator and the rest of the rotor are needed for the generation of a sizable torque. We truncated the protruding portion of the rotor and replaced part of the remaining axle residues such that every residue of the rotor has been deleted or replaced in this or previous truncation mutants. This protrusionless construct showed an unloaded rotary speed about a quarter of the WT, and generated one-third to one-half of the WT torque. No residue-specific interactions are needed for this much performance. F1 is so designed that the basic rotor-stator interactions for torque generation and control of catalysis rely solely upon the shape and size of the rotor at very low resolution. Additional tailored interactions augment the torque to allow ATP synthesis under physiological conditions.
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Affiliation(s)
- Ryohei Chiwata
- Department of Physics, Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo, Japan
| | - Ayako Kohori
- Department of Physics, Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo, Japan
| | - Tomonari Kawakami
- Department of Physics, Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo, Japan
| | - Katsuyuki Shiroguchi
- Department of Physics, Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo, Japan
| | - Shou Furuike
- Department of Physics, Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo, Japan
| | - Kengo Adachi
- Department of Physics, Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo, Japan
| | - Kazuo Sutoh
- Department of Physics, Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo, Japan
| | - Masasuke Yoshida
- ATP Synthesis Regulation Project, ICORP, Japan Science and Technology Agency (JST), Aomi 2-41, Koto-ku, Tokyo, Japan; Department of Molecular Bioscience, Kyoto Sangyo University, Motoyama, Kamigamo, Kyoto, Japan
| | - Kazuhiko Kinosita
- Department of Physics, Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo, Japan.
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24
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Gadakh B, Vondenhoff G, Lescrinier E, Rozenski J, Froeyen M, Van Aerschot A. Base substituted 5'-O-(N-isoleucyl)sulfamoyl nucleoside analogues as potential antibacterial agents. Bioorg Med Chem 2014; 22:2875-86. [PMID: 24746466 DOI: 10.1016/j.bmc.2014.03.040] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 03/26/2014] [Accepted: 03/27/2014] [Indexed: 10/25/2022]
Abstract
Aminoacyl-sulfamoyl adenosines are well-known nanomolar inhibitors of the corresponding prokaryotic and eukaryotic tRNA synthetases in vitro. Inspired by the aryl-tetrazole containing compounds of Cubist Pharmaceuticals and the modified base as found in the natural antibiotic albomycin, the selectivity issue of the sulfamoylated adenosines prompted us to investigate the pharmacophoric importance of the adenine base. We therefore synthesized and evaluated several isoleucyl-sulfamoyl nucleoside analogues with either uracil, cytosine, hypoxanthine, guanine, 1,3-dideaza-adenine (benzimidazole) or 4-nitro-benzimidazole as the heterocyclic base. Based on the structure and antibacterial activity of microcin C, we also prepared their hexapeptidyl conjugates in an effort to improve their uptake potential. We further compared their antibacterial activity with the parent isoleucyl-sulfamoyl adenosine (Ile-SA), both in in vitro and in cellular assays. Surprisingly, the strongest in vitro inhibition was found for the uracil containing analogue 16f. Unfortunately, only very weak growth inhibitory properties were found as of low uptake. The results are discussed in the light of previous literature findings.
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Affiliation(s)
- Bharat Gadakh
- KU Leuven, Medicinal Chemistry, Rega Institute for Medical Research, Leuven, Belgium
| | - Gaston Vondenhoff
- KU Leuven, Medicinal Chemistry, Rega Institute for Medical Research, Leuven, Belgium
| | - Eveline Lescrinier
- KU Leuven, Medicinal Chemistry, Rega Institute for Medical Research, Leuven, Belgium
| | - Jef Rozenski
- KU Leuven, Medicinal Chemistry, Rega Institute for Medical Research, Leuven, Belgium
| | - Mathy Froeyen
- KU Leuven, Medicinal Chemistry, Rega Institute for Medical Research, Leuven, Belgium
| | - Arthur Van Aerschot
- KU Leuven, Medicinal Chemistry, Rega Institute for Medical Research, Leuven, Belgium.
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25
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Pang YLJ, Poruri K, Martinis SA. tRNA synthetase: tRNA aminoacylation and beyond. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 5:461-80. [PMID: 24706556 DOI: 10.1002/wrna.1224] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Revised: 01/14/2014] [Accepted: 02/06/2014] [Indexed: 01/20/2023]
Abstract
The aminoacyl-tRNA synthetases are prominently known for their classic function in the first step of protein synthesis, where they bear the responsibility of setting the genetic code. Each enzyme is exquisitely adapted to covalently link a single standard amino acid to its cognate set of tRNA isoacceptors. These ancient enzymes have evolved idiosyncratically to host alternate activities that go far beyond their aminoacylation role and impact a wide range of other metabolic pathways and cell signaling processes. The family of aminoacyl-tRNA synthetases has also been suggested as a remarkable scaffold to incorporate new domains that would drive evolution and the emergence of new organisms with more complex function. Because they are essential, the tRNA synthetases have served as pharmaceutical targets for drug and antibiotic development. The recent unfolding of novel important functions for this family of proteins offers new and promising pathways for therapeutic development to treat diverse human diseases.
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Affiliation(s)
- Yan Ling Joy Pang
- Department of Biochemistry, University of Illinois at Urbana, Urbana, IL, USA
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26
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Highlights on trypanosomatid aminoacyl-tRNA synthesis. Subcell Biochem 2013; 74:271-304. [PMID: 24264250 DOI: 10.1007/978-94-007-7305-9_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
Aminoacyl-tRNA synthetases aaRSs are responsible for the aminoacylation of tRNAs in the first step of protein synthesis. They comprise a group of enzymes that catalyze the formation of each possible aminoacyl-tRNA necessary for messenger RNA decoding in a cell. These enzymes have been divided into two classes according to structural features of their active sites and, although each class shares a common active site core, they present an assorted array of appended domains that makes them sufficiently diverse among the different living organisms. Here we will explore what is known about the diversity encountered among trypanosomatids' aaRSs that has helped us not only to understand better the biology of these parasites but can be used rationally for the design of drugs against these protozoa.
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27
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Xu X, Shi Y, Yang XL. Crystal structure of human Seryl-tRNA synthetase and Ser-SA complex reveals a molecular lever specific to higher eukaryotes. Structure 2013; 21:2078-86. [PMID: 24095058 DOI: 10.1016/j.str.2013.08.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 08/07/2013] [Accepted: 08/26/2013] [Indexed: 01/13/2023]
Abstract
Seryl-tRNA synthetase (SerRS), an essential enzyme for translation, also regulates vascular development. This "gain-of-function" has been linked to the UNE-S domain added to vertebrate SerRS during evolution. However, the significance of two insertions also specific to higher eukaryotic SerRS remains elusive. Here, we determined the crystal structure of human SerRS in complex with Ser-SA, an aminoacylation reaction intermediate analog, at 2.9 Å resolution. Despite a 70 Å distance, binding of Ser-SA in the catalytic domain dramatically leverages the position of Insertion I in the tRNA binding domain. Importantly, this leverage is specific to higher eukaryotes and not seen in bacterial, archaeal, and lower eukaryotic SerRSs. Deletion of Insertion I does not affect tRNA binding but instead reduce the catalytic efficiency of the synthetase. Thus, a long-range conformational and functional communication specific to higher eukaryotes is found in human SerRS, possibly to coordinate translation with vasculogenesis.
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Affiliation(s)
- Xiaoling Xu
- Departments of Chemical Physiology and Cell and Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA; Institute of Aging Research, School of Medicine, Hangzhou Normal University, Hangzhou, Zhejiang Province 310036, China
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28
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Redwan IN, Bliman D, Tokugawa M, Lawson C, Grøtli M. Synthesis and photophysical characterization of 1- and 4-(purinyl)triazoles. Tetrahedron 2013. [DOI: 10.1016/j.tet.2013.08.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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29
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Tukalo MA, Yaremchuk GD, Kovalenko OP, Kriklivyi IA, Gudzera OI. Recognition of tRNAs with a long variable arm by aminoacyl-tRNA synthetases. ACTA ACUST UNITED AC 2013. [DOI: 10.7124/bc.000825] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- M. A. Tukalo
- Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine
| | - G. D. Yaremchuk
- Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine
| | - O. P. Kovalenko
- Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine
| | - I. A. Kriklivyi
- Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine
| | - O. I. Gudzera
- Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine
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30
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Itoh Y, Sekine SI, Suetsugu S, Yokoyama S. Tertiary structure of bacterial selenocysteine tRNA. Nucleic Acids Res 2013; 41:6729-38. [PMID: 23649835 PMCID: PMC3711452 DOI: 10.1093/nar/gkt321] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Selenocysteine (Sec) is translationally incorporated into proteins in response to the UGA codon. The tRNA specific to Sec (tRNASec) is first ligated with serine by seryl-tRNA synthetase (SerRS). In the present study, we determined the 3.1 Å crystal structure of the tRNASec from the bacterium Aquifex aeolicus, in complex with the heterologous SerRS from the archaeon Methanopyrus kandleri. The bacterial tRNASec assumes the L-shaped structure, from which the long extra arm protrudes. Although the D-arm conformation and the extra-arm orientation are similar to those of eukaryal/archaeal tRNASecs, A. aeolicus tRNASec has unique base triples, G14:C21:U8 and C15:G20a:G48, which occupy the positions corresponding to the U8:A14 and R15:Y48 tertiary base pairs of canonical tRNAs. Methanopyrus kandleri SerRS exhibited serine ligation activity toward A. aeolicus tRNASecin vitro. The SerRS N-terminal domain interacts with the extra-arm stem and the outer corner of tRNASec. Similar interactions exist in the reported tRNASer and SerRS complex structure from the bacterium Thermus thermophilus. Although the catalytic C-terminal domain of M. kandleri SerRS lacks interactions with A. aeolicus tRNASec in the present complex structure, the conformational flexibility of SerRS is likely to allow the CCA terminal region of tRNASec to enter the SerRS catalytic site.
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Affiliation(s)
- Yuzuru Itoh
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Abstract
The aminoacyl-tRNA synthetases (aaRSs) are essential components of the protein synthesis machinery responsible for defining the genetic code by pairing the correct amino acids to their cognate tRNAs. The aaRSs are an ancient enzyme family believed to have origins that may predate the last common ancestor and as such they provide insights into the evolution and development of the extant genetic code. Although the aaRSs have long been viewed as a highly conserved group of enzymes, findings within the last couple of decades have started to demonstrate how diverse and versatile these enzymes really are. Beyond their central role in translation, aaRSs and their numerous homologs have evolved a wide array of alternative functions both inside and outside translation. Current understanding of the emergence of the aaRSs, and their subsequent evolution into a functionally diverse enzyme family, are discussed in this chapter.
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Yanagisawa T, Sumida T, Ishii R, Yokoyama S. A novel crystal form of pyrrolysyl-tRNA synthetase reveals the pre- and post-aminoacyl-tRNA synthesis conformational states of the adenylate and aminoacyl moieties and an asparagine residue in the catalytic site. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2012; 69:5-15. [PMID: 23275158 DOI: 10.1107/s0907444912039881] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Accepted: 09/19/2012] [Indexed: 11/10/2022]
Abstract
Structures of Methanosarcina mazei pyrrolysyl-tRNA synthetase (PylRS) have been determined in a novel crystal form. The triclinic form crystals contained two PylRS dimers (four monomer molecules) in the asymmetric unit, in which the two subunits in one dimer each bind N(ℇ)-(tert-butyloxycarbonyl)-L-lysyladenylate (BocLys-AMP) and the two subunits in the other dimer each bind AMP. The BocLys-AMP molecules adopt a curved conformation and the C(α) position of BocLys-AMP protrudes from the active site. The β7-β8 hairpin structures in the four PylRS molecules represent distinct conformations of different states of the aminoacyl-tRNA synthesis reaction. Tyr384, at the tip of the β7-β8 hairpin, moves from the edge to the inside of the active-site pocket and adopts multiple conformations in each state. Furthermore, a new crystal structure of the BocLys-AMPPNP-bound form is also reported. The bound BocLys adopts an unusually bent conformation, which differs from the previously reported structure. It is suggested that the present BocLys-AMPPNP-bound, BocLys-AMP-bound and AMP-bound complexes represent the initial binding of an amino acid (or pre-aminoacyl-AMP synthesis), pre-aminoacyl-tRNA synthesis and post-aminoacyl-tRNA synthesis states, respectively. The conformational changes of Asn346 that accompany the aminoacyl-tRNA synthesis reaction have been captured by X-ray crystallographic analyses. The orientation of the Asn346 side chain, which hydrogen-bonds to the carbonyl group of the amino-acid substrate, shifts by a maximum of 85-90° around the C(β) atom.
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Affiliation(s)
- Tatsuo Yanagisawa
- RIKEN Systems and Structural Biology Center, Tsurumi, Yokohama, Japan
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33
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Redwan IN, Ingemyr HJ, Ljungdahl T, Lawson CP, Grøtli M. Solid-Phase Synthesis of 5′-O-[N-(Acyl)sulfamoyl]adenosine Derivatives. European J Org Chem 2012. [DOI: 10.1002/ejoc.201200329] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
Aminoacyl tRNA synthetases are ancient proteins that interpret the genetic material in all life forms. They are thought to have appeared during the transition from the RNA world to the theatre of proteins. During translation, they establish the rules of the genetic code, whereby each amino acid is attached to a tRNA that is cognate to the amino acid. Mistranslation occurs when an amino acid is attached to the wrong tRNA and subsequently is misplaced in a nascent protein. Mistranslation can be toxic to bacteria and mammalian cells, and can lead to heritable mutations. The great challenge for nature appears to be serine-for-alanine mistranslation, where even small amounts of this mistranslation cause severe neuropathologies in the mouse. To minimize serine-for-alanine mistranslation, powerful selective pressures developed to prevent mistranslation through a special editing activity imbedded within alanyl-tRNA synthetases (AlaRSs). However, serine-for-alanine mistranslation is so challenging that a separate, genome-encoded fragment of the editing domain of AlaRS is distributed throughout the Tree of Life to redundantly prevent serine-to-alanine mistranslation. Detailed X-ray structural and functional analysis shed light on why serine-for-alanine mistranslation is a universal problem, and on the selective pressures that engendered the appearance of AlaXps at the base of the Tree of Life.
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Affiliation(s)
- Paul Schimmel
- Department of Molecular Biology, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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36
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Dulic M, Pozar J, Bilokapic S, Weygand-Durasevic I, Gruic-Sovulj I. An idiosyncratic serine ordering loop in methanogen seryl-tRNA synthetases guides substrates through seryl-tRNASer formation. Biochimie 2011; 93:1761-9. [DOI: 10.1016/j.biochi.2011.06.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Accepted: 06/10/2011] [Indexed: 10/18/2022]
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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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Blaise M, Fréchin M, Oliéric V, Charron C, Sauter C, Lorber B, Roy H, Kern D. Crystal structure of the archaeal asparagine synthetase: interrelation with aspartyl-tRNA and asparaginyl-tRNA synthetases. J Mol Biol 2011; 412:437-52. [PMID: 21820443 DOI: 10.1016/j.jmb.2011.07.050] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 07/19/2011] [Accepted: 07/21/2011] [Indexed: 11/28/2022]
Abstract
Asparagine synthetase A (AsnA) catalyzes asparagine synthesis using aspartate, ATP, and ammonia as substrates. Asparagine is formed in two steps: the β-carboxylate group of aspartate is first activated by ATP to form an aminoacyl-AMP before its amidation by a nucleophilic attack with an ammonium ion. Interestingly, this mechanism of amino acid activation resembles that used by aminoacyl-tRNA synthetases, which first activate the α-carboxylate group of the amino acid to form also an aminoacyl-AMP before they transfer the activated amino acid onto the cognate tRNA. In a previous investigation, we have shown that the open reading frame of Pyrococcus abyssi annotated as asparaginyl-tRNA synthetase (AsnRS) 2 is, in fact, an archaeal asparagine synthetase A (AS-AR) that evolved from an ancestral aspartyl-tRNA synthetase (AspRS). We present here the crystal structure of this AS-AR. The fold of this protein is similar to that of bacterial AsnA and resembles the catalytic cores of AspRS and AsnRS. The high-resolution structures of AS-AR associated with its substrates and end-products help to understand the reaction mechanism of asparagine formation and release. A comparison of the catalytic core of AS-AR with those of archaeal AspRS and AsnRS and with that of bacterial AsnA reveals a strong conservation. This study uncovers how the active site of the ancestral AspRS rearranged throughout evolution to transform an enzyme activating the α-carboxylate group into an enzyme that is able to activate the β-carboxylate group of aspartate, which can react with ammonia instead of tRNA.
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Affiliation(s)
- Mickaël Blaise
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, Institut de Biologie Moléculaire et Cellulaire, UPR 9002, 15 rue René Descartes, 67084 Strasbourg Cedex, France.
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39
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Christian T, Lahoud G, Liu C, Hou YM. Control of catalytic cycle by a pair of analogous tRNA modification enzymes. J Mol Biol 2010; 400:204-17. [PMID: 20452364 DOI: 10.1016/j.jmb.2010.05.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2009] [Revised: 04/13/2010] [Accepted: 05/03/2010] [Indexed: 10/19/2022]
Abstract
Enzymes that use distinct active site structures to perform identical reactions are known as analogous enzymes. The isolation of analogous enzymes suggests the existence of multiple enzyme structural pathways that can catalyze the same chemical reaction. A fundamental question concerning analogous enzymes is whether their distinct active-site structures would confer the same or different kinetic constraints to the chemical reaction, particularly with respect to the control of enzyme turnover. Here, we address this question with the analogous enzymes of bacterial TrmD and its eukaryotic and archaeal counterpart Trm5. TrmD and Trm5 catalyze methyl transfer to synthesize the m1G37 base at the 3' position adjacent to the tRNA anticodon, using S-adenosyl methionine (AdoMet) as the methyl donor. TrmD features a trefoil-knot active-site structure whereas Trm5 features the Rossmann fold. Pre-steady-state analysis revealed that product synthesis by TrmD proceeds linearly with time, whereas that by Trm5 exhibits a rapid burst followed by a slower and linear increase with time. The burst kinetics of Trm5 suggests that product release is the rate-limiting step of the catalytic cycle, consistent with the observation of higher enzyme affinity to the products of tRNA and AdoMet. In contrast, the lack of burst kinetics of TrmD suggests that its turnover is controlled by a step required for product synthesis. Although TrmD exists as a homodimer, it showed half-of-the-sites reactivity for tRNA binding and product synthesis. The kinetic differences between TrmD and Trm5 are parallel with those between the two classes of aminoacyl-tRNA synthetases, which use distinct active site structures to catalyze tRNA aminoacylation. This parallel suggests that the findings have a fundamental importance for enzymes that catalyze both methyl and aminoacyl transfer to tRNA in the decoding process.
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Affiliation(s)
- Thomas Christian
- Thomas Jefferson University, Department of Biochemistry and Molecular Biology, 233 South 10th Street, BLSB 220, Philadelphia, PA 19107, USA
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40
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Paradox of mistranslation of serine for alanine caused by AlaRS recognition dilemma. Nature 2010; 462:808-12. [PMID: 20010690 PMCID: PMC2799227 DOI: 10.1038/nature08612] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2009] [Accepted: 10/26/2009] [Indexed: 12/02/2022]
Abstract
Mistranslation from confusion of serine for alanine by alanyl-tRNA synthetases (AlaRSs) has profound functional consequences1-3. Throughout evolution, two editing-checkpoints prevent disease-causing mistranslation from confusing glycine or serine for alanine at the active site of AlaRS. In both bacteria and mice, Ser poses a bigger challenge than Gly1,2. One checkpoint is the AlaRS editing center, while the other is from widely distributed AlaXps—free-standing, genome-encoded editing proteins that clear Ser-tRNAAla. The paradox of misincorporating both a smaller (glycine) and a larger amino acid (serine) suggests a deep conflict for nature-designed AlaRS. To understand the chemical basis for this conflict, kinetic and mutational analysis, together with nine crystal structures, provided snapshots of adenylate formation for each amino acid. An inherent dilemma is posed by constraints of a structural design that pins down the α–amino group of the bound amino acid using an acidic residue. This design, of more than 3 billion years, creates a serendipitous interaction with the serine OH that is difficult to avoid. Apparently not able to find better architecture for recognition of alanine, the serine misactivation problem was solved through free-standing AlaXps, which appeared contemporaneously with early AlaRSs. The results reveal unconventional problems and solutions arising from the historical design of the protein synthesis machinery.
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41
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Sakurama H, Takita T, Mikami B, Itoh T, Yasukawa K, Inouye K. Two crystal structures of lysyl-tRNA synthetase from Bacillus stearothermophilus in complex with lysyladenylate-like compounds: insights into the irreversible formation of the enzyme-bound adenylate of L-lysine hydroxamate. J Biochem 2009; 145:555-63. [PMID: 19174549 DOI: 10.1093/jb/mvp014] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Aminoacyl-tRNA synthetase forms an enzyme-bound intermediate, aminoacyladenylate in the amino-acid activation reaction. This reaction is monitored by measuring the ATP-PPi exchange reason in which [(32)P]PPi is incorporated into ATP. We previously reported that L-lysine hydroxamate completely inhibited the L-lysine-dependent ATP-PPi exchange reaction catalysed by lysyl-tRNA synthetase from Bacillus stearothermophilus (BsLysRS). Several experiments suggested that BsLysRS can adenylate L-lysine hydroxamate, but the enzyme-bound lysyladenylate-like compound does not undergo the nucleophilic attack of PPi. This contrasts with the two reports for seryl-tRNA synthetase (SerRS): (i) L-serine hydroxamate was utilized by yeast SerRS as a substrate in the ATP-PPi exchange; and (ii) a seryladenylate-like compound was formed from L-serine hydroxamate in the crystal structure of Thermus thermophilus SerRS. To gain clues about the mechanistic difference, we have determined the crystal structures of two complexes of BsLysRS with the adenylate of L-lysine hydroxamate and with 5'-O-[N-(L-Lysyl)sulphamoyl] adenosine. The comparisons of the two BsLysRS structures and the above SerRS structure revealed the specific side-chain shift of Glu411 of BsLysRS in the complex with the adenylate of L-lysine hydroxamate. In support of other structural comparisons, the result suggested that Glu411 plays a key role in the arrangement of PPi for the nucleophilic attack.
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Affiliation(s)
- Haruko Sakurama
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
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42
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Ciulli A, Scott DE, Ando M, Reyes F, Saldanha SA, Tuck KL, Chirgadze DY, Blundell TL, Abell C. Inhibition of Mycobacterium tuberculosis pantothenate synthetase by analogues of the reaction intermediate. Chembiochem 2008; 9:2606-11. [PMID: 18821554 PMCID: PMC4441726 DOI: 10.1002/cbic.200800437] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Indexed: 11/11/2022]
Affiliation(s)
- Alessio Ciulli
- University Chemical Laboratory, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW (UK)
| | - Duncan E. Scott
- University Chemical Laboratory, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW (UK)
| | - Michiyo Ando
- University Chemical Laboratory, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW (UK)
| | - Fernando Reyes
- University Chemical Laboratory, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW (UK)
| | - S. Adrian Saldanha
- University Chemical Laboratory, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW (UK)
| | - Kellie L. Tuck
- University Chemical Laboratory, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW (UK)
| | - Dimitri Y. Chirgadze
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA (UK)
| | - Tom L. Blundell
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA (UK)
| | - Chris Abell
- University Chemical Laboratory, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW (UK)
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Farrera-Sinfreu J, Español Y, Geslain R, Guitart T, Albericio F, Ribas de Pouplana L, Royo M. Solid-Phase Combinatorial Synthesis of a Lysyl-tRNA Synthetase (LysRS) Inhibitory Library. ACTA ACUST UNITED AC 2008; 10:391-400. [DOI: 10.1021/cc700157j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Josep Farrera-Sinfreu
- Institute for Research in Biomedicine and Combinatorial Chemistry Unit, Barcelona Science Park, University of Barcelona, Josep Samitier 1, 08028-Barcelona, Spain, Department of Organic Chemistry, University of Barcelona, Martí i Franqués 1, 08028-Barcelona, Spain, and Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluís Companys 23, 08010-Barcelona, Spain
| | - Yaiza Español
- Institute for Research in Biomedicine and Combinatorial Chemistry Unit, Barcelona Science Park, University of Barcelona, Josep Samitier 1, 08028-Barcelona, Spain, Department of Organic Chemistry, University of Barcelona, Martí i Franqués 1, 08028-Barcelona, Spain, and Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluís Companys 23, 08010-Barcelona, Spain
| | - Renaud Geslain
- Institute for Research in Biomedicine and Combinatorial Chemistry Unit, Barcelona Science Park, University of Barcelona, Josep Samitier 1, 08028-Barcelona, Spain, Department of Organic Chemistry, University of Barcelona, Martí i Franqués 1, 08028-Barcelona, Spain, and Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluís Companys 23, 08010-Barcelona, Spain
| | - Tanit Guitart
- Institute for Research in Biomedicine and Combinatorial Chemistry Unit, Barcelona Science Park, University of Barcelona, Josep Samitier 1, 08028-Barcelona, Spain, Department of Organic Chemistry, University of Barcelona, Martí i Franqués 1, 08028-Barcelona, Spain, and Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluís Companys 23, 08010-Barcelona, Spain
| | - Fernando Albericio
- Institute for Research in Biomedicine and Combinatorial Chemistry Unit, Barcelona Science Park, University of Barcelona, Josep Samitier 1, 08028-Barcelona, Spain, Department of Organic Chemistry, University of Barcelona, Martí i Franqués 1, 08028-Barcelona, Spain, and Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluís Companys 23, 08010-Barcelona, Spain
| | - Lluís Ribas de Pouplana
- Institute for Research in Biomedicine and Combinatorial Chemistry Unit, Barcelona Science Park, University of Barcelona, Josep Samitier 1, 08028-Barcelona, Spain, Department of Organic Chemistry, University of Barcelona, Martí i Franqués 1, 08028-Barcelona, Spain, and Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluís Companys 23, 08010-Barcelona, Spain
| | - Miriam Royo
- Institute for Research in Biomedicine and Combinatorial Chemistry Unit, Barcelona Science Park, University of Barcelona, Josep Samitier 1, 08028-Barcelona, Spain, Department of Organic Chemistry, University of Barcelona, Martí i Franqués 1, 08028-Barcelona, Spain, and Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluís Companys 23, 08010-Barcelona, Spain
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Bilokapic S, Rokov Plavec J, Ban N, Weygand-Durasevic I. Structural flexibility of the methanogenic-type seryl-tRNA synthetase active site and its implication for specific substrate recognition. FEBS J 2008; 275:2831-44. [DOI: 10.1111/j.1742-4658.2008.06423.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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45
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Yanagisawa T, Ishii R, Fukunaga R, Kobayashi T, Sakamoto K, Yokoyama S. Crystallographic studies on multiple conformational states of active-site loops in pyrrolysyl-tRNA synthetase. J Mol Biol 2008; 378:634-52. [PMID: 18387634 DOI: 10.1016/j.jmb.2008.02.045] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Revised: 01/24/2008] [Accepted: 02/21/2008] [Indexed: 11/25/2022]
Abstract
Pyrrolysine, a lysine derivative with a bulky pyrroline ring, is the "22nd" genetically encoded amino acid. In the present study, the carboxy-terminal catalytic fragment of Methanosarcina mazei pyrrolysyl-tRNA synthetase (PylRS) was analyzed by X-ray crystallography and site-directed mutagenesis. The catalytic fragment ligated tRNA(Pyl) with pyrrolysine nearly as efficiently as the full-length PylRS. We determined the crystal structures of the PylRS catalytic fragment in the substrate-free, ATP analogue (AMPPNP)-bound, and AMPPNP/pyrrolysine-bound forms, and compared them with the previously-reported PylRS structures. The ordering loop and the motif-2 loop undergo conformational changes from the "open" states to the "closed" states upon AMPPNP binding. On the other hand, the beta 7-beta 8 hairpin exhibits multiple conformational states, the open, intermediate (beta 7-open/beta 8-open and beta 7-closed/beta 8-open), and closed states, which are not induced upon substrate binding. The PylRS structures with a docked tRNA suggest that the active-site pocket can accommodate the CCA terminus of tRNA when the motif-2 loop is in the closed state and the beta 7-beta 8 hairpin is in the open or intermediate state. The entrance of the active-site pocket is nearly closed in the closed state of the beta 7-beta 8 hairpin, which may protect the pyrrolysyladenylate intermediate in the absence of tRNA(Pyl). Moreover, a structure-based mutational analysis revealed that hydrophobic residues in the amino acid-binding tunnel are important for accommodating the pyrrolysine side chain and that Asn346 is essential for anchoring the side-chain carbonyl and alpha-amino groups of pyrrolysine. In addition, a docking model of PylRS with tRNA was constructed based on the aspartyl-tRNA synthetase/tRNA structure, and was confirmed by a mutational analysis.
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Affiliation(s)
- Tatsuo Yanagisawa
- Protein Research Group, Genomic Sciences Center, Yokohama Institute, RIKEN, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan
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46
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Förster C, Brauer ABE, Fürste JP, Betzel C, Weber M, Cordes F, Erdmann VA. Superposition of a tRNASer acceptor stem microhelix into the seryl-tRNA synthetase complex. Biochem Biophys Res Commun 2007; 362:415-8. [PMID: 17719008 DOI: 10.1016/j.bbrc.2007.07.178] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2007] [Accepted: 07/31/2007] [Indexed: 11/18/2022]
Abstract
Aminoacyl-tRNA synthetases catalyze the formation of aminoacyl-tRNAs. Seryl-tRNA synthetase is a class II synthetase, which depends on rather few and simple identity elements in tRNA(Ser) to determine the amino acid specificity. tRNA(Ser) acceptor stem microhelices can be aminoacylated with serine, which makes this part of the tRNA a valuable tool for investigating the structural motifs in a tRNA(Ser)-seryl-tRNA synthetase complex. A 1.8A-resolution tRNA(Ser) acceptor stem crystal structure was superimposed to a 2.9A-resolution crystal structure of a tRNA(Ser)-seryl-tRNA synthetase complex for a visualization of the binding environment of the tRNA(Ser) microhelix.
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MESH Headings
- Anticodon/chemistry
- Anticodon/metabolism
- Crystallization
- Crystallography, X-Ray
- Models, Molecular
- Nucleic Acid Conformation
- Protein Binding
- RNA, Transfer, Amino Acyl/chemistry
- RNA, Transfer, Amino Acyl/metabolism
- RNA, Transfer, Ser/chemistry
- RNA, Transfer, Ser/metabolism
- Serine-tRNA Ligase/chemistry
- Serine-tRNA Ligase/metabolism
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Affiliation(s)
- C Förster
- Institute of Chemistry and Biochemistry, Free University Berlin, Thielallee 63, 14195 Berlin, Germany
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Chen BY, Bryant DH, Fofanov VY, Kristensen DM, Cruess AE, Kimmel M, Lichtarge O, Kavraki LE. Cavity scaling: automated refinement of cavity-aware motifs in protein function prediction. J Bioinform Comput Biol 2007; 5:353-82. [PMID: 17589966 DOI: 10.1142/s021972000700276x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Revised: 12/12/2006] [Indexed: 11/18/2022]
Abstract
Algorithms for geometric and chemical comparison of protein substructure can be useful for many applications in protein function prediction. These motif matching algorithms identify matches of geometric and chemical similarity between well-studied functional sites, motifs, and substructures of functionally uncharacterized proteins, targets. For the purpose of function prediction, the accuracy of motif matching algorithms can be evaluated with the number of statistically significant matches to functionally related proteins, true positives (TPs), and the number of statistically insignificant matches to functionally unrelated proteins, false positives (FPs). Our earlier work developed cavity-aware motifs which use motif points to represent functionally significant atoms and C-spheres to represent functionally significant volumes. We observed that cavity-aware motifs match significantly fewer FPs than matches containing only motif points. We also observed that high-impact C-spheres, which significantly contribute to the reduction of FPs, can be isolated automatically with a technique we call Cavity Scaling. This paper extends our earlier work by demonstrating that C-spheres can be used to accelerate point-based geometric and chemical comparison algorithms, maintaining accuracy while reducing runtime. We also demonstrate that the placement of C-spheres can significantly affect the number of TPs and FPs identified by a cavity-aware motif. While the optimal placement of C-spheres remains a difficult open problem, we compared two logical placement strategies to better understand C-sphere placement.
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Affiliation(s)
- Brian Y Chen
- Department of Computer Science, Rice University, Houston, TX 77005, USA
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Ganti S, Vik SB. Chemical modification of mono-cysteine mutants allows a more global look at conformations of the epsilon subunit of the ATP synthase from Escherichia coli. J Bioenerg Biomembr 2007; 39:99-107. [PMID: 17318395 DOI: 10.1007/s10863-006-9066-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2006] [Accepted: 10/31/2006] [Indexed: 12/01/2022]
Abstract
The epsilon subunit of the ATP synthase from E. coli undergoes conformational changes while rotating through 360 degrees during catalysis. The conformation of epsilon was probed in the membrane-bound ATP synthase by reaction of mono-cysteine mutants with 3-N-maleimidyl-propionyl biocytin (MPB) under resting conditions, during ATP hydrolysis, and after inhibition by ADP-AlF(3). The relative extents of labeling were quantified after electrophoresis and blotting of the partially purified epsilon subunit. Residues from the N-terminal beta-sandwich domain showed a position-specific pattern of labeling, consistent with prior structural studies. Some residues near the epsilon-gamma interface showed changes up to two-fold if labeling occurred during ATP hydrolysis or after inhibition by ADP-AlF(3). In contrast, residues found in the C-terminal alpha-helices were all labeled to a moderate or high level with a pattern that was consistent with a partially opened helical hairpin. The results indicate that the two C-terminal alpha-helices do not adopt a fixed conformation under resting conditions, but rather exhibit intrinsic flexibility.
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Affiliation(s)
- Sangeeta Ganti
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275-0376, USA
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Yan Z, Liang Z, Obsil T, Stojilkovic SS. Participation of the Lys313-Ile333 Sequence of the Purinergic P2X4 Receptor in Agonist Binding and Transduction of Signals to the Channel Gate. J Biol Chem 2006; 281:32649-59. [PMID: 16954225 DOI: 10.1074/jbc.m512791200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To study the roles of the Lys(313)-Ile(333) ectodomain sequence of the rat P2X(4) receptor in ATP binding and transduction of signals to the channel gate, the conserved Lys(313), Tyr(315), Gly(316), Ike(317), Arg(318), Asp(320), Val(323), Lys(329), Phe(330), and Ile(333) residues were mutated. Current recordings were done on lifted cells and ATP was applied using an ultrafast solution-switching system. The rates of wild type channel opening and closing in the presence of ATP, but not the rate of washout-induced closing, were dependent on agonist concentration. All mutants other than I317A were expressed in the plasma membrane at comparable levels. The majority of mutants showed significant changes in the peak amplitude of responses and the EC(50) values for ATP. When stimulated with the supramaximal (1.4 mm) ATP concentration, mutants also differed in the kinetics of their activation, deactivation, and/or desensitization. The results suggest a critical role of the Lys(313) residue in receptor function other than coordination of the phosphate group of ATP and possible contribution of the Tyr(315) residue to the agonist binding module. The pattern of changes of receptor function by mutation of other residues was consistent with the operation of the Gly(316)-Ile(333) sequence as a signal transduction module between the ligand binding domain and the channel gate in the second transmembrane domain.
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Affiliation(s)
- Zonghe Yan
- Section on Cellular Signaling, Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, 49 Convent Drive, Bethesda, MD 20892-4510, USA
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Kim SY, Lee YS, Kang T, Kim S, Lee J. Pharmacophore-based virtual screening: The discovery of novel methionyl-tRNA synthetase inhibitors. Bioorg Med Chem Lett 2006; 16:4898-907. [PMID: 16824759 DOI: 10.1016/j.bmcl.2006.06.057] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Revised: 06/01/2006] [Accepted: 06/16/2006] [Indexed: 10/24/2022]
Abstract
We have performed virtual screening of a chemical database of 508,143 commercially available chemicals to search for new methionyl-tRNA synthetase (MetRS) inhibitors. In this study, potent lead compounds with a novel skeleton, including compound 27 with IC50 = 237 nM, were successfully identified as Escherichia coli MetRS inhibitors.
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Affiliation(s)
- Su Yeon Kim
- Laboratory of Medicinal Chemistry, Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Shinlim-Dong, Kwanak-Ku, Seoul 151-742, Republic of Korea
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