1
|
Liu D, Tian Z, Tusong K, Mamat H, Luo Y. Expression, purification and characterization of CTP synthase PyrG in Staphylococcusaureus. Protein Expr Purif 2024; 221:106520. [PMID: 38833752 DOI: 10.1016/j.pep.2024.106520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2024] [Revised: 05/28/2024] [Accepted: 06/03/2024] [Indexed: 06/06/2024]
Abstract
Staphylococcus aureus (S. aureus) presents a significant challenge in both nosocomial and community settings due to its pathogenicity. The emergence of drug-resistant strains exacerbates S. aureus infections, leading to increased mortality rates. PyrG, a member of the cytidine triphosphate (CTP) synthase family, serves as a crucial therapeutic target against S. aureus due to the pivotal role of CTP in cellular metabolism. However, the structural and mechanistic details of S. aureus PyrG remains unknown. Here, we successfully expressed and purified monomeric PyrG. Mutational experiments were conducted based on the results of molecular docking. Based on the results of the molecular docking, we carried out mutation experiments and found that Q386A dramatically decreased the CTP synthase activity compared to the wild-type protein, while Y54A almost completely abolished the activity. Exposure of S. aureus to the kinase inhibitor crizotinib increased expression of gene pyrG. Our results identify the two key sites on PyrG for the CTP synthase activity, and present PyrG gene expression increased during the treatment of crizotinib, which may eventually provide valuable guidance for the development of new drugs against S. aureus infections.
Collapse
Affiliation(s)
- Dafeng Liu
- Xinjiang Key Laboratory of Lavender Conservation and Utilization, College of Biological Sciences and Technology, Yili Normal University, Yining, 835000, Xinjiang, China; School of Life Sciences, Xiamen University, Xiamen, 361102, Fujian, China.
| | - Zhu Tian
- Xinjiang Key Laboratory of Lavender Conservation and Utilization, College of Biological Sciences and Technology, Yili Normal University, Yining, 835000, Xinjiang, China
| | - Kuerban Tusong
- Xinjiang Key Laboratory of Lavender Conservation and Utilization, College of Biological Sciences and Technology, Yili Normal University, Yining, 835000, Xinjiang, China
| | - Hayrinsa Mamat
- Xinjiang Key Laboratory of Lavender Conservation and Utilization, College of Biological Sciences and Technology, Yili Normal University, Yining, 835000, Xinjiang, China
| | - Yihan Luo
- Xinjiang Key Laboratory of Lavender Conservation and Utilization, College of Biological Sciences and Technology, Yili Normal University, Yining, 835000, Xinjiang, China
| |
Collapse
|
2
|
Sahu U, Villa E, Reczek CR, Zhao Z, O'Hara BP, Torno MD, Mishra R, Shannon WD, Asara JM, Gao P, Shilatifard A, Chandel NS, Ben-Sahra I. Pyrimidines maintain mitochondrial pyruvate oxidation to support de novo lipogenesis. Science 2024; 383:1484-1492. [PMID: 38547260 DOI: 10.1126/science.adh2771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 02/20/2024] [Indexed: 04/02/2024]
Abstract
Cellular purines, particularly adenosine 5'-triphosphate (ATP), fuel many metabolic reactions, but less is known about the direct effects of pyrimidines on cellular metabolism. We found that pyrimidines, but not purines, maintain pyruvate oxidation and the tricarboxylic citric acid (TCA) cycle by regulating pyruvate dehydrogenase (PDH) activity. PDH activity requires sufficient substrates and cofactors, including thiamine pyrophosphate (TPP). Depletion of cellular pyrimidines decreased TPP synthesis, a reaction carried out by TPP kinase 1 (TPK1), which reportedly uses ATP to phosphorylate thiamine (vitamin B1). We found that uridine 5'-triphosphate (UTP) acts as the preferred substrate for TPK1, enabling cellular TPP synthesis, PDH activity, TCA-cycle activity, lipogenesis, and adipocyte differentiation. Thus, UTP is required for vitamin B1 utilization to maintain pyruvate oxidation and lipogenesis.
Collapse
Affiliation(s)
- Umakant Sahu
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
| | - Elodie Villa
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
| | - Colleen R Reczek
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Zibo Zhao
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
| | - Brendan P O'Hara
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
| | - Michael D Torno
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
| | | | | | - John M Asara
- Mass Spectrometry Core, Beth Israel Deaconess Medical Center, Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Peng Gao
- Metabolomics Core Facility, Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
| | - Ali Shilatifard
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
| | - Navdeep S Chandel
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Issam Ben-Sahra
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
| |
Collapse
|
3
|
Ballut L, Violot S, Kumar S, Aghajari N, Balaram H. GMP Synthetase: Allostery, Structure, and Function. Biomolecules 2023; 13:1379. [PMID: 37759779 PMCID: PMC10526850 DOI: 10.3390/biom13091379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 09/05/2023] [Accepted: 09/07/2023] [Indexed: 09/29/2023] Open
Abstract
Glutamine amidotransferases (GATs) catalyze the hydrolysis of glutamine and transfer the generated ammonia to diverse metabolites. The two catalytic activities, glutaminolysis and the subsequent amination of the acceptor substrate, happen in two distinct catalytic pockets connected by a channel that facilitates the movement of ammonia. The de novo pathway for the synthesis of guanosine monophosphate (GMP) from xanthosine monophosphate (XMP) is enabled by the GAT GMP synthetase (GMPS). In most available crystal structures of GATs, the ammonia channel is evident in their native state or upon ligand binding, providing molecular details of the conduit. In addition, conformational changes that enable the coordination of the two catalytic chemistries are also informed by the available structures. In contrast, despite the first structure of a GMPS being published in 1996, the understanding of catalysis in the acceptor domain and inter-domain crosstalk became possible only after the structure of a glutamine-bound mutant of Plasmodium falciparum GMPS was determined. In this review, we present the current status of our understanding of the molecular basis of catalysis in GMPS, becoming the first comprehensive assessment of the biochemical function of this intriguing enzyme.
Collapse
Affiliation(s)
- Lionel Ballut
- Molecular Microbiology and Structural Biochemistry, CNRS, University of Lyon1, UMR5086, 7 Passage du Vercors, CEDEX 07, F-69367 Lyon, France; (L.B.); (S.V.)
| | - Sébastien Violot
- Molecular Microbiology and Structural Biochemistry, CNRS, University of Lyon1, UMR5086, 7 Passage du Vercors, CEDEX 07, F-69367 Lyon, France; (L.B.); (S.V.)
| | - Sanjeev Kumar
- Trivedi School of Biosciences, Ashoka University, Rajiv Gandhi Education City, Sonipat 131029, Haryana, India;
| | - Nushin Aghajari
- Molecular Microbiology and Structural Biochemistry, CNRS, University of Lyon1, UMR5086, 7 Passage du Vercors, CEDEX 07, F-69367 Lyon, France; (L.B.); (S.V.)
| | - Hemalatha Balaram
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur 560064, Bangalore, India
| |
Collapse
|
4
|
Darekar S, Laín S. Asymmetric inheritance of cytoophidia could contribute to determine cell fate and plasticity: The onset of alternative differentiation patterns in daughter cells may rely on the acquisition of either CTPS or IMPDH cytoophidia: The onset of alternative differentiation patterns in daughter cells may rely on the acquisition of either CTPS or IMPDH cytoophidia. Bioessays 2022; 44:e2200128. [PMID: 36209393 DOI: 10.1002/bies.202200128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 08/26/2022] [Accepted: 09/21/2022] [Indexed: 12/20/2022]
Abstract
Two enzymes involved in the synthesis of pyrimidine and purine nucleotides, CTP synthase (CTPS) and IMP dehydrogenase (IMPDH), can assemble into a single or very few large filaments called rods and rings (RR) or cytoophidia. Most recently, asymmetric cytoplasmic distribution of organelles during cell division has been described as a decisive event in hematopoietic stem cell fate. We propose that cytoophidia, which could be considered as membrane-less organelles, may also be distributed asymmetrically during mammalian cell division as previously described for Schizosaccharomyces pombe. Furthermore, because each type of nucleotide intervenes in distinct processes (e.g., membrane synthesis, glycosylation, and G protein-signaling), alterations in the rate of synthesis of specific nucleotide types could influence cell differentiation in multiple ways. Therefore, we hypothesize that whether a daughter cell inherits or not CTPS or IMPDH filaments determines its fate and that this asymmetric inheritance, together with the dynamic nature of these structures enables plasticity in a cell population.
Collapse
Affiliation(s)
- Suhas Darekar
- Department of Microbiology, Tumor and Cell Biology (MTC), Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Sonia Laín
- Department of Microbiology, Tumor and Cell Biology (MTC), Biomedicum, Karolinska Institutet, Stockholm, Sweden
| |
Collapse
|
5
|
GTP-Dependent Regulation of CTP Synthase: Evolving Insights into Allosteric Activation and NH3 Translocation. Biomolecules 2022; 12:biom12050647. [PMID: 35625575 PMCID: PMC9138612 DOI: 10.3390/biom12050647] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Revised: 04/21/2022] [Accepted: 04/21/2022] [Indexed: 12/24/2022] Open
Abstract
Cytidine-5′-triphosphate (CTP) synthase (CTPS) is the class I glutamine-dependent amidotransferase (GAT) that catalyzes the last step in the de novo biosynthesis of CTP. Glutamine hydrolysis is catalyzed in the GAT domain and the liberated ammonia is transferred via an intramolecular tunnel to the synthase domain where the ATP-dependent amination of UTP occurs to form CTP. CTPS is unique among the glutamine-dependent amidotransferases, requiring an allosteric effector (GTP) to activate the GAT domain for efficient glutamine hydrolysis. Recently, the first cryo-electron microscopy structure of Drosophila CTPS was solved with bound ATP, UTP, and, notably, GTP, as well as the covalent adduct with 6-diazo-5-oxo-l-norleucine. This structural information, along with the numerous site-directed mutagenesis, kinetics, and structural studies conducted over the past 50 years, provide more detailed insights into the elaborate conformational changes that accompany GTP binding at the GAT domain and their contribution to catalysis. Interactions between GTP and the L2 loop, the L4 loop from an adjacent protomer, the L11 lid, and the L13 loop (or unique flexible “wing” region), induce conformational changes that promote the hydrolysis of glutamine at the GAT domain; however, direct experimental evidence on the specific mechanism by which these conformational changes facilitate catalysis at the GAT domain is still lacking. Significantly, the conformational changes induced by GTP binding also affect the assembly and maintenance of the NH3 tunnel. Hence, in addition to promoting glutamine hydrolysis, the allosteric effector plays an important role in coordinating the reactions catalyzed by the GAT and synthase domains of CTPS.
Collapse
|
6
|
Sharma N, Singh S, Tanwar AS, Mondal J, Anand R. Mechanism of Coordinated Gating and Signal Transduction in Purine Biosynthetic Enzyme Formylglycinamidine Synthetase. ACS Catal 2022. [DOI: 10.1021/acscatal.1c05521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nandini Sharma
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Sukhwinder Singh
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Ajay S. Tanwar
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Jagannath Mondal
- Centre for Interdisciplinary Science, Tata Institute of Fundamental Research, Hyderabad 500107, India
| | - Ruchi Anand
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| |
Collapse
|
7
|
Ejalonibu MA, Elrashedy AA, Lawal MM, Mhlongo NN, Kumalo HM. Pharmacophore mapping of the crucial mediators of dual inhibitor activity of PanK and PyrG in tuberculosis disease. MOLECULAR SIMULATION 2021. [DOI: 10.1080/08927022.2021.2019251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Murtala A. Ejalonibu
- Biomolecular Modeling Research Unit, Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Science, University of KwaZulu-Natal, Durban, South Africa
| | - Ahmed A. Elrashedy
- Natural and Microbial Product Department, National Research Centre, Giza, Egypt
| | - Monsurat M. Lawal
- Biomolecular Modeling Research Unit, Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Science, University of KwaZulu-Natal, Durban, South Africa
| | - Ndumiso N. Mhlongo
- Biomolecular Modeling Research Unit, Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Science, University of KwaZulu-Natal, Durban, South Africa
| | - Hezekiel M. Kumalo
- Biomolecular Modeling Research Unit, Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Science, University of KwaZulu-Natal, Durban, South Africa
| |
Collapse
|
8
|
Hansen JM, Horowitz A, Lynch EM, Farrell DP, Quispe J, DiMaio F, Kollman JM. Cryo-EM structures of CTP synthase filaments reveal mechanism of pH-sensitive assembly during budding yeast starvation. eLife 2021; 10:73368. [PMID: 34734801 PMCID: PMC8641951 DOI: 10.7554/elife.73368] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 11/03/2021] [Indexed: 12/27/2022] Open
Abstract
Many metabolic enzymes self-assemble into micron-scale filaments to organize and regulate metabolism. The appearance of these assemblies often coincides with large metabolic changes as in development, cancer, and stress. Yeast undergo cytoplasmic acidification upon starvation, triggering the assembly of many metabolic enzymes into filaments. However, it is unclear how these filaments assemble at the molecular level and what their role is in the yeast starvation response. CTP Synthase (CTPS) assembles into metabolic filaments across many species. Here, we characterize in vitro polymerization and investigate in vivo consequences of CTPS assembly in yeast. Cryo-EM structures reveal a pH-sensitive assembly mechanism and highly ordered filament bundles that stabilize an inactive state of the enzyme, features unique to yeast CTPS. Disruption of filaments in cells with non-assembly or pH-insensitive mutations decreases growth rate, reflecting the importance of regulated CTPS filament assembly in homeotstasis.
Collapse
Affiliation(s)
- Jesse M Hansen
- Department of Biochemistry, University of Washington, Seattle, United States.,Graduate Program in Biological Physics, Structure, and Design, University of Washington, Seattle, United States
| | - Avital Horowitz
- Department of Biochemistry, University of Washington, Seattle, United States
| | - Eric M Lynch
- Department of Biochemistry, University of Washington, Seattle, United States
| | - Daniel P Farrell
- Department of Biochemistry, University of Washington, Seattle, United States
| | - Joel Quispe
- Department of Biochemistry, University of Washington, Seattle, United States
| | - Frank DiMaio
- Department of Biochemistry, University of Washington, Seattle, United States
| | - Justin M Kollman
- Department of Biochemistry, University of Washington, Seattle, United States
| |
Collapse
|
9
|
Kambhampati S, Pajak A, Marsolais F. Evidence that class I glutamine amidotransferase, GAT1_2.1, acts as a glutaminase in roots of Arabidopsis thaliana. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2021; 312:111033. [PMID: 34620437 DOI: 10.1016/j.plantsci.2021.111033] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 08/18/2021] [Accepted: 08/20/2021] [Indexed: 06/13/2023]
Abstract
The glutamine amidotransferase gene GAT1_2.1 is a marker of N status in Arabidopsis root, linked to a shoot branching phenotype. The protein has an N-terminal glutamine amidotransferase domain and a C-terminal extension with no recognizable protein domain. A purified, recombinant version of the glutamine amidotransferase domain was catalytically active as a glutaminase, with apparent Km value of 0.66 mM and Vmax value of 2.6 μkatal per mg. This form complemented an E. coli glutaminase mutant, ΔYneH. Spiking of root metabolite extracts with either the N-terminal or full length form purified from transformed tobacco leaves led to reciprocal changes in glutamine and ammonia concentration. No product derived from amido-15N-labeled glutamine was identified. Visualization of GAT1_2.1-YPF transiently expressed in tobacco leaves confirmed its mitochondrial localization. gat1_2.1 exhibited reduced growth as compared with wild-type seedlings on media with glutamine as sole nitrogen source. Results of targeted metabolite profiling pointed to a possible activation of the GABA shunt in the mutant following glutamine treatments, with reduced levels of glutamic acid, 2-oxoglutarate and γ-aminobutyric acid and increased levels of succinic acid. GAT1_2.1 may act as a glutaminase, in concert with Glutamate Dehydrogenase 2, to hydrolyze glutamine and channel 2-oxoglutarate to the TCA cycle under high nitrogen conditions.
Collapse
Affiliation(s)
- Shrikaar Kambhampati
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford Street, London, Ontario, N5V 4T3, Canada; Department of Biology, University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 5B7, Canada.
| | - Aga Pajak
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford Street, London, Ontario, N5V 4T3, Canada.
| | - Frédéric Marsolais
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford Street, London, Ontario, N5V 4T3, Canada; Department of Biology, University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 5B7, Canada.
| |
Collapse
|
10
|
Abstract
Cytidine triphosphate synthase (CTPS), which comprises an ammonia ligase domain and a glutamine amidotransferase domain, catalyzes the final step of de novo CTP biosynthesis. The activity of CTPS is regulated by the binding of four nucleotides and glutamine. While glutamine serves as an ammonia donor for the ATP-dependent conversion of UTP to CTP, the fourth nucleotide GTP acts as an allosteric activator. Models have been proposed to explain the mechanisms of action at the active site of the ammonia ligase domain and the conformational changes derived by GTP binding. However, actual GTP/ATP/UTP binding modes and relevant conformational changes have not been revealed fully. Here, we report the discovery of binding modes of four nucleotides and a glutamine analog 6-diazo-5-oxo-L-norleucine in Drosophila CTPS by cryo-electron microscopy with near-atomic resolution. Interactions between GTP and surrounding residues indicate that GTP acts to coordinate reactions at both domains by directly blocking ammonia leakage and stabilizing the ammonia tunnel. Additionally, we observe the ATP-dependent UTP phosphorylation intermediate and determine interacting residues at the ammonia ligase. A noncanonical CTP binding at the ATP binding site suggests another layer of feedback inhibition. Our findings not only delineate the structure of CTPS in the presence of all substrates but also complete our understanding of the underlying mechanisms of the allosteric regulation and CTP synthesis.
Collapse
|
11
|
Rao Y, Wang TY, Qin C, Espinosa B, Liu Q, Ekanayake A, Zhao J, Savas AC, Zhang S, Zarinfar M, Liu Y, Zhu W, Graham N, Jiang T, Zhang C, Feng P. Targeting CTP Synthetase 1 to Restore Interferon Induction and Impede Nucleotide Synthesis in SARS-CoV-2 Infection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2021:2021.02.05.429959. [PMID: 33564769 PMCID: PMC7872357 DOI: 10.1101/2021.02.05.429959] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The newly emerged SARS-CoV-2 caused a global pandemic with astonishing mortality and morbidity. The mechanisms underpinning its highly infectious nature remain poorly understood. We report here that SARS-CoV-2 exploits cellular CTP synthetase 1 (CTPS1) to promote CTP synthesis and suppress interferon (IFN) induction. Screening a SARS-CoV-2 expression library identified ORF7b and ORF8 that suppressed IFN induction via inducing the deamidation of interferon regulatory factor 3 (IRF3). Deamidated IRF3 fails to bind the promoters of classic IRF3-responsible genes, thus muting IFN induction. Conversely, a shRNA-mediated screen focused on cellular glutamine amidotransferases corroborated that CTPS1 deamidates IRF3 to inhibit IFN induction. Functionally, ORF7b and ORF8 activate CTPS1 to promote de novo CTP synthesis while shutting down IFN induction. De novo synthesis of small-molecule inhibitors of CTPS1 enabled CTP depletion and IFN induction in SARS-CoV-2 infection, thus impeding SARS-CoV-2 replication. Our work uncovers a strategy that a viral pathogen couples immune evasion to metabolic activation to fuel viral replication. Inhibition of the cellular CTPS1 offers an attractive means for developing antiviral therapy that would be resistant to SARS-CoV-2 mutation.
Collapse
Affiliation(s)
- Youliang Rao
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90089, USA
| | - Ting-Yu Wang
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90089, USA
| | - Chao Qin
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90089, USA
| | - Bianca Espinosa
- Department of Chemistry, Dornsife College of Arts, Letters and Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Qizhi Liu
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90089, USA
| | - Arunika Ekanayake
- Department of Chemistry, Dornsife College of Arts, Letters and Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Jun Zhao
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90089, USA
- Florida Research and Innovation Center, Cleveland Clinic, FL 34987, USA
| | - Ali Can Savas
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90089, USA
| | - Shu Zhang
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90089, USA
| | - Mehrnaz Zarinfar
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90089, USA
| | - Yongzhen Liu
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90089, USA
| | - Wenjie Zhu
- Center for Systems Medicine, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100005; Suzhou Institute of Systems Medicine, Suzhou, Jiangsu 215123; Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), 510005 Guangzhou, China
| | - Nicholas Graham
- Mork Family Department of Chemical Engineering and Materials Science, Norris Comprehensive Cancer Center, Los Angeles, CA 90089, USA
| | - Taijiao Jiang
- Center for Systems Medicine, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100005; Suzhou Institute of Systems Medicine, Suzhou, Jiangsu 215123; Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), 510005 Guangzhou, China
| | - Chao Zhang
- Department of Chemistry, Dornsife College of Arts, Letters and Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Pinghui Feng
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90089, USA
- Lead Contact
| |
Collapse
|
12
|
Chakraborty A, Lin WC, Lin YT, Huang KJ, Wang PY, Chang IYF, Wang HI, Ma KT, Wang CY, Huang XR, Lee YH, Chen BC, Hsieh YJ, Chien KY, Lin TY, Liu JL, Sung LY, Yu JS, Chang YS, Pai LM. SNAP29 mediates the assembly of histidine-induced CTP synthase filaments in proximity to the cytokeratin network. J Cell Sci 2020; 133:jcs240200. [PMID: 32184263 DOI: 10.1242/jcs.240200] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 03/06/2020] [Indexed: 01/08/2023] Open
Abstract
Under metabolic stress, cellular components can assemble into distinct membraneless organelles for adaptation. One such example is cytidine 5'-triphosphate synthase (CTPS, for which there are CTPS1 and CTPS2 forms in mammals), which forms filamentous structures under glutamine deprivation. We have previously demonstrated that histidine (His)-mediated methylation regulates the formation of CTPS filaments to suppress enzymatic activity and preserve the CTPS protein under glutamine deprivation, which promotes cancer cell growth after stress alleviation. However, it remains unclear where and how these enigmatic structures are assembled. Using CTPS-APEX2-mediated in vivo proximity labeling, we found that synaptosome-associated protein 29 (SNAP29) regulates the spatiotemporal filament assembly of CTPS along the cytokeratin network in a keratin 8 (KRT8)-dependent manner. Knockdown of SNAP29 interfered with assembly and relaxed the filament-induced suppression of CTPS enzymatic activity. Furthermore, APEX2 proximity labeling of keratin 18 (KRT18) revealed a spatiotemporal association of SNAP29 with cytokeratin in response to stress. Super-resolution imaging suggests that during CTPS filament formation, SNAP29 interacts with CTPS along the cytokeratin network. This study links the cytokeratin network to the regulation of metabolism by compartmentalization of metabolic enzymes during nutrient deprivation.
Collapse
Affiliation(s)
- Archan Chakraborty
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
| | - Wei-Cheng Lin
- Department of Biochemistry and Molecular Biology, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
- Molecular Medicine Research Center, Chang Gung University, Taoyuan 33302, Taiwan
| | - Yu-Tsun Lin
- Department of Biochemistry and Molecular Biology, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
| | - Kuang-Jing Huang
- Molecular Medicine Research Center, Chang Gung University, Taoyuan 33302, Taiwan
| | - Pei-Yu Wang
- Department of Biochemistry and Molecular Biology, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
| | - Ian Yi-Feng Chang
- Molecular Medicine Research Center, Chang Gung University, Taoyuan 33302, Taiwan
- Bioinformatics Core Laboratory, Chang Gung University, Taoyuan 33302, Taiwan
| | - Hsiang-Iu Wang
- Bioinformatics Core Laboratory, Chang Gung University, Taoyuan 33302, Taiwan
| | - Kung-Ting Ma
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
| | - Chun-Yen Wang
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
| | - Xuan-Rong Huang
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
| | - Yen-Hsien Lee
- Department of Biochemistry and Molecular Biology, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
| | - Bi-Chang Chen
- Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Ya-Ju Hsieh
- Molecular Medicine Research Center, Chang Gung University, Taoyuan 33302, Taiwan
| | - Kun-Yi Chien
- Department of Biochemistry and Molecular Biology, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
- Clinical Proteomics Core laboratory, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Tzu-Yang Lin
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Ji-Long Liu
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Li-Ying Sung
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan
- Institute of Biotechnology, National Taiwan University, Taipei 106, Taiwan
| | - Jau-Song Yu
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
- Department of Biochemistry and Molecular Biology, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
- Molecular Medicine Research Center, Chang Gung University, Taoyuan 33302, Taiwan
- Liver Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Yu-Sun Chang
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
- Molecular Medicine Research Center, Chang Gung University, Taoyuan 33302, Taiwan
| | - Li-Mei Pai
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
- Department of Biochemistry and Molecular Biology, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
- Molecular Medicine Research Center, Chang Gung University, Taoyuan 33302, Taiwan
- Liver Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan
| |
Collapse
|
13
|
Lynch EM, Kollman JM. Coupled structural transitions enable highly cooperative regulation of human CTPS2 filaments. Nat Struct Mol Biol 2019; 27:42-48. [PMID: 31873303 PMCID: PMC6954954 DOI: 10.1038/s41594-019-0352-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 11/15/2019] [Indexed: 01/26/2023]
Abstract
Many enzymes assemble into defined oligomers, providing a mechanism for cooperatively regulating activity. Recent studies have described a mode of regulation in which enzyme activity is modulated by polymerization into large-scale filaments. Here we describe an ultrasensitive form of polymerization-based regulation employed by human CTP synthase 2 (CTPS2). Cryo-EM structures reveal that CTPS2 filaments dynamically switch between active and inactive forms in response to changes in substrate and product levels. Linking the conformational state of many CTPS2 subunits in a filament results in highly cooperative regulation, greatly exceeding the limits of cooperativity for the CTPS2 tetramer alone. The structures reveal a link between conformation and control of ammonia channeling between the enzyme’s active sites, and explain differences in regulation of human CTPS isoforms. This filament-based mechanism of enhanced cooperativity demonstrates how the widespread phenomenon of enzyme polymerization can be adapted to achieve different regulatory outcomes.
Collapse
Affiliation(s)
- Eric M Lynch
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Justin M Kollman
- Department of Biochemistry, University of Washington, Seattle, WA, USA.
| |
Collapse
|
14
|
Park CK, Horton NC. Structures, functions, and mechanisms of filament forming enzymes: a renaissance of enzyme filamentation. Biophys Rev 2019; 11:927-994. [PMID: 31734826 PMCID: PMC6874960 DOI: 10.1007/s12551-019-00602-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 10/24/2019] [Indexed: 12/19/2022] Open
Abstract
Filament formation by non-cytoskeletal enzymes has been known for decades, yet only relatively recently has its wide-spread role in enzyme regulation and biology come to be appreciated. This comprehensive review summarizes what is known for each enzyme confirmed to form filamentous structures in vitro, and for the many that are known only to form large self-assemblies within cells. For some enzymes, studies describing both the in vitro filamentous structures and cellular self-assembly formation are also known and described. Special attention is paid to the detailed structures of each type of enzyme filament, as well as the roles the structures play in enzyme regulation and in biology. Where it is known or hypothesized, the advantages conferred by enzyme filamentation are reviewed. Finally, the similarities, differences, and comparison to the SgrAI endonuclease system are also highlighted.
Collapse
Affiliation(s)
- Chad K. Park
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721 USA
| | - Nancy C. Horton
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721 USA
| |
Collapse
|
15
|
Zhou X, Guo CJ, Hu HH, Zhong J, Sun Q, Liu D, Zhou S, Chang CC, Liu JL. Drosophila CTP synthase can form distinct substrate- and product-bound filaments. J Genet Genomics 2019; 46:537-545. [PMID: 31902586 DOI: 10.1016/j.jgg.2019.11.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 11/07/2019] [Accepted: 11/10/2019] [Indexed: 01/26/2023]
Abstract
Intracellular compartmentation is a key strategy for the functioning of a cell. In 2010, several studies revealed that the metabolic enzyme CTP synthase (CTPS) can form filamentous structures termed cytoophidia in prokaryotic and eukaryotic cells. However, recent structural studies showed that CTPS only forms inactive product-bound filaments in bacteria while forming active substrate-bound filaments in eukaryotic cells. In this study, using negative staining and cryo-electron microscopy, we demonstrate that Drosophila CTPS, whether in substrate-bound or product-bound form, can form filaments. Our results challenge the previous model and indicate that substrate-bound and product-bound filaments can coexist in the same species. We speculate that the ability to switch between active and inactive cytoophidia in the same cells provides an additional layer of metabolic regulation.
Collapse
Affiliation(s)
- Xian Zhou
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Chen-Jun Guo
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Huan-Huan Hu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China; Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jiale Zhong
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China; Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qianqian Sun
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China; iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
| | - Dandan Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China; iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
| | - Shuang Zhou
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China; Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chia Chun Chang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Ji-Long Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
| |
Collapse
|
16
|
Dual targeting approach for Mycobacterium tuberculosis drug discovery: insights from DFT calculations and molecular dynamics simulations. Struct Chem 2019. [DOI: 10.1007/s11224-019-01422-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
|
17
|
Mapping the Allosteric Communication Network of Aminodeoxychorismate Synthase. J Mol Biol 2019; 431:2718-2728. [DOI: 10.1016/j.jmb.2019.05.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 05/10/2019] [Accepted: 05/13/2019] [Indexed: 01/31/2023]
|
18
|
Leisico F, V Vieira D, Figueiredo TA, Silva M, Cabrita EJ, Sobral RG, Ludovice AM, Trincão J, Romão MJ, de Lencastre H, Santos-Silva T. First insights of peptidoglycan amidation in Gram-positive bacteria - the high-resolution crystal structure of Staphylococcus aureus glutamine amidotransferase GatD. Sci Rep 2018; 8:5313. [PMID: 29593310 PMCID: PMC5871853 DOI: 10.1038/s41598-018-22986-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 02/27/2018] [Indexed: 12/05/2022] Open
Abstract
Gram-positive bacteria homeostasis and antibiotic resistance mechanisms are dependent on the intricate architecture of the cell wall, where amidated peptidoglycan plays an important role. The amidation reaction is carried out by the bi-enzymatic complex MurT-GatD, for which biochemical and structural information is very scarce. In this work, we report the first crystal structure of the glutamine amidotransferase member of this complex, GatD from Staphylococcus aureus, at 1.85 Å resolution. A glutamine molecule is found close to the active site funnel, hydrogen-bonded to the conserved R128. In vitro functional studies using 1H-NMR spectroscopy showed that S. aureus MurT-GatD complex has glutaminase activity even in the absence of lipid II, the MurT substrate. In addition, we produced R128A, C94A and H189A mutants, which were totally inactive for glutamine deamidation, revealing their essential role in substrate sequestration and catalytic reaction. GatD from S. aureus and other pathogenic bacteria share high identity to enzymes involved in cobalamin biosynthesis, which can be grouped in a new sub-family of glutamine amidotransferases. Given the ubiquitous presence of GatD, these results provide significant insights into the molecular basis of the so far undisclosed amidation mechanism, contributing to the development of alternative therapeutics to fight infections.
Collapse
Affiliation(s)
- Francisco Leisico
- UCIBIO, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - Diana V Vieira
- UCIBIO, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
- Oxford Protein Production Facility, Research Complex at Harwell, Didcot, United Kingdom
| | - Teresa A Figueiredo
- UCIBIO, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
- Laboratory of Molecular Genetics, Microbiology of Human Pathogens Unit, Instituto de Tecnologia Química e Biológica António Xavier da Universidade Nova de Lisboa, Oeiras, Portugal
| | - Micael Silva
- UCIBIO, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - Eurico J Cabrita
- UCIBIO, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - Rita G Sobral
- UCIBIO, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - Ana Madalena Ludovice
- UCIBIO, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | | | - Maria João Romão
- UCIBIO, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - Hermínia de Lencastre
- Laboratory of Molecular Genetics, Microbiology of Human Pathogens Unit, Instituto de Tecnologia Química e Biológica António Xavier da Universidade Nova de Lisboa, Oeiras, Portugal.
- Laboratory of Microbiology and Infectious Diseases, The Rockefeller University, New York, USA.
| | - Teresa Santos-Silva
- UCIBIO, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal.
| |
Collapse
|
19
|
Dong J, Wu T, Xiao Y, Chen L, Xu L, Li M, Zhao M. Target-triggered transcription machinery for ultra-selective and sensitive fluorescence detection of nucleoside triphosphates in one minute. Biosens Bioelectron 2017; 100:333-340. [PMID: 28942346 DOI: 10.1016/j.bios.2017.09.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 09/06/2017] [Accepted: 09/17/2017] [Indexed: 01/02/2023]
Abstract
Nucleoside triphosphates (NTPs) play important roles in living organisms. However, no fluorescent assays are currently available to simply and rapidly detect multiple NTPs with satisfactory selectivity, sensitivity and low cost. Here we demonstrate for the first time a target-triggered in-vitro transcription machinery for ultra-selective, sensitive and instant fluorescence detection of multiple NTPs. The machinery assembles RNA polymerase, DNA template and non-target NTPs to convert the target NTP into equivalent RNA signal sequences which are monitored by the fluorescence enhancement of molecular beacon. The machinery offers excellent selectivity for the target NTP against NDP, NMP and dNTP. Notably, to accelerate the kinetics of the machinery while maintain its high specificity, we investigated the sequence of DNA templates systematically and established a set of guidelines for the design of the optimum DNA templates, which allowed for instant detection of the target NTP at fmol level in less than 1min. Furthermore, the machinery could be transformed into logic gates to study the coeffects of two NTPs in biosynthesis and real-time monitoring systems to reflect the distribution of NTP in nucleotide pools. These results provide very useful and low-cost tools for both biochemical tests and point-of-care analysis.
Collapse
Affiliation(s)
- Jiantong Dong
- Beijing National Laboratory for Molecular Sciences, MOE Key Laboratory of Bioorganic Chemistry and Molecular Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Tongbo Wu
- Beijing National Laboratory for Molecular Sciences, MOE Key Laboratory of Bioorganic Chemistry and Molecular Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Yu Xiao
- Beijing National Laboratory for Molecular Sciences, MOE Key Laboratory of Bioorganic Chemistry and Molecular Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Lu Chen
- Beijing National Laboratory for Molecular Sciences, MOE Key Laboratory of Bioorganic Chemistry and Molecular Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Lei Xu
- Beijing National Laboratory for Molecular Sciences, MOE Key Laboratory of Bioorganic Chemistry and Molecular Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Mengyuan Li
- Beijing National Laboratory for Molecular Sciences, MOE Key Laboratory of Bioorganic Chemistry and Molecular Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
| | - Meiping Zhao
- Beijing National Laboratory for Molecular Sciences, MOE Key Laboratory of Bioorganic Chemistry and Molecular Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
| |
Collapse
|
20
|
Lynch EM, Hicks DR, Shepherd M, Endrizzi JA, Maker A, Hansen JM, Barry RM, Gitai Z, Baldwin EP, Kollman JM. Human CTP synthase filament structure reveals the active enzyme conformation. Nat Struct Mol Biol 2017; 24:507-514. [PMID: 28459447 PMCID: PMC5472220 DOI: 10.1038/nsmb.3407] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 04/06/2017] [Indexed: 12/11/2022]
Abstract
The universally conserved enzyme CTP synthase (CTPS) forms filaments in bacteria and eukaryotes. In bacteria, polymerization inhibits CTPS activity and is required for nucleotide homeostasis. Here we show that for human CTPS, polymerization increases catalytic activity. The cryo-EM structures of bacterial and human CTPS filaments differ considerably in overall architecture and in the conformation of the CTPS protomer, explaining the divergent consequences of polymerization on activity. The structure of human CTPS filament, the first structure of the full-length human enzyme, reveals a novel active conformation. The filament structures elucidate allosteric mechanisms of assembly and regulation that rely on a conserved conformational equilibrium. The findings may provide a mechanism for increasing human CTPS activity in response to metabolic state and challenge the assumption that metabolic filaments are generally storage forms of inactive enzymes. Allosteric regulation of CTPS polymerization by ligands likely represents a fundamental mechanism underlying assembly of other metabolic filaments.
Collapse
Affiliation(s)
- Eric M Lynch
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | - Derrick R Hicks
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
- Graduate Program in Molecular and Cellular Biology, University of Washington, Seattle, Washington, USA
| | - Matthew Shepherd
- Department of Biology, McGill University, Montreal, Quebec, Canada
| | - James A Endrizzi
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, California, USA
| | - Allison Maker
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | - Jesse M Hansen
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
- Graduate Program in Biological Physics, Structure, and Design, University of Washington, Seattle, Washington, USA
| | - Rachael M Barry
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Zemer Gitai
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Enoch P Baldwin
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, California, USA
| | - Justin M Kollman
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| |
Collapse
|
21
|
Huang Y, Wang JJ, Ghosh S, Liu JL. Critical roles of CTP synthase N-terminal in cytoophidium assembly. Exp Cell Res 2017; 354:122-133. [PMID: 28342900 PMCID: PMC5405848 DOI: 10.1016/j.yexcr.2017.03.042] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 03/18/2017] [Accepted: 03/20/2017] [Indexed: 01/27/2023]
Abstract
Several metabolic enzymes assemble into distinct intracellular structures in prokaryotes and eukaryotes suggesting an important functional role in cell physiology. The CTP-generating enzyme CTP synthase forms long filamentous structures termed cytoophidia in bacteria, yeast, fruit flies and human cells independent of its catalytic activity. However, the amino acid determinants for protein-protein interaction necessary for polymerisation remained unknown. In this study, we systematically analysed the role of the conserved N-terminal of Drosophila CTP synthase in cytoophidium assembly. Our mutational analyses identified three key amino acid residues within this region that play an instructive role in organisation of CTP synthase into a filamentous structure. Co-transfection assays demonstrated formation of heteromeric CTP synthase filaments which is disrupted by protein carrying a mutated N-terminal alanine residue thus revealing a dominant-negative activity. Interestingly, the dominant-negative activity is supressed by the CTP synthase inhibitor DON. Furthermore, we found that the amino acids at the corresponding position in the human protein exhibit similar properties suggesting conservation of their function through evolution. Our data suggest that cytoophidium assembly is a multi-step process involving N-terminal-dependent sequential interactions between correctly folded structural units and provide insights into the assembly of these enigmatic structures. CTP synthase mutational analyses reveal N-terminal amino acids that regulate filament self-assembly. Amino acid 20 of CTP synthase plays key role in protein interactions necessary for polymerisation. The dominant-negative activity is supressed by CTP synthase inhibitor DON. The functional properties of the amino acids are conserved in Drosophila and human CTP synthases.
Collapse
Affiliation(s)
- Yong Huang
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom; Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China
| | - Jin-Jun Wang
- Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China
| | - Sanjay Ghosh
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom.
| | - Ji-Long Liu
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom; School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.
| |
Collapse
|
22
|
Liu JL. The Cytoophidium and Its Kind: Filamentation and Compartmentation of Metabolic Enzymes. Annu Rev Cell Dev Biol 2016; 32:349-372. [DOI: 10.1146/annurev-cellbio-111315-124907] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Ji-Long Liu
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom;
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China;
| |
Collapse
|
23
|
Habrian C, Chandrasekhara A, Shahrvini B, Hua B, Lee J, Jesinghaus R, Barry R, Gitai Z, Kollman J, Baldwin EP. Inhibition of Escherichia coli CTP Synthetase by NADH and Other Nicotinamides and Their Mutual Interactions with CTP and GTP. Biochemistry 2016; 55:5554-5565. [PMID: 27571563 DOI: 10.1021/acs.biochem.6b00383] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
CTP synthetases catalyze the last step of pyrimidine biosynthesis and provide the sole de novo source of cytosine-containing nucleotides. As a central regulatory hub, they are regulated by ribonucleotide and enzyme concentration through ATP and UTP substrate availability, CTP product inhibition, GTP allosteric modification, and quaternary structural changes including the formation of CTP-inhibited linear polymers (filaments). Here, we demonstrate that nicotinamide redox cofactors are moderate inhibitors of Escherichia coli CTP synthetase (EcCTPS). NADH and NADPH are the most potent, and the primary inhibitory determinant is the reduced nicotinamide ring. Although nicotinamide inhibition is noncompetitive with substrates, it apparently enhances CTP product feedback inhibition and GTP allosteric regulation. Further, CTP and GTP also enhance each other's effects, consistent with the idea that NADH, CTP, and GTP interact with a common intermediate enzyme state. A filament-blocking mutation that reduces CTP inhibitory effects also reduced inhibition by GTP but not NADH. Protein-concentration effects on GTP inhibition suggest that, like CTP, GTP preferentially binds to the filament. All three compounds display nearly linear dose-dependent inhibition, indicating a complex pattern of cooperative interactions between binding sites. The apparent synergy between inhibitors, in consideration with physiological nucleotide concentrations, points to metabolically relevant inhibition by nicotinamides, and implicates cellular redox state as a regulator of pyrimidine biosynthesis.
Collapse
Affiliation(s)
- Chris Habrian
- Department of Molecular and Cellular Biology, University of California, Davis , Davis, California 95616, United States.,Biophysics Graduate Program, University of California, Berkeley , Berkeley, California 94720, United States
| | - Adithi Chandrasekhara
- Department of Molecular and Cellular Biology, University of California, Davis , Davis, California 95616, United States.,Process Development Rotation Program, Genentech Inc. , 1 DNA Way, South San Francisco, California 94080, United States
| | - Bita Shahrvini
- Department of Molecular and Cellular Biology, University of California, Davis , Davis, California 95616, United States
| | - Brian Hua
- Department of Molecular and Cellular Biology, University of California, Davis , Davis, California 95616, United States.,Department of Biology, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Jason Lee
- Department of Molecular and Cellular Biology, University of California, Davis , Davis, California 95616, United States.,Drexel University College of Medicine , Philadelphia, Pennsylvania 19129, United States.,Kaiser Permanente , Sacramento, California 95823, United States
| | - Roger Jesinghaus
- Department of Molecular and Cellular Biology, University of California, Davis , Davis, California 95616, United States
| | - Rachael Barry
- Department of Molecular Biology, Princeton University , Princeton, New Jersey 08544, United States.,Department of Cellular and Molecular Medicine, University of California, San Diego , La Jolla, California 92903, United States
| | - Zemer Gitai
- Department of Molecular Biology, Princeton University , Princeton, New Jersey 08544, United States
| | - Justin Kollman
- Department of Biochemistry, University of Washington , Seattle, Washington 98195, United States
| | - Enoch P Baldwin
- Department of Molecular and Cellular Biology, University of California, Davis , Davis, California 95616, United States
| |
Collapse
|
24
|
Pai LM, Wang PY, Lin WC, Chakraborty A, Yeh CT, Lin YH. Ubiquitination and filamentous structure of cytidine triphosphate synthase. Fly (Austin) 2016; 10:108-14. [PMID: 27116391 PMCID: PMC4970526 DOI: 10.1080/19336934.2016.1182268] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Living organisms respond to nutrient availability by regulating the activity of metabolic enzymes. Therefore, the reversible post-translational modification of an enzyme is a common regulatory mechanism for energy conservation. Recently, cytidine-5'-triphosphate (CTP) synthase was discovered to form a filamentous structure that is evolutionarily conserved from flies to humans. Interestingly, induction of the formation of CTP synthase filament is responsive to starvation or glutamine depletion. However, the biological roles of this structure remain elusive. We have recently shown that ubiquitination regulates CTP synthase activity by promoting filament formation in Drosophila ovaries during endocycles. Intriguingly, although the ubiquitination process was required for filament formation induced by glutamine depletion, CTP synthase ubiquitination was found to be inversely correlated with filament formation in Drosophila and human cell lines. In this article, we discuss the putative dual roles of ubiquitination, as well as its physiological implications, in the regulation of CTP synthase structure.
Collapse
Affiliation(s)
- Li-Mei Pai
- a Department of Biochemistry , Chang Gung University , Taoyuan City , Taiwan.,b Molecular Medicine Research Center, Chang Gung University , Taoyuan City , Taiwan.,c Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University , Taoyuan City , Taiwan.,d Liver Research Center, Chang Gung Memorial Hospital , Taoyuan City , Taiwan
| | - Pei-Yu Wang
- a Department of Biochemistry , Chang Gung University , Taoyuan City , Taiwan.,b Molecular Medicine Research Center, Chang Gung University , Taoyuan City , Taiwan
| | - Wei-Cheng Lin
- b Molecular Medicine Research Center, Chang Gung University , Taoyuan City , Taiwan
| | - Archan Chakraborty
- c Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University , Taoyuan City , Taiwan
| | - Chau-Ting Yeh
- c Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University , Taoyuan City , Taiwan.,d Liver Research Center, Chang Gung Memorial Hospital , Taoyuan City , Taiwan
| | - Yu-Hung Lin
- c Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University , Taoyuan City , Taiwan
| |
Collapse
|
25
|
Bairagya HR, Bansal M. New insight into the architecture of oxy-anion pocket in unliganded conformation of GAT domains: A MD-simulation study. Proteins 2016; 84:360-73. [PMID: 26756917 DOI: 10.1002/prot.24983] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 12/06/2015] [Accepted: 12/19/2015] [Indexed: 11/11/2022]
Abstract
Human Guanine Monophosphate Synthetase (hGMPS) converts XMP to GMP, and acts as a bifunctional enzyme with N-terminal "glutaminase" (GAT) and C-terminal "synthetase" domain. The enzyme is identified as a potential target for anti-cancer and immunosuppressive therapies. GAT domain of enzyme plays central role in metabolism, and contains conserved catalytic residues Cys104, His190, and Glu192. MD simulation studies on GAT domain suggest that position of oxyanion in unliganded conformation is occupied by one conserved water molecule (W1), which also stabilizes that pocket. This position is occupied by a negatively charged atom of the substrate or ligand in ligand bound crystal structures. In fact, MD simulation study of Ser75 to Val indicates that W1 conserved water molecule is stabilized by Ser75, while Thr152, and His190 also act as anchor residues to maintain appropriate architecture of oxyanion pocket through water mediated H-bond interactions. Possibly, four conserved water molecules stabilize oxyanion hole in unliganded state, but they vacate these positions when the enzyme (hGMPS)-substrate complex is formed. Thus this study not only reveals functionally important role of conserved water molecules in GAT domain, but also highlights essential role of other non-catalytic residues such as Ser75 and Thr152 in this enzymatic domain. The results from this computational study could be of interest to experimental community and provide a testable hypothesis for experimental validation. Conserved sites of water molecules near and at oxyanion hole highlight structural importance of water molecules and suggest a rethink of the conventional definition of chemical geometry of inhibitor binding site.
Collapse
Affiliation(s)
- Hridoy R Bairagya
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, 560012, India
| | - Manju Bansal
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, 560012, India
| |
Collapse
|
26
|
Active site coupling in Plasmodium falciparum GMP synthetase is triggered by domain rotation. Nat Commun 2015; 6:8930. [PMID: 26592566 PMCID: PMC4673825 DOI: 10.1038/ncomms9930] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 10/19/2015] [Indexed: 11/24/2022] Open
Abstract
GMP synthetase (GMPS), a key enzyme in the purine biosynthetic pathway performs catalysis through a coordinated process across two catalytic pockets for which the mechanism remains unclear. Crystal structures of Plasmodium falciparum GMPS in conjunction with mutational and enzyme kinetic studies reported here provide evidence that an 85° rotation of the GATase domain is required for ammonia channelling and thus for the catalytic activity of this two-domain enzyme. We suggest that conformational changes in helix 371–375 holding catalytic residues and in loop 376–401 along the rotation trajectory trigger the different steps of catalysis, and establish the central role of Glu374 in allostery and inter-domain crosstalk. These studies reveal the mechanism of domain rotation and inter-domain communication, providing a molecular framework for the function of all single polypeptide GMPSs and form a solid basis for rational drug design targeting this therapeutically important enzyme. GMP synthetase, a key enzyme in purine biosynthesis, is of interest for understanding purine metabolism processes and for developing therapeutic applications. Here, the authors propose a molecular mechanism and the structural basis for the catalytic activity of this enzyme.
Collapse
|
27
|
Verma S, Debnath U, Agarwal P, Srivastava K, Prabhakar YS. In Silico Exploration for New Antimalarials: Arylsulfonyloxy Acetimidamides as Prospective Agents. J Chem Inf Model 2015; 55:1708-19. [DOI: 10.1021/acs.jcim.5b00392] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Saroj Verma
- Medicinal and Process Chemistry Division, ‡Parasitology Division, CSIR-Central Drug Research Institute, Jankipuram Extension, Lucknow-226 031, India
| | - Utsab Debnath
- Medicinal and Process Chemistry Division, ‡Parasitology Division, CSIR-Central Drug Research Institute, Jankipuram Extension, Lucknow-226 031, India
| | - Pooja Agarwal
- Medicinal and Process Chemistry Division, ‡Parasitology Division, CSIR-Central Drug Research Institute, Jankipuram Extension, Lucknow-226 031, India
| | - Kumkum Srivastava
- Medicinal and Process Chemistry Division, ‡Parasitology Division, CSIR-Central Drug Research Institute, Jankipuram Extension, Lucknow-226 031, India
| | - Yenamandra S. Prabhakar
- Medicinal and Process Chemistry Division, ‡Parasitology Division, CSIR-Central Drug Research Institute, Jankipuram Extension, Lucknow-226 031, India
| |
Collapse
|
28
|
Mori G, Chiarelli LR, Esposito M, Makarov V, Bellinzoni M, Hartkoorn RC, Degiacomi G, Boldrin F, Ekins S, de Jesus Lopes Ribeiro AL, Marino LB, Centárová I, Svetlíková Z, Blaško J, Kazakova E, Lepioshkin A, Barilone N, Zanoni G, Porta A, Fondi M, Fani R, Baulard AR, Mikušová K, Alzari PM, Manganelli R, de Carvalho LPS, Riccardi G, Cole ST, Pasca MR. Thiophenecarboxamide Derivatives Activated by EthA Kill Mycobacterium tuberculosis by Inhibiting the CTP Synthetase PyrG. ACTA ACUST UNITED AC 2015; 22:917-27. [PMID: 26097035 PMCID: PMC4521081 DOI: 10.1016/j.chembiol.2015.05.016] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 05/25/2015] [Accepted: 05/30/2015] [Indexed: 11/06/2022]
Abstract
To combat the emergence of drug-resistant strains of Mycobacterium tuberculosis, new antitubercular agents and novel drug targets are needed. Phenotypic screening of a library of 594 hit compounds uncovered two leads that were active against M. tuberculosis in its replicating, non-replicating, and intracellular states: compounds 7947882 (5-methyl-N-(4-nitrophenyl)thiophene-2-carboxamide) and 7904688 (3-phenyl-N-[(4-piperidin-1-ylphenyl)carbamothioyl]propanamide). Mutants resistant to both compounds harbored mutations in ethA (rv3854c), the gene encoding the monooxygenase EthA, and/or in pyrG (rv1699) coding for the CTP synthetase, PyrG. Biochemical investigations demonstrated that EthA is responsible for the activation of the compounds, and by mass spectrometry we identified the active metabolite of 7947882, which directly inhibits PyrG activity. Metabolomic studies revealed that pharmacological inhibition of PyrG strongly perturbs DNA and RNA biosynthesis, and other metabolic processes requiring nucleotides. Finally, the crystal structure of PyrG was solved, paving the way for rational drug design with this newly validated drug target. Two compounds activated by EthA kill M. tuberculosis through PyrG inhibition EthA metabolite is active against PyrG and M. tuberculosis growth Definition of the mechanism of activation and validation of PyrG as a new drug target
Collapse
Affiliation(s)
- Giorgia Mori
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, 27100 Pavia, Italy
| | - Laurent R Chiarelli
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, 27100 Pavia, Italy
| | - Marta Esposito
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, 27100 Pavia, Italy
| | - Vadim Makarov
- A. N. Bakh Institute of Biochemistry, Russian Academy of Science, 119071 Moscow, Russia
| | - Marco Bellinzoni
- Institut Pasteur, Unité de Microbiologie Structurale, CNRS-UMR3528, Université Paris Diderot, Sorbonne Paris Cité, 25 rue du Dr. Roux, 75724 Paris Cedex 15, France
| | - Ruben C Hartkoorn
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland
| | - Giulia Degiacomi
- Department of Molecular Medicine, University of Padova, 35128 Padua, Italy
| | - Francesca Boldrin
- Department of Molecular Medicine, University of Padova, 35128 Padua, Italy
| | - Sean Ekins
- Collaborative Drug Discovery, 1633 Bayshore Highway, Suite 342, Burlingame, CA 94010, USA
| | | | - Leonardo B Marino
- Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK; Faculty of Pharmaceutical Sciences, UNESP - Univ Estadual Paulista, Araraquara, São Paulo 14801-902, Brazil
| | - Ivana Centárová
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, Mlynská dolina, 84215 Bratislava, Slovakia
| | - Zuzana Svetlíková
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, Mlynská dolina, 84215 Bratislava, Slovakia
| | - Jaroslav Blaško
- Institute of Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, Mlynská dolina, 84215 Bratislava, Slovak Republic
| | - Elena Kazakova
- A. N. Bakh Institute of Biochemistry, Russian Academy of Science, 119071 Moscow, Russia
| | - Alexander Lepioshkin
- A. N. Bakh Institute of Biochemistry, Russian Academy of Science, 119071 Moscow, Russia
| | - Nathalie Barilone
- Institut Pasteur, Unité de Microbiologie Structurale, CNRS-UMR3528, Université Paris Diderot, Sorbonne Paris Cité, 25 rue du Dr. Roux, 75724 Paris Cedex 15, France
| | - Giuseppe Zanoni
- Department of Chemistry, University of Pavia, 27100 Pavia, Italy
| | - Alessio Porta
- Department of Chemistry, University of Pavia, 27100 Pavia, Italy
| | - Marco Fondi
- Department of Biology, University of Florence, Sesto Fiorentino, Florence 50019, Italy
| | - Renato Fani
- Department of Biology, University of Florence, Sesto Fiorentino, Florence 50019, Italy
| | - Alain R Baulard
- Institut Pasteur de Lille, Center for Infection and Immunity, 59019 Lille, France
| | - Katarína Mikušová
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, Mlynská dolina, 84215 Bratislava, Slovakia
| | - Pedro M Alzari
- Institut Pasteur, Unité de Microbiologie Structurale, CNRS-UMR3528, Université Paris Diderot, Sorbonne Paris Cité, 25 rue du Dr. Roux, 75724 Paris Cedex 15, France
| | | | | | - Giovanna Riccardi
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, 27100 Pavia, Italy
| | - Stewart T Cole
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland.
| | - Maria Rosalia Pasca
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, 27100 Pavia, Italy.
| |
Collapse
|
29
|
Aughey GN, Grice SJ, Shen QJ, Xu Y, Chang CC, Azzam G, Wang PY, Freeman-Mills L, Pai LM, Sung LY, Yan J, Liu JL. Nucleotide synthesis is regulated by cytoophidium formation during neurodevelopment and adaptive metabolism. Biol Open 2014; 3:1045-56. [PMID: 25326513 PMCID: PMC4232762 DOI: 10.1242/bio.201410165] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The essential metabolic enzyme CTP synthase (CTPsyn) can be compartmentalised to form an evolutionarily-conserved intracellular structure termed the cytoophidium. Recently, it has been demonstrated that the enzymatic activity of CTPsyn is attenuated by incorporation into cytoophidia in bacteria and yeast cells. Here we demonstrate that CTPsyn is regulated in a similar manner in Drosophila tissues in vivo. We show that cytoophidium formation occurs during nutrient deprivation in cultured cells, as well as in quiescent and starved neuroblasts of the Drosophila larval central nervous system. We also show that cytoophidia formation is reversible during neurogenesis, indicating that filament formation regulates pyrimidine synthesis in a normal developmental context. Furthermore, our global metabolic profiling demonstrates that CTPsyn overexpression does not significantly alter CTPsyn-related enzymatic activity, suggesting that cytoophidium formation facilitates metabolic stabilisation. In addition, we show that overexpression of CTPsyn only results in moderate increase of CTP pool in human stable cell lines. Together, our study provides experimental evidence, and a mathematical model, for the hypothesis that inactive CTPsyn is incorporated into cytoophidia.
Collapse
Affiliation(s)
- Gabriel N Aughey
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Stuart J Grice
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Qing-Ji Shen
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Yichi Xu
- CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Chia-Chun Chang
- Institute of Biotechnology, National Taiwan University, Taipei 106, Taiwan, Republic of China
| | - Ghows Azzam
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Pei-Yu Wang
- Department of Biochemistry, College of Medicine, Chang Gung University, Tao-Yuan, 333, Taiwan, Republic of China Molecular Medicine Research Center, College of Medicine, Chang Gung University, Tao-Yuan 333, Taiwan, Republic of China
| | - Luke Freeman-Mills
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Li-Mei Pai
- Department of Biochemistry, College of Medicine, Chang Gung University, Tao-Yuan, 333, Taiwan, Republic of China Molecular Medicine Research Center, College of Medicine, Chang Gung University, Tao-Yuan 333, Taiwan, Republic of China Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan 333, Taiwan, Republic of China
| | - Li-Ying Sung
- Institute of Biotechnology, National Taiwan University, Taipei 106, Taiwan, Republic of China Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan, Republic of China
| | - Jun Yan
- CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Ji-Long Liu
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| |
Collapse
|
30
|
Calise SJ, Carcamo WC, Krueger C, Yin JD, Purich DL, Chan EKL. Glutamine deprivation initiates reversible assembly of mammalian rods and rings. Cell Mol Life Sci 2014; 71:2963-73. [PMID: 24477477 PMCID: PMC11113311 DOI: 10.1007/s00018-014-1567-6] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 12/21/2013] [Accepted: 01/16/2014] [Indexed: 02/06/2023]
Abstract
Rods and rings (RR) are protein assemblies composed of cytidine triphosphate synthetase type 1 (CTPS1) and inosine monophosphate dehydrogenase type 2 (IMPDH2), key enzymes in CTP and GTP biosynthesis. Small-molecule inhibitors of CTPS1 or IMPDH2 induce RR assembly in various cancer cell lines within 15 min to hours. Since glutamine is an essential amide nitrogen donor in these nucleotide biosynthetic pathways, glutamine deprivation was examined to determine whether it leads to RR formation. HeLa cells cultured in normal conditions did not show RR, but after culturing in media lacking glutamine, short rods (<2 μm) assembled after 24 h, and longer rods (>5 μm) formed after 48 h. Upon supplementation with glutamine or guanosine, these RR underwent almost complete disassembly within 15 min. Inhibition of glutamine synthetase with methionine sulfoximine also increased RR assembly in cells deprived of glutamine. Taken together, our data support the hypothesis that CTP/GTP biosynthetic enzymes polymerize to form RR in response to a decreased intracellular level of glutamine. We speculate that rod and ring formation is an adaptive metabolic response linked to disruption of glutamine homeostasis.
Collapse
Affiliation(s)
- S. John Calise
- Department of Oral Biology, University of Florida, 1395 Center Drive, Gainesville, FL 32610-0424 USA
| | - Wendy C. Carcamo
- Department of Oral Biology, University of Florida, 1395 Center Drive, Gainesville, FL 32610-0424 USA
| | - Claire Krueger
- Department of Oral Biology, University of Florida, 1395 Center Drive, Gainesville, FL 32610-0424 USA
| | - Joyce D. Yin
- Department of Oral Biology, University of Florida, 1395 Center Drive, Gainesville, FL 32610-0424 USA
| | - Daniel L. Purich
- Department of Biochemistry and Molecular Biology, University of Florida, 1600 SW Archer Rd., Gainesville, FL 32610-0245 USA
| | - Edward K. L. Chan
- Department of Oral Biology, University of Florida, 1395 Center Drive, Gainesville, FL 32610-0424 USA
| |
Collapse
|
31
|
Barry RM, Bitbol AF, Lorestani A, Charles EJ, Habrian CH, Hansen JM, Li HJ, Baldwin EP, Wingreen NS, Kollman JM, Gitai Z. Large-scale filament formation inhibits the activity of CTP synthetase. eLife 2014; 3:e03638. [PMID: 25030911 PMCID: PMC4126345 DOI: 10.7554/elife.03638] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
CTP Synthetase (CtpS) is a universally conserved and essential metabolic enzyme. While many enzymes form small oligomers, CtpS forms large-scale filamentous structures of unknown function in prokaryotes and eukaryotes. By simultaneously monitoring CtpS polymerization and enzymatic activity, we show that polymerization inhibits activity, and CtpS's product, CTP, induces assembly. To understand how assembly inhibits activity, we used electron microscopy to define the structure of CtpS polymers. This structure suggests that polymerization sterically hinders a conformational change necessary for CtpS activity. Structure-guided mutagenesis and mathematical modeling further indicate that coupling activity to polymerization promotes cooperative catalytic regulation. This previously uncharacterized regulatory mechanism is important for cellular function since a mutant that disrupts CtpS polymerization disrupts E. coli growth and metabolic regulation without reducing CTP levels. We propose that regulation by large-scale polymerization enables ultrasensitive control of enzymatic activity while storing an enzyme subpopulation in a conformationally restricted form that is readily activatable. DOI:http://dx.doi.org/10.7554/eLife.03638.001 Enzymes are proteins that perform reactions that can convert one or more chemicals (the substrates) into others (the products). The rate at which an enzyme produces its product is often carefully regulated. Some molecules slow or stop an enzyme by binding to and blocking the site where its substrates normally bind: its ‘active site’. Other molecules can also bind to sites other than the active site, which can cause the enzyme to become either more or less active. Almost all living things have an enzyme called CTP synthetase that makes one of the building blocks that is used to build DNA and a similar molecule called RNA. This enzyme converts a molecule called uridine triphosphate (or UTP) into another called cytidine triphosphate (CTP): a reaction that is powered by breaking down molecules of adenosine triphosphate (ATP). The amount of CTP synthetase made by a cell is carefully controlled. The enzyme's activity is also regulated by the levels of UTP and CTP, and by another molecule (called GTP) that binds to a site outside of its active site. Four copies of the CTP synthetase protein must work together before this enzyme can turn UTP into CTP. The enzyme also forms much larger aggregates, or polymers; however, it is not clear what causes these polymers to form, or what they do in a cell. Barry et al. have now discovered that CTP synthetase is almost completely inactivated when these polymers are formed. Furthermore, CTP encourages the polymers to form, whilst UTP and ATP cause them to disassemble. Therefore, this enzyme is least active when there is excess product in the cell, and most active when its substrates are plentiful. By determining the three-dimensional structure of a CTP synthetase polymer, Barry et al. reveal that although CTP is bound to the enzymes, their active sites are still freely accessible. However, the enzymes in the polymer appear to be locked into a shape that makes them unable to carry out their function. When Barry et al. then mutated the enzyme so that it was unable to form polymers it was also no longer inactivated in the same way by CTP. Bacterial cells with only these mutant versions of CTP synthetase are unable to properly control their levels of CTP. This suggests that polymer formation is important for regulating this enzyme in response to a build up of its product. Further work is needed to see whether the regulation of CTP synthetase activity by forming polymers is specific to this enzyme or a widespread mechanism that is used to control other enzymes too. DOI:http://dx.doi.org/10.7554/eLife.03638.002
Collapse
Affiliation(s)
- Rachael M Barry
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Anne-Florence Bitbol
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, United States
| | - Alexander Lorestani
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Emeric J Charles
- Department of Anatomy and Cell Biology, McGill University, Montreal, Canada
| | - Chris H Habrian
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
| | - Jesse M Hansen
- Department of Anatomy and Cell Biology, McGill University, Montreal, Canada
| | - Hsin-Jung Li
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Enoch P Baldwin
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
| | - Ned S Wingreen
- Department of Molecular Biology, Princeton University, Princeton, United States Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, United States
| | - Justin M Kollman
- Department of Anatomy and Cell Biology, McGill University, Montreal, Canada Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, Canada
| | - Zemer Gitai
- Department of Molecular Biology, Princeton University, Princeton, United States
| |
Collapse
|
32
|
Zhu M, Sun W, Wang Y, Meng J, Zhang D, Guo T, Ouyang P, Ying H, Xie J. Engineered cytidine triphosphate synthetase with reduced product inhibition. Protein Eng Des Sel 2014; 27:225-33. [PMID: 24902851 DOI: 10.1093/protein/gzu019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cytidine triphosphate (CTP) synthetase (CTPS) (EC number 6.3.4.2) is a key enzyme involved in de novo synthesis of CTP. It catalyzes the rate-limiting step of the process due to the product inhibition effects on the enzyme. In this study, a novel CTPS from Corynebacterium glutamicum ATCC 13032 (CgCTPS) was cloned, expressed and characterized. A series of mutagenesis in its N-terminal ammonia ligase (ALase) domain was performed in order to reduce CTP product inhibition. All single mutation variants (D160E, E162A, E168K) lowered product inhibition by lowering the enzyme's binding affinity for CTP. The homology model of CgCTPS showed that D160E mutant caused steric hindrance for the pyrimidine ring of CTP stacking, E162A disrupted the hydrogen bond between CTP ribose and side chain and D168K caused minor localized structure perturbations of CTP binding pocket. The triple mutant of CTPS (D160E-E162A-E168K) with halved Km, doubled Vmax and the 23.5-fold increased IC50 for CTP shows a potential for use in industrial-scale CTP production by its better performance in enzyme kinetics and product inhibition.
Collapse
Affiliation(s)
- Mengzhu Zhu
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Wujin Sun
- Joint Department of Biomedical Engineering, The University of North Carolina at Chapel Hill and North Carolina State University, Raleigh 27695, USA
| | - Yan Wang
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Jie Meng
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Dalu Zhang
- International Cooperation Division, China National Center for Biotechnology Development, Beijing 100036, People's Republic of China
| | - Ting Guo
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, Nanjing 211816, People's Republic of China Guangzhou Sugarcane Industry Research Institute, Guangzhou 510316, People's Republic of China
| | - Pingkai Ouyang
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Hanjie Ying
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Jingjing Xie
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, Nanjing 211816, People's Republic of China Present address: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, South Puzhu Road 30, Nanjing 211816, People's Republic of China
| |
Collapse
|
33
|
Affiliation(s)
- Artur Gora
- Loschmidt Laboratories,
Department
of Experimental Biology and Research Centre for Toxic Compounds in
the Environment, Faculty of Science, Masaryk University, Kamenice 5/A13, 625 00 Brno, Czech Republic
| | - Jan Brezovsky
- Loschmidt Laboratories,
Department
of Experimental Biology and Research Centre for Toxic Compounds in
the Environment, Faculty of Science, Masaryk University, Kamenice 5/A13, 625 00 Brno, Czech Republic
| | - Jiri Damborsky
- Loschmidt Laboratories,
Department
of Experimental Biology and Research Centre for Toxic Compounds in
the Environment, Faculty of Science, Masaryk University, Kamenice 5/A13, 625 00 Brno, Czech Republic
- International Centre for Clinical
Research, St. Anne’s University Hospital Brno, Pekarska 53, 656 91 Brno, Czech Republic
| |
Collapse
|
34
|
List F, Vega M, Razeto A, Häger M, Sterner R, Wilmanns M. Catalysis Uncoupling in a Glutamine Amidotransferase Bienzyme by Unblocking the Glutaminase Active Site. ACTA ACUST UNITED AC 2012; 19:1589-99. [DOI: 10.1016/j.chembiol.2012.10.012] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Revised: 10/02/2012] [Accepted: 10/11/2012] [Indexed: 11/30/2022]
|
35
|
Tanwar AS, Morar M, Panjikar S, Anand R. Formylglycinamide ribonucleotide amidotransferase from Salmonella typhimurium: role of ATP complexation and the glutaminase domain in catalytic coupling. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2012; 68:627-36. [PMID: 22683785 DOI: 10.1107/s0907444912006543] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2011] [Accepted: 02/14/2012] [Indexed: 11/10/2022]
Abstract
Formylglycinamide ribonucleotide (FGAR) amidotransferase (FGAR-AT) takes part in purine biosynthesis and is a multidomain enzyme with multiple spatially separated active sites. FGAR-AT contains a glutaminase domain that is responsible for the generation of ammonia from glutamine. Ammonia is then transferred via a channel to a second active site located in the synthetase domain and utilized to convert FGAR to formylglycinamidine ribonucleotide (FGAM) in an adenosine triphosphate (ATP) dependent reaction. In some ammonia-channelling enzymes ligand binding triggers interdomain signalling between the two diverse active centres and also assists in formation of the ammonia channel. Previously, the structure of FGAR-AT from Salmonella typhimurium containing a glutamyl thioester intermediate covalently bound in the glutaminase active site was determined. In this work, the roles played by various ligands of FGAR-AT in inducing catalytic coupling are investigated. Structures of FGAR-AT from S. typhimurium were determined in two different states: the unliganded form and the binary complex with an ATP analogue in the presence of the glutamyl thioester intermediate. The structures were compared in order to decipher the roles of these two states in interdomain communication. Using a process of elimination, the results indicated that binding of FGAR is most likely to be the major mechanism by which catalytic coupling occurs. This is because conformational changes do not occur either upon formation of the glutamyl thioester intermediate or upon subsequent ATP complexation. A model of the FGAR-bound form of the enzyme suggested that the loop in the synthetase domain may be responsible for initiating catalytic coupling via its interaction with the N-terminal domain.
Collapse
Affiliation(s)
- Ajay Singh Tanwar
- Department of Chemistry, Indian Institute of Technology, IIT-Bombay, Mumbai 400 076, India
| | | | | | | |
Collapse
|
36
|
Lauritsen I, Willemoës M, Jensen KF, Johansson E, Harris P. Structure of the dimeric form of CTP synthase from Sulfolobus solfataricus. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:201-8. [PMID: 21301086 PMCID: PMC3034608 DOI: 10.1107/s1744309110052334] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Accepted: 12/13/2010] [Indexed: 11/10/2022]
Abstract
CTP synthase catalyzes the last committed step in de novo pyrimidine-nucleotide biosynthesis. Active CTP synthase is a tetrameric enzyme composed of a dimer of dimers. The tetramer is favoured in the presence of the substrate nucleotides ATP and UTP; when saturated with nucleotide, the tetramer completely dominates the oligomeric state of the enzyme. Furthermore, phosphorylation has been shown to regulate the oligomeric states of the enzymes from yeast and human. The crystal structure of a dimeric form of CTP synthase from Sulfolobus solfataricus has been determined at 2.5 Å resolution. A comparison of the dimeric interface with the intermolecular interfaces in the tetrameric structures of Thermus thermophilus CTP synthase and Escherichia coli CTP synthase shows that the dimeric interfaces are almost identical in the three systems. Residues that are involved in the tetramerization of S. solfataricus CTP synthase according to a structural alignment with the E. coli enzyme all have large thermal parameters in the dimeric form. Furthermore, they are seen to undergo substantial movement upon tetramerization.
Collapse
Affiliation(s)
- Iben Lauritsen
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark
| | - Martin Willemoës
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark
| | - Kaj Frank Jensen
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark
| | - Eva Johansson
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
- Diabetes Protein Engineering, Novo Nordisk A/S, Novo Nordisk Park, DK-2760 Måløv, Denmark
| | - Pernille Harris
- Department of Chemistry, Technical University of Denmark, Kemitorvet, Building 207, DK-2800 Kgs. Lyngby, Denmark
| |
Collapse
|
37
|
Liu JL. The enigmatic cytoophidium: compartmentation of CTP synthase via filament formation. Bioessays 2011; 33:159-64. [PMID: 21254152 DOI: 10.1002/bies.201000129] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Ji-Long Liu
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, UK.
| |
Collapse
|
38
|
Kassel KM, Au DR, Higgins MJ, Hines M, Graves LM. Regulation of human cytidine triphosphate synthetase 2 by phosphorylation. J Biol Chem 2010; 285:33727-36. [PMID: 20739275 DOI: 10.1074/jbc.m110.178566] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytidine triphosphate synthetase (CTPS) is the rate-limiting enzyme in de novo CTP synthesis and is required for the formation of RNA, DNA, and phospholipids. This study determined the kinetic properties of the individual human CTPS isozymes (hCTPS1 and hCTPS2) and regulation through substrate concentration, oligomerization, and phosphorylation. Kinetic analysis demonstrated that both hCTPS1 and hCTPS2 were maximally active at physiological concentrations of ATP, GTP, and glutamine, whereas the K(m) and IC(50) values for the substrate UTP and the product CTP, respectively, were close to their physiological concentrations, indicating that the intracellular concentrations of UTP and CTP may precisely regulate hCTPS activity. Low serum treatment increased hCTPS2 phosphorylation, and five probable phosphorylation sites were identified in the hCTPS2 C-terminal domain. Metabolic labeling of hCTPS2 with [(32)P]H(3)PO(4) demonstrated that Ser(568) and Ser(571) were two major phosphorylation sites, and additional studies demonstrated that Ser(568) was phosphorylated by casein kinase 1 both in vitro and in vivo. Interestingly, mutation of Ser(568) (S568A) but not Ser(571) significantly increased hCTPS2 activity, demonstrating that Ser(568) is a major inhibitory phosphorylation site. The S568A mutation had a greater effect on the glutamine than ammonia-dependent activity, indicating that phosphorylation of this site may influence the glutaminase domain of hCTPS2. Deletion of the C-terminal regulatory domain of hCTPS1 also greatly increased the V(max) of this enzyme. In summary, this is the first study to characterize the kinetic properties of hCTPS1 and hCTPS2 and to identify Ser(568) as a major site of CTPS2 regulation by phosphorylation.
Collapse
Affiliation(s)
- Karen M Kassel
- Department of Pharmacology, University of North Carolina at Chapel Hill, North Carolina 27599, USA
| | | | | | | | | |
Collapse
|
39
|
Morar M, Hoskins AA, Stubbe J, Ealick SE. Formylglycinamide ribonucleotide amidotransferase from Thermotoga maritima: structural insights into complex formation. Biochemistry 2008; 47:7816-30. [PMID: 18597481 PMCID: PMC2646663 DOI: 10.1021/bi800329p] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In the fourth step of the purine biosynthetic pathway, formyl glycinamide ribonucleotide (FGAR) amidotransferase, also known as PurL, catalyzes the conversion of FGAR, ATP, and glutamine to formyl glycinamidine ribonucleotide (FGAM), ADP, P i, and glutamate. Two forms of PurL have been characterized, large and small. Large PurL, present in most Gram-negative bacteria and eukaryotes, consists of a single polypeptide chain and contains three major domains: the N-terminal domain, the FGAM synthetase domain, and the glutaminase domain, with a putative ammonia channel located between the active sites of the latter two. Small PurL, present in Gram-positive bacteria and archaea, is structurally homologous to the FGAM synthetase domain of large PurL, and forms a complex with two additional gene products, PurQ and PurS. The structure of the PurS dimer is homologous with the N-terminal domain of large PurL, while PurQ, whose structure has not been reported, contains the glutaminase activity. In Bacillus subtilis, the formation of the PurLQS complex is dependent on glutamine and ADP and has been demonstrated by size-exclusion chromatography. In this work, a structure of the PurLQS complex from Thermotoga maritima is described revealing a 2:1:1 stoichiometry of PurS:Q:L, respectively. The conformational changes observed in TmPurL upon complex formation elucidate the mechanism of metabolite-mediated recruitment of PurQ and PurS. The flexibility of the PurS dimer is proposed to play a role in the activation of the complex and the formation of the ammonia channel. A potential path for the ammonia channel is identified.
Collapse
Affiliation(s)
- Mariya Morar
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | | | | | | |
Collapse
|
40
|
Mutational analysis of conserved glycine residues 142, 143 and 146 reveals Gly(142) is critical for tetramerization of CTP synthase from Escherichia coli. Biochem J 2008; 412:113-21. [PMID: 18260824 DOI: 10.1042/bj20071163] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
CTPS (cytidine 5'-triphosphate synthase) catalyses the ATP-dependent formation of CTP from UTP using either ammonia or L-glutamine as the nitrogen source. Binding of the substrates ATP and UTP, or the product CTP, promotes oligomerization of CTPS from inactive dimers to active tetramers. In the present study, site-directed mutagenesis was used to replace the fully conserved glycine residues 142 and 143 within the UTP-binding site and 146 within the CTP-binding site of Escherchia coli CTPS. CD spectral analyses of wild-type CTPS and the glycine mutants showed a slight reduction of approximately 15% in alpha-helical content for G142A and G143A relative to G146A and wild-type CTPS, suggesting some local alterations in structure. Relative to wild-type CTPS, the values of k(cat)/K(m) for ammonia-dependent and glutamine-dependent CTP formation catalysed by G143A were reduced 22- and 16-fold respectively, whereas the corresponding values for G146A were reduced only 1.4- and 1.8-fold respectively. The glutaminase activity (k(cat)) of G146A was similar to that exhibited by the wild-type enzyme, whereas that of G143A was reduced 7.5-fold. G146A exhibited substrate inhibition at high concentrations of ammonia and a partial uncoupling of glutamine hydrolysis from CTP production. Although the apparent affinity (1/[S](0.5)) of G143A and G146A for UTP was reduced approximately 4-fold, G146A exhibited increased co-operativity with respect to UTP. Thus mutations in the CTP-binding site can affect UTP-dependent activity. Surprisingly, G142A was inactive with both ammonia and glutamine as substrates. Gel-filtration HPLC experiments revealed that both G143A and G146A were able to form active tetramers in the presence of ATP and UTP; however, nucleotide-dependent tetramerization of G142A was significantly impaired. Our observations highlight the sensitivity of the structure of CTPS to mutations in the UTP- and CTP-binding sites, with Gly(142) being critical for nucleotide-dependent oligomerization of CTPS to active tetramers. This 'structural sensitivity' may limit the number and/or types of mutations that could be selected for during the development of resistance to cytotoxic pyrimidine nucleotide analogues.
Collapse
|
41
|
Chang YF, Carman GM. CTP synthetase and its role in phospholipid synthesis in the yeast Saccharomyces cerevisiae. Prog Lipid Res 2008; 47:333-9. [PMID: 18439916 DOI: 10.1016/j.plipres.2008.03.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
CTP synthetase is a cytosolic-associated glutamine amidotransferase enzyme that catalyzes the ATP-dependent transfer of the amide nitrogen from glutamine to the C-4 position of UTP to form CTP. In the yeast Saccharomyces cerevisiae, the reaction product CTP is an essential precursor of all membrane phospholipids that are synthesized via the Kennedy (CDP-choline and CDP-ethanolamine branches) and CDP-diacylglycerol pathways. The URA7 and URA8 genes encode CTP synthetase in S. cerevisiae, and the URA7 gene is responsible for the majority of CTP synthesized in vivo. The CTP synthetase enzymes are allosterically regulated by CTP product inhibition. Mutations that alleviate this regulation result in an elevated cellular level of CTP and an increase in phospholipid synthesis via the Kennedy pathway. The URA7-encoded enzyme is phosphorylated by protein kinases A and C, and these phosphorylations stimulate CTP synthetase activity and increase cellular CTP levels and the utilization of the Kennedy pathway. The CTPS1 and CTPS2 genes that encode human CTP synthetase enzymes are functionally expressed in S. cerevisiae, and rescue the lethal phenotype of the ura7Deltaura8Delta double mutant that lacks CTP synthetase activity. The expression in yeast has revealed that the human CTPS1-encoded enzyme is also phosphorylated and regulated by protein kinases A and C.
Collapse
Affiliation(s)
- Yu-Fang Chang
- Department of Food Science, Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, United States
| | | |
Collapse
|
42
|
Lunn FA, MacDonnell JE, Bearne SL. Structural requirements for the activation of Escherichia coli CTP synthase by the allosteric effector GTP are stringent, but requirements for inhibition are lax. J Biol Chem 2007; 283:2010-20. [PMID: 18003612 DOI: 10.1074/jbc.m707803200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Cytidine 5'-triphosphate synthase catalyzes the ATP-dependent formation of CTP from UTP using either NH(3) or l-glutamine (Gln) as the source of nitrogen. GTP acts as an allosteric effector promoting Gln hydrolysis but inhibiting Gln-dependent CTP formation at concentrations of >0.15 mM and NH(3)-dependent CTP formation at all concentrations. A structure-activity study using a variety of GTP and guanosine analogues revealed that only a few GTP analogues were capable of activating Gln-dependent CTP formation to varying degrees: GTP approximately 6-thio-GTP > ITP approximately guanosine 5'-tetraphosphate > O(6)-methyl-GTP > 2'-deoxy-GTP. No activation was observed with guanosine, GMP, GDP, 2',3'-dideoxy-GTP, acycloguanosine, and acycloguanosine monophosphate, indicating that the 5'-triphosphate, 2'-OH, and 3'-OH are required for full activation. The 2-NH(2) group plays an important role in binding recognition, whereas substituents at the 6-position play an important role in activation. The presence of a 6-NH(2) group obviates activation, consistent with the inability of ATP to substitute for GTP. Nucleotide and nucleoside analogues of GTP and guanosine, respectively, all inhibited NH(3)- and Gln-dependent CTP formation (often in a cooperative manner) to a similar extent (IC(50) approximately 0.2-0.5 mM). This inhibition appeared to be due solely to the purine base and was relatively insensitive to the identity of the purine with the exception of inosine, ITP, and adenosine (IC(50) approximately 4-12 mM). 8-Oxoguanosine was the best inhibitor identified (IC(50) = 80 microM). Our findings suggest that modifying 2-aminopurine or 2-aminopurine riboside may serve as an effective strategy for developing cytidine 5'-triphosphate synthase inhibitors.
Collapse
Affiliation(s)
- Faylene A Lunn
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada
| | | | | |
Collapse
|
43
|
Mouilleron S, Golinelli-Pimpaneau B. Conformational changes in ammonia-channeling glutamine amidotransferases. Curr Opin Struct Biol 2007; 17:653-64. [PMID: 17951049 DOI: 10.1016/j.sbi.2007.09.003] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Revised: 09/04/2007] [Accepted: 09/06/2007] [Indexed: 11/28/2022]
Abstract
Glutamine amidotransferases (GATs), which catalyze the synthesis of different aminated products, channel ammonia over 10-40 A from a glutamine substrate at the glutaminase site to an acceptor substrate at the synthase site. Ammonia production usually uses a cysteine-histidine-glutamate triad or a N-terminal cysteine residue. Crystal structures of several amidotransferase ligand complexes, mimicking intermediates along the catalytic cycle, have now been determined. In most cases, acceptor binding triggers glutaminase activation through domain-hinged movements and other conformational changes. Structural information shows how flexible loops of the synthase and glutaminase domains move to shield the two catalytic sites and anchor the substrates, and how the ammonia channel forms and opens or closes.
Collapse
Affiliation(s)
- Stéphane Mouilleron
- Laboratoire d'Enzymologie et Biochimie structurales, CNRS Bâtiment 34, 1 avenue de la Terrasse, 91190 Gif-sur-Yvette, France
| | | |
Collapse
|
44
|
Higgins MJ, Graves PR, Graves LM. Regulation of Human Cytidine Triphosphate Synthetase 1 by Glycogen Synthase Kinase 3. J Biol Chem 2007; 282:29493-503. [PMID: 17681942 DOI: 10.1074/jbc.m703948200] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytidine triphosphate synthetase (CTPS) catalyzes the rate-limiting step in the de novo synthesis of CTP, and both the yeast and human enzymes have been reported to be regulated by protein kinase A or protein kinase C phosphorylation. Here, we provide evidence that stimulation or inhibition of protein kinase A and protein kinase C does not alter the phosphorylation of endogenous human CTPS1 in human embryonic kidney 293 cells under the conditions tested. Unexpectedly, we found that low serum conditions increased phosphorylation of endogenous CTPS1 and this phosphorylation was inhibited by the glycogen synthase kinase 3 (GSK3) inhibitor indirubin-3'-monoxime and GSK3beta short interfering RNAs, demonstrating the involvement of GSK3 in phosphorylation of endogenous human CTPS1. Separating tryptic peptides from [(32)P]orthophosphate-labeled cells and analyzing the phosphopeptides by mass spectrometry identified Ser-574 and Ser-575 as phosphorylated residues. Mutation of Ser-571 demonstrated that Ser-571 was the major site phosphorylated by GSK3 in intact human embryonic kidney 293 cells by GSK3 in vitro. Furthermore, mutation of Ser-575 prevented the phosphorylation of Ser-571, suggesting that phosphorylation of Ser-575 was necessary for priming the GSK3 phosphorylation of Ser-571. Low serum was found to decrease CTPS1 activity, and incubation with the GSK3 inhibitor indirubin-3'-monoxime protected against this decrease in activity. Incubation with an alkaline phosphatase increased CTPS1 activity in a time-dependent manner, demonstrating that phosphorylation inhibits CTPS1 activity. This is the first study to investigate the phosphorylation and regulation of human CTPS1 in human cells and suggests that GSK3 is a novel regulator of CTPS activity.
Collapse
Affiliation(s)
- Matthew J Higgins
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7365, USA
| | | | | |
Collapse
|
45
|
Braun O, Knipp M, Chesnov S, Vasák M. Specific reactions of S-nitrosothiols with cysteine hydrolases: A comparative study between dimethylargininase-1 and CTP synthetase. Protein Sci 2007; 16:1522-34. [PMID: 17600152 PMCID: PMC2203367 DOI: 10.1110/ps.062718507] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
S-Transnitrosation is an important bioregulatory process whereby NO(+) equivalents are transferred between S-nitrosothiols and Cys of target proteins. This reaction proceeds through a common intermediate R-S-N(O(-))-S-R' and it has been proposed that products different from S-nitrosothiols may be formed in protein cavities. Recently, we have reported on the formation of such a product, an N-thiosulfoximide, at the active site of the Cys hydrolase dimethylargininase-1 (DDAH-1) upon reaction with S-nitroso-l-homocysteine (HcyNO). Here we have addressed the question of whether this novel product can also be formed with the endogenously occurring S-nitrosothiols S-nitroso-l-cysteine (CysNO) and S-nitrosoglutathione (GSNO). Further, to explore the reason responsible for the unique formation of an N-thiosulfoximide in DDAH-1 we have expanded these studies to cytidine triphosphate synthetase (CTPS), which shows a similar active site architecture. ESI-MS and activity measurements showed that the bulky GSNO does not react with both enzymes. In contrast, S-nitrosylation of the active site Cys occurred in DDAH-1 with CysNO and in CTPS with CysNO and HcyNO. Although kinetic analysis indicated that these compounds act as specific irreversible inhibitors, no N-thiosulfoximide was formed. The reasons likely responsible for the absence of the N-thiosulfoximide formation are discussed using molecular models of DDAH-1 and CTPS. In tissue extracts DDAH was inhibited only by HcyNO, with an IC(50) value similar to that of the isolated protein. Biological implications of these studies for the function of both enzymes are discussed.
Collapse
Affiliation(s)
- Oliver Braun
- Department of Biochemistry, University of Zürich, CH-8057 Zürich, Switzerland
| | | | | | | |
Collapse
|
46
|
Chang YF, Martin SS, Baldwin EP, Carman GM. Phosphorylation of human CTP synthetase 1 by protein kinase C: identification of Ser(462) and Thr(455) as major sites of phosphorylation. J Biol Chem 2007; 282:17613-22. [PMID: 17463002 PMCID: PMC2081159 DOI: 10.1074/jbc.m702799200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phosphorylation of human CTP synthetase 1 by mammalian protein kinase C was examined. Using purified Escherichia coli-expressed CTP synthetase 1 as a substrate, protein kinase C activity was time- and dose-dependent and dependent on the concentrations of ATP and CTP synthetase 1. The protein kinase C phosphorylation of the recombinant enzyme was accompanied by a 95-fold increase in CTP synthetase 1 activity. Phosphopeptide mapping and phosphoamino acid analyses showed that CTP synthetase 1 was phosphorylated on multiple serine and threonine residues. The induction of PKC1(R398A)-encoded protein kinase C resulted in a 50% increase for human CTP synthetase 1 phosphorylation in the Saccharomyces cerevisiae ura7Delta ura8Delta mutant lacking yeast CTP synthetase activity. Synthetic peptides that contain the protein kinase C motif for Ser(462) and Thr(455) were substrates for mammalian protein kinase C, and S462A and T455A mutations resulted in decreases in the extent of CTP synthetase 1 phosphorylation that occurred in vivo. Phosphopeptide mapping analysis of S. cerevisiae-expressed CTP synthetase 1 mutant enzymes phosphorylated with mammalian protein kinase C confirmed that Ser(462) and Thr(455) were phosphorylation sites. The S. cerevisiae-expressed and purified S462A mutant enzyme exhibited a 2-fold reduction in CTP synthetase 1 activity, whereas the purified T455A mutant enzyme exhibited a 2-fold elevation in CTP synthetase 1 activity (Choi, M.-G., and Carman, G.M. (2006) J. Biol. Chem. 282, 5367-5377). These data indicated that protein kinase C phosphorylation at Ser(462) stimulates human CTP synthetase 1 activity, whereas phosphorylation at Thr(455) inhibits activity.
Collapse
Affiliation(s)
- Yu-Fang Chang
- Department of Food Science, Rutgers University, New Brunswick, New Jersey 08901
| | - Shelley S. Martin
- Departments of Molecular and Cellular Biology and Chemistry, University of California, Davis, California 95616
| | - Enoch P. Baldwin
- Departments of Molecular and Cellular Biology and Chemistry, University of California, Davis, California 95616
| | - George M. Carman
- Department of Food Science, Rutgers University, New Brunswick, New Jersey 08901
- To whom correspondence should be addressed. Dept of Food Science, Rutgers University, 65 Dudley Rd., New Brunswick, NJ 08901. Tel: 732-932-9611 (ext. 217); E-mail:
| |
Collapse
|
47
|
Fijolek A, Hofer A, Thelander L. Expression, purification, characterization, and in vivo targeting of trypanosome CTP synthetase for treatment of African sleeping sickness. J Biol Chem 2007; 282:11858-65. [PMID: 17331943 DOI: 10.1074/jbc.m611580200] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
African sleeping sickness is a fatal disease caused by two parasite subspecies: Trypanosoma brucei gambiense and T. b. rhodesiense. We previously reported that trypanosomes have extraordinary low CTP pools compared with mammalian cells. Trypanosomes also lack salvage of cytidine/cytosine making the parasite CTP synthetase a potential target for treatment of the disease. In this study, we have expressed and purified recombinant T. brucei CTP synthetase. The enzyme has a higher K(m) value for UTP than the mammalian CTP synthetase, which in combination with a lower UTP pool may account for the low CTP pool in trypanosomes. The activity of the trypanosome CTP synthetase is irreversibly inhibited by the glutamine analogue acivicin, a drug extensively tested as an antitumor agent. There is a rapid uptake of acivicin in mice both given intraperitoneally and orally by gavage. Daily injection of acivicin in trypanosome-infected mice suppressed the infection up to one month without any significant loss of weight. Experiments with cultured bloodstream T. brucei showed that acivicin is trypanocidal if present at 1 mum concentration for at least 4 days. Therefore, acivicin may qualify as a drug with "desirable" properties, i.e. cure within 7 days, according to the current Target Product Profiles of WHO and DNDi.
Collapse
Affiliation(s)
- Artur Fijolek
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå, Sweden.
| | | | | |
Collapse
|
48
|
Choi MG, Carman GM. Phosphorylation of human CTP synthetase 1 by protein kinase A: identification of Thr455 as a major site of phosphorylation. J Biol Chem 2006; 282:5367-77. [PMID: 17189248 PMCID: PMC2014738 DOI: 10.1074/jbc.m610993200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CTP synthetase is an essential enzyme that generates the CTP required for the synthesis of nucleic acids and membrane phospholipids. In this study, we examined the phosphorylation of the human CTPS1-encoded CTP synthetase 1 by protein kinase A. CTP synthetase 1 was expressed and purified from a Saccharomyces cerevisiae ura7Delta ura8Delta double mutant that lacks CTP synthetase activity. Using purified CTP synthetase 1 as a substrate, protein kinase A activity was time- and dose-dependent. The phosphorylation, which primarily occurred on a threonine residue, was accompanied by a 50% decrease in CTP synthetase 1 activity. The synthetic peptide LGKRRTLFQT that contains the protein kinase A motif for Thr(455) was a substrate for protein kinase A. A Thr(455) to Ala (T455A) mutation in CTP synthetase 1 was constructed by site-directed mutagenesis and was expressed and purified from the S. cerevisiae ura7Delta ura8Delta mutant. The T455A mutation caused a 78% decrease in protein kinase A phosphorylation and the loss of the phosphothreonine residue and a major phosphopeptide that were present in the purified wild type enzyme phosphorylated by protein kinase A. The CTP synthetase 1 activity of the T455A mutant enzyme was 2-fold higher than the wild type enzyme. In addition, the T455A mutation caused a 44% decrease in the amount of human CTP synthetase 1 that was phosphorylated in S. cerevisiae cells, and this was accompanied by a 2.5-fold increase in the cellular concentration of CTP and a 1.5-fold increase in the choline-dependent synthesis of phosphatidylcholine.
Collapse
Affiliation(s)
| | - George M. Carman
- To whom correspondence should be addressed. Dept of Food Science, Rutgers University, 65 Dudley Rd., New Brunswick, NJ 08901. Tel: 732-932-9611 (ext. 217); E-mail:
| |
Collapse
|
49
|
Yoshimune K, Shirakihara Y, Shiratori A, Wakayama M, Chantawannakul P, Moriguchi M. Crystal structure of a major fragment of the salt-tolerant glutaminase from Micrococcus luteus K-3. Biochem Biophys Res Commun 2006; 346:1118-24. [PMID: 16793004 DOI: 10.1016/j.bbrc.2006.04.188] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2006] [Accepted: 04/26/2006] [Indexed: 10/24/2022]
Abstract
Glutaminase of Micrococcus luteus K-3 (intact glutaminase; 48kDa) is digested to a C-terminally truncated fragment (glutaminase fragment; 42kDa) that shows higher salt tolerance than that of the intact glutaminase. The crystal structure of the glutaminase fragment was determined at 2.4A resolution using multiple-wavelength anomalous dispersion (MAD). The glutaminase fragment is composed of N-terminal and C-terminal domains, and a putative catalytic serine-lysine dyad (S64 and K67) is located in a cleft of the N-terminal domain. Mutations of the S64 or K67 residues abolished the enzyme activity. The N-terminal domain has abundant glutamic acid residues on its surface, which may explain its salt-tolerant mechanism. A diffraction analysis of the intact glutaminase crystals (a twinning fraction of 0.43) located the glutaminase fragment in the unit cell but failed to turn up clear densities for the missing C-terminal portion of the molecule.
Collapse
Affiliation(s)
- Kazuaki Yoshimune
- Research Institute of Genome-based Biofactory, National Institute of Advanced Industrial Science and Technology (AIST), Tsukisamu-Higashi 2-17-2-1, Toyohira-ku, Sapporo 062-8517, Japan.
| | | | | | | | | | | |
Collapse
|
50
|
Endrizzi JA, Kim H, Anderson PM, Baldwin EP. Mechanisms of product feedback regulation and drug resistance in cytidine triphosphate synthetases from the structure of a CTP-inhibited complex. Biochemistry 2006; 44:13491-9. [PMID: 16216072 PMCID: PMC2891682 DOI: 10.1021/bi051282o] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cytidine triphosphate synthetases (CTPSs) synthesize CTP and regulate its intracellular concentration through direct interactions with the four ribonucleotide triphosphates. In particular, CTP product is a feedback inhibitor that competes with UTP substrate. Selected CTPS mutations that impart resistance to pyrimidine antimetabolite inhibitors also relieve CTP inhibition and cause a dramatic increase in intracellular CTP concentration, indicating that the drugs act by binding to the CTP inhibitory site. Resistance mutations map to a pocket that, although adjacent, does not coincide with the expected UTP binding site in apo Escherichia coli CTPS [EcCTPS; Endrizzi, J. A., et al. (2004) Biochemistry 43, 6447-6463], suggesting allosteric rather than competitive inhibition. Here, bound CTP and ADP were visualized in catalytically active EcCTPS crystals soaked in either ATP and UTP substrates or ADP and CTP products. The CTP cytosine ring resides in the pocket predicted by the resistance mutations, while the triphosphate moiety overlaps the putative UTP triphosphate binding site, explaining how CTP competes with UTP while CTP resistance mutations are acquired without loss of catalytic efficiency. Extensive complementarity and interaction networks at the interfacial binding sites provide the high specificity for pyrimidine triphosphates and mediate nucleotide-dependent tetramer formation. Overall, these results depict a novel product inhibition strategy in which shared substrate and product moieties bind to a single subsite while specificity is conferred by separate subsites. This arrangement allows for independent adaptation of UTP and CTP binding affinities while efficiently utilizing the enzyme surface.
Collapse
Affiliation(s)
| | | | | | - Enoch P. Baldwin
- To whom correspondence should be addressed. . Phone: (530) 752-1108. Fax: (530) 752-3085
| |
Collapse
|