1
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Guo C, Wang Z, Liu J. Filamentation and inhibition of prokaryotic CTP synthase with ligands. MLIFE 2024; 3:240-250. [PMID: 38948148 PMCID: PMC11211670 DOI: 10.1002/mlf2.12119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 01/18/2024] [Accepted: 02/06/2024] [Indexed: 07/02/2024]
Abstract
Cytidine triphosphate synthase (CTPS) plays a pivotal role in the de novo synthesis of cytidine triphosphate (CTP), a fundamental building block for RNA and DNA that is essential for life. CTPS is capable of directly binding to all four nucleotide triphosphates: adenine triphosphate, uridine triphosphate, CTP, and guanidine triphosphate. Furthermore, CTPS can form cytoophidia in vivo and metabolic filaments in vitro, undergoing regulation at multiple levels. CTPS is considered a potential therapeutic target for combating invasions or infections by viral or prokaryotic pathogens. Utilizing cryo-electron microscopy, we determined the structure of Escherichia coli CTPS (ecCTPS) filament in complex with CTP, nicotinamide adenine dinucleotide (NADH), and the covalent inhibitor 6-diazo-5-oxo- l-norleucine (DON), achieving a resolution of 2.9 Å. We constructed a phylogenetic tree based on differences in filament-forming interfaces and designed a variant to validate our hypothesis, providing an evolutionary perspective on CTPS filament formation. Our computational analysis revealed a solvent-accessible ammonia tunnel upon DON binding. Through comparative structural analysis, we discern a distinct mode of CTP binding of ecCTPS that differs from eukaryotic counterparts. Combining biochemical assays and structural analysis, we determined and validated the synergistic inhibitory effects of CTP with NADH or adenine on CTPS. Our results expand our comprehension of the diverse regulatory aspects of CTPS and lay a foundation for the design of specific inhibitors targeting prokaryotic CTPS.
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Affiliation(s)
- Chenjun Guo
- School of Life Science and TechnologyShanghaiTech UniversityShanghaiChina
| | - Zixuan Wang
- School of Life Science and TechnologyShanghaiTech UniversityShanghaiChina
| | - Ji‐Long Liu
- School of Life Science and TechnologyShanghaiTech UniversityShanghaiChina
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
- Shanghai Clinical Research and Trial CenterShanghaiChina
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2
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Calise SJ, O’Neill AG, Burrell AL, Dickinson MS, Molfino J, Clarke C, Quispe J, Sokolov D, Buey RM, Kollman JM. Light-sensitive phosphorylation regulates retinal IMPDH1 activity and filament assembly. J Cell Biol 2024; 223:e202310139. [PMID: 38323936 PMCID: PMC10849882 DOI: 10.1083/jcb.202310139] [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: 10/27/2023] [Revised: 01/11/2024] [Accepted: 01/23/2024] [Indexed: 02/08/2024] Open
Abstract
Inosine monophosphate dehydrogenase (IMPDH) is the rate-limiting enzyme in guanosine triphosphate (GTP) synthesis and assembles into filaments in cells, which desensitizes the enzyme to feedback inhibition and boosts nucleotide production. The vertebrate retina expresses two splice variants IMPDH1(546) and IMPDH1(595). In bovine retinas, residue S477 is preferentially phosphorylated in the dark, but the effects on IMPDH1 activity and regulation are unclear. Here, we generated phosphomimetic mutants to investigate structural and functional consequences of S477 phosphorylation. The S477D mutation resensitized both variants to GTP inhibition but only blocked assembly of IMPDH1(595) filaments. Cryo-EM structures of both variants showed that S477D specifically blocks assembly of a high-activity assembly interface, still allowing assembly of low-activity IMPDH1(546) filaments. Finally, we discovered that S477D exerts a dominant-negative effect in cells, preventing endogenous IMPDH filament assembly. By modulating the structure and higher-order assembly of IMPDH, S477 phosphorylation acts as a mechanism for downregulating retinal GTP synthesis in the dark when nucleotide turnover is decreased.
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Affiliation(s)
- S. John Calise
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Audrey G. O’Neill
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Anika L. Burrell
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | | | - Josephine Molfino
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Charlie Clarke
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Joel Quispe
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - David Sokolov
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Rubén M. Buey
- Metabolic Engineering Group, Departamento de Microbiología y Genética, Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain
| | - Justin M. Kollman
- Department of Biochemistry, University of Washington, Seattle, WA, USA
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3
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Lynch EM, Hansen H, Salay L, Cooper M, Timr S, Kollman JM, Webb BA. Structural basis for allosteric regulation of human phosphofructokinase-1. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.15.585110. [PMID: 38559074 PMCID: PMC10980016 DOI: 10.1101/2024.03.15.585110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Phosphofructokinase-1 (PFK1) catalyzes the rate-limiting step of glycolysis, committing glucose to conversion into cellular energy. PFK1 is highly regulated to respond to the changing energy needs of the cell. In bacteria, the structural basis of PFK1 regulation is a textbook example of allostery; molecular signals of low and high cellular energy promote transition between an active R-state and inactive T-state conformation, respectively Little is known, however, about the structural basis for regulation of eukaryotic PFK1. Here, we determine structures of the human liver isoform of PFK1 (PFKL) in the R- and T-state by cryoEM, providing insight into eukaryotic PFK1 allosteric regulatory mechanisms. The T-state structure reveals conformational differences between the bacterial and eukaryotic enzyme, the mechanisms of allosteric inhibition by ATP binding at multiple sites, and an autoinhibitory role of the C-terminus in stabilizing the T-state. We also determine structures of PFKL filaments that define the mechanism of higher-order assembly and demonstrate that these structures are necessary for higher-order assembly of PFKL in cells.
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Affiliation(s)
- Eric M Lynch
- Department of Biochemistry, University of Washington
| | - Heather Hansen
- Department of Biochemistry and Molecular Medicine, West Virginia University
| | - Lauren Salay
- Department of Biochemistry, University of Washington
| | - Madison Cooper
- Department of Biochemistry and Molecular Medicine, West Virginia University
| | - Stepan Timr
- Department of Computational Chemistry, J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences
| | | | - Bradley A Webb
- Department of Biochemistry and Molecular Medicine, West Virginia University
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4
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Ghadirian N, Morgan RD, Horton NC. DNA Sequence Control of Enzyme Filamentation and Activation of the SgrAI Endonuclease. Biochemistry 2024; 63:326-338. [PMID: 38207281 DOI: 10.1021/acs.biochem.3c00313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2024]
Abstract
Enzyme polymerization (also known as filamentation) has emerged as a new layer of enzyme regulation. SgrAI is a sequence-dependent DNA endonuclease that forms polymeric filaments with enhanced DNA cleavage activity as well as altered DNA sequence specificity. To better understand this unusual regulatory mechanism, full global kinetic modeling of the reaction pathway, including the enzyme filamentation steps, has been undertaken. Prior work with the primary DNA recognition sequence cleaved by SgrAI has shown how the kinetic rate constants of each reaction step are tuned to maximize activation and DNA cleavage while minimizing the extent of DNA cleavage to the host genome. In the current work, we expand on our prior study by now including DNA cleavage of a secondary recognition sequence, to understand how the sequence of the bound DNA modulates filamentation and activation of SgrAI. The work shows that an allosteric equilibrium between low and high activity states is modulated by the sequence of bound DNA, with primary sequences more prone to activation and filament formation, while SgrAI bound to secondary recognition sequences favor the low (and nonfilamenting) state by up to 40-fold. In addition, the degree of methylation of secondary sequences in the host organism, Streptomyces griseus, is now reported for the first time and shows that as predicted, these sequences are left unprotected from the SgrAI endonuclease making sequence specificity critical in this unusual filament-forming enzyme.
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Affiliation(s)
- Niloofar Ghadirian
- Department of Chemistry & Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Richard D Morgan
- New England Biolabs, Inc., Ipswich, Massachusetts 01938, United States
| | - Nancy C Horton
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721, United States
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5
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Chang J, Yuan W, Gao C, Zhang B, Liu JL, Chen G, Tan YW. Single-Molecule Fluorescence Imaging Reveals Coassembly of CTPS and P5CS. J Phys Chem B 2024; 128:949-959. [PMID: 38236746 DOI: 10.1021/acs.jpcb.3c06498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2024]
Abstract
The cellular compartmentation induced by self-assembly of natural proteins has recently attracted widespread attention due to its structural-functional significance. Among them, as a highly conserved metabolic enzyme and one of the potential targets for cancers and parasitic diseases in drug development, CTP synthase (CTPS) has also been reported to self-assemble into filamentous structures termed cytoophidia. To elucidate the dynamical mechanism of cytoophidium filamentation, we utilize single-molecule fluorescence imaging to observe the real-time self-assembly dynamics of CTPS and the coordinated assembly between CTPS and its interaction partner, Δ1-pyrroline-5-carboxylate synthase (P5CS). Significant differences exist in the direction of growth and extension when the two proteins self-assemble. The oligomer state distribution analysis of the CTPS minimum structural subunit under different conditions and the stoichiometry statistics of binding CTPS and P5CS by single-molecule fluorescence photobleach counting further confirm that the CTPS cytoophidia are mainly stacked with tetramers. CTPS can act as the nucleation core to induce the subsequent growth of the P5CS filaments. Our work not only provide evidence from the molecular level for the self-assembly and coordinated assembly (coassembly) of CTPS with its interaction partner P5CS in vitro but also offer new experimental perspectives for the dynamics research of coordinated regulation between other protein polymers.
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Affiliation(s)
- Jian Chang
- State Key Laboratory of Surface Physics, Shanghai Key Laboratory of Metasurfaces for Light Manipulation, Department of Physics, Fudan University, Shanghai 200433, China
| | - Weijie Yuan
- State Key Laboratory of Surface Physics, Shanghai Key Laboratory of Metasurfaces for Light Manipulation, Department of Physics, Fudan University, Shanghai 200433, China
| | - Chendi Gao
- The State Key Laboratory of Molecular Engineering of Polymers and Department of Macromolecular Science, Fudan University, Shanghai 200433, China
| | - Bo Zhang
- 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
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Guosong Chen
- The State Key Laboratory of Molecular Engineering of Polymers and Department of Macromolecular Science, Fudan University, Shanghai 200433, China
| | - Yan-Wen Tan
- State Key Laboratory of Surface Physics, Shanghai Key Laboratory of Metasurfaces for Light Manipulation, Department of Physics, Fudan University, Shanghai 200433, China
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6
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Deng R, Li YL, Liu JL. Cytoophidia Influence Cell Cycle and Size in Schizosaccharomyces pombe. Int J Mol Sci 2024; 25:608. [PMID: 38203781 PMCID: PMC10779087 DOI: 10.3390/ijms25010608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 11/09/2023] [Accepted: 11/27/2023] [Indexed: 01/12/2024] Open
Abstract
Cytidine triphosphate synthase (CTPS) forms cytoophidia in all three domains of life. Here we focus on the function of cytoophidia in cell proliferation using Schizosaccharomyces pombe as a model system. We find that converting His359 of CTPS into Ala359 leads to cytoophidium disassembly. By reducing the level of CTPS protein or specific mutation, the loss of cytoophidia prolongs the G2 phase and expands cell size. In addition, the loss-filament mutant of CTPS leads to a decrease in the expression of genes related to G2/M transition and cell growth, including histone chaperone slm9. The overexpression of slm9 alleviates the G2 phase elongation and cell size enlargement induced by CTPS loss-filament mutants. Overall, our results connect cytoophidia with cell cycle and cell size control in Schizosaccharomyces pombe.
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Affiliation(s)
- Ruolan Deng
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yi-Lan Li
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ji-Long Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK
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7
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Romero-Romero ML, Garcia-Seisdedos H. Agglomeration: when folded proteins clump together. Biophys Rev 2023; 15:1987-2003. [PMID: 38192350 PMCID: PMC10771401 DOI: 10.1007/s12551-023-01172-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 11/25/2023] [Indexed: 01/10/2024] Open
Abstract
Protein self-association is a widespread phenomenon that results in the formation of multimeric protein structures with critical roles in cellular processes. Protein self-association can lead to finite protein complexes or open-ended, and potentially, infinite structures. This review explores the concept of protein agglomeration, a process that results from the infinite self-assembly of folded proteins. We highlight its differences from other better-described processes with similar macroscopic features, such as aggregation and liquid-liquid phase separation. We review the sequence, structural, and biophysical factors influencing protein agglomeration. Lastly, we briefly discuss the implications of agglomeration in evolution, disease, and aging. Overall, this review highlights the need to study protein agglomeration for a better understanding of cellular processes.
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Affiliation(s)
- M. L. Romero-Romero
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- Center for Systems Biology, Dresden, Germany
| | - H. Garcia-Seisdedos
- Department of Structural and Molecular Biology, Institut de Biologia Molecular de Barcelona (IBMB-CSIC), Barcelona, Spain
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8
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Sivadas A, McDonald EF, Shuster SO, Davis CM, Plate L. Site-specific crosslinking reveals Phosphofructokinase-L inhibition drives self-assembly and attenuation of protein interactions. Adv Biol Regul 2023; 90:100987. [PMID: 37806136 PMCID: PMC11108229 DOI: 10.1016/j.jbior.2023.100987] [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: 09/15/2023] [Accepted: 09/25/2023] [Indexed: 10/10/2023]
Abstract
Phosphofructokinase is the central enzyme in glycolysis and constitutes a highly regulated step. The liver isoform (PFKL) compartmentalizes during activation and inhibition in vitro and in vivo, respectively. Compartmentalized PFKL is hypothesized to modulate metabolic flux consistent with its central role as the rate limiting step in glycolysis. PFKL tetramers self-assemble at two interfaces in the monomer (interface 1 and 2), yet how these interfaces contribute to PFKL compartmentalization and drive protein interactions remains unclear. Here, we used site-specific incorporation of noncanonical photocrosslinking amino acids to identify PFKL interactors at interface 1, 2, and the active site. Tandem mass tag-based quantitative interactomics reveals interface 2 as a hotspot for PFKL interactions, particularly with cytoskeletal, glycolytic, and carbohydrate derivative metabolic proteins. Furthermore, PFKL compartmentalization into puncta was observed in human cells using citrate inhibition. Puncta formation attenuated crosslinked protein-protein interactions with the cytoskeleton at interface 2. This result suggests that PFKL compartmentalization sequesters interface 2, but not interface 1, and may modulate associated protein assemblies with the cytoskeleton.
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Affiliation(s)
- Athira Sivadas
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
| | - Eli Fritz McDonald
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | | | - Caitlin M Davis
- Department of Chemistry, Yale University, New Haven, CT, USA
| | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA; Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA; Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.
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9
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Jentoft IMA, Bäuerlein FJB, Welp LM, Cooper BH, Petrovic A, So C, Penir SM, Politi AZ, Horokhovskyi Y, Takala I, Eckel H, Moltrecht R, Lénárt P, Cavazza T, Liepe J, Brose N, Urlaub H, Fernández-Busnadiego R, Schuh M. Mammalian oocytes store proteins for the early embryo on cytoplasmic lattices. Cell 2023; 186:5308-5327.e25. [PMID: 37922900 DOI: 10.1016/j.cell.2023.10.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 08/01/2023] [Accepted: 10/02/2023] [Indexed: 11/07/2023]
Abstract
Mammalian oocytes are filled with poorly understood structures called cytoplasmic lattices. First discovered in the 1960s and speculated to correspond to mammalian yolk, ribosomal arrays, or intermediate filaments, their function has remained enigmatic to date. Here, we show that cytoplasmic lattices are sites where oocytes store essential proteins for early embryonic development. Using super-resolution light microscopy and cryoelectron tomography, we show that cytoplasmic lattices are composed of filaments with a high surface area, which contain PADI6 and subcortical maternal complex proteins. The lattices associate with many proteins critical for embryonic development, including proteins that control epigenetic reprogramming of the preimplantation embryo. Loss of cytoplasmic lattices by knocking out PADI6 or the subcortical maternal complex prevents the accumulation of these proteins and results in early embryonic arrest. Our work suggests that cytoplasmic lattices enrich maternally provided proteins to prevent their premature degradation and cellular activity, thereby enabling early mammalian development.
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Affiliation(s)
- Ida M A Jentoft
- Department of Meiosis, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany
| | - Felix J B Bäuerlein
- Institute for Neuropathology, University Medical Center Göttingen, 37077 Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37077 Göttingen, Germany
| | - Luisa M Welp
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany; Institute of Clinical Chemistry, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Benjamin H Cooper
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, 37075 Göttingen, Germany
| | - Arsen Petrovic
- Institute for Neuropathology, University Medical Center Göttingen, 37077 Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37077 Göttingen, Germany
| | - Chun So
- Department of Meiosis, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany
| | - Sarah Mae Penir
- Department of Meiosis, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany
| | - Antonio Z Politi
- Facility for Light Microscopy, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany
| | - Yehor Horokhovskyi
- Quantitative and Systems Biology Group, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany
| | - Iina Takala
- Quantitative and Systems Biology Group, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany
| | - Heike Eckel
- Kinderwunschzentrum Göttingen, 37081 Göttingen, Germany
| | | | - Peter Lénárt
- Facility for Light Microscopy, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany
| | - Tommaso Cavazza
- Department of Meiosis, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany
| | - Juliane Liepe
- Quantitative and Systems Biology Group, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany
| | - Nils Brose
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37077 Göttingen, Germany; Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, 37075 Göttingen, Germany
| | - Henning Urlaub
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37077 Göttingen, Germany; Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany; Institute of Clinical Chemistry, University Medical Center Göttingen, 37075 Göttingen, Germany; Göttingen Center for Molecular Biosciences, Georg-August University Göttingen, 37077 Göttingen, Germany
| | - Rubén Fernández-Busnadiego
- Institute for Neuropathology, University Medical Center Göttingen, 37077 Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37077 Göttingen, Germany; Faculty of Physics, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - Melina Schuh
- Department of Meiosis, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37077 Göttingen, Germany.
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10
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Calise SJ, O’Neill AG, Burrell AL, Dickinson MS, Molfino J, Clarke C, Quispe J, Sokolov D, Buey RM, Kollman JM. Light-sensitive phosphorylation regulates enzyme activity and filament assembly of human IMPDH1 retinal splice variants. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.21.558867. [PMID: 37790411 PMCID: PMC10542554 DOI: 10.1101/2023.09.21.558867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Inosine monophosphate dehydrogenase (IMPDH) is the rate-limiting enzyme in de novo guanosine triphosphate (GTP) synthesis and is controlled by feedback inhibition and allosteric regulation. IMPDH assembles into micron-scale filaments in cells, which desensitizes the enzyme to feedback inhibition by GTP and boosts nucleotide production. The vertebrate retina expresses two tissue-specific splice variants IMPDH1(546) and IMPDH1(595). IMPDH1(546) filaments adopt high and low activity conformations, while IMPDH1(595) filaments maintain high activity. In bovine retinas, residue S477 is preferentially phosphorylated in the dark, but the effects on IMPDH1 activity and regulation are unclear. Here, we generated phosphomimetic mutants to investigate structural and functional consequences of phosphorylation in IMPDH1 variants. The S477D mutation re-sensitized both variants to GTP inhibition, but only blocked assembly of IMPDH1(595) filaments and not IMPDH1(546) filaments. Cryo-EM structures of both variants showed that S477D specifically blocks assembly of the high activity assembly interface, still allowing assembly of low activity IMPDH1(546) filaments. Finally, we discovered that S477D exerts a dominant-negative effect in cells, preventing endogenous IMPDH filament assembly. By modulating the structure and higher-order assembly of IMPDH, phosphorylation at S477 acts as a mechanism for downregulating retinal GTP synthesis in the dark, when nucleotide turnover is decreased. Like IMPDH1, many other metabolic enzymes dynamically assemble filamentous polymers that allosterically regulate activity. Our work suggests that posttranslational modifications may be yet another layer of regulatory control to finely tune activity by modulating filament assembly in response to changing metabolic demands.
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Affiliation(s)
- S. John Calise
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Audrey G. O’Neill
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Anika L. Burrell
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | | | - Josephine Molfino
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Charlie Clarke
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Joel Quispe
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - David Sokolov
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Rubén M. Buey
- Metabolic Engineering Group, Departamento de Microbiología y Genética, Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain
| | - Justin M. Kollman
- Department of Biochemistry, University of Washington, Seattle, WA, USA
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11
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Sivadas A, McDonald EF, Shuster SO, Davis CM, Plate L. Site-Specific Crosslinking Reveals Phosphofructokinase-L Inhibition Drives Self-Assembly and Attenuation of Protein Interactions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.19.558525. [PMID: 37781627 PMCID: PMC10541129 DOI: 10.1101/2023.09.19.558525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
Phosphofructokinase is the central enzyme in glycolysis and constitutes a highly regulated step. The liver isoform (PFKL) compartmentalizes during activation and inhibition in vitro and in vivo respectively. Compartmentalized PFKL is hypothesized to modulate metabolic flux consistent with its central role as the rate limiting step in glycolysis. PFKL tetramers self-assemble at two interfaces in the monomer (interface 1 and 2), yet how these interfaces contribute to PFKL compartmentalization and drive protein interactions remains unclear. Here, we used site-specific incorporation of noncanonical photocrosslinking amino acids to identify PFKL interactors at interface 1, 2, and the active site. Tandem mass tag-based quantitative interactomics reveals interface 2 as a hotspot for PFKL interactions, particularly with cytoskeletal, glycolytic, and carbohydrate derivative metabolic proteins. Furthermore, PFKL compartmentalization into puncta was observed in human cells using citrate inhibition. Puncta formation attenuated crosslinked protein-protein interactions with the cytoskeleton at interface 2. This result suggests that PFKL compartmentalization sequesters interface 2, but not interface 1, and may modulate associated protein assemblies with the cytoskeleton.
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Affiliation(s)
- Athira Sivadas
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
| | - Eli Fritz McDonald
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | | | | | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
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12
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Liu J, Zhang Y, Wang QQ, Zhou Y, Liu JL. Fat body-specific reduction of CTPS alleviates HFD-induced obesity. eLife 2023; 12:e85293. [PMID: 37695169 PMCID: PMC10495109 DOI: 10.7554/elife.85293] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 08/25/2023] [Indexed: 09/12/2023] Open
Abstract
Obesity induced by high-fat diet (HFD) is a multi-factorial disease including genetic, physiological, behavioral, and environmental components. Drosophila has emerged as an effective metabolic disease model. Cytidine 5'-triphosphate synthase (CTPS) is an important enzyme for the de novo synthesis of CTP, governing the cellular level of CTP and the rate of phospholipid synthesis. CTPS is known to form filamentous structures called cytoophidia, which are found in bacteria, archaea, and eukaryotes. Our study demonstrates that CTPS is crucial in regulating body weight and starvation resistance in Drosophila by functioning in the fat body. HFD-induced obesity leads to increased transcription of CTPS and elongates cytoophidia in larval adipocytes. Depleting CTPS in the fat body prevented HFD-induced obesity, including body weight gain, adipocyte expansion, and lipid accumulation, by inhibiting the PI3K-Akt-SREBP axis. Furthermore, a dominant-negative form of CTPS also prevented adipocyte expansion and downregulated lipogenic genes. These findings not only establish a functional link between CTPS and lipid homeostasis but also highlight the potential role of CTPS manipulation in the treatment of HFD-induced obesity.
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Affiliation(s)
- Jingnan Liu
- School of Life Science and Technology, ShanghaiTech UniversityShanghaiChina
- College of Life Sciences, Shanghai Normal UniversityShanghaiChina
| | - Yuanbing Zhang
- School of Life Science and Technology, ShanghaiTech UniversityShanghaiChina
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Qiao-Qi Wang
- School of Life Science and Technology, ShanghaiTech UniversityShanghaiChina
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Youfang Zhou
- School of Life Science and Technology, ShanghaiTech UniversityShanghaiChina
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Ji-Long Liu
- School of Life Science and Technology, ShanghaiTech UniversityShanghaiChina
- Department of Physiology, Anatomy and Genetics, University of OxfordOxfordUnited Kingdom
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13
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Minet N, Boschat AC, Lane R, Laughton D, Beer P, Asnagli H, Soudais C, Bourne T, Fischer A, Martin E, Latour S. Differential roles of CTP synthetases CTPS1 and CTPS2 in cell proliferation. Life Sci Alliance 2023; 6:e202302066. [PMID: 37348953 PMCID: PMC10288033 DOI: 10.26508/lsa.202302066] [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: 03/29/2023] [Revised: 06/06/2023] [Accepted: 06/07/2023] [Indexed: 06/24/2023] Open
Abstract
The CTP nucleotide is a key precursor of nucleic acids metabolism essential for DNA replication. De novo CTP production relies on CTP synthetases 1 and 2 (CTPS1 and CTPS2) that catalyze the conversion of UTP into CTP. CTP synthetase activity is high in proliferating cells including cancer cells; however, the respective roles of CTPS1 and CTPS2 in cell proliferation are not known. By inactivation of CTPS1 and/or CTPS2 and complementation experiments, we showed that both CTPS1 and CTPS2 are differentially required for cell proliferation. CTPS1 was more efficient in promoting proliferation than CTPS2, in association with a higher intrinsic enzymatic activity that was more resistant to inhibition by 3-deaza-uridine, an UTP analog. The contribution of CTPS2 to cell proliferation was modest when CTPS1 was expressed but essential in absence of CTPS1. Public databases analysis of more than 1,000 inactivated cancer cell lines for CTPS1 or CTPS2 confirmed that cell growth is highly dependent of CTPS1 but less or not of CTPS2. Therefore, our results demonstrate that CTPS1 is the main contributor to cell proliferation.
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Affiliation(s)
- Norbert Minet
- Laboratory of Lymphocyte Activation and Susceptibility to EBV Infection, Inserm UMR 1163, Imagine Institute, Paris, France
- Université de Paris, Paris, France
| | - Anne-Claire Boschat
- Université de Paris, Paris, France
- Plateforme Spectrométrie de masse, Institut Imagine, Paris, France
- Laboratoire de Biochimie Métabolomique et Protéomique, Hôpital Necker Enfants-Malades, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France
| | | | | | | | | | - Claire Soudais
- Laboratory of Lymphocyte Activation and Susceptibility to EBV Infection, Inserm UMR 1163, Imagine Institute, Paris, France
- Université de Paris, Paris, France
| | - Tim Bourne
- Step-Pharma, Saint-Genis-Pouilly, France
| | - Alain Fischer
- Collège de France, Paris, France
- Imagine Institute, Paris, France
| | - Emmanuel Martin
- Laboratory of Lymphocyte Activation and Susceptibility to EBV Infection, Inserm UMR 1163, Imagine Institute, Paris, France
- Université de Paris, Paris, France
| | - Sylvain Latour
- Laboratory of Lymphocyte Activation and Susceptibility to EBV Infection, Inserm UMR 1163, Imagine Institute, Paris, France
- Université de Paris, Paris, France
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14
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O'Neill AG, Burrell AL, Zech M, Elpeleg O, Harel T, Edvardson S, Mor-Shaked H, Rippert AL, Nomakuchi T, Izumi K, Kollman JM. Neurodevelopmental disorder mutations in the purine biosynthetic enzyme IMPDH2 disrupt its allosteric regulation. J Biol Chem 2023; 299:105012. [PMID: 37414152 PMCID: PMC10407431 DOI: 10.1016/j.jbc.2023.105012] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 06/23/2023] [Accepted: 06/28/2023] [Indexed: 07/08/2023] Open
Abstract
Inosine 5' monophosphate dehydrogenase (IMPDH) is a critical regulatory enzyme in purine nucleotide biosynthesis that is inhibited by the downstream product GTP. Multiple point mutations in the human isoform IMPDH2 have recently been associated with dystonia and other neurodevelopmental disorders, but the effect of the mutations on enzyme function has not been described. Here, we report the identification of two additional missense variants in IMPDH2 from affected individuals and show that all of the disease-associated mutations disrupt GTP regulation. Cryo-EM structures of one IMPDH2 mutant suggest this regulatory defect arises from a shift in the conformational equilibrium toward a more active state. This structural and functional analysis provides insight into IMPDH2-associated disease mechanisms that point to potential therapeutic approaches and raises new questions about fundamental aspects of IMPDH regulation.
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Affiliation(s)
- Audrey G O'Neill
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | - Anika L Burrell
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | - Michael Zech
- Institute of Neurogenomics, Helmholtz Zentrum München, Munich, Germany; Institute of Human Genetics, School of Medicine, Technical University of Munich, Munich, Germany
| | - Orly Elpeleg
- Department of Genetics, Hadassah Medical Center, Jerusalem, Israel; Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Tamar Harel
- Department of Genetics, Hadassah Medical Center, Jerusalem, Israel; Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Simon Edvardson
- Alyn Hospital, Hebrew University School of Medicine, Jerusalem, Israel
| | - Hagar Mor-Shaked
- Department of Genetics, Hadassah Medical Center, Jerusalem, Israel; Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Alyssa L Rippert
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Tomoki Nomakuchi
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Kosuke Izumi
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Justin M Kollman
- Department of Biochemistry, University of Washington, Seattle, Washington, USA.
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15
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Lu GM, Hu HH, Chang CC, Zhong J, Zhou X, Guo CJ, Zhang T, Li YL, Yin B, Liu JL. Structural basis of human PRPS2 filaments. Cell Biosci 2023; 13:100. [PMID: 37248548 DOI: 10.1186/s13578-023-01037-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 04/19/2023] [Indexed: 05/31/2023] Open
Abstract
BACKGROUND PRPP synthase (PRPS) transfers the pyrophosphate groups from ATP to ribose-5-phosphate to produce 5-phosphate ribose-1-pyrophosphate (PRPP), a key intermediate in the biosynthesis of several metabolites including nucleotides, dinucleotides and some amino acids. There are three PRPS isoforms encoded in human genome. While human PRPS1 (hPRPS1) and human PRPS2 (hPRPS2) are expressed in most tissues, human PRPS3 (hPRPS3) is exclusively expressed in testis. Although hPRPS1 and hPRPS2 share 95% sequence identity, hPRPS2 has been shown to be less sensitive to allosteric inhibition and specifically upregulated in certain cancers in the translational level. Recent studies demonstrate that PRPS can form a subcellular compartment termed the cytoophidium in multiple organisms across prokaryotes and eukaryotes. Forming filaments and cytoophidia is considered as a distinctive mechanism involving the polymerization of the protein. Previously we solved the filament structures of Escherichia coli PRPS (ecPRPS) using cryo-electron microscopy (cryo-EM) 1. RESULTS Order to investigate the function and molecular mechanism of hPRPS2 polymerization, here we solve the polymer structure of hPRPS2 at 3.08 Å resolution. hPRPS2 hexamers stack into polymers in the conditions with the allosteric/competitive inhibitor ADP. The binding modes of ADP at the canonical allosteric site and at the catalytic active site are clearly determined. A point mutation disrupting the inter-hexamer interaction prevents hPRPS2 polymerization and results in significantly reduced catalytic activity. CONCLUSION Findings suggest that the regulation of hPRPS2 polymer is distinct from ecPRPS polymer and provide new insights to the regulation of hPRPS2 with structural basis.
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Affiliation(s)
- Guang-Ming Lu
- 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
| | - Chia-Chun Chang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Jiale Zhong
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - 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
| | - Tianyi Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Yi-Lan Li
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Boqi Yin
- 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.
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK.
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16
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Hvorecny KL, Kollman JM. Greater than the sum of parts: Mechanisms of metabolic regulation by enzyme filaments. Curr Opin Struct Biol 2023; 79:102530. [PMID: 36709625 PMCID: PMC10023394 DOI: 10.1016/j.sbi.2023.102530] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 11/28/2022] [Accepted: 12/19/2022] [Indexed: 01/28/2023]
Abstract
Recent work in structural biology is shedding light on how many of the enzymes of intermediary metabolism are self- and co-assembling into large, filamentous polymers or agglomerates to organize and regulate the complex and essential biochemical pathways in cells. Filament assembly provides an additional layer of regulation by modulating the intrinsic allostery of the enzyme protomers which tunes activity in response to a variety of environmental cues. Enzyme filaments dynamically assemble and disassemble in response to changes in metabolite levels and environmental cues, shifting metabolic flux on a more rapid timescale than transcriptional or translational reprogramming. Here we present recent examples of high-resolution structures of filaments from proteins in intermediary metabolism and we discuss how filament assembly modulates the activities of these and other proteins.
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Affiliation(s)
- Kelli L Hvorecny
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Justin M Kollman
- Department of Biochemistry, University of Washington, Seattle, WA, USA.
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17
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Zhong J, Cui J, Liu J, Zhong C, Hu F, Dong J, Cheng J, Hu K. Fine-mapping and candidate gene analysis of the Mcgy1 locus responsible for gynoecy in bitter gourd (Momordica spp.). TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2023; 136:81. [PMID: 36952023 DOI: 10.1007/s00122-023-04314-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 01/28/2023] [Indexed: 06/18/2023]
Abstract
The Mcgy1 locus responsible for gynoecy was fine-mapped into a 296.94-kb region, in which four single-nucleotide variations and six genes adjacent to them might be associate with sex differentiation in bitter gourd. Gynoecy plays an important role in high-efficiency hybrid seed production, and gynoecious plants are excellent materials for dissecting sex differentiation in Cucurbitaceae crop species, including bitter gourd. However, the gene responsible for gynoecy in bitter gourd is unknown. Here, we first identified a gynoecy locus designated Mcgy1 using the F2 population (n = 291) crossed from the gynoecious line S156G and the monoecious line K8-201 via bulked segregant analysis with whole-genome resequencing (BSA-seq) and molecular marker linkage analysis. Then, a large S156G × K8-201 F2 population (n = 5,656) was used for fine-mapping to delimit the Mcgy1 locus into a 296.94-kb physical region on pseudochromosome MC01, where included 33 annotated genes different from any homologous gynoecy genes previously reported in Cucurbitaceae species. Within this region, four underlying single-nucleotide variations (SNVs) that might cause gynoecy were identified by multiple genomic sequence variation analysis, and their six neighbouring genes were considered as potential candidate genes for Mcgy1. Of these, only MC01g1681 showed a significant differential expression at two-leaf developmental stage between S156G and its monoecious near-isogenic line S156 based on RNA sequencing (RNA-seq) and qRT-PCR analyses. In addition, transcriptome analysis revealed 21 key differentially expressed genes (DEGs) and possible regulatory pathways of the formation of gynoecy in bitter gourd. Our findings provide a new clue for researching on gynoecious plants in Cucurbitaceae species and a theoretical basis for breeding gynoecious bitter gourd lines by the use of molecular markers-assisted selection.
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Affiliation(s)
- Jian Zhong
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (South China), Ministry of Agriculture and Rural Affairs/Guangdong Vegetables Engineering Research Center, College of Horticulture, South China Agricultural University, Guangzhou, 510642, China
| | - Junjie Cui
- Department of Horticulture, Foshan University, Foshan, 528225, China
| | - Jia Liu
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (South China), Ministry of Agriculture and Rural Affairs/Guangdong Vegetables Engineering Research Center, College of Horticulture, South China Agricultural University, Guangzhou, 510642, China
| | - Chunfeng Zhong
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (South China), Ministry of Agriculture and Rural Affairs/Guangdong Vegetables Engineering Research Center, College of Horticulture, South China Agricultural University, Guangzhou, 510642, China
| | - Fang Hu
- Henry Fok School of Biology and Agricultural, Shaoguan University, Shaoguan, 512023, China
| | - Jichi Dong
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (South China), Ministry of Agriculture and Rural Affairs/Guangdong Vegetables Engineering Research Center, College of Horticulture, South China Agricultural University, Guangzhou, 510642, China
| | - Jiaowen Cheng
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (South China), Ministry of Agriculture and Rural Affairs/Guangdong Vegetables Engineering Research Center, College of Horticulture, South China Agricultural University, Guangzhou, 510642, China.
| | - Kailin Hu
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (South China), Ministry of Agriculture and Rural Affairs/Guangdong Vegetables Engineering Research Center, College of Horticulture, South China Agricultural University, Guangzhou, 510642, China.
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18
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Kim-Holzapfel DM, Dey R, Richardson BC, Arachchige D, Reddy K, De Vitto H, Bhandari J, French JB. Human uridine 5'-monophosphate synthase stores metabolic potential in inactive biomolecular condensates. J Biol Chem 2023; 299:102949. [PMID: 36708921 PMCID: PMC9978035 DOI: 10.1016/j.jbc.2023.102949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 01/02/2023] [Accepted: 01/06/2023] [Indexed: 01/27/2023] Open
Abstract
Human uridine 5'-monophosphate synthase (HsUMPS) is a bifunctional enzyme that catalyzes the final two steps in de novo pyrimidine biosynthesis. The individual orotate phosphoribosyl transferase and orotidine monophosphate domains have been well characterized, but little is known about the overall structure of the protein and how the organization of domains impacts function. Using a combination of chromatography, electron microscopy, and complementary biophysical methods, we report herein that HsUMPS can be observed in two structurally distinct states, an enzymatically active dimeric form and a nonactive multimeric form. These two states readily interconvert to reach an equilibrium that is sensitive to perturbations of the active site and the presence of substrate. We determined that the smaller molecular weight form of HsUMPS is an S-shaped dimer that can self-assemble into relatively well-ordered globular condensates. Our analysis suggests that the transition between dimer and multimer is driven primarily by oligomerization of the orotate phosphoribosyl transferase domain. While the cellular distribution of HsUMPS is unaffected, quantification by mass spectrometry revealed that de novo pyrimidine biosynthesis is dysregulated when this protein is unable to assemble into inactive condensates. Taken together, our data suggest that HsUMPS self-assembles into biomolecular condensates as a means to store metabolic potential for the regulation of metabolic rates.
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Affiliation(s)
- Deborah M Kim-Holzapfel
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, USA; Molecular and Cellular Biology PhD Program, Stony Brook University, Stony Brook, New York, USA
| | - Raja Dey
- The Hormel Institute, University of Minnesota, Austin, Minnesota, USA
| | | | | | - Kanamata Reddy
- The Hormel Institute, University of Minnesota, Austin, Minnesota, USA
| | - Humberto De Vitto
- The Hormel Institute, University of Minnesota, Austin, Minnesota, USA
| | - Janarjan Bhandari
- The Hormel Institute, University of Minnesota, Austin, Minnesota, USA
| | - Jarrod B French
- The Hormel Institute, University of Minnesota, Austin, Minnesota, USA.
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19
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Hu JJ, Lee JKJ, Liu YT, Yu C, Huang L, Aphasizheva I, Aphasizhev R, Zhou ZH. Discovery, structure, and function of filamentous 3-methylcrotonyl-CoA carboxylase. Structure 2023; 31:100-110.e4. [PMID: 36543169 PMCID: PMC9825669 DOI: 10.1016/j.str.2022.11.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/17/2022] [Accepted: 11/24/2022] [Indexed: 12/24/2022]
Abstract
3-methylcrotonyl-CoA carboxylase (MCC) is a biotin-dependent mitochondrial enzyme necessary for leucine catabolism in most organisms. While the crystal structure of recombinant bacterial MCC has been characterized, the structure and potential polymerization of native MCC remain elusive. Here, we discovered that native MCC from Leishmania tarentolae (LtMCC) forms filaments, and determined the structures of different filament regions at 3.4, 3.9, and 7.3 Å resolution using cryoEM. α6β6 LtMCCs assemble in a twisted-stacks architecture, manifesting as supramolecular rods up to 400 nm. Filamentous LtMCCs bind biotin non-covalently and lack coenzyme A. Filaments elongate by stacking α6β6 LtMCCs onto the exterior α-trimer of the terminal LtMCC. This stacking immobilizes the biotin carboxylase domains, sequestering the enzyme in an inactive state. Our results support a new model for LtMCC catalysis, termed the dual-swinging-domains model, and cast new light on the function of polymerization in the carboxylase superfamily and beyond.
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Affiliation(s)
- Jason J Hu
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA; California NanoSystems Institute, UCLA, Los Angeles, CA 90095, USA; Department of Mathematics, UCLA, Los Angeles, CA 90095, USA
| | - Jane K J Lee
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA; California NanoSystems Institute, UCLA, Los Angeles, CA 90095, USA; Department of Psychology, UCLA, Los Angeles, CA 90095, USA
| | - Yun-Tao Liu
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA; California NanoSystems Institute, UCLA, Los Angeles, CA 90095, USA
| | - Clinton Yu
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA 92697, USA
| | - Lan Huang
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA 92697, USA
| | - Inna Aphasizheva
- Department of Molecular and Cell Biology, Boston University Medical Campus (BUMC), Boston, MA 02118, USA
| | - Ruslan Aphasizhev
- Department of Molecular and Cell Biology, Boston University Medical Campus (BUMC), Boston, MA 02118, USA; Department of Biochemistry, BUMC, Boston, MA 02118, USA
| | - Z Hong Zhou
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA; California NanoSystems Institute, UCLA, Los Angeles, CA 90095, USA.
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20
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The role of filamentation in activation and DNA sequence specificity of the sequence-specific endonuclease SgrAI. Biochem Soc Trans 2022; 50:1703-1714. [PMID: 36398769 PMCID: PMC9788392 DOI: 10.1042/bst20220547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 10/09/2022] [Accepted: 10/12/2022] [Indexed: 11/19/2022]
Abstract
Filament formation by metabolic, biosynthetic, and other enzymes has recently come into focus as a mechanism to fine-tune enzyme activity in the cell. Filamentation is key to the function of SgrAI, a sequence-specific DNA endonuclease that has served as a model system to provide some of the deepest insights into the biophysical characteristics of filamentation and its functional consequences. Structure-function analyses reveal that, in the filamentous state, SgrAI stabilizes an activated enzyme conformation that leads to accelerated DNA cleavage activity and expanded DNA sequence specificity. The latter is thought to be mediated by sequence-specific DNA structure, protein-DNA interactions, and a disorder-to-order transition in the protein, which collectively affect the relative stabilities of the inactive, non-filamentous conformation and the active, filamentous conformation of SgrAI bound to DNA. Full global kinetic modeling of the DNA cleavage pathway reveals a slow, rate-limiting, second-order association rate constant for filament assembly, and simulations of in vivo activity predict that filamentation is superior to non-filamenting mechanisms in ensuring rapid activation and sequestration of SgrAI's DNA cleavage activity on phage DNA and away from the host chromosome. In vivo studies demonstrate the critical requirement for accelerated DNA cleavage by SgrAI in its biological role to safeguard the bacterial host. Collectively, these data have advanced our understanding of how filamentation can regulate enzyme structure and function, while the experimental strategies used for SgrAI can be applied to other enzymatic systems to identify novel functional roles for filamentation.
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21
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Wang QQ, You DD, Liu JL. Cytoophidia Maintain the Integrity of Drosophila Follicle Epithelium. Int J Mol Sci 2022; 23:ijms232315282. [PMID: 36499609 PMCID: PMC9740582 DOI: 10.3390/ijms232315282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 11/25/2022] [Accepted: 11/25/2022] [Indexed: 12/12/2022] Open
Abstract
CTP synthase (CTPS) forms a filamentous structure termed the cytoophidium in all three domains of life. The female reproductive system of Drosophila is an excellent model for studying the physiological function of cytoophidia. Here, we use CTPSH355A, a point mutation that destroys the cytoophidium-forming ability of CTPS, to explore the in vivo function of cytoophidia. In CTPSH355A egg chambers, we observe the ingression and increased heterogeneity of follicle cells. In addition, we find that the cytoophidium-forming ability of CTPS, rather than the protein level, is the cause of the defects observed in CTPSH355A mutants. To sum up, our data indicate that cytoophidia play an important role in maintaining the integrity of follicle epithelium.
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Affiliation(s)
- Qiao-Qi Wang
- School of Life Science and Technology, Shanghai Technology University, Shanghai 201210, China
| | - Dong-Dong You
- School of Life Science and Technology, Shanghai Technology University, Shanghai 201210, China
| | - Ji-Long Liu
- School of Life Science and Technology, Shanghai Technology University, Shanghai 201210, China
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK
- Correspondence: or
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22
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Lin JMG, Kourtis S, Ghose R, Pardo Lorente N, Kubicek S, Sdelci S. Metabolic modulation of transcription: The role of one-carbon metabolism. Cell Chem Biol 2022; 29:S2451-9456(22)00415-9. [PMID: 36513079 DOI: 10.1016/j.chembiol.2022.11.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 10/05/2022] [Accepted: 11/18/2022] [Indexed: 12/15/2022]
Abstract
While it is well known that expression levels of metabolic enzymes regulate the metabolic state of the cell, there is mounting evidence that the converse is also true, that metabolite levels themselves can modulate gene expression via epigenetic modifications and transcriptional regulation. Here we focus on the one-carbon metabolic pathway, which provides the essential building blocks of many classes of biomolecules, including purine nucleotides, thymidylate, serine, and methionine. We review the epigenetic roles of one-carbon metabolic enzymes and their associated metabolites and introduce an interactive computational resource that places enzyme essentiality in the context of metabolic pathway topology. Therefore, we briefly discuss examples of metabolic condensates and higher-order complexes of metabolic enzymes downstream of one-carbon metabolism. We speculate that they may be required to the formation of transcriptional condensates and gene expression control. Finally, we discuss new ways to exploit metabolic pathway compartmentalization to selectively target these enzymes in cancer.
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Affiliation(s)
- Jung-Ming G Lin
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Vienna 1090, Austria
| | - Savvas Kourtis
- Centre for Genomic Regulation (CRG), the Barcelona Institute of Science and Technology, Barcelona, Catalonia 08003, Spain
| | - Ritobrata Ghose
- Centre for Genomic Regulation (CRG), the Barcelona Institute of Science and Technology, Barcelona, Catalonia 08003, Spain
| | - Natalia Pardo Lorente
- Centre for Genomic Regulation (CRG), the Barcelona Institute of Science and Technology, Barcelona, Catalonia 08003, Spain
| | - Stefan Kubicek
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Vienna 1090, Austria
| | - Sara Sdelci
- Centre for Genomic Regulation (CRG), the Barcelona Institute of Science and Technology, Barcelona, Catalonia 08003, Spain.
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23
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Bennett JA, Steward LR, Rudolph J, Voss AP, Aydin H. The structure of the human LACTB filament reveals the mechanisms of assembly and membrane binding. PLoS Biol 2022; 20:e3001899. [PMID: 36534696 PMCID: PMC9815587 DOI: 10.1371/journal.pbio.3001899] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 01/05/2023] [Accepted: 10/31/2022] [Indexed: 12/23/2022] Open
Abstract
Mitochondria are complex organelles that play a central role in metabolism. Dynamic membrane-associated processes regulate mitochondrial morphology and bioenergetics in response to cellular demand. In tumor cells, metabolic reprogramming requires active mitochondrial metabolism for providing key metabolites and building blocks for tumor growth and rapid proliferation. To counter this, the mitochondrial serine beta-lactamase-like protein (LACTB) alters mitochondrial lipid metabolism and potently inhibits the proliferation of a variety of tumor cells. Mammalian LACTB is localized in the mitochondrial intermembrane space (IMS), where it assembles into filaments to regulate the efficiency of essential metabolic processes. However, the structural basis of LACTB polymerization and regulation remains incompletely understood. Here, we describe how human LACTB self-assembles into micron-scale filaments that increase their catalytic activity. The electron cryo-microscopy (cryoEM) structure defines the mechanism of assembly and reveals how highly ordered filament bundles stabilize the active state of the enzyme. We identify and characterize residues that are located at the filament-forming interface and further show that mutations that disrupt filamentation reduce enzyme activity. Furthermore, our results provide evidence that LACTB filaments can bind lipid membranes. These data reveal the detailed molecular organization and polymerization-based regulation of human LACTB and provide new insights into the mechanism of mitochondrial membrane organization that modulates lipid metabolism.
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Affiliation(s)
- Jeremy A. Bennett
- Department of Biochemistry, University of Colorado Boulder, Boulder, Colorado, United States of America
| | - Lottie R. Steward
- Department of Biochemistry, University of Colorado Boulder, Boulder, Colorado, United States of America
| | - Johannes Rudolph
- Department of Biochemistry, University of Colorado Boulder, Boulder, Colorado, United States of America
| | - Adam P. Voss
- Department of Biochemistry, University of Colorado Boulder, Boulder, Colorado, United States of America
| | - Halil Aydin
- Department of Biochemistry, University of Colorado Boulder, Boulder, Colorado, United States of America
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24
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Andreadis C, Li T, Liu JL. Ubiquitination regulates cytoophidium assembly in Schizosaccharomyces pombe. Exp Cell Res 2022; 420:113337. [PMID: 36087798 DOI: 10.1016/j.yexcr.2022.113337] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 08/26/2022] [Accepted: 08/27/2022] [Indexed: 12/30/2022]
Abstract
CTP synthase (CTPS), a metabolic enzyme responsible for the de novo synthesis of CTP, can form filamentous structures termed cytoophidia, which are evolutionarily conserved from bacteria to humans. Here we used Schizosaccharomyces pombe to study the cytoophidium assembly regulation by ubiquitination. We tested the CTP synthase's capacity to be post-translationally modified by ubiquitin or be affected by the ubiquitination state of the cell and showed that ubiquitination is important for the maintenance of the CTPS filamentous structure in fission yeast. We have identified proteins which are in complex with CTPS, including specific ubiquitination regulators which significantly affect CTPS filamentation, and mapped probable ubiquitination targets on CTPS. Furthermore, we discovered that a cohort of deubiquitinating enzymes is important for the regulation of cytoophidium's filamentous morphology. Our study provides a framework for the analysis of the effects that ubiquitination and deubiquitination have on the formation of cytoophidia.
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Affiliation(s)
- Christos Andreadis
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Tianhao Li
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Ji-Long Liu
- School of Life Science and Technology, ShanghaiTech University, 201210, Shanghai, China; Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, United Kingdom.
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25
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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.
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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
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26
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Gillis TD, Bearne SL. Effects of the 5'-Triphosphate Metabolites of Ribavirin, Sofosbuvir, Vidarabine, and Molnupiravir on CTP Synthase Catalysis and Filament Formation: Implications for Repurposing Antiviral Agents against SARS-CoV-2. ChemMedChem 2022; 17:e202200399. [PMID: 36184568 PMCID: PMC9538051 DOI: 10.1002/cmdc.202200399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 09/22/2022] [Indexed: 01/14/2023]
Abstract
Repurposing of antiviral drugs affords a rapid and effective strategy to develop therapies to counter pandemics such as COVID-19. SARS-CoV-2 replication is closely linked to the metabolism of cytosine-containing nucleotides, especially cytidine-5'-triphosphate (CTP), such that the integrity of the viral genome is highly sensitive to intracellular CTP levels. CTP synthase (CTPS) catalyzes the rate-limiting step for the de novo biosynthesis of CTP. Hence, it is of interest to know the effects of the 5'-triphosphate (TP) metabolites of repurposed antiviral agents on CTPS activity. Using E. coli CTPS as a model enzyme, we show that ribavirin-5'-TP is a weak allosteric activator of CTPS, while sofosbuvir-5'-TP and adenine-arabinofuranoside-5'-TP are both substrates. β-d-N4 -Hydroxycytidine-5'-TP is a weak competitive inhibitor relative to CTP, but induces filament formation by CTPS. Alternatively, sofosbuvir-5'-TP prevented CTP-induced filament formation. These results reveal the underlying potential for repurposed antivirals to affect the activity of a critical pyrimidine nucleotide biosynthetic enzyme.
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Affiliation(s)
- Thomas D. Gillis
- Dalhousie UniversityDepartment of Biochemistry & Molecular Biology5850 College St.Tupper Medical Building, 9JB3H 4R2HalifaxCANADA
| | - Stephen L. Bearne
- Dalhousie UniversityBiochemistry & Molecular Biology5850 College StreetTupper Medical BuildingB3H 4R2HalifaxCANADA
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27
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Fang YF, Li YL, Li XM, Liu JL. Super-Resolution Imaging Reveals Dynamic Reticular Cytoophidia. Int J Mol Sci 2022; 23:11698. [PMID: 36233000 PMCID: PMC9569780 DOI: 10.3390/ijms231911698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 09/22/2022] [Accepted: 09/27/2022] [Indexed: 11/16/2022] Open
Abstract
CTP synthase (CTPS) can form filamentous structures termed cytoophidia in cells in all three domains of life. In order to study the mesoscale structure of cytoophidia, we perform fluorescence recovery after photobleaching (FRAP) and stimulated emission depletion (STED) microscopy in human cells. By using an EGFP dimeric tag as a tool to explore the physical properties of cytoophidia, we find that cytoophidia are dynamic and reticular. The reticular structure of CTPS cytoophidia may provide space for other components, such as IMPDH. In addition, we observe CTPS granules with tentacles.
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Affiliation(s)
- Yi-Fan Fang
- School of Life Science and Technology, Shanghai Tech University, Shanghai 201210, China
| | - Yi-Lan Li
- School of Life Science and Technology, Shanghai Tech University, Shanghai 201210, China
| | - Xiao-Ming Li
- School of Life Science and Technology, Shanghai Tech University, Shanghai 201210, China
| | - Ji-Long Liu
- School of Life Science and Technology, Shanghai Tech University, Shanghai 201210, China
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK
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28
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Liu J, Zhang Y, Zhou Y, Wang QQ, Ding K, Zhao S, Lu P, Liu JL. Cytoophidia coupling adipose architecture and metabolism. Cell Mol Life Sci 2022; 79:534. [PMID: 36180607 DOI: 10.1007/s00018-022-04567-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 09/19/2022] [Accepted: 09/20/2022] [Indexed: 01/05/2023]
Abstract
Tissue architecture determines its unique physiology and function. How these properties are intertwined has remained unclear. Here we show that the metabolic enzyme CTP synthase (CTPS) form filamentous structures termed cytoophidia along the adipocyte cortex in Drosophila adipose tissue. Loss of cytoophidia, whether due to reduced CTPS expression or a point mutation that specifically abrogates its polymerization ability, causes impaired adipocyte adhesion and defective adipose tissue architecture. Moreover, CTPS influences integrin distribution and dot-like deposition of type IV collagen (Col IV). Col IV-integrin signaling reciprocally regulates the assembly of cytoophidia in adipocytes. Our results demonstrate that a positive feedback signaling loop containing both cytoophidia and integrin adhesion complex couple tissue architecture and metabolism in Drosophila adipose tissue.
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Affiliation(s)
- Jingnan Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Yuanbing Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Youfang Zhou
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Qiao-Qi Wang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Kang Ding
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China.,iHuman Institute, ShanghaiTech University, Shanghai, China
| | - Suwen Zhao
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,iHuman Institute, ShanghaiTech University, Shanghai, China
| | - Pengfei Lu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Ji-Long Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China. .,Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK.
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29
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Bar-Peled L, Kory N. Principles and functions of metabolic compartmentalization. Nat Metab 2022; 4:1232-1244. [PMID: 36266543 PMCID: PMC10155461 DOI: 10.1038/s42255-022-00645-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 08/24/2022] [Indexed: 01/20/2023]
Abstract
Metabolism has historically been studied at the levels of whole cells, whole tissues and whole organisms. As a result, our understanding of how compartmentalization-the spatial and temporal separation of pathways and components-shapes organismal metabolism remains limited. At its essence, metabolic compartmentalization fulfils three important functions or 'pillars': establishing unique chemical environments, providing protection from reactive metabolites and enabling the regulation of metabolic pathways. However, how these pillars are established, regulated and maintained at both the cellular and systemic levels remains unclear. Here we discuss how the three pillars are established, maintained and regulated within the cell and discuss the consequences of dysregulation of metabolic compartmentalization in human disease. Organelles are increasingly emerging as 'command-and-control centres' and the increased understanding of metabolic compartmentalization is revealing new aspects of metabolic homeostasis, with this knowledge being translated into therapies for the treatment of cancer and certain neurodegenerative diseases.
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Affiliation(s)
- Liron Bar-Peled
- Center for Cancer Research, Massachusetts General Hospital and Department of Medicine, Harvard Medical School, Boston, MA, USA.
| | - Nora Kory
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
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30
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Fu X, Chen W, Pan Y, Liu C, Zhang Z, Shao S, Zhang W. CTPS cytoophidia formation affects cell cycle progression and promotes TSN‑induced apoptosis of MKN45 cells. Mol Med Rep 2022; 26:319. [PMID: 36043523 PMCID: PMC9471557 DOI: 10.3892/mmr.2022.12835] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 08/03/2022] [Indexed: 11/06/2022] Open
Abstract
Cytidine triphosphate synthase (CTPS) forms filamentous structures termed cytoophidia in numerous types of cell. Toosendanin (TSN) is a tetracyclic triterpenoid and induces CTPS to form cytoophidia in MKN45 cells. However, the effects of CTPS cytoophidia on the proliferation and apoptosis of human gastric cancer cells remain poorly understood. In the present study, CTPS‑overexpression and R294D‑CTPS mutant vectors were generated to assess the effect of CTPS cytoophidia on the proliferation and apoptosis of gastric cancer MKN45 cells. Formation of CTPS cytoophidia significantly inhibited MKN45 cell proliferation (evaluated using EdU incorporation assay), significantly blocked the cell cycle in G1 phase (assessed using flow cytometry) and significantly decreased mRNA and protein expression levels of cyclin D1 (assessed by reverse transcription‑quantitative PCR and western blotting, respectively). Furthermore, the number of apoptotic bodies and apoptosis rate were markedly elevated and mitochondrial membrane potential was markedly decreased. Moreover, mRNA and protein expression levels of Bax increased and Bcl‑2 decreased markedly in MKN45 cells following transfection with the CTPS‑overexpression vector. The proliferation rate increased, percentage of G1/G0‑phase cells decreased and apoptosis was attenuated in cells transfected with the R294D‑CTPS mutant vector and this mutation did not lead to formation of cytoophidia. The results of the present study suggested that formation of CTPS cytoophidia inhibited proliferation and promoted apoptosis in MKN45 cells. These results may provide insights into the role of CTPS cytoophidia in cancer cell proliferation and apoptosis.
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Affiliation(s)
- Xuepeng Fu
- Department of Life Science and Agroforestry, Qiqihar University, Qiqihar, Heilongjiang 161006, P.R. China
| | - Wen Chen
- Department of Life Science and Agroforestry, Qiqihar University, Qiqihar, Heilongjiang 161006, P.R. China
| | - Yang Pan
- Department of Life Science and Agroforestry, Qiqihar University, Qiqihar, Heilongjiang 161006, P.R. China
| | - Chang Liu
- Department of Life Science and Agroforestry, Qiqihar University, Qiqihar, Heilongjiang 161006, P.R. China
| | - Zhenzhu Zhang
- Department of Life Science and Agroforestry, Qiqihar University, Qiqihar, Heilongjiang 161006, P.R. China
| | - Shuli Shao
- Department of Life Science and Agroforestry, Qiqihar University, Qiqihar, Heilongjiang 161006, P.R. China
| | - Weiwei Zhang
- Department of Life Science and Agroforestry, Qiqihar University, Qiqihar, Heilongjiang 161006, P.R. China
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31
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Abstract
Despite the importance of microcompartments in prokaryotic biology and bioengineering, structural heterogeneity has prevented a complete understanding of their architecture, ultrastructure, and spatial organization. Here, we employ cryo-electron tomography to image α-carboxysomes, a pseudo-icosahedral microcompartment responsible for carbon fixation. We have solved a high-resolution subtomogram average of the Rubisco cargo inside the carboxysome, and determined the arrangement of the enzyme. We find that the H. neapolitanus Rubisco polymerizes in vivo, mediated by the small Rubisco subunit. These fibrils can further pack to form a lattice with six-fold pseudo-symmetry. This arrangement preserves freedom of motion and accessibility around the Rubisco active site and the binding sites for two other carboxysome proteins, CsoSCA (a carbonic anhydrase) and the disordered CsoS2, even at Rubisco concentrations exceeding 800 μM. This characterization of Rubisco cargo inside the α-carboxysome provides insight into the balance between order and disorder in microcompartment organization.
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32
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Chang CC, Peng M, Zhong J, Zhang Z, Keppeke GD, Sung LY, Liu JL. Molecular crowding facilitates bundling of IMPDH polymers and cytoophidium formation. Cell Mol Life Sci 2022; 79:420. [PMID: 35833994 PMCID: PMC11072341 DOI: 10.1007/s00018-022-04448-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 06/14/2022] [Accepted: 06/21/2022] [Indexed: 11/29/2022]
Abstract
The cytoophidium is a unique type of membraneless compartment comprising of filamentous protein polymers. Inosine monophosphate dehydrogenase (IMPDH) catalyzes the rate-limiting step of de novo GTP biosynthesis and plays critical roles in active cell metabolism. However, the molecular regulation of cytoophidium formation is poorly understood. Here we show that human IMPDH2 polymers bundle up to form cytoophidium-like aggregates in vitro when macromolecular crowders are present. The self-association of IMPDH polymers is suggested to rely on electrostatic interactions. In cells, the increase of molecular crowding with hyperosmotic medium induces cytoophidia, while the decrease of that by the inhibition of RNA synthesis perturbs cytoophidium assembly. In addition to IMPDH, CTPS and PRPS cytoophidium could be also induced by hyperosmolality, suggesting a universal phenomenon of cytoophidium-forming proteins. Finally, our results indicate that the cytoophidium can prolong the half-life of IMPDH, which is proposed to be one of conserved functions of this subcellular compartment.
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Affiliation(s)
- Chia-Chun Chang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
- Institute of Biotechnology, National Taiwan University, Taipei, 106, Taiwan
| | - Min Peng
- Institute of Biotechnology, National Taiwan University, Taipei, 106, Taiwan
| | - Jiale Zhong
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Ziheng Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Gerson Dierley Keppeke
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
- Rheumatology Division, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, Sao Paulo, SP, 04023-062, Brazil
| | - Li-Ying Sung
- Institute of Biotechnology, National Taiwan University, Taipei, 106, Taiwan
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 115, Taiwan
| | - Ji-Long Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK.
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33
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Hu HH, Lu GM, Chang CC, Li Y, Zhong J, Guo CJ, Zhou X, Yin B, Zhang T, Liu JL. Filamentation modulates allosteric regulation of PRPS. eLife 2022; 11:79552. [PMID: 35736577 PMCID: PMC9232217 DOI: 10.7554/elife.79552] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 06/10/2022] [Indexed: 11/13/2022] Open
Abstract
Phosphoribosyl pyrophosphate (PRPP) is a key intermediate in the biosynthesis of purine and pyrimidine nucleotides, histidine, tryptophan, and cofactors NAD and NADP. Abnormal regulation of PRPP synthase (PRPS) is associated with human disorders, including Arts syndrome, retinal dystrophy, and gouty arthritis. Recent studies have demonstrated that PRPS can form filamentous cytoophidia in eukaryotes. Here, we show that PRPS forms cytoophidia in prokaryotes both in vitro and in vivo. Moreover, we solve two distinct filament structures of E. coli PRPS at near-atomic resolution using Cryo-EM. The formation of the two types of filaments is controlled by the binding of different ligands. One filament type is resistant to allosteric inhibition. The structural comparison reveals conformational changes of a regulatory flexible loop, which may regulate the binding of the allosteric inhibitor and the substrate ATP. A noncanonical allosteric AMP/ADP binding site is identified to stabilize the conformation of the regulatory flexible loop. Our findings not only explore a new mechanism of PRPS regulation with structural basis, but also propose an additional layer of cell metabolism through PRPS filamentation.
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Affiliation(s)
- Huan-Huan Hu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Guang-Ming Lu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Chia-Chun Chang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Yilan Li
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Jiale Zhong
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Chen-Jun Guo
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Xian Zhou
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Boqi Yin
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Tianyi Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Ji-Long Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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34
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Wu Z, Liu JL. CTP synthase does not form cytoophidia in Drosophila interfollicular stalks. Exp Cell Res 2022; 418:113250. [PMID: 35691380 DOI: 10.1016/j.yexcr.2022.113250] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 06/05/2022] [Accepted: 06/06/2022] [Indexed: 11/26/2022]
Abstract
CTP synthase (CTPS) catalyzes the final step of de novo synthesis of the nucleotide CTP. In 2010, CTPS has been found to form filamentous structures termed cytoophidia in Drosophila follicle cells and germline cells. Subsequently, cytoophidia have been reported in many species across three domains of life: bacteria, eukaryotes and archaea. Forming cytoophidia appears to be a highly conserved and ancient property of CTPS. To our surprise, here we find that polar cells and stalk cells, two specialized types of cells composing Drosophila interfollicular stalks, do not possess obvious cytoophidia. We show that Myc level is low in these two types of cells. Treatment with a glutamine analog, 6-diazo-5-oxo-l-norleucine (DON), increases cytoophidium assembly in main follicle cells, but not in polar cells or stalk cells. Moreover, overexpressing Myc induces cytoophidium formation in stalk cells. When CTPS is overexpressed, cytoophidia can be observed both in stalk cells and polar cells. Our findings provide an interesting paradigm for the in vivo study of cytoophidium assembly and disassembly among different populations of follicle cells.
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Affiliation(s)
- Zheng Wu
- School of Life Science and Technology, ShanghaiTech University, 230 Haike Road, 201210, Shanghai, China
| | - Ji-Long Liu
- School of Life Science and Technology, ShanghaiTech University, 230 Haike Road, 201210, Shanghai, China; Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford, OX1 3PT, United Kingdom.
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35
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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.
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36
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Huang P, Chen S, Chiang W, Ho M, Wu K. Structural basis for the helical filament formation of
Escherichia coli
glutamine synthetase. Protein Sci 2022; 31:e4304. [PMID: 35481643 PMCID: PMC8996467 DOI: 10.1002/pro.4304] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 03/15/2022] [Accepted: 03/17/2022] [Indexed: 02/01/2023]
Abstract
Escherichia coli glutamine synthetase (EcGS) spontaneously forms a dodecamer that catalytically converts glutamate to glutamine. EcGS stacks with other dodecamers to create a filament-like polymer visible under transmission electron microscopy. Filamentous EcGS is induced by environmental metal ions. We used cryo-electron microscopy (cryo-EM) to decipher the structure of metal ion (nickel)-induced EcGS helical filament at a sub-3Å resolution. EcGS filament formation involves stacking of native dodecamers by chelating nickel ions to residues His5 and His13 in the first N-terminal helix (H1). His5 and His13 from paired parallel H1 helices provide salt bridges and hydrogen bonds to tightly stack two dodecamers. One subunit of the EcGS filament hosts two nickel ions, whereas the dodecameric interface and the ATP/Mg-binding site both host a nickel ion each. We reveal that upon adding glutamate or ATP for catalytic reactions, nickel-induced EcGS filament reverts to individual dodecamers. Such tunable filament formation is often associated with stress responses. Our results provide detailed structural information on the mechanism underlying reversible and tunable EcGS filament formation.
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Affiliation(s)
- Pei‐Chi Huang
- Institute of Biological Chemistry Academia Sinica Taipei Taiwan
- Department of Chemistry National Taiwan Normal University Taipei Taiwan
| | - Shao‐Kang Chen
- Institute of Biological Chemistry Academia Sinica Taipei Taiwan
| | - Wei‐Hung Chiang
- Institute of Biological Chemistry Academia Sinica Taipei Taiwan
| | - Meng‐Ru Ho
- Institute of Biological Chemistry Academia Sinica Taipei Taiwan
| | - Kuen‐Phon Wu
- Institute of Biological Chemistry Academia Sinica Taipei Taiwan
- Institute of Biochemical Science College of Life Science, National Taiwan University Taipei Taiwan
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37
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Connecting Ras and CTP synthase in Drosophila. Exp Cell Res 2022; 416:113155. [DOI: 10.1016/j.yexcr.2022.113155] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 04/03/2022] [Accepted: 04/08/2022] [Indexed: 11/04/2022]
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38
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Miller JG, Hughes SA, Modlin C, Conticello VP. Structures of synthetic helical filaments and tubes based on peptide and peptido-mimetic polymers. Q Rev Biophys 2022; 55:1-103. [PMID: 35307042 DOI: 10.1017/s0033583522000014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractSynthetic peptide and peptido-mimetic filaments and tubes represent a diverse class of nanomaterials with a broad range of potential applications, such as drug delivery, vaccine development, synthetic catalyst design, encapsulation, and energy transduction. The structures of these filaments comprise supramolecular polymers based on helical arrangements of subunits that can be derived from self-assembly of monomers based on diverse structural motifs. In recent years, structural analyses of these materials at near-atomic resolution (NAR) have yielded critical insights into the relationship between sequence, local conformation, and higher-order structure and morphology. This structural information offers the opportunity for development of new tools to facilitate the predictable and reproduciblede novodesign of synthetic helical filaments. However, these studies have also revealed several significant impediments to the latter process – most notably, the common occurrence of structural polymorphism due to the lability of helical symmetry in structural space. This article summarizes the current state of knowledge on the structures of designed peptide and peptido-mimetic filamentous assemblies, with a focus on structures that have been solved to NAR for which reliable atomic models are available.
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Affiliation(s)
- Jessalyn G Miller
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA30322
| | - Spencer A Hughes
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA30322
| | - Charles Modlin
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA30322
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Sun Z, Zhang Z, Wang QQ, Liu JL. Combined Inactivation of CTPS1 and ATR Is Synthetically Lethal to MYC-Overexpressing Cancer Cells. Cancer Res 2022; 82:1013-1024. [PMID: 35022212 PMCID: PMC9359733 DOI: 10.1158/0008-5472.can-21-1707] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 09/30/2021] [Accepted: 12/28/2021] [Indexed: 01/07/2023]
Abstract
The "undruggable" oncogene MYC supports cancer cell proliferation and survival through parallel induction of multiple anabolic processes. Here we find that inhibiting CTP synthase (CTPS) selectively decreases cell viability and induces DNA replication stress in MYC-overexpressing cells. MYC-driven rRNA synthesis caused the selective DNA replication stress upon CTPS inhibition. Combined inhibition of CTPS and ataxia telangiectasia and Rad3-related protein (ATR) is synthetically lethal in MYC-overexpressing cells, promoting cell death in vitro and decreasing tumor growth in vivo. Unexpectedly, interfering with CTPS1 but not CTPS2 is required to induce replication stress in MYC-deregulated cancer cells and consequent cell death in the presence of an ATR inhibitor. These results highlight a specific and key role of CTPS1 in MYC-driven cancer, suggesting that selectively inhibiting CTPS1 in combination with ATR could be a promising strategy to combat disease progression. SIGNIFICANCE Inhibition of CTPS in MYC-overexpressing cells blocks pyrimidine synthesis while maintaining ribosome synthesis activity to create an anabolic imbalance that induces replication stress, providing a new approach to selectively target MYC-driven cancer. See related commentary by Chabanon and Postel-Vinay, p. 969.
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Affiliation(s)
- Zhe Sun
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Ziheng Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Qiao-Qi Wang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Ji-Long Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,Corresponding Author: Ji-Long Liu, School of Life Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Pudong, Shanghai, 201210, China. Phone: 8618-2176-28315; E-mail:
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40
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Krämer M, Dörfer E, Hickl D, Bellin L, Scherer V, Möhlmann T. Cytidine Triphosphate Synthase Four From Arabidopsis thaliana Attenuates Drought Stress Effects. FRONTIERS IN PLANT SCIENCE 2022; 13:842156. [PMID: 35360303 PMCID: PMC8960734 DOI: 10.3389/fpls.2022.842156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 02/08/2022] [Indexed: 06/14/2023]
Abstract
Cytidine triphosphate synthase (CTPS) catalyzes the final step in pyrimidine de novo synthesis. In Arabidopsis, this protein family consists of five members (CTPS1-5), and all of them localize to the cytosol. Specifically, CTPS4 showed a massive upregulation of transcript levels during abiotic stress, in line with increased staining of CTPS4 promoter:GUS lines in hypocotyl, root and to lesser extend leaf tissues. In a setup to study progressive drought stress, CTPS4 knockout mutants accumulated less fresh and dry weight at days 5-7 and showed impaired ability to recover from this stress after 3 days of rewatering. Surprisingly, a thorough physiological characterization of corresponding plants only revealed alterations in assimilation and accumulation of soluble sugars including those related to drought stress in the mutant. Bimolecular fluorescence complementation (BiFC) studies indicated the interaction of CTPS4 with other isoforms, possibly affecting cytoophidia (filaments formed by CTPS formation. Although the function of these structures has not been thoroughly investigated in plants, altered enzyme activity and effects on cell structure are reported in other organisms. CTPS activity is required for cell cycle progression and growth. Furthermore, drought can lead to the accumulation of reactive oxygen species (ROS) and by this, to DNA damage. We hypothesize that effects on the cell cycle or DNA repair might be relevant for the observed impaired reduced drought stress tolerance of CTPS4 mutants.
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41
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Mutant libraries reveal negative design shielding proteins from supramolecular self-assembly and relocalization in cells. Proc Natl Acad Sci U S A 2022; 119:2101117119. [PMID: 35078932 PMCID: PMC8812688 DOI: 10.1073/pnas.2101117119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2021] [Indexed: 01/07/2023] Open
Abstract
Genetic mutations fuel organismal evolution but can also cause disease. As proteins are the cell’s workhorses, the ways in which mutations can disrupt their structure, stability, function, and interactions have been studied extensively. However, proteins evolve and function in a cellular context, and our ability to relate changes in protein sequence to cell-level phenotypes remains limited. In particular, the molecular mechanism underlying most disease-associated mutations is unknown. Here, we show that mutations changing a protein’s surface chemistry can dramatically impact its supramolecular self-assembly and localization in the cell. These results highlight the complex nature of genotype–phenotype relationships with a simple system. Understanding the molecular consequences of mutations in proteins is essential to map genotypes to phenotypes and interpret the increasing wealth of genomic data. While mutations are known to disrupt protein structure and function, their potential to create new structures and localization phenotypes has not yet been mapped to a sequence space. To map this relationship, we employed two homo-oligomeric protein complexes in which the internal symmetry exacerbates the impact of mutations. We mutagenized three surface residues of each complex and monitored the mutations’ effect on localization and assembly phenotypes in yeast cells. While surface mutations are classically viewed as benign, our analysis of several hundred mutants revealed they often trigger three main phenotypes in these proteins: nuclear localization, the formation of puncta, and fibers. Strikingly, more than 50% of random mutants induced one of these phenotypes in both complexes. Analyzing the mutant’s sequences showed that surface stickiness and net charge are two key physicochemical properties associated with these changes. In one complex, more than 60% of mutants self-assembled into fibers. Such a high frequency is explained by negative design: charged residues shield the complex from self-interacting with copies of itself, and the sole removal of the charges induces its supramolecular self-assembly. A subsequent analysis of several other complexes targeted with alanine mutations suggested that such negative design is common. These results highlight that minimal perturbations in protein surfaces’ physicochemical properties can frequently drive assembly and localization changes in a cellular context.
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42
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Miura N. Condensate Formation by Metabolic Enzymes in Saccharomyces cerevisiae. Microorganisms 2022; 10:microorganisms10020232. [PMID: 35208686 PMCID: PMC8876316 DOI: 10.3390/microorganisms10020232] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/17/2022] [Accepted: 01/18/2022] [Indexed: 12/31/2022] Open
Abstract
Condensate formation by a group of metabolic enzymes in the cell is an efficient way of regulating cell metabolism through the formation of “membrane-less organelles.” Because of the use of green fluorescent protein (GFP) for investigating protein localization, various enzymes were found to form condensates or filaments in living Saccharomyces cerevisiae, mammalian cells, and in other organisms, thereby regulating cell metabolism in the certain status of the cells. Among different environmental stresses, hypoxia triggers the spatial reorganization of many proteins, including more than 20 metabolic enzymes, to form numerous condensates, including “Glycolytic body (G-body)” and “Purinosome.” These individual condensates are collectively named “Metabolic Enzymes Transiently Assembling (META) body”. This review overviews condensate or filament formation by metabolic enzymes in S. cerevisiae, focusing on the META body, and recent reports in elucidating regulatory machinery of META body formation.
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Affiliation(s)
- Natsuko Miura
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai 599-8531, Japan
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43
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Thangadurai S, Bajgiran M, Manickam S, Mohana-Kumaran N, Azzam G. CTP synthase: the hissing of the cellular serpent. Histochem Cell Biol 2022; 158:517-534. [PMID: 35881195 PMCID: PMC9314535 DOI: 10.1007/s00418-022-02133-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2022] [Indexed: 12/24/2022]
Abstract
CTP biosynthesis is carried out by two pathways: salvage and de novo. CTPsyn catalyzes the latter. The study of CTPsyn activity in mammalian cells began in the 1970s, and various fascinating discoveries were made regarding the role of CTPsyn in cancer and development. However, its ability to fit into a cellular serpent-like structure, termed 'cytoophidia,' was only discovered a decade ago by three independent groups of scientists. Although the self-assembly of CTPsyn into a filamentous structure is evolutionarily conserved, the enzyme activity upon this self-assembly varies in different species. CTPsyn is required for cellular development and homeostasis. Changes in the expression of CTPsyn cause developmental changes in Drosophila melanogaster. A high level of CTPsyn activity and formation of cytoophidia are often observed in rapidly proliferating cells such as in stem and cancer cells. Meanwhile, the deficiency of CTPsyn causes severe immunodeficiency leading to immunocompromised diseases caused by bacteria, viruses, and parasites, making CTPsyn an attractive therapeutic target. Here, we provide an overview of the role of CTPsyn in cellular and disease perspectives along with its potential as a drug target.
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Affiliation(s)
- Shallinie Thangadurai
- grid.11875.3a0000 0001 2294 3534School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
| | - Morteza Bajgiran
- grid.11875.3a0000 0001 2294 3534School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
| | - Sharvin Manickam
- grid.11875.3a0000 0001 2294 3534School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
| | - Nethia Mohana-Kumaran
- grid.11875.3a0000 0001 2294 3534School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
| | - Ghows Azzam
- grid.11875.3a0000 0001 2294 3534School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia ,grid.454125.3Malaysia Genome and Vaccine Institute, National Institutes of Biotechnology Malaysia, Jalan Bangi, 43000 Kajang, Selangor Malaysia
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44
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Burrell AL, Nie C, Said M, Simonet JC, Fernández-Justel D, Johnson MC, Quispe J, Buey RM, Peterson JR, Kollman JM. IMPDH1 retinal variants control filament architecture to tune allosteric regulation. Nat Struct Mol Biol 2022; 29:47-58. [PMID: 35013599 PMCID: PMC9044917 DOI: 10.1038/s41594-021-00706-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 11/23/2021] [Indexed: 01/06/2023]
Abstract
Inosine-5'-monophosphate dehydrogenase (IMPDH), a key regulatory enzyme in purine nucleotide biosynthesis, dynamically assembles filaments in response to changes in metabolic demand. Humans have two isoforms: IMPDH2 filaments reduce sensitivity to feedback inhibition, while IMPDH1 assembly remains uncharacterized. IMPDH1 plays a unique role in retinal metabolism, and point mutants cause blindness. Here, in a series of cryogenic-electron microscopy structures we show that human IMPDH1 assembles polymorphic filaments with different assembly interfaces in extended and compressed states. Retina-specific splice variants introduce structural elements that reduce sensitivity to GTP inhibition, including stabilization of the extended filament form. Finally, we show that IMPDH1 disease mutations fall into two classes: one disrupts GTP regulation and the other has no effect on GTP regulation or filament assembly. These findings provide a foundation for understanding the role of IMPDH1 in retinal function and disease and demonstrate the diverse mechanisms by which metabolic enzyme filaments are allosterically regulated.
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Affiliation(s)
- Anika L Burrell
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Chuankai Nie
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
| | - Meerit Said
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Jacqueline C Simonet
- Cancer Epigenetics and Signaling Program, Fox Chase Cancer Center, Philadelphia, PA, USA
- Department of Biology, Arcadia University, Glenside, PA, USA
| | - David Fernández-Justel
- Metabolic Engineering Group, Departamento de Microbiología y Genética, Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain
| | - Matthew C Johnson
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Department of Structural Biology, Genentech, South San Francisco, CA, USA
| | - Joel Quispe
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Rubén M Buey
- Metabolic Engineering Group, Departamento de Microbiología y Genética, Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain
| | - Jeffrey R Peterson
- Cancer Epigenetics and Signaling Program, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Justin M Kollman
- Department of Biochemistry, University of Washington, Seattle, WA, USA.
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45
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Bellin L, Scherer V, Dörfer E, Lau A, Vicente AM, Meurer J, Hickl D, Möhlmann T. Cytosolic CTP Production Limits the Establishment of Photosynthesis in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2021; 12:789189. [PMID: 34917117 PMCID: PMC8669480 DOI: 10.3389/fpls.2021.789189] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 11/02/2021] [Indexed: 06/14/2023]
Abstract
CTP synthases (CTPS) comprise a protein family of the five members CTPS1-CTPS5 in Arabidopsis, all located in the cytosol. Specifically, downregulation of CTPS2 by amiRNA technology results in plants with defects in chlorophyll accumulation and photosynthetic performance early in development. CTP and its deoxy form dCTP are present at low levels in developing seedlings. Thus, under conditions of fast proliferation, the synthesis of CTP (dCTP) can become a limiting factor for RNA and DNA synthesis. The higher sensitivity of ami-CTPS2 lines toward the DNA-Gyrase inhibitor ciprofloxacin, together with reduced plastid DNA copy number and 16S and 23S chloroplast ribosomal RNA support this view. High expression and proposed beneficial biochemical features render CTPS2 the most important isoform for early seedling development. In addition, CTPS2 was identified as an essential enzyme in embryo development before, as knock-out mutants were embryo lethal. In line with this, ami-CTPS2 lines also exhibited reduced seed numbers per plant.
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Affiliation(s)
- Leo Bellin
- Plant Physiology, Faculty of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Vanessa Scherer
- Plant Physiology, Faculty of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Eva Dörfer
- Plant Physiology, Faculty of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Anne Lau
- Plant Physiology, Faculty of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Alexandre Magno Vicente
- Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-University Munich, Planegg-Martinsried, Germany
| | - Jörg Meurer
- Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-University Munich, Planegg-Martinsried, Germany
| | - Daniel Hickl
- Plant Physiology, Faculty of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Torsten Möhlmann
- Plant Physiology, Faculty of Biology, University of Kaiserslautern, Kaiserslautern, Germany
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46
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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: 21] [Impact Index Per Article: 7.0] [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.
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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
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47
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Drosophila intestinal homeostasis requires CTP synthase. Exp Cell Res 2021; 408:112838. [PMID: 34560103 DOI: 10.1016/j.yexcr.2021.112838] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/12/2021] [Accepted: 09/17/2021] [Indexed: 11/22/2022]
Abstract
CTP synthase (CTPS) senses all four nucleotides and forms filamentous structures termed cytoophidia in all three domains of life. How CTPS and cytoophidia function in a developmental context, however, remains underexplored. We report that CTPS forms cytoophidia in a subset of cells in the Drosophila midgut. We found that cytoophidia exist in intestinal stem cells (ISC) and enteroblasts in similar proportions. Both refeeding after starvation and feeding with dextran sulfate sodium (DSS) induce ISC proliferation and elongate cytoophidia. Knockdown of CTPS inhibits ISC proliferation. Remarkably, disruption of CTPS cytoophidia inhibits DSS-induced ISC proliferation. Taken together, these data suggest that both the expression level and the filament-form property of CTPS are crucial for intestinal homeostasis in Drosophila.
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48
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Yoon J, Cho L, Kim S, Tun W, Peng X, Pasriga R, Moon S, Hong W, Ji H, Jung K, Jeon J, An G. CTP synthase is essential for early endosperm development by regulating nuclei spacing. PLANT BIOTECHNOLOGY JOURNAL 2021; 19:2177-2191. [PMID: 34058048 PMCID: PMC8541778 DOI: 10.1111/pbi.13644] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 05/04/2021] [Accepted: 05/22/2021] [Indexed: 06/12/2023]
Abstract
Cereal grain endosperms are an important source of human nutrition. Nuclear division in early endosperm development plays a major role in determining seed size; however, this development is not well understood. We identified the rice mutant endospermless 2 (enl2), which shows defects in the early stages of endosperm development. These phenotypes arise from mutations in OsCTPS1 that encodes a cytidine triphosphate synthase (CTPS). Both wild-type and mutant endosperms were normal at 8 h after pollination (HAP). In contrast, at 24 HAP, enl2 endosperm had approximately 10-16 clumped nuclei while wild-type nuclei had increased in number and migrated to the endosperm periphery. Staining of microtubules in endosperm at 24 HAP revealed that wild-type nuclei were evenly distributed by microtubules while the enl2-2 nuclei were tightly packed due to their reduction in microtubule association. In addition, OsCTPS1 interacts with tubulins; thus, these observations suggest that OsCTPS1 may be involved in microtubule formation. OsCTPS1 transiently formed macromolecular structures in the endosperm during early developmental stages, further supporting the idea that OsCTPS1 may function as a structural component during endosperm development. Finally, overexpression of OsCTPS1 increased seed weight by promoting endosperm nuclear division, suggesting that this trait could be used to increase grain yield.
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Affiliation(s)
- Jinmi Yoon
- Crop Biotech Institute and Graduate School of BiotechnologyKyung Hee UniversityYonginRepublic of Korea
- Department of Plant BioscienceCollege of Natural Resources and Life SciencePusan National UniversityMiryangRepublic of Korea
| | - Lae‐Hyeon Cho
- Crop Biotech Institute and Graduate School of BiotechnologyKyung Hee UniversityYonginRepublic of Korea
- Department of Plant BioscienceCollege of Natural Resources and Life SciencePusan National UniversityMiryangRepublic of Korea
| | - Sung‐Ryul Kim
- Gene Identification and Validation GroupGenetic Design and Validation UnitInternational Rice Research Institute (IRRI)Metro ManilaPhilippines
| | - Win Tun
- Crop Biotech Institute and Graduate School of BiotechnologyKyung Hee UniversityYonginRepublic of Korea
| | - Xin Peng
- Crop Biotech Institute and Graduate School of BiotechnologyKyung Hee UniversityYonginRepublic of Korea
- Institution of Genomics and BioinformaticsSouth China Agricultural UniversityGuangzhouChina
| | - Richa Pasriga
- Crop Biotech Institute and Graduate School of BiotechnologyKyung Hee UniversityYonginRepublic of Korea
| | - Sunok Moon
- Crop Biotech Institute and Graduate School of BiotechnologyKyung Hee UniversityYonginRepublic of Korea
| | - Woo‐Jong Hong
- Crop Biotech Institute and Graduate School of BiotechnologyKyung Hee UniversityYonginRepublic of Korea
| | - Hyeonso Ji
- National Institute of Agricultural Sciences, Rural Development AdministrationJeonjuRepublic of Korea
| | - Ki‐Hong Jung
- Crop Biotech Institute and Graduate School of BiotechnologyKyung Hee UniversityYonginRepublic of Korea
| | - Jong‐Seong Jeon
- Crop Biotech Institute and Graduate School of BiotechnologyKyung Hee UniversityYonginRepublic of Korea
| | - Gynheung An
- Crop Biotech Institute and Graduate School of BiotechnologyKyung Hee UniversityYonginRepublic of Korea
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Pan M, Liu Y, Zheng X, Zhou M, You C, Dai X. Comprehensive profiling of CTP-binding proteins using a biotinylated CTP affinity probe. CHINESE CHEM LETT 2021. [DOI: 10.1016/j.cclet.2021.05.057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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50
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Structural basis for isoform-specific inhibition of human CTPS1. Proc Natl Acad Sci U S A 2021; 118:2107968118. [PMID: 34583994 PMCID: PMC8501788 DOI: 10.1073/pnas.2107968118] [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] [Accepted: 08/13/2021] [Indexed: 12/17/2022] Open
Abstract
An effective immune response depends on the proliferation of T cells, a process that requires the enzyme CTP synthase 1 (CTPS1). Individuals lacking CTPS1 due to a rare genetic disorder exhibit severe immunodeficiencies but lack other major clinical consequences; the requirement for CTP synthase outside of the immune response is met by a second isoform, CTPS2. Inhibiting CTPS1 without affecting CTPS2 is therefore a promising strategy for treating autoimmune disorders and T cell cancers while avoiding off-target effects. We characterize both CTPS1-selective and nonselective inhibitors. Structures of CTPS bound to inhibitors reveal the mechanisms of inhibition and CTPS1 selectivity. Differences in product feedback inhibition between CTPS1 and CTPS2 explain how CTPS1 may sustain enzymatic activity required for T cell proliferation. Cytidine triphosphate synthase 1 (CTPS1) is necessary for an effective immune response, as revealed by severe immunodeficiency in CTPS1-deficient individuals [E. Martin et al.], [Nature] [510], [288–292] ([2014]). CTPS1 expression is up-regulated in activated lymphocytes to expand CTP pools [E. Martin et al.], [Nature] [510], [288–292] ([2014]), satisfying increased demand for nucleic acid and lipid synthesis [L. D. Fairbanks, M. Bofill, K. Ruckemann, H. A. Simmonds], [J. Biol. Chem. ] [270], [29682–29689] ([1995]). Demand for CTP in other tissues is met by the CTPS2 isoform and nucleoside salvage pathways [E. Martin et al.], [Nature] [510], [288–292] ([2014]). Selective inhibition of the proliferative CTPS1 isoform is therefore desirable in the treatment of immune disorders and lymphocyte cancers, but little is known about differences in regulation of the isoforms or mechanisms of known inhibitors. We show that CTP regulates both isoforms by binding in two sites that clash with substrates. CTPS1 is less sensitive to CTP feedback inhibition, consistent with its role in increasing CTP levels in proliferation. We also characterize recently reported small-molecule inhibitors, both CTPS1 selective and nonselective. Cryo-electron microscopy (cryo-EM) structures reveal these inhibitors mimic CTP binding in one inhibitory site, where a single amino acid substitution explains selectivity for CTPS1. The inhibitors bind to CTPS assembled into large-scale filaments, which for CTPS1 normally represents a hyperactive form of the enzyme [E. M. Lynch et al.], [Nat. Struct. Mol. Biol.] [24], [507–514] ([2017]). This highlights the utility of cryo-EM in drug discovery, particularly for cases in which targets form large multimeric assemblies not amenable to structure determination by other techniques. Both inhibitors also inhibit the proliferation of human primary T cells. The mechanisms of selective inhibition of CTPS1 lay the foundation for the design of immunosuppressive therapies.
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