1
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Lynch EM, Lu Y, Park JH, Shao L, Kollman J, Rego EH. Evolutionarily divergent Mycobacterium tuberculosis CTP synthase filaments are under selective pressure. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.25.605180. [PMID: 39091829 PMCID: PMC11291164 DOI: 10.1101/2024.07.25.605180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
The final and rate-limiting enzyme in pyrimidine biosynthesis, CTP synthase (CTPS), is essential for the viability of Mycobacterium tuberculosis and other mycobacteria. Its product, CTP, is critical for RNA, DNA, lipid and cell wall synthesis, and is involved in chromosome segregation. In various organisms across the tree of life, CTPS assembles into higher-order filaments, leading us to hypothesize that M. tuberculosis CTPS (mtCTPS) also forms higher-order structures. Here, we show that mtCTPS does assemble into filaments but with an unusual architecture not seen in other organisms. Through a combination of structural, biochemical, and cellular techniques, we show that polymerization stabilizes the active conformation of the enzyme and resists product inhibition, potentially allowing for the highly localized production of CTP within the cell. Indeed, CTPS filaments localize near the CTP-dependent complex needed for chromosome segregation, and cells expressing mutant enzymes unable to polymerize are altered in their ability to robustly form this complex. Intriguingly, mutants that alter filament formation are under positive selection in clinical isolates of M. tuberculosis , pointing to a critical role needed to withstand pressures imposed by the host and/or antibiotics. Taken together, our data reveal an unexpected mechanism for the spatially organized production of a critical nucleotide in M. tuberculosis , which may represent a vulnerability of the pathogen that can be exploited with chemotherapy.
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2
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Shan Z, Rivero-Gamez A, Lyumkis D, Horton NC. Two-metal ion mechanism of DNA cleavage by activated, filamentous SgrAI. J Biol Chem 2024; 300:107576. [PMID: 39009341 DOI: 10.1016/j.jbc.2024.107576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Revised: 06/21/2024] [Accepted: 07/09/2024] [Indexed: 07/17/2024] Open
Abstract
Enzymes that form filamentous assemblies with modulated enzymatic activities have gained increasing attention in recent years. SgrAI is a sequence specific type II restriction endonuclease that forms polymeric filaments with accelerated DNA cleavage activity and expanded DNA sequence specificity. Prior studies have suggested a mechanistic model linking the structural changes accompanying SgrAI filamentation to its accelerated DNA cleavage activity. In this model, the conformational changes that are specific to filamentous SgrAI maximize contacts between different copies of the enzyme within the filament and create a second divalent cation binding site in each subunit, which in turn facilitates the DNA cleavage reaction. However, our understanding of the atomic mechanism of catalysis is incomplete. Herein, we present two new structures of filamentous SgrAI solved using cryo-EM. The first structure, resolved to 3.3 Å, is of filamentous SgrAI containing an active site mutation that is designed to stall the DNA cleavage reaction, which reveals the enzymatic configuration prior to DNA cleavage. The second structure, resolved to 3.1 Å, is of WT filamentous SgrAI containing cleaved substrate DNA, which reveals the enzymatic configuration at the end of the enzymatic cleavage reaction. Both structures contain the phosphate moiety at the cleavage site and the biologically relevant divalent cation cofactor Mg2+ and define how the Mg2+ cation reconfigures during enzymatic catalysis. The data support a model for the activation mechanism that involves binding of a second Mg2+ in the SgrAI active site as a direct result of filamentation induced conformational changes.
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Affiliation(s)
- Zelin Shan
- The Salk Institute of Biological Sciences, La Jolla, California, USA
| | - Andres Rivero-Gamez
- The Salk Institute of Biological Sciences, La Jolla, California, USA; Department of Molecular Biology, School of Biological Sciences, University of California, San Diego La Jolla, California, USA
| | - Dmitry Lyumkis
- The Salk Institute of Biological Sciences, La Jolla, California, USA; Department of Molecular Biology, School of Biological Sciences, University of California, San Diego La Jolla, California, USA.
| | - Nancy C Horton
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, USA.
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3
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Guo CJ, Zhang T, Leng Q, Zhou X, Zhong J, Liu JL. Dynamic Arabidopsis P5CS filament facilitates substrate channelling. NATURE PLANTS 2024; 10:880-889. [PMID: 38740943 PMCID: PMC11208152 DOI: 10.1038/s41477-024-01697-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 04/11/2024] [Indexed: 05/16/2024]
Abstract
In plants, the rapid accumulation of proline is a common response to combat abiotic stress1-7. Delta-1-pyrroline-5-carboxylate synthase (P5CS) is a rate-limiting enzyme in proline synthesis, catalysing the initial two-step conversion from glutamate to proline8. Here we determine the first structure of plant P5CS. Our results show that Arabidopsis thaliana P5CS1 (AtP5CS1) and P5CS2 (AtP5CS2) can form enzymatic filaments in a substrate-sensitive manner. The destruction of AtP5CS filaments by mutagenesis leads to a significant reduction in enzymatic activity. Furthermore, separate activity tests on two domains reveal that filament-based substrate channelling is essential for maintaining the high catalytic efficiency of AtP5CS. Our study demonstrates the unique mechanism for the efficient catalysis of AtP5CS, shedding light on the intricate mechanisms underlying plant proline metabolism and stress response.
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Affiliation(s)
- Chen-Jun Guo
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Tianyi Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Qingqing Leng
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Xian Zhou
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Jiale Zhong
- 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, UK.
- Shanghai Clinical Research and Trial Center, Shanghai, China.
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4
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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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5
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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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6
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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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7
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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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8
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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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9
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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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10
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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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11
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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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12
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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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13
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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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14
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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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15
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Asnagli H, Minet N, Pfeiffer C, Hoeben E, Lane R, Laughton D, Birch L, Jones G, Novak A, Parker AE, Ludwig H, Fischer A, Latour S, Beer PA. CTP Synthase 1 Is a Novel Therapeutic Target in Lymphoma. Hemasphere 2023; 7:e864. [PMID: 37008165 PMCID: PMC10060080 DOI: 10.1097/hs9.0000000000000864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 02/08/2023] [Indexed: 03/29/2023] Open
Abstract
Lymphoma is the most common hematological malignancy and is among the 10 most prevalent cancers worldwide. Although survival has been improved by modern immunochemotherapeutic regimens, there remains a significant need for novel targeted agents to treat both B-cell and T-cell malignancies. Cytidine triphosphate synthase 1 (CTPS1), which catalyzes the rate-limiting step in pyrimidine synthesis, plays an essential and nonredundant role in B-cell and T-cell proliferation but is complemented by the homologous CTPS2 isoform outside the hemopoietic system. This report describes the identification and characterization of CTPS1 as a novel target in B- and T-cell cancers. A series of small molecules have been developed which show potent and highly selective inhibition of CTPS1. Site-directed mutagenesis studies identified the adenosine triphosphate pocket of CTPS1 as the binding site for this small molecule series. In preclinical studies, a potent and highly selective small molecule inhibitor of CTPS1 blocked the in vitro proliferation of human neoplastic cells, showing the highest potency against lymphoid neoplasms. Importantly, pharmacological CTPS1 inhibition induced cell death by apoptosis in the majority of lymphoid cell lines tested, thus demonstrating a cytotoxic mechanism of action. Selective CTPS1 inhibition also inhibited the growth of neoplastic human B- and T- cells in vivo. These findings identify CTPS1 as a novel therapeutic target in lymphoid malignancy. A compound from this series is in phase 1/2 clinical studies for the treatment of relapsed/refractory B- and T-cell lymphoma (NCT05463263).
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16
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Hvorecny KL, Hargett K, Quispe JD, Kollman JM. Human PRPS1 filaments stabilize allosteric sites to regulate activity. Nat Struct Mol Biol 2023; 30:391-402. [PMID: 36747094 PMCID: PMC10033377 DOI: 10.1038/s41594-023-00921-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 01/10/2023] [Indexed: 02/08/2023]
Abstract
The universally conserved enzyme phosphoribosyl pyrophosphate synthetase (PRPS) assembles filaments in evolutionarily diverse organisms. PRPS is a key regulator of nucleotide metabolism, and mutations in the human enzyme PRPS1 lead to a spectrum of diseases. Here we determine structures of human PRPS1 filaments in active and inhibited states, with fixed assembly contacts accommodating both conformations. The conserved assembly interface stabilizes the binding site for the essential activator phosphate, increasing activity in the filament. Some disease mutations alter assembly, supporting the link between filament stability and activity. Structures of active PRPS1 filaments turning over substrate also reveal coupling of catalysis in one active site with product release in an adjacent site. PRPS1 filaments therefore provide an additional layer of allosteric control, conserved throughout evolution, with likely impact on metabolic homeostasis. Stabilization of allosteric binding sites by polymerization adds to the growing diversity of assembly-based enzyme regulatory mechanisms.
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Affiliation(s)
- Kelli L Hvorecny
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Kenzee Hargett
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Joel D Quispe
- 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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Hu X, Han Y, Liu J, Wang H, Tian Z, Zhang X, Zhang Y, Wang X. CTP synthase 2 predicts inferior survival and mediates DNA damage response via interacting with BRCA1 in chronic lymphocytic leukemia. Exp Hematol Oncol 2023; 12:6. [PMID: 36635772 PMCID: PMC9835321 DOI: 10.1186/s40164-022-00364-0] [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: 09/13/2022] [Accepted: 12/29/2022] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Cytidine triphosphate synthase 2 (CTPS2) is an essential metabolic enzyme that catalyzes the biosynthesis of CTP. CTP synthases contribute to lymphocytes proliferation and tumorigenesis, but the role of CTPS2 in chronic lymphocytic leukemia (CLL) remains undefined. METHODS In silico analysis was performed to quantified the expression and clinical analysis of CTPS2 and BRCA1. The expression was then validated on the internal sets. Loss-and gain-of-function assays were conducted to investigate the physiological phenotypes in CLL. RNA-seq was employed to probe the molecular mechanism of CTPS2. RESULTS Herein, significant elevated expression of CTPS2 was observed in CLL patients compared to normal CD19 + B cells, which was verified in three independent cohorts. Furthermore, overexpression of CTPS2 was closely associated with undesired prognostic indicators, including unmutated IGHV status and chromosome 11q23 deletion. Additionally, elevated CTPS2 expression predicted adverse overall survival and treatment-free survival with independent prognostic significance. Downregulation of CTPS2 in CLL cells exhibited attenuated cell proliferation, arrested G2/M cell cycle and increased apoptosis. The addition of CTP or glutamine could reverse the above effects. Since RNA-seq showed the enrichment in DNA damage and response signaling, we subsequently found that silence of CTPS2 remarkably elevated DNA damage and decreased DNA repair. It was demonstrated that CTPS2 mediated DNA damage response via interacting with Breast Cancer 1 (BRCA1) protein in CLL through CoIP assays and rescued experiments. CONCLUSIONS Collectively, our study generated the novel findings that CTPS2 promoted CLL progression via DNA damage response and repair pathway. Targeting nucleotide metabolism potentially became an attractive strategy for treatment against CLL.
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Affiliation(s)
- Xinting Hu
- grid.27255.370000 0004 1761 1174Department of Hematology, Shandong Provincial Hospital, Shandong University, No.324, Jingwu Road, Jinan, 250021 Shandong China ,Shandong Provincial Engineering Research Center of Lymphoma, Jinan, 250021 Shandong China ,Branch of National Clinical Research Center for Hematologic Diseases, Jinan, 250021 Shandong China ,grid.429222.d0000 0004 1798 0228National Clinical Research Center for Hematologic Diseases, The First Affiliated Hospital of Soochow University, Suzhou, 251006 China
| | - Yang Han
- grid.460018.b0000 0004 1769 9639Department of Hematology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, No.324, Jingwu Road, Jinan, 250021 Shandong China ,Shandong Provincial Engineering Research Center of Lymphoma, Jinan, 250021 Shandong China ,Branch of National Clinical Research Center for Hematologic Diseases, Jinan, 250021 Shandong China ,grid.429222.d0000 0004 1798 0228National Clinical Research Center for Hematologic Diseases, The First Affiliated Hospital of Soochow University, Suzhou, 251006 China
| | - Jiarui Liu
- grid.460018.b0000 0004 1769 9639Department of Hematology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, No.324, Jingwu Road, Jinan, 250021 Shandong China ,Shandong Provincial Engineering Research Center of Lymphoma, Jinan, 250021 Shandong China ,Branch of National Clinical Research Center for Hematologic Diseases, Jinan, 250021 Shandong China ,grid.429222.d0000 0004 1798 0228National Clinical Research Center for Hematologic Diseases, The First Affiliated Hospital of Soochow University, Suzhou, 251006 China
| | - Hua Wang
- grid.460018.b0000 0004 1769 9639Department of Hematology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, No.324, Jingwu Road, Jinan, 250021 Shandong China ,Shandong Provincial Engineering Research Center of Lymphoma, Jinan, 250021 Shandong China ,Branch of National Clinical Research Center for Hematologic Diseases, Jinan, 250021 Shandong China ,grid.429222.d0000 0004 1798 0228National Clinical Research Center for Hematologic Diseases, The First Affiliated Hospital of Soochow University, Suzhou, 251006 China
| | - Zheng Tian
- grid.27255.370000 0004 1761 1174Department of Hematology, Shandong Provincial Hospital, Shandong University, No.324, Jingwu Road, Jinan, 250021 Shandong China ,Shandong Provincial Engineering Research Center of Lymphoma, Jinan, 250021 Shandong China ,Branch of National Clinical Research Center for Hematologic Diseases, Jinan, 250021 Shandong China ,grid.429222.d0000 0004 1798 0228National Clinical Research Center for Hematologic Diseases, The First Affiliated Hospital of Soochow University, Suzhou, 251006 China
| | - Xin Zhang
- grid.27255.370000 0004 1761 1174Department of Hematology, Shandong Provincial Hospital, Shandong University, No.324, Jingwu Road, Jinan, 250021 Shandong China ,Shandong Provincial Engineering Research Center of Lymphoma, Jinan, 250021 Shandong China ,Branch of National Clinical Research Center for Hematologic Diseases, Jinan, 250021 Shandong China ,grid.429222.d0000 0004 1798 0228National Clinical Research Center for Hematologic Diseases, The First Affiliated Hospital of Soochow University, Suzhou, 251006 China
| | - Ya Zhang
- grid.460018.b0000 0004 1769 9639Department of Hematology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, No.324, Jingwu Road, Jinan, 250021 Shandong China ,Shandong Provincial Engineering Research Center of Lymphoma, Jinan, 250021 Shandong China ,Branch of National Clinical Research Center for Hematologic Diseases, Jinan, 250021 Shandong China ,grid.429222.d0000 0004 1798 0228National Clinical Research Center for Hematologic Diseases, The First Affiliated Hospital of Soochow University, Suzhou, 251006 China
| | - Xin Wang
- grid.27255.370000 0004 1761 1174Department of Hematology, Shandong Provincial Hospital, Shandong University, No.324, Jingwu Road, Jinan, 250021 Shandong China ,grid.460018.b0000 0004 1769 9639Department of Hematology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, No.324, Jingwu Road, Jinan, 250021 Shandong China ,Shandong Provincial Engineering Research Center of Lymphoma, Jinan, 250021 Shandong China ,Branch of National Clinical Research Center for Hematologic Diseases, Jinan, 250021 Shandong China ,grid.429222.d0000 0004 1798 0228National Clinical Research Center for Hematologic Diseases, The First Affiliated Hospital of Soochow University, Suzhou, 251006 China
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18
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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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19
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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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20
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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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21
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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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22
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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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23
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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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24
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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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25
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Koehler FC, Fu CY, Späth MR, Hoyer-Allo KJR, Bohl K, Göbel H, Lackmann JW, Grundmann F, Osterholt T, Gloistein C, Steiner JD, Antebi A, Benzing T, Schermer B, Schwarz G, Burst V, Müller RU. A systematic analysis of diet-induced nephroprotection reveals overlapping changes in cysteine catabolism. Transl Res 2022; 244:32-46. [PMID: 35189406 DOI: 10.1016/j.trsl.2022.02.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 02/03/2022] [Accepted: 02/14/2022] [Indexed: 01/28/2023]
Abstract
Caloric Restriction (CR) extends lifespan and augments cellular stress-resistance from yeast to primates, making CR an attractive strategy for organ protection in the clinic. Translation of CR to patients is complex, due to problems regarding adherence, feasibility, and safety concerns in frail patients. Novel tailored dietary regimens, which modulate the dietary composition of macro- and micronutrients rather than reducing calorie intake promise similar protective effects and increased translatability. However, a direct head-to-head comparison to identify the most potent approach for organ protection, as well as overlapping metabolic consequences have not been performed. We systematically analyzed six dietary preconditioning protocols - fasting mimicking diet (FMD), ketogenic diet (KD), dietary restriction of branched chained amino acids (BCAA), two dietary regimens restricting sulfur-containing amino acids (SR80/100) and CR - in a rodent model of renal ischemia-reperfusion injury (IRI) to quantify diet-induced resilience in kidneys. Of the administered diets, FMD, SR80/100 and CR efficiently protect from kidney damage after IRI. Interestingly, these approaches show overlapping changes in oxidative and hydrogen sulfide (H2S)-dependent cysteine catabolism as a potential common mechanism of organ protection.
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Affiliation(s)
- Felix C Koehler
- Department II of Internal Medicine, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; CECAD, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Chun-Yu Fu
- Institute of Biochemistry, Faculty of Mathematics and Natural Sciences, University of Cologne, Cologne, Germany
| | - Martin R Späth
- Department II of Internal Medicine, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; CECAD, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - K Johanna R Hoyer-Allo
- Department II of Internal Medicine, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; CECAD, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Katrin Bohl
- Department II of Internal Medicine, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; CECAD, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Heike Göbel
- Institute for Pathology, Diagnostic and Experimental Nephropathology Unit, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Jan-Wilm Lackmann
- CECAD, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Franziska Grundmann
- Department II of Internal Medicine, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Thomas Osterholt
- Department II of Internal Medicine, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Claas Gloistein
- Department II of Internal Medicine, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Joachim D Steiner
- Department II of Internal Medicine, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Adam Antebi
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Thomas Benzing
- Department II of Internal Medicine, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; CECAD, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Bernhard Schermer
- Department II of Internal Medicine, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; CECAD, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Günter Schwarz
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany; Institute of Biochemistry, Faculty of Mathematics and Natural Sciences, University of Cologne, Cologne, Germany.
| | - Volker Burst
- Department II of Internal Medicine, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Roman-Ulrich Müller
- Department II of Internal Medicine, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; CECAD, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
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26
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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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27
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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: 20] [Impact Index Per Article: 10.0] [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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28
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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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29
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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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30
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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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31
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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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32
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Abstract
Cytidine triphosphate synthase (CTPS), which comprises an ammonia ligase domain and a glutamine amidotransferase domain, catalyzes the final step of de novo CTP biosynthesis. The activity of CTPS is regulated by the binding of four nucleotides and glutamine. While glutamine serves as an ammonia donor for the ATP-dependent conversion of UTP to CTP, the fourth nucleotide GTP acts as an allosteric activator. Models have been proposed to explain the mechanisms of action at the active site of the ammonia ligase domain and the conformational changes derived by GTP binding. However, actual GTP/ATP/UTP binding modes and relevant conformational changes have not been revealed fully. Here, we report the discovery of binding modes of four nucleotides and a glutamine analog 6-diazo-5-oxo-L-norleucine in Drosophila CTPS by cryo-electron microscopy with near-atomic resolution. Interactions between GTP and surrounding residues indicate that GTP acts to coordinate reactions at both domains by directly blocking ammonia leakage and stabilizing the ammonia tunnel. Additionally, we observe the ATP-dependent UTP phosphorylation intermediate and determine interacting residues at the ammonia ligase. A noncanonical CTP binding at the ATP binding site suggests another layer of feedback inhibition. Our findings not only delineate the structure of CTPS in the presence of all substrates but also complete our understanding of the underlying mechanisms of the allosteric regulation and CTP synthesis.
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Abstract
Epstein-Barr virus (EBV) is associated with 200,000 cancers annually, including B-cell lymphomas in immunosuppressed hosts. Hypomorphic mutations of the de novo pyrimidine synthesis pathway enzyme cytidine 5′ triphosphate synthase 1 (CTPS1) suppress cell-mediated immunity, resulting in fulminant EBV infection and EBV+ central nervous system (CNS) lymphomas. Since CTP is a critical precursor for DNA, RNA, and phospholipid synthesis, this observation raises the question of whether the isozyme CTPS2 or cytidine salvage pathways help meet CTP demand in EBV-infected B cells. Here, we found that EBV upregulated CTPS1 and CTPS2 with distinct kinetics in newly infected B cells. While CRISPR CTPS1 knockout caused DNA damage and proliferation defects in lymphoblastoid cell lines (LCLs), which express the EBV latency III program observed in CNS lymphomas, double CTPS1/2 knockout caused stronger phenotypes. EBNA2, MYC, and noncanonical NF-κB positively regulated CTPS1 expression. CTPS1 depletion impaired EBV lytic DNA synthesis, suggesting that latent EBV may drive pathogenesis with CTPS1 deficiency. Cytidine rescued CTPS1/2 deficiency phenotypes in EBV-transformed LCLs and Burkitt B cells, highlighting CTPS1/2 as a potential therapeutic target for EBV-driven lymphoproliferative disorders. Collectively, our results suggest that CTPS1 and CTPS2 have partially redundant roles in EBV-transformed B cells and provide insights into EBV pathogenesis with CTPS1 deficiency.
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34
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Zhang S, Feng HC, Liu JL. ASNS disruption shortens CTPS cytoophidia in Saccharomyces cerevisiae. G3-GENES GENOMES GENETICS 2021; 11:6080684. [PMID: 33561249 PMCID: PMC8022725 DOI: 10.1093/g3journal/jkaa060] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 12/09/2020] [Indexed: 02/07/2023]
Abstract
Asparagine synthetase (ASNS) and CTP synthase (CTPS) are two metabolic enzymes that catalyze the biosynthesis of asparagine and CTP, respectively. Both CTPS and ASNS have been identified to form cytoophidia in Saccharomyces cerevisiae. Glutamine is a common substrate for both these enzymes, and they play an important role in glutamine homeostasis. Here, we find that the ASNS cytoophidia are shorter than the CTPS cytoophidia, and that disruption of ASNS shortens the length of CTPS cytoophidia. However, the deletion of CTPS has no effect on the formation and length of ASNS cytoophidia, or on the ASNS protein level. We also find that Asn1 overexpression induces the formation of a multi-dot structure in diauxic phase which suggests that the increased protein level may trigger cytoophidia formation. Collectively, our results reveal a connection between ASNS cytoophidia and CTPS cytoophidia.
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Affiliation(s)
- Shanshan Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.,University of Chinese Academy of Sciences, Beijing, 100049, China.,Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Han-Chao Feng
- 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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35
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Chang CC, Keppeke GD, Antos CL, Peng M, Andrade LEC, Sung LY, Liu JL. CTPS forms the cytoophidium in zebrafish. Exp Cell Res 2021; 405:112684. [PMID: 34129847 DOI: 10.1016/j.yexcr.2021.112684] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 05/30/2021] [Accepted: 06/01/2021] [Indexed: 12/26/2022]
Abstract
Cytidine triphosphate synthase (CTPS) catalyzes the rate-limiting step of de novo CTP biosynthesis. An intracellular structure of CTPS, the cytoophidium, has been found in many organisms including prokaryotes and eukaryotes. Formation of the cytoophidium has been suggested to regulate the activity and stability of CTPS and may participate in certain physiological events. Herein, we demonstrate that both CTPS1a and CTPS1b in zebrafish are able to form the cytoophidium in cultured cells. A point mutation, H355A, abrogates cytoophidium assembly of zebrafish CTPS1a and CTPS1b. In addition, we show the presence of CTPS cytoophidia in multiple tissues of larval and adult fish under normal conditions, while treatment with a CTPS inhibitor 6-diazo-5-oxo-l-norleucine (DON) can induce more cytoophidia in some tissues. Our findings reveal that forming the CTPS cytoophidium is a natural phenomenon of zebrafish and provide valuable information for future research on the physiological importance of this intracellular structure in vertebrates.
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Affiliation(s)
- Chia-Chun Chang
- 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
| | - Christopher L Antos
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Min Peng
- Institute of Biotechnology, National Taiwan University, Taipei, 106, Taiwan
| | - Luis Eduardo Coelho Andrade
- 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, United Kingdom.
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36
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Simonet JC, Burrell AL, Kollman JM, Peterson JR. Freedom of assembly: metabolic enzymes come together. Mol Biol Cell 2021; 31:1201-1205. [PMID: 32463766 PMCID: PMC7353150 DOI: 10.1091/mbc.e18-10-0675] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Many different enzymes in intermediate metabolism dynamically assemble filamentous polymers in cells, often in response to changes in physiological conditions. Most of the enzyme filaments known to date have only been observed in cells, but in a handful of cases structural and biochemical studies have revealed the mechanisms and consequences of assembly. In general, enzyme polymerization functions as a mechanism to allosterically tune enzyme kinetics, and it may play a physiological role in integrating metabolic signaling. Here, we highlight some principles of metabolic filaments by focusing on two well-studied examples in nucleotide biosynthesis pathways—inosine-5’-monophosphate (IMP) dehydrogenase and cytosine triphosphate (CTP) synthase.
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Affiliation(s)
| | - Anika L Burrell
- Department of Biochemistry, University of Washington, Seattle, Washington 98195
| | - Justin M Kollman
- Department of Biochemistry, University of Washington, Seattle, Washington 98195
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37
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Peng M, Chang CC, Liu JL, Sung LY. CTPS and IMPDH form cytoophidia in developmental thymocytes. Exp Cell Res 2021; 405:112662. [PMID: 34022203 DOI: 10.1016/j.yexcr.2021.112662] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 05/13/2021] [Accepted: 05/15/2021] [Indexed: 02/06/2023]
Abstract
The cytoophidium, a filamentous structure formed by metabolic enzymes, has emerged as a novel regulatory machinery for certain proteins. The rate-limiting enzymes of de novo CTP and GTP synthesis, cytidine triphosphate synthase (CTPS) and inosine monophosphate dehydrogenase (IMPDH), are the most characterized cytoophidium-forming enzymes in mammalian models. Although the assembly of CTPS cytoophidia has been demonstrated in various organisms including multiple human cancers, a systemic survey for the presence of CTPS cytoophidia in mammalian tissues in normal physiological conditions has not yet been reported. Herein, we examine major organs of adult mouse and observe that CTPS cytoophidia are displayed by a specific thymocyte population ranging between DN3 to early DP stages. Most of these cytoophidium-presenting cells have both CTPS and IMPDH cytoophidia and undergo rapid cell proliferation. In addition, we show that cytoophidium formation is associated with active glycolytic metabolism as the cytoophidium-presenting cells exhibit higher levels of c-Myc, phospho-Akt and PFK. Inhibition of glycolysis with 2DG, however, disrupts most of cytoophidium structures and impairs cell proliferation. Our findings not only indicate that the regulation of CTPS and IMPDH cytoophidia are correlated with the metabolic switch triggered by pre-TCR signaling, but also suggest physiological roles of the cytoophidium in thymocyte development.
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Affiliation(s)
- Min Peng
- Institute of Biotechnology, National Taiwan University, Taipei, 106, Taiwan
| | - Chia-Chun Chang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Ji-Long Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
| | - Li-Ying Sung
- Institute of Biotechnology, National Taiwan University, Taipei, 106, Taiwan; Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 115, Taiwan; Animal Resource Center, National Taiwan University, Taipei, 106, Taiwan.
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38
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Noree C, Sirinonthanawech N. Nuclear targeted Saccharomyces cerevisiae asparagine synthetases associate with the mitotic spindle regardless of their enzymatic activity. PLoS One 2020; 15:e0243742. [PMID: 33347445 PMCID: PMC7751962 DOI: 10.1371/journal.pone.0243742] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 11/28/2020] [Indexed: 12/14/2022] Open
Abstract
Recently, human asparagine synthetase has been found to be associated with the mitotic spindle. However, this event cannot be seen in yeast because yeast takes a different cell division process via closed mitosis (there is no nuclear envelope breakdown to allow the association between any cytosolic enzyme and mitotic spindle). To find out if yeast asparagine synthetase can also (but hiddenly) have this feature, the coding sequences of green fluorescent protein (GFP) and nuclear localization signal (NLS) were introduced downstream of ASN1 and ASN2, encoding asparagine synthetases Asn1p and Asn2p, respectively, in the yeast genome having mCherrry coding sequence downstream of TUB1 encoding alpha-tubulin, a building block of the mitotic spindle. The genomically engineered yeast strains showed co-localization of Asn1p-GFP-NLS (or Asn2p-GFP-NLS) and Tub1p-mCherry in dividing nuclei. In addition, an activity-disrupted mutation was introduced to ASN1 (or ASN2). The yeast mutants still exhibited co-localization between defective asparagine synthetase and mitotic spindle, indicating that the biochemical activity of asparagine synthetase is not required for its association with the mitotic spindle. Furthermore, nocodazole treatment was used to depolymerize the mitotic spindle, resulting in lack of association between the enzyme and the mitotic spindle. Although yeast cell division undergoes closed mitosis, preventing the association of its asparagine synthetase with the mitotic spindle, however, by using yeast constructs with re-localized Asn1/2p have suggested the moonlighting role of asparagine synthetase in cell division of higher eukaryotes.
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Affiliation(s)
- Chalongrat Noree
- Institute of Molecular Biosciences, Mahidol University, Salaya, Phuttamonthon, Nakhon Pathom, Thailand
| | - Naraporn Sirinonthanawech
- Institute of Molecular Biosciences, Mahidol University, Salaya, Phuttamonthon, Nakhon Pathom, Thailand
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Montrose K, López Cabezas RM, Paukštytė J, Saarikangas J. Winter is coming: Regulation of cellular metabolism by enzyme polymerization in dormancy and disease. Exp Cell Res 2020; 397:112383. [PMID: 33212148 DOI: 10.1016/j.yexcr.2020.112383] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 11/12/2020] [Accepted: 11/14/2020] [Indexed: 12/20/2022]
Abstract
Metabolism feeds growth. Accordingly, metabolism is regulated by nutrient-sensing pathways that converge growth promoting signals into biosynthesis by regulating the activity of metabolic enzymes. When the environment does not support growth, organisms invest in survival. For cells, this entails transitioning into a dormant, quiescent state (G0). In dormancy, the activity of biosynthetic pathways is dampened, and catabolic metabolism and stress tolerance pathways are activated. Recent work in yeast has demonstrated that dormancy is associated with alterations in the physicochemical properties of the cytoplasm, including changes in pH, viscosity and macromolecular crowding. Accompanying these changes, numerous metabolic enzymes transition from soluble to polymerized assemblies. These large-scale self-assemblies are dynamic and depolymerize when cells resume growth. Here we review how enzyme polymerization enables metabolic plasticity by tuning carbohydrate, nucleic acid, amino acid and lipid metabolic pathways, with particular focus on its potential adaptive value in cellular dormancy.
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Affiliation(s)
- Kristopher Montrose
- Helsinki Institute of Life Science, HiLIFE, University of Helsinki, Finland; Research Programme in Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland
| | - Rosa María López Cabezas
- Helsinki Institute of Life Science, HiLIFE, University of Helsinki, Finland; Research Programme in Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland
| | - Jurgita Paukštytė
- Helsinki Institute of Life Science, HiLIFE, University of Helsinki, Finland; Research Programme in Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland
| | - Juha Saarikangas
- Helsinki Institute of Life Science, HiLIFE, University of Helsinki, Finland; Research Programme in Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland; Neuroscience Center, University of Helsinki, Finland.
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Simonet JC, Foster MJ, Lynch EM, Kollman JM, Nicholas E, O'Reilly AM, Peterson JR. CTP synthase polymerization in germline cells of the developing Drosophila egg supports egg production. Biol Open 2020; 9:bio050328. [PMID: 32580972 PMCID: PMC7390647 DOI: 10.1242/bio.050328] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 06/16/2020] [Indexed: 01/19/2023] Open
Abstract
Polymerization of metabolic enzymes into micron-scale assemblies is an emerging mechanism for regulating their activity. CTP synthase (CTPS) is an essential enzyme in the biosynthesis of the nucleotide CTP and undergoes regulated and reversible assembly into large filamentous structures in organisms from bacteria to humans. The purpose of these assemblies is unclear. A major challenge to addressing this question has been the inability to abolish assembly without eliminating CTPS protein. Here we demonstrate that a recently reported point mutant in CTPS, Histidine 355A (H355A), prevents CTPS filament assembly in vivo and dominantly inhibits the assembly of endogenous wild-type CTPS in the Drosophila ovary. Expressing this mutant in ovarian germline cells, we show that disruption of CTPS assembly in early stage egg chambers reduces egg production. This effect is exacerbated in flies fed the glutamine antagonist 6-diazo-5-oxo-L-norleucine, which inhibits de novo CTP synthesis. These findings introduce a general approach to blocking the assembly of polymerizing enzymes without eliminating their catalytic activity and demonstrate a role for CTPS assembly in supporting egg production, particularly under conditions of limited glutamine metabolism.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Jacqueline C Simonet
- Cancer Biology Program, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA
| | - Maya J Foster
- Immersion Science Program, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA
| | - Eric M Lynch
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Justin M Kollman
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Emmanuelle Nicholas
- Cancer Biology Program, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA
| | - Alana M O'Reilly
- Molecular Therapeutics Program, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA
| | - Jeffrey R Peterson
- Cancer Biology Program, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA
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Lynch EM, Kollman JM, Webb BA. Filament formation by metabolic enzymes-A new twist on regulation. Curr Opin Cell Biol 2020; 66:28-33. [PMID: 32417394 DOI: 10.1016/j.ceb.2020.04.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 04/07/2020] [Accepted: 04/08/2020] [Indexed: 01/18/2023]
Abstract
Compartmentalization of metabolic enzymes through protein-protein interactions is an emerging mechanism for localizing and regulating metabolic activity. Self-assembly into linear filaments is a common strategy for cellular compartmentalization of enzymes. Polymerization is often driven by changes in the metabolic state of the cell, suggesting that it is a strategy for shifting metabolic flux in response to cellular demand. Although polymerization of metabolic enzymes is widespread, observed from bacteria to humans, we are just beginning to appreciate their role in regulating cellular metabolism. In most cases, one functional role of metabolic enzyme filaments is allosteric control of enzyme activity. Here, we highlight recent findings, providing insight into the structural and functional significance of filamentation of metabolic enzymes in cells.
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Affiliation(s)
- Eric M Lynch
- Department of Biochemistry, University of Washington, USA
| | | | - Bradley A Webb
- Department of Biochemistry, West Virginia University, USA.
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42
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The structure of helical lipoprotein lipase reveals an unexpected twist in lipase storage. Proc Natl Acad Sci U S A 2020; 117:10254-10264. [PMID: 32332168 DOI: 10.1073/pnas.1916555117] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Lipases are enzymes necessary for the proper distribution and utilization of lipids in the human body. Lipoprotein lipase (LPL) is active in capillaries, where it plays a crucial role in preventing dyslipidemia by hydrolyzing triglycerides from packaged lipoproteins. Thirty years ago, the existence of a condensed and inactive LPL oligomer was proposed. Although recent work has shed light on the structure of the LPL monomer, the inactive oligomer remained opaque. Here we present a cryo-EM reconstruction of a helical LPL oligomer at 3.8-Å resolution. Helix formation is concentration-dependent, and helices are composed of inactive dihedral LPL dimers. Heparin binding stabilizes LPL helices, and the presence of substrate triggers helix disassembly. Superresolution fluorescent microscopy of endogenous LPL revealed that LPL adopts a filament-like distribution in vesicles. Mutation of one of the helical LPL interaction interfaces causes loss of the filament-like distribution. Taken together, this suggests that LPL is condensed into its inactive helical form for storage in intracellular vesicles.
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43
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Zhou S, Xiang H, Liu JL. CTP synthase forms cytoophidia in archaea. J Genet Genomics 2020; 47:213-223. [DOI: 10.1016/j.jgg.2020.03.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 03/12/2020] [Accepted: 03/18/2020] [Indexed: 12/14/2022]
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Zhang B, Tastan ÖY, Zhou X, Guo CJ, Liu X, Thind A, Hu HH, Zhao S, Liu JL. The proline synthesis enzyme P5CS forms cytoophidia in Drosophila. J Genet Genomics 2020; 47:131-143. [PMID: 32317150 DOI: 10.1016/j.jgg.2020.02.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 02/25/2020] [Accepted: 02/29/2020] [Indexed: 01/26/2023]
Abstract
Compartmentation of enzymes via filamentation has arisen as a mechanism for the regulation of metabolism. In 2010, three groups independently reported that CTP synthase (CTPS) can assemble into a filamentous structure termed the cytoophidium. In searching for CTPS-interacting proteins, here we perform a yeast two-hybrid screening of Drosophila proteins and identify a putative CTPS-interacting protein, △1-pyrroline-5-carboxylate synthase (P5CS). Using the Drosophila follicle cell as the in vivo model, we confirm that P5CS forms cytoophidia, which are associated with CTPS cytoophidia. Overexpression of P5CS increases the length of CTPS cytoophidia. Conversely, filamentation of CTPS affects the morphology of P5CS cytoophidia. Finally, in vitro analyses confirm the filament-forming property of P5CS. Our work links CTPS with P5CS, two enzymes involved in the rate-limiting steps in pyrimidine and proline biosynthesis, respectively.
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Affiliation(s)
- Bo Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China; Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ömür Y Tastan
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, United Kingdom
| | - 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
| | - Xuyang Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China; iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
| | - Aaron Thind
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, United Kingdom
| | - Huan-Huan Hu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Suwen Zhao
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China; iHuman Institute, 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.
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45
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Johnson MC, Kollman JM. Cryo-EM structures demonstrate human IMPDH2 filament assembly tunes allosteric regulation. eLife 2020; 9:e53243. [PMID: 31999252 PMCID: PMC7018514 DOI: 10.7554/elife.53243] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 01/29/2020] [Indexed: 02/06/2023] Open
Abstract
Inosine monophosphate dehydrogenase (IMPDH) mediates the first committed step in guanine nucleotide biosynthesis and plays important roles in cellular proliferation and the immune response. IMPDH reversibly polymerizes in cells and tissues in response to changes in metabolic demand. Self-assembly of metabolic enzymes is increasingly recognized as a general mechanism for regulating activity, typically by stabilizing specific conformations of an enzyme, but the regulatory role of IMPDH filaments has remained unclear. Here, we report a series of human IMPDH2 cryo-EM structures in both active and inactive conformations. The structures define the mechanism of filament assembly, and reveal how filament-dependent allosteric regulation of IMPDH2 makes the enzyme less sensitive to feedback inhibition, explaining why assembly occurs under physiological conditions that require expansion of guanine nucleotide pools. Tuning sensitivity to an allosteric inhibitor distinguishes IMPDH from other metabolic filaments, and highlights the diversity of regulatory outcomes that can emerge from self-assembly.
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Affiliation(s)
- Matthew C Johnson
- Department of BiochemistryUniversity of WashingtonSeattleUnited States
| | - Justin M Kollman
- Department of BiochemistryUniversity of WashingtonSeattleUnited States
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