1
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Cecil JH, Padilla CM, Lipinski AA, Langlais PR, Luo X, Capaldi AP. The Molecular Logic of Gtr1/2 and Pib2 Dependent TORC1 Regulation in Budding Yeast. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.06.570342. [PMID: 38106135 PMCID: PMC10723367 DOI: 10.1101/2023.12.06.570342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
The Target of Rapamycin kinase Complex I (TORC1) regulates cell growth and metabolism in eukaryotes. Previous studies have shown that, in Saccharomyces cerevisiae, nitrogen and amino acid signals activate TORC1 via the highly conserved small GTPases, Gtr1/2, and the phosphatidylinositol 3-phosphate binding protein, Pib2. However, it was unclear if/how Gtr1/2 and Pib2 cooperate to control TORC1. Here we report that this dual regulator system pushes TORC1 into three distinct signaling states: (i) a Gtr1/2 on, Pib2 on, rapid growth state in nutrient replete conditions; (ii) a Gtr1/2 off, Pib2 on, adaptive/slow growth state in poor-quality growth medium; and (iii) a Gtr1/2 off, Pib2 off, quiescent state in starvation conditions. We suggest that other signaling pathways work in a similar way, to drive a multi-level response via a single kinase, but the behavior has been overlooked since most studies follow signaling to a single reporter protein.
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Affiliation(s)
- Jacob H. Cecil
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ, 85721
| | - Cristina M. Padilla
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ, 85721
| | | | - Paul R. Langlais
- Department of Medicine, University of Arizona, Tucson, AZ, 85721
| | - Xiangxia Luo
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ, 85721
| | - Andrew P. Capaldi
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ, 85721
- Bio5 Institute, University of Arizona, Tucson, AZ, 85721
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2
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Abeliovich H. Mitophagy in yeast: known unknowns and unknown unknowns. Biochem J 2023; 480:1639-1657. [PMID: 37850532 PMCID: PMC10586778 DOI: 10.1042/bcj20230279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 09/06/2023] [Accepted: 09/22/2023] [Indexed: 10/19/2023]
Abstract
Mitophagy, the autophagic breakdown of mitochondria, is observed in eukaryotic cells under various different physiological circumstances. These can be broadly categorized into two types: mitophagy related to quality control events and mitophagy induced during developmental transitions. Quality control mitophagy involves the lysosomal or vacuolar degradation of malfunctioning or superfluous mitochondria within lysosomes or vacuoles, and this is thought to serve as a vital maintenance function in respiring eukaryotic cells. It plays a crucial role in maintaining physiological balance, and its disruption has been associated with the progression of late-onset diseases. Developmentally induced mitophagy has been reported in the differentiation of metazoan tissues which undergo metabolic shifts upon developmental transitions, such as in the differentiation of red blood cells and muscle cells. Although the mechanistic studies of mitophagy in mammalian cells were initiated after the initial mechanistic findings in Saccharomyces cerevisiae, our current understanding of the physiological role of mitophagy in yeast remains more limited, despite the presence of better-defined assays and tools. In this review, I present my perspective on our present knowledge of mitophagy in yeast, focusing on physiological and mechanistic aspects. I aim to focus on areas where our understanding is still incomplete, such as the role of mitochondrial dynamics and the phenomenon of protein-level selectivity.
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Affiliation(s)
- Hagai Abeliovich
- Institute of Biochemistry, Food Science and Nutrition, Hebrew University of Jerusalem, 1 Hankin St, Rehovot 7610001, Israel
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3
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Xu S, Qiao W, Wang Z, Fu X, Liu Z, Shi S. Exploiting a heterologous construction of the 3-hydroxypropionic acid carbon fixation pathway with mesaconate as an indicator in Saccharomyces cerevisiae. BIORESOUR BIOPROCESS 2023; 10:33. [PMID: 38647598 PMCID: PMC10991142 DOI: 10.1186/s40643-023-00652-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 05/14/2023] [Indexed: 04/25/2024] Open
Abstract
The 3-Hydroxypropionic acid (3-HP) pathway is one of the six known natural carbon fixation pathways, in which the carbon species used is bicarbonate. It has been considered to be the most suitable pathway for aerobic CO2 fixation among the six natural carbon fixation pathways. Mesaconate is a high value-added derivative in the 3-HP pathway and can be used as a co-monomer to produce fire-retardant materials and hydrogels. In this study, we use mesaconate as a reporting compound to evaluate the construction and optimization of the sub-part of the 3-HP pathway in Saccharomyces cerevisiae. Combined with fine-tuning of the malonyl-CoA reductase (MCR-C and MCR-N) expression level and optimization of 3-Hydroxypropionyl-CoA synthase, the 3-HP sub-pathway was optimized using glucose or ethanol as the substrate, with the productions of mesaconate reaching 90.78 and 61.2 mg/L, respectively.
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Affiliation(s)
- Shijie Xu
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Weibo Qiao
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Zuanwen Wang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Xiaoying Fu
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Zihe Liu
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Shuobo Shi
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029, China.
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4
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Wallace RL, Lu E, Luo X, Capaldi AP. Ait1 regulates TORC1 signaling and localization in budding yeast. eLife 2022; 11:68773. [PMID: 36047762 PMCID: PMC9499541 DOI: 10.7554/elife.68773] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 08/31/2022] [Indexed: 11/23/2022] Open
Abstract
The target of rapamycin complex I (TORC1) regulates cell growth and metabolism in eukaryotes. Previous studies have shown that nitrogen and amino acid signals activate TORC1 via the highly conserved small GTPases, Gtr1/2 (RagA/C in humans), and the GTPase activating complex SEAC/GATOR. However, it remains unclear if, and how, other proteins/pathways regulate TORC1 in simple eukaryotes like yeast. Here, we report that the previously unstudied GPCR-like protein, Ait1, binds to TORC1-Gtr1/2 in Saccharomyces cerevisiae and holds TORC1 around the vacuole during log-phase growth. Then, during amino acid starvation, Ait1 inhibits TORC1 via Gtr1/2 using a loop that resembles the RagA/C-binding domain in the human protein SLC38A9. Importantly, Ait1 is only found in the Saccharomycetaceae/codaceae, two closely related families of yeast that have lost the ancient TORC1 regulators Rheb and TSC1/2. Thus, the TORC1 circuit found in the Saccharomycetaceae/codaceae, and likely other simple eukaryotes, has undergone significant rewiring during evolution.
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Affiliation(s)
- Ryan L Wallace
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States
| | - Eric Lu
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States
| | - Xiangxia Luo
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States
| | - Andrew P Capaldi
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States
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5
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Liu Y, Zhang X, Wang W, Liu T, Ren J, Chen S, Lu T, Tie Y, Yuan X, Mo F, Yang J, Wei Y, Wei X. Ammonia promotes the proliferation of bone marrow-derived mesenchymal stem cells by regulating the Akt/mTOR/S6k pathway. Bone Res 2022; 10:57. [PMID: 36028500 PMCID: PMC9418171 DOI: 10.1038/s41413-022-00215-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 02/28/2022] [Accepted: 03/20/2022] [Indexed: 11/11/2022] Open
Abstract
Ammonia plays an important role in cellular metabolism. However, ammonia is considered a toxic product. In bone marrow-derived mesenchymal stem cells, multipotent stem cells with high expression of glutamine synthetase (GS) in bone marrow, ammonia and glutamate can be converted to glutamine via glutamine synthetase activity to support the proliferation of MSCs. As a major nutritional amino acid for biosynthesis, glutamine can activate the Akt/mTOR/S6k pathway to stimulate cell proliferation. The activation of mTOR can promote cell entry into S phase, thereby enhancing DNA synthesis and cell proliferation. Our studies demonstrated that mesenchymal stem cells can convert the toxic waste product ammonia into nutritional glutamine via GS activity. Then, the Akt/mTOR/S6k pathway is activated to promote bone marrow-derived mesenchymal stem cell proliferation. These results suggest a new therapeutic strategy and potential target for the treatment of diseases involving hyperammonemia.
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Affiliation(s)
- Yu Liu
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, Sichuan, 610041, PR China
| | - Xiangxian Zhang
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, Sichuan, 610041, PR China
| | - Wei Wang
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, Sichuan, 610041, PR China
| | - Ting Liu
- Department of Clinical Laboratory, The West China Second University Hospital of Sichuan University (WCSUH-SCU), Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, Sichuan, 610041, PR China
| | - Jun Ren
- Department of Prenatal Diagnosis Center, The West China Second University Hospital of Sichuan University (WCSUH-SCU), Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, Sichuan, 610041, PR China
| | - Siyuan Chen
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, Sichuan, 610041, PR China
| | - Tianqi Lu
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, Sichuan, 610041, PR China
| | - Yan Tie
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, Sichuan, 610041, PR China
| | - Xia Yuan
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, Sichuan, 610041, PR China
| | - Fei Mo
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, Sichuan, 610041, PR China
| | - Jingyun Yang
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, Sichuan, 610041, PR China
| | - Yuquan Wei
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, Sichuan, 610041, PR China
| | - Xiawei Wei
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, Sichuan, 610041, PR China.
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6
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Dentel B, Angeles-Perez L, Ren C, Jakkamsetti V, Holley AJ, Caballero D, Oh E, Gibson J, Pascual JM, Huber KM, Tu BP, Tsai PT. Increased glycine contributes to synaptic dysfunction and early mortality in Nprl2 seizure model. iScience 2022; 25:104334. [PMID: 35602938 PMCID: PMC9118754 DOI: 10.1016/j.isci.2022.104334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 09/16/2021] [Accepted: 04/26/2022] [Indexed: 10/25/2022] Open
Abstract
Targeted therapies for epilepsies associated with the mTORC1 signaling negative regulator GATOR1 are lacking. NPRL2 is a subunit of the GATOR1 complex and mutations in GATOR1 subunits, including NPRL2, are associated with epilepsy. To delineate the mechanisms underlying NPRL2-related epilepsies, we created a mouse (Mus musculus) model with neocortical loss of Nprl2. Mutant mice have increased mTORC1 signaling and exhibit spontaneous seizures. They also display abnormal synaptic function characterized by increased evoked and spontaneous EPSC and decreased evoked and spontaneous IPSC frequencies, respectively. Proteomic and metabolomics studies of Nprl2 mutants revealed alterations in known epilepsy-implicated proteins and metabolic pathways, including increases in the neurotransmitter, glycine. Furthermore, glycine actions on the NMDA receptor contribute to the electrophysiological and survival phenotypes of these mice. Taken together, in this neuronal Nprl2 model, we delineate underlying molecular, metabolic, and electrophysiological mechanisms contributing to mTORC1-related epilepsy, providing potential therapeutic targets for epilepsy.
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Affiliation(s)
- Brianne Dentel
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | | | - Chongyu Ren
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Vikram Jakkamsetti
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Andrew J. Holley
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Daniel Caballero
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Emily Oh
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Jay Gibson
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Juan M. Pascual
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Kimberly M. Huber
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Benjamin P. Tu
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Peter T. Tsai
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75235, USA
- Departments of Pediatrics and Psychiatry, UT Southwestern Medical Center, Dallas, TX 75235, USA
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7
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Tate JJ, Marsikova J, Vachova L, Palkova Z, Cooper TG. Effects of abolishing Whi2 on the proteome and nitrogen catabolite repression-sensitive protein production. G3 (BETHESDA, MD.) 2022; 12:jkab432. [PMID: 35100365 PMCID: PMC9210300 DOI: 10.1093/g3journal/jkab432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 12/08/2021] [Indexed: 11/17/2022]
Abstract
In yeast physiology, a commonly used reference condition for many experiments, including those involving nitrogen catabolite repression (NCR), is growth in synthetic complete (SC) medium. Four SC formulations, SCCSH,1990, SCCSH,1994, SCCSH,2005, and SCME, have been used interchangeably as the nitrogen-rich medium of choice [Cold Spring Harbor Yeast Course Manuals (SCCSH) and a formulation in the methods in enzymology (SCME)]. It has been tacitly presumed that all of these formulations support equivalent responses. However, a recent report concluded that (i) TorC1 activity is downregulated by the lower concentration of primarily leucine in SCME relative to SCCSH. (ii) The Whi2-Psr1/2 complex is responsible for this downregulation. TorC1 is a primary nitrogen-responsive regulator in yeast. Among its downstream targets is control of NCR-sensitive transcription activators Gln3 and Gat1. They in turn control production of catabolic transporters and enzymes needed to scavenge poor nitrogen sources (e.g., Proline) and activate autophagy (ATG14). One of the reporters used in Chen et al. was an NCR-sensitive DAL80-GFP promoter fusion. This intrigued us because we expected minimal if any DAL80 expression in SC medium. Therefore, we investigated the source of the Dal80-GFP production and the proteomes of wild-type and whi2Δ cells cultured in SCCSH and SCME. We found a massive and equivalent reorientation of amino acid biosynthetic proteins in both wild-type and whi2Δ cells even though both media contained high overall concentrations of amino acids. Gcn2 appears to play a significant regulatory role in this reorientation. NCR-sensitive DAL80 expression and overall NCR-sensitive protein production were only marginally affected by the whi2Δ. In contrast, the levels of 58 proteins changed by an absolute value of log2 between 3 and 8 when Whi2 was abolished relative to wild type. Surprisingly, with only two exceptions could those proteins be related in GO analyses, i.e., GO terms associated with carbohydrate metabolism and oxidative stress after shifting a whi2Δ from SCCSH to SCME for 6 h. What was conspicuously missing were proteins related by TorC1- and NCR-associated GO terms.
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Affiliation(s)
- Jennifer J Tate
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Jana Marsikova
- Department of Genetics and Microbiology, Faculty of Science, Charles University, BIOCEV, 128 00 Prague, Czech Republic
| | - Libuse Vachova
- Institute of Microbiology of the Czech Academy of Sciences, BIOCEV, 142 20 Prague, Czech Republic
| | - Zdena Palkova
- Department of Genetics and Microbiology, Faculty of Science, Charles University, BIOCEV, 128 00 Prague, Czech Republic
| | - Terrance G Cooper
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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8
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Loissell-Baltazar YA, Dokudovskaya S. SEA and GATOR 10 Years Later. Cells 2021; 10:cells10102689. [PMID: 34685669 PMCID: PMC8534245 DOI: 10.3390/cells10102689] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/30/2021] [Accepted: 10/03/2021] [Indexed: 12/17/2022] Open
Abstract
The SEA complex was described for the first time in yeast Saccharomyces cerevisiae ten years ago, and its human homologue GATOR complex two years later. During the past decade, many advances on the SEA/GATOR biology in different organisms have been made that allowed its role as an essential upstream regulator of the mTORC1 pathway to be defined. In this review, we describe these advances in relation to the identification of multiple functions of the SEA/GATOR complex in nutrient response and beyond and highlight the consequence of GATOR mutations in cancer and neurodegenerative diseases.
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9
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Phithakrotchanakoon C, Puseenam A, Kruasuwan W, Likhitrattanapisal S, Phaonakrop N, Roytrakul S, Ingsriswang S, Tanapongpipat S, Roongsawang N. Identification of proteins responsive to heterologous protein production in thermotolerant methylotrophic yeast Ogataea thermomethanolica TBRC656. Yeast 2021; 38:316-325. [PMID: 33445217 DOI: 10.1002/yea.3548] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 01/04/2021] [Accepted: 01/05/2021] [Indexed: 11/09/2022] Open
Abstract
The thermotolerant methylotrophic yeast Ogataea thermomethanolica TBRC656 is a potential host for heterologous protein production. However, overproduction of heterologous protein can induce cellular stress and limit the level of its secretion. To improve the secretion of heterologous protein, we identified the candidate proteins with altered production during production of heterologous protein in O. thermomethanolica by using a label-free comparative proteomic approach. Four hundred sixty-four proteins with various biological functions showed differential abundance between O. thermomethanolica expressing fungal xylanase (OT + Xyl) and a control strain. The induction of proteins in transport and proteasomal proteolysis was prominently observed. Eight candidate proteins involved in cell wall biosynthesis (Chs3, Gas4), chaperone (Sgt2, Pex19), glycan metabolism (Csf1), protein transport (Ypt35), and vacuole and protein sorting (Cof1, Npr2) were mutated by a CRISPR/Cas9 approach. An Sgt2 mutant showed higher phytase and xylanase activity compared with the control strain (13%-20%), whereas mutants of other genes including Cof1, Pex19, Gas4, and Ypt35 showed lower xylanase activity compared with the control strain (15%-25%). In addition, an Npr2 mutant showed defective growth, while overproduction of Npr2 enhanced xylanase activity. These results reveal genes that can be mutated to modulate heterologous protein production and growth of O. thermomethanolica TBRC656.
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Affiliation(s)
- Chitwadee Phithakrotchanakoon
- Microbial Systems and Computational Biology Research Team, Thailand Bioresource Research Center, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathum Thani, Thailand
| | - Aekkachai Puseenam
- Microbial Cell Factory Research Team, Biorefinery and Bioproduct Technology Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathum Thani, Thailand
| | - Worarat Kruasuwan
- Microbial Cell Factory Research Team, Biorefinery and Bioproduct Technology Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathum Thani, Thailand
| | - Somsak Likhitrattanapisal
- Microbial Systems and Computational Biology Research Team, Thailand Bioresource Research Center, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathum Thani, Thailand
| | - Narumon Phaonakrop
- Functional Proteomics Technology, Functional Ingredients and Food Innovation Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathum Thani, Thailand
| | - Sittiruk Roytrakul
- Functional Proteomics Technology, Functional Ingredients and Food Innovation Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathum Thani, Thailand
| | - Supawadee Ingsriswang
- Microbial Systems and Computational Biology Research Team, Thailand Bioresource Research Center, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathum Thani, Thailand
| | - Sutipa Tanapongpipat
- Microbial Cell Factory Research Team, Biorefinery and Bioproduct Technology Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathum Thani, Thailand
| | - Niran Roongsawang
- Microbial Cell Factory Research Team, Biorefinery and Bioproduct Technology Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathum Thani, Thailand
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10
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Walvekar AS, Kadamur G, Sreedharan S, Gupta R, Srinivasan R, Laxman S. Methylated PP2A stabilizes Gcn4 to enable a methionine-induced anabolic program. J Biol Chem 2020; 295:18390-18405. [PMID: 33122193 PMCID: PMC7939465 DOI: 10.1074/jbc.ra120.014248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 10/25/2020] [Indexed: 11/06/2022] Open
Abstract
Methionine, through S-adenosylmethionine, activates a multifaceted growth program in which ribosome biogenesis, carbon metabolism, and amino acid and nucleotide biosynthesis are induced. This growth program requires the activity of the Gcn4 transcription factor (called ATF4 in mammals), which facilitates the supply of metabolic precursors that are essential for anabolism. However, how Gcn4 itself is regulated in the presence of methionine is unknown. Here, we discover that Gcn4 protein levels are increased by methionine, despite conditions of high cell growth and translation (in which the roles of Gcn4 are not well-studied). We demonstrate that this mechanism of Gcn4 induction is independent of transcription, as well as the conventional Gcn2/eIF2α-mediated increased translation of Gcn4. Instead, when methionine is abundant, Gcn4 phosphorylation is decreased, which reduces its ubiquitination and therefore degradation. Gcn4 is dephosphorylated by the protein phosphatase 2A (PP2A); our data show that when methionine is abundant, the conserved methyltransferase Ppm1 methylates and alters the activity of the catalytic subunit of PP2A, shifting the balance of Gcn4 toward a dephosphorylated, stable state. The absence of Ppm1 or the loss of the PP2A methylation destabilizes Gcn4 even when methionine is abundant, leading to collapse of the Gcn4-dependent anabolic program. These findings reveal a novel, methionine-dependent signaling and regulatory axis. Here methionine directs the conserved methyltransferase Ppm1 via its target phosphatase PP2A to selectively stabilize Gcn4. Through this, cells conditionally modify a major phosphatase to stabilize a metabolic master regulator and drive anabolism.
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Affiliation(s)
- Adhish S Walvekar
- Institute for Stem Cell Science and Regenerative Medicine (inStem), Bangalore, India
| | - Ganesh Kadamur
- Institute for Stem Cell Science and Regenerative Medicine (inStem), Bangalore, India
| | - Sreesa Sreedharan
- Institute for Stem Cell Science and Regenerative Medicine (inStem), Bangalore, India; School of Chemical and Biotechnology, SASTRA University, Tanjavur, India
| | - Ritu Gupta
- Institute for Stem Cell Science and Regenerative Medicine (inStem), Bangalore, India
| | | | - Sunil Laxman
- Institute for Stem Cell Science and Regenerative Medicine (inStem), Bangalore, India.
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11
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Ouyang Y, Wu Q, Li J, Sun S, Sun S. S-adenosylmethionine: A metabolite critical to the regulation of autophagy. Cell Prolif 2020; 53:e12891. [PMID: 33030764 PMCID: PMC7653241 DOI: 10.1111/cpr.12891] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 07/21/2020] [Accepted: 08/04/2020] [Indexed: 02/06/2023] Open
Abstract
Autophagy is a mechanism that enables cells to maintain cellular homeostasis by removing damaged materials and mobilizing energy reserves in conditions of starvation. Although nutrient availability strongly impacts the process of autophagy, the specific metabolites that regulate autophagic responses have not yet been determined. Recent results indicate that S-adenosylmethionine (SAM) represents a critical inhibitor of methionine starvation-induced autophagy. SAM is primarily involved in four key metabolic pathways: transmethylation, transsulphuration, polyamine synthesis and 5'-deoxyadenosyl 5'-radical-mediated biochemical transformations. SAM is the sole methyl group donor involved in the methylation of DNA, RNA and histones, modulating the autophagic process by mediating epigenetic effects. Moreover, the metabolites of SAM, such as homocysteine, glutathione, decarboxylated SAM and spermidine, also exert important influences on the regulation of autophagy. From our perspective, nuclear-cytosolic SAM is a conserved metabolic inhibitor that connects cellular metabolic status and the regulation of autophagy. In the future, SAM might be a new target of autophagy regulators and be widely used in the treatment of various diseases.
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Affiliation(s)
- Yang Ouyang
- Department of Breast and Thyroid SurgeryRenmin Hospital of Wuhan UniversityWuhanChina
| | - Qi Wu
- Department of Breast and Thyroid SurgeryRenmin Hospital of Wuhan UniversityWuhanChina
| | - Juanjuan Li
- Department of Breast and Thyroid SurgeryRenmin Hospital of Wuhan UniversityWuhanChina
| | - Si Sun
- Department of Clinical LaboratoryRenmin Hospital of Wuhan UniversityWuhanChina
| | - Shengrong Sun
- Department of Breast and Thyroid SurgeryRenmin Hospital of Wuhan UniversityWuhanChina
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12
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Agmon N, Temple J, Tang Z, Schraink T, Baron M, Chen J, Mita P, Martin JA, Tu BP, Yanai I, Fenyö D, Boeke JD. Phylogenetic debugging of a complete human biosynthetic pathway transplanted into yeast. Nucleic Acids Res 2020; 48:486-499. [PMID: 31745563 PMCID: PMC7145547 DOI: 10.1093/nar/gkz1098] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 11/04/2019] [Accepted: 11/16/2019] [Indexed: 12/30/2022] Open
Abstract
Cross-species pathway transplantation enables insight into a biological process not possible through traditional approaches. We replaced the enzymes catalyzing the entire Saccharomyces cerevisiae adenine de novo biosynthesis pathway with the human pathway. While the 'humanized' yeast grew in the absence of adenine, it did so poorly. Dissection of the phenotype revealed that PPAT, the human ortholog of ADE4, showed only partial function whereas all other genes complemented fully. Suppressor analysis revealed other pathways that play a role in adenine de-novo pathway regulation. Phylogenetic analysis pointed to adaptations of enzyme regulation to endogenous metabolite level 'setpoints' in diverse organisms. Using DNA shuffling, we isolated specific amino acids combinations that stabilize the human protein in yeast. Thus, using adenine de novo biosynthesis as a proof of concept, we suggest that the engineering methods used in this study as well as the debugging strategies can be utilized to transplant metabolic pathway from any origin into yeast.
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Affiliation(s)
- Neta Agmon
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Jasmine Temple
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Zuojian Tang
- Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Tobias Schraink
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, USA
| | - Maayan Baron
- Institute for Computational Medicine and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Jun Chen
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Paolo Mita
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - James A Martin
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Benjamin P Tu
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Itai Yanai
- Institute for Computational Medicine and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - David Fenyö
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Jef D Boeke
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
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13
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Anabolic SIRT4 Exerts Retrograde Control over TORC1 Signaling by Glutamine Sparing in the Mitochondria. Mol Cell Biol 2020; 40:MCB.00212-19. [PMID: 31685549 DOI: 10.1128/mcb.00212-19] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 10/28/2019] [Indexed: 12/30/2022] Open
Abstract
Anabolic and catabolic signaling mediated via mTOR and AMPK (AMP-activated kinase) have to be intrinsically coupled to mitochondrial functions for maintaining homeostasis and mitigate cellular/organismal stress. Although glutamine is known to activate mTOR, whether and how differential mitochondrial utilization of glutamine impinges on mTOR signaling has been less explored. Mitochondrial SIRT4, which unlike other sirtuins is induced in a fed state, is known to inhibit catabolic signaling/pathways through the AMPK-PGC1α/SIRT1-peroxisome proliferator-activated receptor α (PPARα) axis and negatively regulate glutamine metabolism via the tricarboxylic acid cycle. However, physiological significance of SIRT4 functions during a fed state is still unknown. Here, we establish SIRT4 as key anabolic factor that activates TORC1 signaling and regulates lipogenesis, autophagy, and cell proliferation. Mechanistically, we demonstrate that the ability of SIRT4 to inhibit anaplerotic conversion of glutamine to α-ketoglutarate potentiates TORC1. Interestingly, we also show that mitochondrial glutamine sparing or utilization is critical for differentially regulating TORC1 under fed and fasted conditions. Moreover, we conclusively show that differential expression of SIRT4 during fed and fasted states is vital for coupling mitochondrial energetics and glutamine utilization with anabolic pathways. These significant findings also illustrate that SIRT4 integrates nutrient inputs with mitochondrial retrograde signals to maintain a balance between anabolic and catabolic pathways.
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14
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Dutchak PA, Estill-Terpack SJ, Plec AA, Zhao X, Yang C, Chen J, Ko B, Deberardinis RJ, Yu Y, Tu BP. Loss of a Negative Regulator of mTORC1 Induces Aerobic Glycolysis and Altered Fiber Composition in Skeletal Muscle. Cell Rep 2019; 23:1907-1914. [PMID: 29768191 PMCID: PMC6038807 DOI: 10.1016/j.celrep.2018.04.058] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 12/28/2017] [Accepted: 04/13/2018] [Indexed: 01/11/2023] Open
Abstract
The conserved GATOR1 complex consisting of NPRL2-NPRL3-DEPDC5 inhibits mammalian target of rapamycin complex 1 (mTORC1) in response to amino acid insufficiency. Here, we show that loss of NPRL2 and GATOR1 function in skeletal muscle causes constitutive activation of mTORC1 signaling in the fed and fasted states. Muscle fibers of NPRL2 knockout animals are significantly larger and show altered fiber-type composition, with more fast-twitch glycolytic and fewer slow-twitch oxidative fibers. NPRL2 muscle knockout mice also have altered running behavior and enhanced glucose tolerance. Furthermore, loss of NPRL2 induces aerobic glycolysis and suppresses glucose entry into the TCA cycle. Such chronic activation of mTORC1 leads to compensatory increases in anaplerotic pathways to replenish TCA intermediates that are consumed for biosynthetic purposes. These phenotypes reveal a fundamental role for the GATOR1 complex in the homeostatic regulation of mitochondrial functions (biosynthesis versus ATP) to mediate carbohydrate utilization in muscle.
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Affiliation(s)
- Paul A Dutchak
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Psychiatry and Neuroscience, Université Laval, Québec, QC, Canada; CERVO Brain Research Centre, 2601 Chemin de la Canardière, Québec, QC, Canada
| | - Sandi J Estill-Terpack
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Abigail A Plec
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Xiaozheng Zhao
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Chendong Yang
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jun Chen
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Bookyung Ko
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Ralph J Deberardinis
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yonghao Yu
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Benjamin P Tu
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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15
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Walvekar AS, Laxman S. Methionine at the Heart of Anabolism and Signaling: Perspectives From Budding Yeast. Front Microbiol 2019; 10:2624. [PMID: 31798560 PMCID: PMC6874139 DOI: 10.3389/fmicb.2019.02624] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 10/28/2019] [Indexed: 12/18/2022] Open
Abstract
Studies using a fungal model, Saccharomyces cerevisiae, have been instrumental in advancing our understanding of sulfur metabolism in eukaryotes. Sulfur metabolites, particularly methionine and its derivatives, induce anabolic programs in yeast, and drive various processes integral to metabolism (one-carbon metabolism, nucleotide synthesis, and redox balance). Thereby, methionine also connects these processes with autophagy and epigenetic regulation. The direct involvement of methionine-derived metabolites in diverse chemistries such as transsulfuration and methylation reactions comes from the elegant positioning and safe handling of sulfur through these molecules. In this mini-review, we highlight studies from yeast that reveal how this amino acid holds a unique position in both metabolism and cell signaling, and illustrate cell fate decisions that methionine governs. We further discuss the interconnections between sulfur and NADPH metabolism, and highlight critical nodes around methionine metabolism that are promising for antifungal drug development.
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Affiliation(s)
| | - Sunil Laxman
- Regulation of Cell Fate, Institute for Stem Cell Science and Regenerative Medicine (inStem), Bangalore, India
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16
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Kato M, Yang YS, Sutter BM, Wang Y, McKnight SL, Tu BP. Redox State Controls Phase Separation of the Yeast Ataxin-2 Protein via Reversible Oxidation of Its Methionine-Rich Low-Complexity Domain. Cell 2019; 177:711-721.e8. [PMID: 30982603 DOI: 10.1016/j.cell.2019.02.044] [Citation(s) in RCA: 95] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 11/28/2018] [Accepted: 02/25/2019] [Indexed: 12/16/2022]
Abstract
Yeast ataxin-2, also known as Pbp1, senses the activity state of mitochondria in order to regulate TORC1. A domain of Pbp1 required to adapt cells to mitochondrial activity is of low sequence complexity. The low-complexity (LC) domain of Pbp1 forms labile, cross-β polymers that facilitate phase transition of the protein into liquid-like or gel-like states. Phase transition for other LC domains is reliant upon widely distributed aromatic amino acids. In place of tyrosine or phenylalanine residues prototypically used for phase separation, Pbp1 contains 24 similarly disposed methionine residues. Here, we show that the Pbp1 methionine residues are sensitive to hydrogen peroxide (H2O2)-mediated oxidation in vitro and in living cells. Methionine oxidation melts Pbp1 liquid-like droplets in a manner reversed by methionine sulfoxide reductase enzymes. These observations explain how reversible formation of labile polymers by the Pbp1 LC domain enables the protein to function as a sensor of cellular redox state.
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Affiliation(s)
- Masato Kato
- Department of Biochemistry, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA
| | - Yu-San Yang
- Department of Biochemistry, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA
| | - Benjamin M Sutter
- Department of Biochemistry, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA
| | - Yun Wang
- Department of Biochemistry, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA
| | - Steven L McKnight
- Department of Biochemistry, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA.
| | - Benjamin P Tu
- Department of Biochemistry, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA.
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17
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Yeast Ataxin-2 Forms an Intracellular Condensate Required for the Inhibition of TORC1 Signaling during Respiratory Growth. Cell 2019; 177:697-710.e17. [PMID: 30982600 DOI: 10.1016/j.cell.2019.02.043] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 10/04/2018] [Accepted: 02/25/2019] [Indexed: 12/20/2022]
Abstract
Yeast ataxin-2, also known as Pbp1 (polyA binding protein-binding protein 1), is an intrinsically disordered protein implicated in stress granule formation, RNA biology, and neurodegenerative disease. To understand the endogenous function of this protein, we identify Pbp1 as a dedicated regulator of TORC1 signaling and autophagy under conditions that require mitochondrial respiration. Pbp1 binds to TORC1 specifically during respiratory growth, but utilizes an additional methionine-rich, low complexity (LC) region to inhibit TORC1. This LC region causes phase separation, forms reversible fibrils, and enables self-association into assemblies required for TORC1 inhibition. Mutants that weaken phase separation in vitro exhibit reduced capacity to inhibit TORC1 and induce autophagy. Loss of Pbp1 leads to mitochondrial dysfunction and reduced fitness during nutritional stress. Thus, Pbp1 forms a condensate in response to respiratory status to regulate TORC1 signaling.
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18
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Ma Y, Moors A, Camougrand N, Dokudovskaya S. The SEACIT complex is involved in the maintenance of vacuole-mitochondria contact sites and controls mitophagy. Cell Mol Life Sci 2019; 76:1623-1640. [PMID: 30673821 PMCID: PMC11105764 DOI: 10.1007/s00018-019-03015-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 12/17/2018] [Accepted: 01/15/2019] [Indexed: 12/19/2022]
Abstract
The major signaling pathway that regulates cell growth and metabolism is under the control of the target of rapamycin complex 1 (TORC1). In Saccharomyces cerevisiae the SEA complex is one of the TORC1 upstream regulators involved in amino acid sensing and autophagy. Here, we performed analysis of the expression, interactions and localization of SEA complex proteins under different conditions, varying parameters such as sugar source, nitrogen availability and growth phase. Our results show that the SEA complex promotes mitochondria degradation either by mitophagy or by general autophagy. In addition, the SEACIT subcomplex is involved in the maintenance of the vacuole-mitochondria contact sites. Thus, the SEA complex appears to be an important link between the TORC1 pathway and regulation of mitochondria quality control.
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Affiliation(s)
- Yinxing Ma
- CNRS, UMR 8126, Université Paris-Sud 11, Institut Gustave Roussy, 114, rue Edouard Vaillant, 94805, Villejuif, France
| | - Alexis Moors
- CNRS, UMR 8126, Université Paris-Sud 11, Institut Gustave Roussy, 114, rue Edouard Vaillant, 94805, Villejuif, France
| | - Nadine Camougrand
- CNRS, IBGC, UMR 5095, 1, rue Camille Saint-Saens, 33000, Bordeaux, France
- Université de Bordeaux, IBGC, 1, rue Camille Saint-Saens, 33000, Bordeaux, France
| | - Svetlana Dokudovskaya
- CNRS, UMR 8126, Université Paris-Sud 11, Institut Gustave Roussy, 114, rue Edouard Vaillant, 94805, Villejuif, France.
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19
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Walvekar AS, Srinivasan R, Gupta R, Laxman S. Methionine coordinates a hierarchically organized anabolic program enabling proliferation. Mol Biol Cell 2018; 29:3183-3200. [PMID: 30354837 PMCID: PMC6340205 DOI: 10.1091/mbc.e18-08-0515] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 10/12/2018] [Accepted: 10/19/2018] [Indexed: 12/21/2022] Open
Abstract
Methionine availability during overall amino acid limitation metabolically reprograms cells to support proliferation, the underlying basis for which remains unclear. Here we construct the organization of this methionine-mediated anabolic program using yeast. Combining comparative transcriptome analysis and biochemical and metabolic flux-based approaches, we discover that methionine rewires overall metabolic outputs by increasing the activity of a key regulatory node. This comprises the pentose phosphate pathway (PPP) coupled with reductive biosynthesis, the glutamate dehydrogenase (GDH)-dependent synthesis of glutamate/glutamine, and pyridoxal-5-phosphate (PLP)-dependent transamination capacity. This PPP-GDH-PLP node provides the required cofactors and/or substrates for subsequent rate-limiting reactions in the synthesis of amino acids and therefore nucleotides. These rate-limiting steps in amino acid biosynthesis are also induced in a methionine-dependent manner. This thereby results in a biochemical cascade establishing a hierarchically organized anabolic program. For this methionine-mediated anabolic program to be sustained, cells co-opt a "starvation stress response" regulator, Gcn4p. Collectively, our data suggest a hierarchical metabolic framework explaining how methionine mediates an anabolic switch.
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Affiliation(s)
- Adhish S. Walvekar
- Institute for Stem Cell biology and Regenerative Medicine (inStem), NCBS-TIFR campus, Bangalore 560065, India
| | - Rajalakshmi Srinivasan
- Institute for Stem Cell biology and Regenerative Medicine (inStem), NCBS-TIFR campus, Bangalore 560065, India
| | - Ritu Gupta
- Institute for Stem Cell biology and Regenerative Medicine (inStem), NCBS-TIFR campus, Bangalore 560065, India
| | - Sunil Laxman
- Institute for Stem Cell biology and Regenerative Medicine (inStem), NCBS-TIFR campus, Bangalore 560065, India
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20
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Bourdeau Julien I, Sephton CF, Dutchak PA. Metabolic Networks Influencing Skeletal Muscle Fiber Composition. Front Cell Dev Biol 2018; 6:125. [PMID: 30324104 PMCID: PMC6172607 DOI: 10.3389/fcell.2018.00125] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 09/10/2018] [Indexed: 12/19/2022] Open
Abstract
Advancements in metabolomic and genomic research tools are revealing new insights into how metabolic networks can influence skeletal muscle fiber composition. In this mini-review, we summarize the recent progress of metabolite-dependent signaling pathways and transcriptional regulators that control glycolytic and oxidative metabolism and ultimately influence the type of fibers in muscle depots. These mechanisms expand the role of metabolites beyond that of basic building blocks of cellular components, and illustrate how particular metabolites can take an active role in regulating metabolic homeostasis and fiber adaptation. As new metabolite-dependent mechanisms emerge, ongoing metabolomic studies have begun to help explain why distinct metabolic pathways are used in different biological contexts and widen the view of seminal observations like the Warburg effect.
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Affiliation(s)
- Isabelle Bourdeau Julien
- Department of Psychiatry and Neuroscience, Université Laval, Quebec, QC, Canada.,CERVO Brain Research Centre, Quebec, QC, Canada
| | - Chantelle F Sephton
- Department of Psychiatry and Neuroscience, Université Laval, Quebec, QC, Canada.,CERVO Brain Research Centre, Quebec, QC, Canada
| | - Paul A Dutchak
- Department of Psychiatry and Neuroscience, Université Laval, Quebec, QC, Canada.,CERVO Brain Research Centre, Quebec, QC, Canada
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21
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Walvekar A, Rashida Z, Maddali H, Laxman S. A versatile LC-MS/MS approach for comprehensive, quantitative analysis of central metabolic pathways. Wellcome Open Res 2018; 3:122. [PMID: 30345389 PMCID: PMC6171562 DOI: 10.12688/wellcomeopenres.14832.1] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/17/2018] [Indexed: 11/23/2022] Open
Abstract
Liquid chromatography-mass spectrometry (LC-MS/MS) based approaches are widely used for the identification and quantitation of specific metabolites, and are a preferred approach towards analyzing cellular metabolism. Most methods developed come with specific requirements such as unique columns, ion-pairing reagents and pH conditions, and typically allow measurements in a specific pathway alone. Here, we present a single column-based set of methods for simultaneous coverage of multiple pathways, primarily focusing on central carbon, amino acid, and nucleotide metabolism. We further demonstrate the use of this method for quantitative, stable isotope-based metabolic flux experiments, expanding its use beyond steady-state level measurements of metabolites. The expected kinetics of label accumulation pertinent to the pathway under study are presented with some examples. The methods discussed here are broadly applicable, minimize the need for multiple chromatographic resolution methods, and highlight how simple labeling experiments can be valuable in facilitating a comprehensive understanding of the metabolic state of cells.
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Affiliation(s)
- Adhish Walvekar
- Institute for Stem Cell biology and Regenerative Medicine (inStem), Bangalore, Karnataka, 560065, India
| | - Zeenat Rashida
- Institute for Stem Cell biology and Regenerative Medicine (inStem), Bangalore, Karnataka, 560065, India
- Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Hemanth Maddali
- Institute for Stem Cell biology and Regenerative Medicine (inStem), Bangalore, Karnataka, 560065, India
| | - Sunil Laxman
- Institute for Stem Cell biology and Regenerative Medicine (inStem), Bangalore, Karnataka, 560065, India
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22
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Eleutherio E, Brasil ADA, França MB, de Almeida DSG, Rona GB, Magalhães RSS. Oxidative stress and aging: Learning from yeast lessons. Fungal Biol 2018; 122:514-525. [DOI: 10.1016/j.funbio.2017.12.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 12/04/2017] [Accepted: 12/05/2017] [Indexed: 02/06/2023]
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23
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Spinelli JB, Yoon H, Ringel AE, Jeanfavre S, Clish CB, Haigis MC. Metabolic recycling of ammonia via glutamate dehydrogenase supports breast cancer biomass. Science 2017; 358:941-946. [PMID: 29025995 PMCID: PMC5748897 DOI: 10.1126/science.aam9305] [Citation(s) in RCA: 270] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 09/29/2017] [Indexed: 12/12/2022]
Abstract
Ammonia is a ubiquitous by-product of cellular metabolism; however, the biological consequences of ammonia production are not fully understood, especially in cancer. We found that ammonia is not merely a toxic waste product but is recycled into central amino acid metabolism to maximize nitrogen utilization. In our experiments, human breast cancer cells primarily assimilated ammonia through reductive amination catalyzed by glutamate dehydrogenase (GDH); secondary reactions enabled other amino acids, such as proline and aspartate, to directly acquire this nitrogen. Metabolic recycling of ammonia accelerated proliferation of breast cancer. In mice, ammonia accumulated in the tumor microenvironment and was used directly to generate amino acids through GDH activity. These data show that ammonia is not only a secreted waste product but also a fundamental nitrogen source that can support tumor biomass.
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Affiliation(s)
- Jessica B Spinelli
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Haejin Yoon
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Alison E Ringel
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Sarah Jeanfavre
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Clary B Clish
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Marcia C Haigis
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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24
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Chen J, Sutter BM, Shi L, Tu BP. GATOR1 regulates nitrogenic cataplerotic reactions of the mitochondrial TCA cycle. Nat Chem Biol 2017; 13:1179-1186. [PMID: 28920930 PMCID: PMC5659745 DOI: 10.1038/nchembio.2478] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 08/10/2017] [Indexed: 12/14/2022]
Abstract
The GATOR1/SEACIT complex consisting of Iml1-Npr2-Npr3 inhibits Target of Rapamycin Complex 1 (TORC1) in response to amino acid insufficiency. In glucose medium, Saccharomyces cerevisiae mutants lacking the function of this complex grow poorly in the absence of amino acid supplementation, despite hallmarks of increased TORC1 signaling. Such mutants perceive they are amino acid-replete and thus repress metabolic activities that are important for achieving this state. We find that npr2Δ mutants have defective mitochondrial TCA cycle activity and retrograde response. Supplementation of glutamine, and especially aspartate, which are nitrogen-containing forms of TCA cycle intermediates, rescue growth of npr2Δ mutants. These amino acids are then consumed in biosynthetic pathways that require nitrogen to support proliferative metabolism. Our findings reveal that negative regulators of TORC1 such as GATOR1/SEACIT regulate the cataplerotic synthesis of these amino acids from the TCA cycle in tune with the amino acid and nitrogen status of cells.
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Affiliation(s)
- Jun Chen
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Benjamin M Sutter
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Lei Shi
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Benjamin P Tu
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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25
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An LC-MS Approach to Quantitative Measurement of Ammonia Isotopologues. Sci Rep 2017; 7:10304. [PMID: 28871132 PMCID: PMC5583358 DOI: 10.1038/s41598-017-09993-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 08/01/2017] [Indexed: 11/22/2022] Open
Abstract
Ammonia is a fundamental aspect of metabolism spanning all of phylogeny. Metabolomics, including metabolic tracing studies, are an integral part of elucidating the role of ammonia in these systems. However, current methods for measurement of ammonia are spectrophotometric, and cannot distinguish isotopologues of ammonia, significantly limiting metabolic tracing studies. Here, we describe a novel LC-MS-based method that quantitatively assesses both 14N-and 15N-isotopologues of ammonia in polar metabolite extracts. This assay (1) quantitatively measures the concentration of ammonia in polar metabolite isolates used for metabolomic studies, and (2) accurately determines the percent isotope abundance of 15N-ammonia in a cell lysate for 15N-isotope tracing studies. We apply this assay to quantitatively measure glutamine-derived ammonia in lung cancer cell lines with differential expression of glutaminase.
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26
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Cohen N, Breker M, Bakunts A, Pesek K, Chas A, Argemí J, Orsi A, Gal L, Chuartzman S, Wigelman Y, Jonas F, Walter P, Ernst R, Aragón T, van Anken E, Schuldiner M. Iron affects Ire1 clustering propensity and the amplitude of endoplasmic reticulum stress signaling. J Cell Sci 2017; 130:3222-3233. [PMID: 28794014 PMCID: PMC5665437 DOI: 10.1242/jcs.201715] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 08/02/2017] [Indexed: 01/10/2023] Open
Abstract
The unfolded protein response (UPR) allows cells to adjust secretory pathway capacity according to need. Ire1, the endoplasmic reticulum (ER) stress sensor and central activator of the UPR is conserved from the budding yeast Saccharomyces cerevisiae to humans. Under ER stress conditions, Ire1 clusters into foci that enable optimal UPR activation. To discover factors that affect Ire1 clustering, we performed a high-content screen using a whole-genome yeast mutant library expressing Ire1–mCherry. We imaged the strains following UPR induction and found 154 strains that displayed alterations in Ire1 clustering. The hits were enriched for iron and heme effectors and binding proteins. By performing pharmacological depletion and repletion, we confirmed that iron (Fe3+) affects UPR activation in both yeast and human cells. We suggest that Ire1 clustering propensity depends on membrane composition, which is governed by heme-dependent biosynthesis of sterols. Our findings highlight the diverse cellular functions that feed into the UPR and emphasize the cross-talk between organelles required to concertedly maintain homeostasis. Highlighted Article: To respond to folding stress in the ER, cells activate the conserved sensor Ire1. We show that iron is required for optimal Ire1 activation and suggest this is because iron is required for ergosterol biosynthesis.
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Affiliation(s)
- Nir Cohen
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Michal Breker
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.,The Rockefeller University, New York, NY 10065, USA
| | - Anush Bakunts
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Ospedale San Raffaele, Via Olgettina 58, 20132, Milan, Italy
| | - Kristina Pesek
- Institute of Biochemistry and Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Max-von-Laue Str. 15, 60438 Frankfurt, Germany
| | - Ainara Chas
- Center for Applied Medical Research, Department of Gene Therapy and Regulation of Gene Expression. University of Navarra, 55 Pio XII St. 31008 Pamplona, Spain
| | - Josepmaria Argemí
- Center for Applied Medical Research, Department of Gene Therapy and Regulation of Gene Expression. University of Navarra, 55 Pio XII St. 31008 Pamplona, Spain
| | - Andrea Orsi
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Ospedale San Raffaele, Via Olgettina 58, 20132, Milan, Italy
| | - Lihi Gal
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Silvia Chuartzman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Yoav Wigelman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Peter Walter
- Department of Biochemistry & Biophysics, University of California San Francisco and Howard Hughes Medical Institute, San Francisco, CA 94143, USA
| | - Robert Ernst
- Center for Molecular Signaling, Institute of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany
| | - Tomás Aragón
- Center for Applied Medical Research, Department of Gene Therapy and Regulation of Gene Expression. University of Navarra, 55 Pio XII St. 31008 Pamplona, Spain
| | - Eelco van Anken
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Ospedale San Raffaele, Via Olgettina 58, 20132, Milan, Italy
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
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Ferrari E, Bruhn C, Peretti M, Cassani C, Carotenuto WV, Elgendy M, Shubassi G, Lucca C, Bermejo R, Varasi M, Minucci S, Longhese MP, Foiani M. PP2A Controls Genome Integrity by Integrating Nutrient-Sensing and Metabolic Pathways with the DNA Damage Response. Mol Cell 2017. [PMID: 28648781 PMCID: PMC5526790 DOI: 10.1016/j.molcel.2017.05.027] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mec1ATR mediates the DNA damage response (DDR), integrating chromosomal signals and mechanical stimuli. We show that the PP2A phosphatases, ceramide-activated enzymes, couple cell metabolism with the DDR. Using genomic screens, metabolic analysis, and genetic and pharmacological studies, we found that PP2A attenuates the DDR and that three metabolic circuits influence the DDR by modulating PP2A activity. Irc21, a putative cytochrome b5 reductase that promotes the condensation reaction generating dihydroceramides (DHCs), and Ppm1, a PP2A methyltransferase, counteract the DDR by activating PP2A; conversely, the nutrient-sensing TORC1-Tap42 axis sustains DDR activation by inhibiting PP2A. Loss-of-function mutations in IRC21, PPM1, and PP2A and hyperactive tap42 alleles rescue mec1 mutants. Ceramides synergize with rapamycin, a TORC1 inhibitor, in counteracting the DDR. Hence, PP2A integrates nutrient-sensing and metabolic pathways to attenuate the Mec1ATR response. Our observations imply that metabolic changes affect genome integrity and may help with exploiting therapeutic options and repositioning known drugs.
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Affiliation(s)
- Elisa Ferrari
- Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
| | - Christopher Bruhn
- Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
| | - Marta Peretti
- Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
| | - Corinne Cassani
- Università degli Studi di Milano-Bicocca, 20126 Milan, Italy
| | | | - Mohamed Elgendy
- Istituto Europeo di Oncologia, Via Adamello 16, 20139 Milan, Italy
| | - Ghadeer Shubassi
- Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
| | - Chiara Lucca
- Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
| | - Rodrigo Bermejo
- Centro de Investigaciones Biológicas (CIB-CSIC), 28040 Madrid, Spain
| | - Mario Varasi
- Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy
| | - Saverio Minucci
- Istituto Europeo di Oncologia, Via Adamello 16, 20139 Milan, Italy; Università degli Studi di Milano, 20133 Milan, Italy
| | | | - Marco Foiani
- Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milan, Italy; Università degli Studi di Milano, 20133 Milan, Italy.
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28
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Fabiani IM, Rocha SL. Avaliação do tratamento da sepse com glutamina via enteral em ratos. Rev Col Bras Cir 2017; 44:231-237. [DOI: 10.1590/0100-69912017003002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 12/22/2016] [Indexed: 11/22/2022] Open
Abstract
RESUMO Objetivo: analisar a influência da glutamina nas alterações morfo-histológicas observadas em íleo, pulmão, rim e fígado de ratos Wistar submetidos à sepse. Métodos: a sepse foi induzida por meio de ligadura e punção do ceco. Os animais foram divididos em dois grupos: grupo A, controle, com cinco animais, e grupo B, experimento, com dez animais que utilizaram previamente glutamina por dois dias por via enteral. Na análise histológica, classificou-se as lesões de acordo com um escore cujo valor atribuído dependia da gravidade da lesão e do órgão acometido. A somatória dos valores atribuídos a cada animal resultou em sua nota final. No íleo, avaliaram-se as vilosidades; no fígado, esteatose microgoticular; no pulmão, pneumonite intersticial; e no rim, vacuolização dos túbulos contorcidos proximais. Resultados: a lise celular e a destruição das vilosidades no íleo do grupo controle foram mais intensas em relação aos animais que receberam glutamina. No rim, verificou-se vacuolização mais acentuada dos túbulos contorcidos proximais no grupo controle em relação aos animais que receberam glutamina. Tanto a esteatose microgoticular como a pneumonite intersticial mostraram-se semelhantes em ambos os grupos. Conclusão: o uso de glutamina via enteral previamente à sepse na dose de 0,5 g/kg/dia preservou de maneira significativa a estrutura histológica do intestino delgado e os rins em ratos.
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29
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Deshpande AA, Bhatia M, Laxman S, Bachhawat AK. Thiol trapping and metabolic redistribution of sulfur metabolites enable cells to overcome cysteine overload. MICROBIAL CELL 2017; 4:112-126. [PMID: 28435838 PMCID: PMC5376351 DOI: 10.15698/mic2017.04.567] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Cysteine is an essential requirement in living organisms. However, due to its reactive thiol side chain, elevated levels of intracellular cysteine can be toxic and therefore need to be rapidly eliminated from the cellular milieu. In mammals and many other organisms, excess cysteine is believed to be primarily eliminated by the cysteine dioxygenase dependent oxidative degradation of cysteine, followed by the removal of the oxidative products. However, other mechanisms of tackling excess cysteine are also likely to exist, but have not thus far been explored. In this study, we use Saccharomyces cerevisiae, which naturally lacks a cysteine dioxygenase, to investigate mechanisms for tackling cysteine overload. Overexpressing the high affinity cysteine transporter, YCT1, enabled yeast cells to rapidly accumulate high levels of intracellular cysteine. Using targeted metabolite analysis, we observe that cysteine is initially rapidly interconverted to non-reactive cystine in vivo. A time course revealed that cells systematically convert excess cysteine to inert thiol forms; initially to cystine, and subsequently to cystathionine, S-Adenosyl-L-homocysteine (SAH) and S-Adenosyl L-methionine (SAM), in addition to eventually accumulating glutathione (GSH) and polyamines. Microarray based gene expression studies revealed the upregulation of arginine/ornithine biosynthesis a few hours after the cysteine overload, and suggest that the non-toxic, non-reactive thiol based metabolic products are eventually utilized for amino acid and polyamine biogenesis, thereby enabling cell growth. Thus, cells can handle potentially toxic amounts of cysteine by a combination of thiol trapping, metabolic redistribution to non-reactive thiols and subsequent consumption for anabolism.
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Affiliation(s)
- Anup Arunrao Deshpande
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER Mohali), S.A.S. Nagar, Punjab 140306, India
| | - Muskan Bhatia
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER Mohali), S.A.S. Nagar, Punjab 140306, India
| | - Sunil Laxman
- Institute for Stem Cell Biology and Regenerative Medicine (inStem), NCBS campus, Bangalore 560065, India
| | - Anand Kumar Bachhawat
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER Mohali), S.A.S. Nagar, Punjab 140306, India
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30
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Abstract
For almost all cells, nutrient availability, from glucose to amino acids, dictates their growth or developmental programs. This nutrient availability is closely coupled to the overall intracellular metabolic state of the cell. Therefore, cells have evolved diverse, robust and versatile modules to sense intracellular metabolic states, activate signaling outputs and regulate outcomes to these states. Yet, signaling and metabolism have been viewed as important but separate. This short review attempts to position aspects of intracellular signaling from a metabolic perspective, highlighting how conserved, core principles of metabolic sensing and signaling can emerge from an understanding of metabolic regulation. I briefly explain the nature of metabolic sensors, using the example of the AMP activated protein kinase (AMPK) as an "energy sensing" hub. Subsequently, I explore how specific central metabolites, particularly acetyl-CoA, but also S -adenosyl methionine and SAICAR, can act as signaling molecules. I extensively illustrate the nature of a metabolic signaling hub using the specific example of the Target of Rapamycin Complex 1 (TORC1), and amino acid sensing. A highlight is the emergence of the lysosome/vacuole as a metabolic and signaling hub. Finally, the need to expand our understanding of the intracellular dynamics (in concentration and localization) of several metabolites, and their signaling hubs is emphasized.
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Affiliation(s)
- Sunil Laxman
- Institute for Stem Cell Biology and Regenerative Medicine (inStem), NCBS Campus, GKVK, Bellary Road, Bangalore 560065, India
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31
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Low escape-rate genome safeguards with minimal molecular perturbation of Saccharomyces cerevisiae. Proc Natl Acad Sci U S A 2017; 114:E1470-E1479. [PMID: 28174266 DOI: 10.1073/pnas.1621250114] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
As the use of synthetic biology both in industry and in academia grows, there is an increasing need to ensure biocontainment. There is growing interest in engineering bacterial- and yeast-based safeguard (SG) strains. First-generation SGs were based on metabolic auxotrophy; however, the risk of cross-feeding and the cost of growth-controlling nutrients led researchers to look for other avenues. Recent strategies include bacteria engineered to be dependent on nonnatural amino acids and yeast SG strains that have both transcriptional- and recombinational-based biocontainment. We describe improving yeast Saccharomyces cerevisiae-based transcriptional SG strains, which have near-WT fitness, the lowest possible escape rate, and nanomolar ligands controlling growth. We screened a library of essential genes, as well as the best-performing promoter and terminators, yielding the best SG strains in yeast. The best constructs were fine-tuned, resulting in two tightly controlled inducible systems. In addition, for potential use in the prevention of industrial espionage, we screened an array of possible "decoy molecules" that can be used to mask any proprietary supplement to the SG strain, with minimal effect on strain fitness.
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32
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Multiple Targets on the Gln3 Transcription Activator Are Cumulatively Required for Control of Its Cytoplasmic Sequestration. G3-GENES GENOMES GENETICS 2016; 6:1391-408. [PMID: 26976442 PMCID: PMC4856090 DOI: 10.1534/g3.116.027615] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A remarkable characteristic of nutritional homeostatic mechanisms is the breadth of metabolite concentrations to which they respond, and the resolution of those responses; adequate but rarely excessive. Two general ways of achieving such exquisite control are known: stoichiometric mechanisms where increasing metabolite concentrations elicit proportionally increasing responses, and the actions of multiple independent metabolic signals that cumulatively generate appropriately measured responses. Intracellular localization of the nitrogen-responsive transcription activator, Gln3, responds to four distinct nitrogen environments: nitrogen limitation or short-term starvation, i.e., nitrogen catabolite repression (NCR), long-term starvation, glutamine starvation, and rapamycin inhibition of mTorC1. We have previously identified unique sites in Gln3 required for rapamycin-responsiveness, and Gln3-mTor1 interaction. Alteration of the latter results in loss of about 50% of cytoplasmic Gln3 sequestration. However, except for the Ure2-binding domain, no evidence exists for a Gln3 site responsible for the remaining cytoplasmic Gln3-Myc13 sequestration in nitrogen excess. Here, we identify a serine/threonine-rich (Gln3477–493) region required for effective cytoplasmic Gln3-Myc13 sequestration in excess nitrogen. Substitutions of alanine but not aspartate for serines in this peptide partially abolish cytoplasmic Gln3 sequestration. Importantly, these alterations have no effect on the responses of Gln3-Myc13 to rapamycin, methionine sulfoximine, or limiting nitrogen. However, cytoplasmic Gln3-Myc13 sequestration is additively, and almost completely, abolished when mutations in the Gln3-Tor1 interaction site are combined with those in Gln3477–493 cytoplasmic sequestration site. These findings clearly demonstrate that multiple individual regulatory pathways cumulatively control cytoplasmic Gln3 sequestration.
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33
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Péli-Gulli MP, Sardu A, Panchaud N, Raucci S, De Virgilio C. Amino Acids Stimulate TORC1 through Lst4-Lst7, a GTPase-Activating Protein Complex for the Rag Family GTPase Gtr2. Cell Rep 2015; 13:1-7. [PMID: 26387955 DOI: 10.1016/j.celrep.2015.08.059] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 07/21/2015] [Accepted: 08/20/2015] [Indexed: 10/23/2022] Open
Abstract
Rag GTPases assemble into heterodimeric complexes consisting of RagA or RagB and RagC or RagD in higher eukaryotes, or Gtr1 and Gtr2 in yeast, to relay amino acid signals toward the growth-regulating target of rapamycin complex 1 (TORC1). The TORC1-stimulating state of Rag GTPase heterodimers, containing GTP- and GDP-loaded RagA/B/Gtr1 and RagC/D/Gtr2, respectively, is maintained in part by the FNIP-Folliculin RagC/D GAP complex in mammalian cells. Here, we report the existence of a similar Lst4-Lst7 complex in yeast that functions as a GAP for Gtr2 and that clusters at the vacuolar membrane in amino acid-starved cells. Refeeding of amino acids, such as glutamine, stimulated the Lst4-Lst7 complex to transiently bind and act on Gtr2, thereby entailing TORC1 activation and Lst4-Lst7 dispersal from the vacuolar membrane. Given the remarkable functional conservation of the RagC/D/Gtr2 GAP complexes, our findings could be relevant for understanding the glutamine addiction of mTORC1-dependent cancers.
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Affiliation(s)
| | - Alessandro Sardu
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Nicolas Panchaud
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Serena Raucci
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
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34
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Dutchak PA, Laxman S, Estill SJ, Wang C, Wang Y, Wang Y, Bulut GB, Gao J, Huang LJ, Tu BP. Regulation of Hematopoiesis and Methionine Homeostasis by mTORC1 Inhibitor NPRL2. Cell Rep 2015; 12:371-9. [PMID: 26166573 DOI: 10.1016/j.celrep.2015.06.042] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 05/08/2015] [Accepted: 06/08/2015] [Indexed: 01/23/2023] Open
Abstract
Nitrogen permease regulator-like 2 (NPRL2) is a component of a conserved complex that inhibits mTORC1 (mammalian Target Of Rapamycin Complex 1) in response to amino acid insufficiency. Here, we show that NPRL2 is required for mouse viability and that its absence significantly compromises fetal liver hematopoiesis in developing embryos. Moreover, NPRL2 KO embryos have significantly reduced methionine levels and exhibit phenotypes reminiscent of cobalamin (vitamin B12) deficiency. Consistent with this idea, NPRL2 KO liver and mouse embryonic fibroblasts (MEFs) show defective processing of the cobalamin-transport protein transcobalamin 2, along with impaired lysosomal acidification and lysosomal gene expression. NPRL2 KO MEFs exhibit a significant defect in the cobalamin-dependent synthesis of methionine from homocysteine, which can be rescued by supplementation with cyanocobalamin. Taken together, these findings demonstrate a role for NPRL2 and mTORC1 in the regulation of lysosomal-dependent cobalamin processing, methionine synthesis, and maintenance of cellular re-methylation potential, which are important during hematopoiesis.
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Affiliation(s)
- Paul A Dutchak
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA
| | - Sunil Laxman
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA
| | - Sandi Jo Estill
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA
| | - Chensu Wang
- Simmons Comprehensive Cancer Center and Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390-8807, USA
| | - Yun Wang
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA
| | - Yiguang Wang
- Simmons Comprehensive Cancer Center and Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390-8807, USA
| | - Gamze B Bulut
- Department of Cell Biology, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390-9039, USA
| | - Jinming Gao
- Simmons Comprehensive Cancer Center and Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390-8807, USA
| | - Lily J Huang
- Department of Cell Biology, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390-9039, USA
| | - Benjamin P Tu
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA.
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35
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Chantranupong L, Wolfson RL, Sabatini DM. Nutrient-sensing mechanisms across evolution. Cell 2015; 161:67-83. [PMID: 25815986 DOI: 10.1016/j.cell.2015.02.041] [Citation(s) in RCA: 229] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Indexed: 12/11/2022]
Abstract
For organisms to coordinate their growth and development with nutrient availability, they must be able to sense nutrient levels in their environment. Here, we review select nutrient-sensing mechanisms in a few diverse organisms. We discuss how these mechanisms reflect the nutrient requirements of specific species and how they have adapted to the emergence of multicellularity in eukaryotes.
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Affiliation(s)
- Lynne Chantranupong
- Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Department of Biology, 9 Cambridge Center, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Rachel L Wolfson
- Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Department of Biology, 9 Cambridge Center, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - David M Sabatini
- Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Department of Biology, 9 Cambridge Center, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
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36
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Dokudovskaya S, Rout MP. SEA you later alli-GATOR--a dynamic regulator of the TORC1 stress response pathway. J Cell Sci 2015; 128:2219-28. [PMID: 25934700 DOI: 10.1242/jcs.168922] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Cells constantly adapt to various environmental changes and stresses. The way in which nutrient and stress levels in a cell feed back to control metabolism and growth are, unsurprisingly, extremely complex, as responding with great sensitivity and speed to the 'feast or famine, slack or stress' status of its environment is a central goal for any organism. The highly conserved target of rapamycin complex 1 (TORC1) controls eukaryotic cell growth and response to a variety of signals, including nutrients, hormones and stresses, and plays the key role in the regulation of autophagy. A lot of attention has been paid recently to the factors in this pathway functioning upstream of TORC1. In this Commentary, we focus on a major, newly discovered upstream regulator of TORC1--the multiprotein SEA complex, also known as GATOR. We describe the structural and functional features of the yeast complex and its mammalian homolog, and their involvement in the regulation of the TORC1 pathway and TORC1-independent processes. We will also provide an overview of the consequences of GATOR deregulation in cancer and other diseases.
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Affiliation(s)
- Svetlana Dokudovskaya
- CNRS UMR 8126, Université Paris-Sud 11, Institut Gustave Roussy, 114, rue Edouard Vaillant, 94805, Villejuif, France
| | - Michael P Rout
- Laboratory of Cellular and Structural Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
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37
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Journal Club. Kidney Int 2015. [DOI: 10.1038/ki.2015.24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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38
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Tu BP, VanHook AM. Science Signaling
Podcast: 16 December 2014. Sci Signal 2014. [DOI: 10.1126/scisignal.aaa4034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Npr2 and TORC1 regulate the ability of yeast to synthesize and utilize glutamine when the cells are grown on a nonfermentable carbon source.
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Affiliation(s)
- Benjamin P. Tu
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA
| | - Annalisa M. VanHook
- Web Editor, Science Signaling, American Association for the Advancement of Science, 1200 New York Avenue, NW, Washington, DC 20005, USA
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