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Phetruen T, van Dam B, Chanarat S. Andrographolide Induces ROS-Mediated Cytotoxicity, Lipid Peroxidation, and Compromised Cell Integrity in Saccharomyces cerevisiae. Antioxidants (Basel) 2023; 12:1765. [PMID: 37760068 PMCID: PMC10525756 DOI: 10.3390/antiox12091765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 09/08/2023] [Accepted: 09/11/2023] [Indexed: 09/29/2023] Open
Abstract
Andrographolide, a bioactive compound found in Andrographis paniculata, has gained significant attention for its potential therapeutic properties. Despite its promising benefits, the understanding of its side effects and underlying mechanisms remains limited. Here, we investigated the impact of andrographolide in Saccharomyces cerevisiae and observed that andrographolide induced cytotoxicity, particularly when oxidative phosphorylation was active. Furthermore, andrographolide affected various cellular processes, including vacuole fragmentation, endoplasmic reticulum stress, lipid droplet accumulation, reactive oxygen species levels, and compromised cell integrity. Moreover, we unexpectedly observed that andrographolide induced the precipitation of biomolecules secreted from yeast cells, adding an additional source of stress. Overall, this study provides insights into the cellular effects and potential mechanisms of andrographolide in yeast, shedding light on its side effects and underlying cytotoxicity pathways.
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Affiliation(s)
| | | | - Sittinan Chanarat
- Laboratory of Molecular Cell Biology, Department of Biochemistry, Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
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2
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Wang F, Yang Y, Boudagh G, Eskelinen EL, Klionsky DJ, Malek SN. Follicular lymphoma-associated mutations in the V-ATPase chaperone VMA21 activate autophagy creating a targetable dependency. Autophagy 2022; 18:1982-2000. [PMID: 35287545 PMCID: PMC9450968 DOI: 10.1080/15548627.2022.2050663] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
The discovery of recurrent mutations in subunits and regulators of the vacuolar-type H+-translocating ATPase (V-ATPase) in follicular lymphoma (FL) highlights a role for macroautophagy/autophagy, amino-acid, and nutrient-sensing pathways in the pathogenesis of this disease. Here, we report on novel mutations in the ER-resident chaperone VMA21, which is involved in V-ATPase assembly in 12% of FL. Mutations in a novel VMA21 hotspot (p.93X) result in the removal of a C-terminal non-canonical ER retrieval signal thus causing VMA21 mislocalization to lysosomes. The resulting impairment in V-ATPase activity prevents full lysosomal acidification and function, including impaired pH-dependent protein degradation as shown via lysosomal metabolomics and ultimately causes a degree of amino acid depletion in the cytoplasm. These deficiencies result in compensatory autophagy activation, as measured using multiple complementary assays in human and yeast cells. Of translational significance, the compensatory activation of autophagy creates a dependency for survival for VMA21-mutated primary human FL as shown using inhibitors to ULK1, the proximal autophagy-regulating kinase. Using high-throughput microscopy-based screening assays for autophagy-inhibiting compounds, we identify multiple clinical grade cyclin-dependent kinase inhibitors as promising drugs and thus provide new rationale for innovative clinical trials in FL harboring aberrant V-ATPase.Abbreviations: ALs: autolysosomes; APs: autophagosomes; ER: endoplasmic reticulum; FL: follicular lymphoma; GFP: green fluorescent protein; IP: immunoprecipitation; LE/LY: late endosomes/lysosomes; Lyso-IP: lysosomal immunoprecipitation; OST: oligosaccharide transferase; prApe1: precursor aminopeptidase I; SEP: super ecliptic pHluorin; V-ATPase: vacuolar-type H+-translocating ATPase.
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Affiliation(s)
- Fangyang Wang
- Internal Medicine, Division of Hematology and Oncology, University of Michigan, Ann Arbor, MI, USA
| | - Ying Yang
- Departments of Molecular, Cellular and Developmental Biology, and Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Gabriel Boudagh
- Internal Medicine, Division of Hematology and Oncology, University of Michigan, Ann Arbor, MI, USA
| | | | - Daniel J. Klionsky
- Departments of Molecular, Cellular and Developmental Biology, and Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Sami N. Malek
- Internal Medicine, Division of Hematology and Oncology, University of Michigan, Ann Arbor, MI, USA
- CONTACT Sami N. Malek Department of Internal Medicine, Division of Hematology and Oncology, University of Michigan, 1500 E. Medical Center Drive, Ann Arbor, MI48109-0936, USA
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3
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Conan P, Léon A, Gourdel M, Rollet C, Chaïr L, Caroff N, Le Goux N, Le Jossic-Corcos C, Sinane M, Gentile L, Maillebouis L, Loaëc N, Martin J, Vilaire M, Corcos L, Mignen O, Croyal M, Voisset C, Bihel F, Friocourt G. Identification of 8-Hydroxyquinoline Derivatives That Decrease Cystathionine Beta Synthase (CBS) Activity. Int J Mol Sci 2022; 23:ijms23126769. [PMID: 35743210 PMCID: PMC9223588 DOI: 10.3390/ijms23126769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 06/09/2022] [Accepted: 06/16/2022] [Indexed: 12/04/2022] Open
Abstract
CBS encodes a pyridoxal 5′-phosphate-dependent enzyme that catalyses the condensation of homocysteine and serine to form cystathionine. Due to its implication in some cancers and in the cognitive pathophysiology of Down syndrome, the identification of pharmacological inhibitors of this enzyme is urgently required. However, thus far, attempts to identify such molecules have only led to the identification of compounds with low potency and limited selectivity. We consequently developed an original, yeast-based screening method that identified three FDA-approved drugs of the 8-hydroxyquinoline family: clioquinol, chloroxine and nitroxoline. These molecules reduce CBS enzymatic activity in different cellular models, proving that the molecular mechanisms involved in yeast phenotypic rescue are conserved in mammalian cells. A combination of genetic and chemical biology approaches also revealed the importance of copper and zinc intracellular levels in the regulation of CBS enzymatic activity—copper promoting CBS activity and zinc inhibiting its activity. Taken together, these results indicate that our effective screening approach identified three new potent CBS inhibitors and provides new findings for the regulation of CBS activity, which is crucial to develop new therapies for CBS-related human disorders.
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Affiliation(s)
- Pierre Conan
- Inserm, Université de Brest, EFS, UMR 1078, GGB, 29200 Brest, France; (P.C.); (A.L.); (C.R.); (L.C.); (N.C.); (C.L.J.-C.); (M.S.); (L.G.); (N.L.); (J.M.); (L.C.); (C.V.)
| | - Alice Léon
- Inserm, Université de Brest, EFS, UMR 1078, GGB, 29200 Brest, France; (P.C.); (A.L.); (C.R.); (L.C.); (N.C.); (C.L.J.-C.); (M.S.); (L.G.); (N.L.); (J.M.); (L.C.); (C.V.)
| | - Mathilde Gourdel
- Inserm, Université de Nantes, CHU Nantes, CNRS, L’Institut Du Thorax, 44000 Nantes, France; (M.G.); (M.C.)
- CRNH-Ouest Mass Spectrometry Core Facility, 44000 Nantes, France
| | - Claire Rollet
- Inserm, Université de Brest, EFS, UMR 1078, GGB, 29200 Brest, France; (P.C.); (A.L.); (C.R.); (L.C.); (N.C.); (C.L.J.-C.); (M.S.); (L.G.); (N.L.); (J.M.); (L.C.); (C.V.)
| | - Loubna Chaïr
- Inserm, Université de Brest, EFS, UMR 1078, GGB, 29200 Brest, France; (P.C.); (A.L.); (C.R.); (L.C.); (N.C.); (C.L.J.-C.); (M.S.); (L.G.); (N.L.); (J.M.); (L.C.); (C.V.)
| | - Noéline Caroff
- Inserm, Université de Brest, EFS, UMR 1078, GGB, 29200 Brest, France; (P.C.); (A.L.); (C.R.); (L.C.); (N.C.); (C.L.J.-C.); (M.S.); (L.G.); (N.L.); (J.M.); (L.C.); (C.V.)
| | - Nelig Le Goux
- Inserm U1227, Lymphocytes B, Autoimmunité et Immunothérapies, Université de Brest, 29200 Brest, France; (N.L.G.); (O.M.)
| | - Catherine Le Jossic-Corcos
- Inserm, Université de Brest, EFS, UMR 1078, GGB, 29200 Brest, France; (P.C.); (A.L.); (C.R.); (L.C.); (N.C.); (C.L.J.-C.); (M.S.); (L.G.); (N.L.); (J.M.); (L.C.); (C.V.)
| | - Maha Sinane
- Inserm, Université de Brest, EFS, UMR 1078, GGB, 29200 Brest, France; (P.C.); (A.L.); (C.R.); (L.C.); (N.C.); (C.L.J.-C.); (M.S.); (L.G.); (N.L.); (J.M.); (L.C.); (C.V.)
| | - Lucile Gentile
- Inserm, Université de Brest, EFS, UMR 1078, GGB, 29200 Brest, France; (P.C.); (A.L.); (C.R.); (L.C.); (N.C.); (C.L.J.-C.); (M.S.); (L.G.); (N.L.); (J.M.); (L.C.); (C.V.)
| | - Louise Maillebouis
- CRB-Biojel, Institut Jérôme Lejeune, 75015 Paris, France; (L.M.); (M.V.)
| | - Nadège Loaëc
- Inserm, Université de Brest, EFS, UMR 1078, GGB, 29200 Brest, France; (P.C.); (A.L.); (C.R.); (L.C.); (N.C.); (C.L.J.-C.); (M.S.); (L.G.); (N.L.); (J.M.); (L.C.); (C.V.)
| | - Jennifer Martin
- Inserm, Université de Brest, EFS, UMR 1078, GGB, 29200 Brest, France; (P.C.); (A.L.); (C.R.); (L.C.); (N.C.); (C.L.J.-C.); (M.S.); (L.G.); (N.L.); (J.M.); (L.C.); (C.V.)
| | - Marie Vilaire
- CRB-Biojel, Institut Jérôme Lejeune, 75015 Paris, France; (L.M.); (M.V.)
| | - Laurent Corcos
- Inserm, Université de Brest, EFS, UMR 1078, GGB, 29200 Brest, France; (P.C.); (A.L.); (C.R.); (L.C.); (N.C.); (C.L.J.-C.); (M.S.); (L.G.); (N.L.); (J.M.); (L.C.); (C.V.)
| | - Olivier Mignen
- Inserm U1227, Lymphocytes B, Autoimmunité et Immunothérapies, Université de Brest, 29200 Brest, France; (N.L.G.); (O.M.)
| | - Mikael Croyal
- Inserm, Université de Nantes, CHU Nantes, CNRS, L’Institut Du Thorax, 44000 Nantes, France; (M.G.); (M.C.)
- CRNH-Ouest Mass Spectrometry Core Facility, 44000 Nantes, France
- Inserm, Université de Nantes, CHU Nantes, CNRS, SFR Santé, Inserm UMS 016, CNRS UMS 3556, 44000 Nantes, France
| | - Cécile Voisset
- Inserm, Université de Brest, EFS, UMR 1078, GGB, 29200 Brest, France; (P.C.); (A.L.); (C.R.); (L.C.); (N.C.); (C.L.J.-C.); (M.S.); (L.G.); (N.L.); (J.M.); (L.C.); (C.V.)
| | - Frédéric Bihel
- Laboratoire d’Innovation Thérapeutique, LIT, UMR7200, IMS MEDALIS, Faculty of Pharmacy, CNRS, Université de Strasbourg, 67400 Illkirch, France;
| | - Gaëlle Friocourt
- Inserm, Université de Brest, EFS, UMR 1078, GGB, 29200 Brest, France; (P.C.); (A.L.); (C.R.); (L.C.); (N.C.); (C.L.J.-C.); (M.S.); (L.G.); (N.L.); (J.M.); (L.C.); (C.V.)
- Correspondence: ; Tel.: +33-(0)2-98-01-83-87
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4
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Vasanthakumar T, Keon KA, Bueler SA, Jaskolka MC, Rubinstein JL. Coordinated conformational changes in the V 1 complex during V-ATPase reversible dissociation. Nat Struct Mol Biol 2022; 29:430-439. [PMID: 35469063 DOI: 10.1038/s41594-022-00757-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 03/03/2022] [Indexed: 11/10/2022]
Abstract
Vacuolar-type ATPases (V-ATPases) are rotary enzymes that acidify intracellular compartments in eukaryotic cells. These multi-subunit complexes consist of a cytoplasmic V1 region that hydrolyzes ATP and a membrane-embedded VO region that transports protons. V-ATPase activity is regulated by reversible dissociation of the two regions, with the isolated V1 and VO complexes becoming autoinhibited on disassembly and subunit C subsequently detaching from V1. In yeast, assembly of the V1 and VO regions is mediated by the regulator of the ATPase of vacuoles and endosomes (RAVE) complex through an unknown mechanism. We used cryogenic-electron microscopy of yeast V-ATPase to determine structures of the intact enzyme, the dissociated but complete V1 complex and the V1 complex lacking subunit C. On separation, V1 undergoes a dramatic conformational rearrangement, with its rotational state becoming incompatible for reassembly with VO. Loss of subunit C allows V1 to match the rotational state of VO, suggesting how RAVE could reassemble V1 and VO by recruiting subunit C.
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Affiliation(s)
- Thamiya Vasanthakumar
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Biochemistry, The University of Toronto, Toronto, Ontario, Canada
| | - Kristine A Keon
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, The University of Toronto, Toronto, Ontario, Canada
| | - Stephanie A Bueler
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Michael C Jaskolka
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - John L Rubinstein
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada. .,Department of Biochemistry, The University of Toronto, Toronto, Ontario, Canada. .,Department of Medical Biophysics, The University of Toronto, Toronto, Ontario, Canada.
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5
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Eising S, Esch B, Wälte M, Vargas Duarte P, Walter S, Ungermann C, Bohnert M, Fröhlich F. A lysosomal biogenesis map reveals the cargo spectrum of yeast vacuolar protein targeting pathways. J Cell Biol 2022; 221:213011. [PMID: 35175277 PMCID: PMC8859911 DOI: 10.1083/jcb.202107148] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 12/20/2021] [Accepted: 01/18/2022] [Indexed: 12/15/2022] Open
Abstract
The lysosome is the major catabolic organelle in the cell that has been established as a key metabolic signaling center. Mutations in many lysosomal proteins have catastrophic effects and cause neurodegeneration, cancer, and age-related diseases. The vacuole is the lysosomal analog of Saccharomyces cerevisiae that harbors many evolutionary conserved proteins. Proteins reach vacuoles via the Vps10-dependent endosomal vacuolar protein sorting pathway, via the alkaline phosphatase (ALP or AP-3) pathway, and via the cytosol-to-vacuole transport (CVT) pathway. A systematic understanding of the cargo spectrum of each pathway is completely lacking. Here, we use quantitative proteomics of purified vacuoles to generate the yeast lysosomal biogenesis map. This dataset harbors information on the cargo-receptor relationship of almost all vacuolar proteins. We map binding motifs of Vps10 and the AP-3 complex and identify a novel cargo of the CVT pathway under nutrient-rich conditions. Our data show how organelle purification and quantitative proteomics can uncover fundamental insights into organelle biogenesis.
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Affiliation(s)
- Sebastian Eising
- Molecular Membrane Biology Group, Department of Biology/Chemistry, Osnabrück University, Osnabrück, Germany
| | - Bianca Esch
- Molecular Membrane Biology Group, Department of Biology/Chemistry, Osnabrück University, Osnabrück, Germany
| | - Mike Wälte
- Institute of Cell Dynamics and Imaging, University of Münster, Münster, Germany
| | - Prado Vargas Duarte
- Biochemistry Section, Department of Biology/Chemistry, Osnabrück University, Osnabrück, Germany
| | - Stefan Walter
- Center of Cellular Nanoanalytics Osnabrück, Osnabrück University, Osnabrück, Germany
| | - Christian Ungermann
- Biochemistry Section, Department of Biology/Chemistry, Osnabrück University, Osnabrück, Germany.,Center of Cellular Nanoanalytics Osnabrück, Osnabrück University, Osnabrück, Germany
| | - Maria Bohnert
- Institute of Cell Dynamics and Imaging, University of Münster, Münster, Germany.,Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | - Florian Fröhlich
- Molecular Membrane Biology Group, Department of Biology/Chemistry, Osnabrück University, Osnabrück, Germany.,Biochemistry Section, Department of Biology/Chemistry, Osnabrück University, Osnabrück, Germany
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6
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7
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Lv Q, Yan L, Jiang Y. The Importance of Vacuolar Ion Homeostasis and Trafficking in Hyphal Development and Virulence in Candida albicans. Front Microbiol 2021; 12:779176. [PMID: 34956142 PMCID: PMC8696117 DOI: 10.3389/fmicb.2021.779176] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Accepted: 11/12/2021] [Indexed: 11/13/2022] Open
Abstract
The vacuole of Candida albicans plays a significant role in many processes including homeostasis control, cellular trafficking, dimorphic switching, and stress tolerance. Thus, understanding the factors affecting vacuole function is important for the identification of new drug targets needed in response to the world’s increasing levels of invasive infections and the growing issue of fungal drug resistance. Past studies have shown that vacuolar proton-translocating ATPases (V-ATPases) play a central role in pH homeostasis and filamentation. Vacuolar protein sorting components (VPS) regulate V-ATPases assembly and at the same time affect hyphal development. As well, vacuolar calcium exchange systems like Yvc1 and Pmc1 maintain cytosolic calcium levels while being affected by V-ATPases function. All these proteins play a role in the virulence and pathogenesis of C. albicans. This review highlights the relationships among V-ATPases, VPS, and vacuolar calcium exchange proteins while summarizing their importance in C. albicans infections.
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Affiliation(s)
- Quanzhen Lv
- School of Pharmacy, Naval Medical University, Shanghai, China
| | - Lan Yan
- School of Pharmacy, Naval Medical University, Shanghai, China
| | - Yuanying Jiang
- Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
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8
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Nassiri Toosi Z, Su X, Austin R, Choudhury S, Li W, Pang YT, Gumbart JC, Torres MP. Combinatorial phosphorylation modulates the structure and function of the G protein γ subunit in yeast. Sci Signal 2021; 14:14/688/eabd2464. [PMID: 34158397 DOI: 10.1126/scisignal.abd2464] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intrinsically disordered regions (IDRs) in proteins are often targets of combinatorial posttranslational modifications, which serve to regulate protein structure and function. Emerging evidence suggests that the N-terminal tails of G protein γ subunits, which are essential components of heterotrimeric G proteins, are intrinsically disordered, phosphorylation-dependent determinants of G protein signaling. Here, we found that the yeast Gγ subunit Ste18 underwent combinatorial, multisite phosphorylation events within its N-terminal IDR. G protein-coupled receptor (GPCR) activation and osmotic stress induced phosphorylation at Ser7, whereas glucose and acid stress induced phosphorylation at Ser3, which was a quantitative indicator of intracellular pH. Each site was phosphorylated by a distinct set of kinases, and phosphorylation of one site affected phosphorylation of the other, as determined through exposure to serial stimuli and through phosphosite mutagenesis. Last, we showed that phosphorylation resulted in changes in IDR structure and that different combinations of phosphorylation events modulated the activation rate and amplitude of the downstream mitogen-activated protein kinase Fus3. These data place Gγ subunits among intrinsically disordered proteins that undergo combinatorial posttranslational modifications that govern signaling pathway output.
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Affiliation(s)
- Zahra Nassiri Toosi
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Xinya Su
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Ruth Austin
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Shilpa Choudhury
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Wei Li
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA.,Southeast Center for Mathematics and Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Yui Tik Pang
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - James C Gumbart
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Matthew P Torres
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA. .,Southeast Center for Mathematics and Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA
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9
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Kim JE, Vali SW, Nguyen TQ, Dancis A, Lindahl PA. Mössbauer and LC-ICP-MS investigation of iron trafficking between vacuoles and mitochondria in vma2ΔSaccharomyces cerevisiae. J Biol Chem 2020; 296:100141. [PMID: 33268384 PMCID: PMC7948489 DOI: 10.1074/jbc.ra120.015907] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 11/24/2020] [Accepted: 12/02/2020] [Indexed: 01/09/2023] Open
Abstract
Vacuoles are acidic organelles that store FeIII polyphosphate, participate in iron homeostasis, and have been proposed to deliver iron to mitochondria for iron–sulfur cluster (ISC) and heme biosynthesis. Vma2Δ cells have dysfunctional V-ATPases, rendering their vacuoles nonacidic. These cells have mitochondria that are iron-dysregulated, suggesting disruption of a putative vacuole-to-mitochondria iron trafficking pathway. To investigate this potential pathway, we examined the iron content of a vma2Δ mutant derived from W303 cells using Mössbauer and EPR spectroscopies and liquid chromatography interfaced with inductively-coupled-plasma mass spectrometry. Relative to WT cells, vma2Δ cells contained WT concentrations of iron but nonheme FeII dominated the iron content of fermenting and respiring vma2Δ cells, indicating that the vacuolar FeIII ions present in WT cells had been reduced. However, vma2Δ cells synthesized WT levels of ISCs/hemes and had normal aconitase activity. The iron content of vma2Δ mitochondria was similar to WT, all suggesting that iron delivery to mitochondria was not disrupted. Chromatograms of cytosolic flow–through solutions exhibited iron species with apparent masses of 600 and 800 Da for WT and vma2∆, respectively. Mutant cells contained high copper concentrations and high concentrations of a species assigned to metallothionein, indicating copper dysregulation. vma2Δ cells from previously studied strain BY4741 exhibited iron-associated properties more consistent with prior studies, suggesting subtle strain differences. Vacuoles with functional V-ATPases appear unnecessary in W303 cells for iron to enter mitochondria and be used in ISC/heme biosynthesis; thus, there appears to be no direct or dedicated vacuole-to-mitochondria iron trafficking pathway. The vma2Δ phenotype may arise from alterations in trafficking of iron directly from cytosol to mitochondria.
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Affiliation(s)
- Joshua E Kim
- Department of Chemistry, Texas A&M University, College Station, Texas, USA
| | - Shaik Waseem Vali
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Trang Q Nguyen
- Department of Chemistry, Texas A&M University, College Station, Texas, USA
| | - Andrew Dancis
- Department of Pharmacology, Physiology, and Neuroscience, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA; Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Paul A Lindahl
- Department of Chemistry, Texas A&M University, College Station, Texas, USA; Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.
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10
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Oxidative Stress Responses and Nutrient Starvation in MCHM Treated Saccharomyces cerevisiae. G3-GENES GENOMES GENETICS 2020; 10:4665-4678. [PMID: 33109726 PMCID: PMC7718757 DOI: 10.1534/g3.120.401661] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In 2014, the coal cleaning chemical 4-methylcyclohexane methanol (MCHM) spilled into the water supply for 300,000 West Virginians. Initial toxicology tests showed relatively mild results, but the underlying effects on cellular biology were underexplored. Treated wildtype yeast cells grew poorly, but there was only a small decrease in cell viability. Cell cycle analysis revealed an absence of cells in S phase within thirty minutes of treatment. Cells accumulated in G1 over a six-hour time course, indicating arrest instead of death. A genetic screen of the haploid knockout collection revealed 329 high confidence genes required for optimal growth in MCHM. These genes encode three major cell processes: mitochondrial gene expression/translation, the vacuolar ATPase, and aromatic amino acid biosynthesis. The transcriptome showed an upregulation of pleiotropic drug response genes and amino acid biosynthetic genes and downregulation in ribosome biosynthesis. Analysis of these datasets pointed to environmental stress response activation upon treatment. Overlap in datasets included the aromatic amino acid genes ARO1, ARO3, and four of the five TRP genes. This implicated nutrient deprivation as the signal for stress response. Excess supplementation of nutrients and amino acids did not improve growth on MCHM, so the source of nutrient deprivation signal is still unclear. Reactive oxygen species and DNA damage were directly detected with MCHM treatment, but timepoints showed these accumulated slower than cells arrested. We propose that wildtype cells arrest from nutrient deprivation and survive, accumulating oxidative damage through the implementation of robust environmental stress responses.
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11
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Banerjee S, Kane PM. Regulation of V-ATPase Activity and Organelle pH by Phosphatidylinositol Phosphate Lipids. Front Cell Dev Biol 2020; 8:510. [PMID: 32656214 PMCID: PMC7324685 DOI: 10.3389/fcell.2020.00510] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 05/28/2020] [Indexed: 12/14/2022] Open
Abstract
Luminal pH and the distinctive distribution of phosphatidylinositol phosphate (PIP) lipids are central identifying features of organelles in all eukaryotic cells that are also critical for organelle function. V-ATPases are conserved proton pumps that populate and acidify multiple organelles of the secretory and the endocytic pathway. Complete loss of V-ATPase activity causes embryonic lethality in higher animals and conditional lethality in yeast, while partial loss of V-ATPase function is associated with multiple disease states. On the other hand, many cancer cells increase their virulence by upregulating V-ATPase expression and activity. The pH of individual organelles is tightly controlled and essential for function, but the mechanisms for compartment-specific pH regulation are not completely understood. There is substantial evidence indicating that the PIP content of membranes influences organelle pH. We present recent evidence that PIPs interact directly with subunit isoforms of the V-ATPase to dictate localization of V-ATPase subpopulations and participate in their regulation. In yeast cells, which have only one set of organelle-specific V-ATPase subunit isoforms, the Golgi-enriched lipid PI(4)P binds to the cytosolic domain of the Golgi-enriched a-subunit isoform Stv1, and loss of PI(4)P binding results in mislocalization of Stv1-containing V-ATPases from the Golgi to the vacuole/lysosome. In contrast, levels of the vacuole/lysosome-enriched signaling lipid PI(3,5)P2 affect assembly and activity of V-ATPases containing the Vph1 a-subunit isoform. Mutations in the Vph1 isoform that disrupt the lipid interaction increase sensitivity to stress. These studies have decoded “zip codes” for PIP lipids in the cytosolic N-terminal domain of the a-subunit isoforms of the yeast V-ATPase, and similar interactions between PIP lipids and the V-ATPase subunit isoforms are emerging in higher eukaryotes. In addition to direct effects on the V-ATPase, PIP lipids are also likely to affect organelle pH indirectly, through interactions with other membrane transporters. We discuss direct and indirect effects of PIP lipids on organelle pH, and the functional consequences of the interplay between PIP lipid content and organelle pH.
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Affiliation(s)
- Subhrajit Banerjee
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, United States
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12
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Techo T, Jindarungrueng S, Tatip S, Limcharoensuk T, Pokethitiyook P, Kruatrachue M, Auesukaree C. Vacuolar H + -ATPase is involved in preventing heavy metal-induced oxidative stress in Saccharomyces cerevisiae. Environ Microbiol 2020; 22:2403-2418. [PMID: 32291875 DOI: 10.1111/1462-2920.15022] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Accepted: 04/12/2020] [Indexed: 12/31/2022]
Abstract
In Saccharomyces cerevisiae, vacuolar H+ -ATPase (V-ATPase) involved in the regulation of intracellular pH homeostasis has been shown to be important for tolerances to cadmium, cobalt and nickel. However, the molecular mechanism underlying the protective role of V-ATPase against these metals remains unclear. In this study, we show that cadmium, cobalt and nickel disturbed intracellular pH balance by triggering cytosolic acidification and vacuolar alkalinization, likely via their membrane permeabilizing effects. Since V-ATPase plays a crucial role in pumping excessive cytosolic protons into the vacuole, the metal-sensitive phenotypes of the Δvma2 and Δvma3 mutants lacking V-ATPase activity were supposed to result from highly acidified cytosol. However, we found that the metal-sensitive phenotypes of these mutants were caused by increased production of reactive oxygen species, likely as a result of decreased expression and activities of manganese superoxide dismutase and catalase. In addition, the loss of V-ATPase function led to aberrant vacuolar morphology and defective endocytic trafficking. Furthermore, the sensitivities of the Δvma mutants to other chemical compounds (i.e. acetic acid, H2 O2 , menadione, tunicamycin and cycloheximide) were a consequence of increased endogenous oxidative stress. These findings, therefore, suggest the important role of V-ATPase in preventing endogenous oxidative stress induced by metals and other chemical compounds.
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Affiliation(s)
- Todsapol Techo
- Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand.,Center of Excellence on Environmental Health and Toxicology, CHE, Ministry of Education, Bangkok, Thailand.,Mahidol University-Osaka University Collaborative Research Center for Bioscience and Biotechnology (MU-OU:CRC), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Supat Jindarungrueng
- Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand.,Center of Excellence on Environmental Health and Toxicology, CHE, Ministry of Education, Bangkok, Thailand
| | - Supinda Tatip
- Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand.,Center of Excellence on Environmental Health and Toxicology, CHE, Ministry of Education, Bangkok, Thailand.,Mahidol University-Osaka University Collaborative Research Center for Bioscience and Biotechnology (MU-OU:CRC), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Tossapol Limcharoensuk
- Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand.,Center of Excellence on Environmental Health and Toxicology, CHE, Ministry of Education, Bangkok, Thailand.,Mahidol University-Osaka University Collaborative Research Center for Bioscience and Biotechnology (MU-OU:CRC), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Prayad Pokethitiyook
- Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand.,Center of Excellence on Environmental Health and Toxicology, CHE, Ministry of Education, Bangkok, Thailand
| | - Maleeya Kruatrachue
- Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Choowong Auesukaree
- Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand.,Center of Excellence on Environmental Health and Toxicology, CHE, Ministry of Education, Bangkok, Thailand.,Mahidol University-Osaka University Collaborative Research Center for Bioscience and Biotechnology (MU-OU:CRC), Faculty of Science, Mahidol University, Bangkok, Thailand.,Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
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13
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Vasanthakumar T, Rubinstein JL. Structure and Roles of V-type ATPases. Trends Biochem Sci 2020; 45:295-307. [PMID: 32001091 DOI: 10.1016/j.tibs.2019.12.007] [Citation(s) in RCA: 93] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/05/2019] [Accepted: 12/31/2019] [Indexed: 12/19/2022]
Abstract
V-ATPases are membrane-embedded protein complexes that function as ATP hydrolysis-driven proton pumps. V-ATPases are the primary source of organellar acidification in all eukaryotes, making them essential for many fundamental cellular processes. Enzymatic activity can be modulated by regulated and reversible disassembly of the complex, and several subunits of mammalian V-ATPase have multiple isoforms that are differentially localized. Although the biochemical properties of the different isoforms are currently unknown, mutations in specific subunit isoforms have been associated with various diseases, making V-ATPases potential drug targets. V-ATPase structure and activity have been best characterized in Saccharomyces cerevisiae, where recent structures have revealed details about the dynamics of the enzyme, the proton translocation pathway, and conformational changes associated with regulated disassembly and autoinhibition.
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Affiliation(s)
- Thamiya Vasanthakumar
- The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - John L Rubinstein
- The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Medical Biophysics, The University of Toronto, Toronto, ON M5G 1L7, Canada.
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14
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Hayek SR, Rane HS, Parra KJ. Reciprocal Regulation of V-ATPase and Glycolytic Pathway Elements in Health and Disease. Front Physiol 2019; 10:127. [PMID: 30828305 PMCID: PMC6384264 DOI: 10.3389/fphys.2019.00127] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 01/31/2019] [Indexed: 12/24/2022] Open
Abstract
The ability of cells to adapt to fluctuations in glucose availability is crucial for their survival and involves the vacuolar proton-translocating ATPase (V-ATPase), a proton pump found in all eukaryotes. V-ATPase hydrolyzes ATP via its V1 domain and uses the energy released to transport protons across membranes via its Vo domain. This activity is critical for pH homeostasis and generation of a membrane potential that drives cellular metabolism. A number of stimuli have been reported to alter V-ATPase assembly in yeast and higher eukaryotes. Glucose flux is one of the strongest and best-characterized regulators of V-ATPase; this review highlights current models explaining how glycolysis and V-ATPase are coordinated in both the Saccharomyces cerevisiae model fungus and in mammalian systems. Glucose-dependent assembly and trafficking of V-ATPase, V-ATPase-dependent modulations in glycolysis, and the recent discovery that glucose signaling through V-ATPase acts as a molecular switch to dictate anabolic versus catabolic metabolism are discussed. Notably, metabolic plasticity and altered glycolytic flux are critical drivers of numerous human pathologies, and the expression and activity of V-ATPase is often altered in disease states or can be pharmacologically manipulated as treatment. This overview will specifically discuss connections between V-ATPase and glycolysis in cancer.
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Affiliation(s)
- Summer R Hayek
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, United States
| | - Hallie S Rane
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, United States
| | - Karlett J Parra
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, NM, United States
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15
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Hohlweg W, Wagner GE, Hofbauer HF, Sarkleti F, Setz M, Gubensäk N, Lichtenegger S, Falsone SF, Wolinski H, Kosol S, Oostenbrink C, Kohlwein SD, Zangger K. A cation-π interaction in a transmembrane helix of vacuolar ATPase retains the proton-transporting arginine in a hydrophobic environment. J Biol Chem 2018; 293:18977-18988. [PMID: 30209131 DOI: 10.1074/jbc.ra118.005276] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Revised: 08/24/2018] [Indexed: 11/06/2022] Open
Abstract
Vacuolar ATPases are multisubunit protein complexes that are indispensable for acidification and pH homeostasis in a variety of physiological processes in all eukaryotic cells. An arginine residue (Arg735) in transmembrane helix 7 (TM7) of subunit a of the yeast ATPase is known to be essential for proton translocation. However, the specific mechanism of its involvement in proton transport remains to be determined. Arginine residues are usually assumed to "snorkel" toward the protein surface when exposed to a hydrophobic environment. Here, using solution NMR spectroscopy, molecular dynamics simulations, and in vivo yeast assays, we obtained evidence for the formation of a transient, membrane-embedded cation-π interaction in TM7 between Arg735 and two highly conserved nearby aromatic residues, Tyr733 and Trp737 We propose a mechanism by which the transient, membrane-embedded cation-π complex provides the necessary energy to keep the charged side chain of Arg735 within the hydrophobic membrane. Such cation-π interactions may define a general mechanism to retain charged amino acids in a hydrophobic membrane environment.
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Affiliation(s)
| | - Gabriel E Wagner
- the Institute of Hygiene, Microbiology, and Environmental Medicine, Medical University of Graz, 8010 Graz, Austria
| | - Harald F Hofbauer
- the Institute of Molecular Biosciences, BioTechMed-Graz, University of Graz, 8010 Graz, Austria
| | - Florian Sarkleti
- the Institute of Molecular Biosciences, BioTechMed-Graz, University of Graz, 8010 Graz, Austria
| | - Martina Setz
- the Institute of Molecular Modeling and Simulation, University of Natural Resources and Life Sciences, 1190 Vienna, Austria
| | | | - Sabine Lichtenegger
- the Institute of Hygiene, Microbiology, and Environmental Medicine, Medical University of Graz, 8010 Graz, Austria
| | | | - Heimo Wolinski
- the Institute of Molecular Biosciences, BioTechMed-Graz, University of Graz, 8010 Graz, Austria
| | - Simone Kosol
- the Department of Chemistry, University of Warwick, Gibbet Hill, Coventry CV4 7AL, United Kingdom
| | - Chris Oostenbrink
- the Institute of Molecular Modeling and Simulation, University of Natural Resources and Life Sciences, 1190 Vienna, Austria
| | - Sepp D Kohlwein
- the Institute of Molecular Biosciences, BioTechMed-Graz, University of Graz, 8010 Graz, Austria
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16
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Sun G, Elowsky C, Li G, Wilson RA. TOR-autophagy branch signaling via Imp1 dictates plant-microbe biotrophic interface longevity. PLoS Genet 2018; 14:e1007814. [PMID: 30462633 PMCID: PMC6281275 DOI: 10.1371/journal.pgen.1007814] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 12/05/2018] [Accepted: 11/06/2018] [Indexed: 01/07/2023] Open
Abstract
Like other intracellular eukaryotic phytopathogens, the devastating rice blast fungus Magnaporthe (Pyricularia) oryzae first infects living host cells by elaborating invasive hyphae (IH) surrounded by a plant-derived membrane. This forms an extended biotrophic interface enclosing an apoplastic compartment into which fungal effectors can be deployed to evade host detection. M. oryzae also forms a focal, plant membrane-rich structure, the biotrophic interfacial complex (BIC), that accumulates cytoplasmic effectors for translocation into host cells. Molecular decision-making processes integrating fungal growth and metabolism in host cells with interface function and dynamics are unknown. Here, we report unanticipated roles for the M. oryzae Target-of-Rapamycin (TOR) nutrient-signaling pathway in mediating plant-fungal biotrophic interface membrane integrity. Through a forward genetics screen for M. oryzae mutant strains resistant to the specific TOR kinase inhibitor rapamycin, we discovered IMP1 encoding a novel vacuolar protein required for membrane trafficking, V-ATPase assembly, organelle acidification and autophagy induction. During infection, Δimp1 deletants developed intracellular IH in the first infected rice cell following cuticle penetration. However, fluorescently labeled effector probes revealed that interface membrane integrity became compromised as biotrophy progressed, abolishing the BIC and releasing apoplastic effectors into host cytoplasm. Growth between rice cells was restricted. TOR-independent autophagy activation in Δimp1 deletants (following infection) remediated interface function and cell-to-cell growth. Autophagy inhibition in wild type (following infection) recapitulated Δimp1. In addition to vacuoles, Imp1GFP localized to IH membranes in an autophagy-dependent manner. Collectively, our results suggest TOR-Imp1-autophagy branch signaling mediates membrane homeostasis to prevent catastrophic erosion of the biotrophic interface, thus facilitating fungal growth in living rice cells. The significance of this work lays in elaborating a novel molecular mechanism of infection stressing the dominance of fungal metabolism and metabolic control in sustaining long-term plant-microbe interactions. This work also has implications for understanding the enigmatic biotrophy to necrotrophy transition. Plant-associated fungi can form intimate connections with living host cells. Clarifying the molecular drivers of these interactions, and which partner is dominant, might be important in understanding how beneficial plant-fungal relationships can be enhanced to improve crop yields while pathogenic interactions that threaten crop health are disrupted. In common with other symbionts and phytopathogens, the devastating rice blast fungus Magnaporthe oryzae elaborates invasive hyphae in living host cells surrounded by plant-derived membranes. Nothing is known at the molecular signaling level about how such plant-microbe biotrophic interfacial zones are maintained as the fungus grows in and between host cells. Here, we report that fungal membrane trafficking processes controlled by nutrient signaling pathways are critical for maintaining biotrophic interface integrity during M. oryzae growth in rice cells. Impairing these processes resulted in erosion of the plant-microbe interface and failure of the fungus to thrive. To our knowledge, this work presents the first evidence indicating that the fungal partner is dominant in propagating the plant-microbe boundary. This suggests that the biotrophic interface is a fungal construct and provides clues on how such interfaces might be modulated to benefit the host plant.
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Affiliation(s)
- Guangchao Sun
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Christian Elowsky
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Gang Li
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Richard A. Wilson
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
- * E-mail:
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17
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Bhakt P, Shivarathri R, Choudhary DK, Borah S, Kaur R. Fluconazole-induced actin cytoskeleton remodeling requires phosphatidylinositol 3-phosphate 5-kinase in the pathogenic yeast Candida glabrata. Mol Microbiol 2018; 110:425-443. [PMID: 30137648 PMCID: PMC6221164 DOI: 10.1111/mmi.14110] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 08/09/2018] [Accepted: 08/10/2018] [Indexed: 11/29/2022]
Abstract
Known azole antifungal resistance mechanisms include mitochondrial dysfunction and overexpression of the sterol biosynthetic target enzyme and multidrug efflux pumps. Here, we identify, through a genetic screen, the vacuolar membrane‐resident phosphatidylinositol 3‐phosphate 5‐kinase (CgFab1) to be a novel determinant of azole tolerance. We demonstrate for the first time that fluconazole promotes actin cytoskeleton reorganization in the emerging, inherently less azole‐susceptible fungal pathogen Candida glabrata, and genetic or chemical perturbation of actin structures results in intracellular sterol accumulation and azole susceptibility. Further, CgFAB1 disruption impaired vacuole homeostasis and actin organization, and the F‐actin‐stabilizing compound jasplakinolide rescued azole toxicity in cytoskeleton defective‐mutants including the Cgfab1Δ mutant. In vitro assays revealed that the actin depolymerization factor CgCof1 binds to multiple lipids including phosphatidylinositol 3,5‐bisphosphate. Consistently, CgCof1 distribution along with the actin filament‐capping protein CgCap2 was altered upon both CgFAB1 disruption and fluconazole exposure. Altogether, these data implicate CgFab1 in azole tolerance through actin network remodeling. Finally, we also show that actin polymerization inhibition rendered fluconazole fully and partially fungicidal in azole‐susceptible and azole‐resistant C. glabrata clinical isolates, respectively, thereby, underscoring the role of fluconazole‐effectuated actin remodeling in azole resistance.
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Affiliation(s)
- Priyanka Bhakt
- Laboratory of Fungal Pathogenesis, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana, India.,Graduate Studies, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Raju Shivarathri
- Laboratory of Fungal Pathogenesis, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana, India
| | - Deepak Kumar Choudhary
- Laboratory of Fungal Pathogenesis, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana, India
| | - Sapan Borah
- Laboratory of Fungal Pathogenesis, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana, India
| | - Rupinder Kaur
- Laboratory of Fungal Pathogenesis, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana, India
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18
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Role of the phosphatase Ptc1 in stress responses mediated by CWI and HOG pathways in Fusarium oxysporum. Fungal Genet Biol 2018; 118:10-20. [DOI: 10.1016/j.fgb.2018.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/24/2018] [Accepted: 05/27/2018] [Indexed: 01/09/2023]
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19
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Corso M, Schvartzman MS, Guzzo F, Souard F, Malkowski E, Hanikenne M, Verbruggen N. Contrasting cadmium resistance strategies in two metallicolous populations of Arabidopsis halleri. THE NEW PHYTOLOGIST 2018; 218:283-297. [PMID: 29292826 DOI: 10.1111/nph.14948] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 11/05/2017] [Indexed: 05/10/2023]
Abstract
While cadmium (Cd) tolerance is a constitutive trait in the Arabidopsis halleri species, Cd accumulation is highly variable. Recent adaptation to anthropogenic metal stress has occurred independently within the genetic units of A. halleri and the evolution of different mechanisms involved in Cd tolerance and accumulation has been suggested. To gain a better understanding of the mechanisms underlying Cd tolerance and accumulation in A. halleri, ionomic inductively coupled plasma mass spectrometry (ICP-MS), transcriptomic (RNA sequencing) and metabolomic (high-performance liquid chromatography-mass spectrometry) profiles were analysed in two A. halleri metallicolous populations from different genetic units (PL22 from Poland and I16 from Italy). The PL22 and I16 populations were both hypertolerant to Cd, but PL22 hyperaccumulated Cd while I16 behaved as an excluder both in situ and when grown hydroponically. The observed hyperaccumulator vs excluder behaviours were paralleled by large differences in the expression profiles of transporter genes. Flavonoid-related transcripts and metabolites were strikingly more abundant in PL22 than in I16 shoots. The role of novel A. halleri candidate genes possibly involved in Cd hyperaccumulation or exclusion was supported by the study of corresponding A. thaliana knockout mutants. Taken together, our results are suggestive of the evolution of divergent strategies for Cd uptake, transport and detoxification in different genetic units of A. halleri.
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Affiliation(s)
- Massimiliano Corso
- Laboratory of Plant Physiology and Molecular Genetics, Université Libre de Bruxelles, 1050, Brussels, Belgium
| | - M Sol Schvartzman
- InBioS-PhytoSystems, Functional Genomics and Plant Molecular Imaging, University of Liège, B-4000, Liège, Belgium
| | - Flavia Guzzo
- Department of Biotechnology, University of Verona, 37134, Verona, Italy
| | - Florence Souard
- Département de Pharmacochimie Moléculaire, CNRS UMR5063, University Grenoble Alpes, 38400, St Martin d'Hères, France
- Laboratoire de Pharmacognosie, de Bromatologie et de Nutrition Humaine, Université Libre de Bruxelles, 1050, Brussels, Belgium
| | - Eugeniusz Malkowski
- Department of Plant Physiology, Faculty of Biology and Environmental Protection, University of Silesia in Katowice, 40-032, Katowice, Poland
| | - Marc Hanikenne
- InBioS-PhytoSystems, Functional Genomics and Plant Molecular Imaging, University of Liège, B-4000, Liège, Belgium
| | - Nathalie Verbruggen
- Laboratory of Plant Physiology and Molecular Genetics, Université Libre de Bruxelles, 1050, Brussels, Belgium
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20
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Prasad H, Rao R. Histone deacetylase-mediated regulation of endolysosomal pH. J Biol Chem 2018; 293:6721-6735. [PMID: 29567836 DOI: 10.1074/jbc.ra118.002025] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Revised: 03/19/2018] [Indexed: 11/06/2022] Open
Abstract
The pH of the endolysosomal system is tightly regulated by a balance of proton pump and leak mechanisms that are critical for storage, recycling, turnover, and signaling functions in the cell. Dysregulation of endolysosomal pH has been linked to aging, amyloidogenesis, synaptic dysfunction, and various neurodegenerative disorders, including Alzheimer's disease. Therefore, understanding the mechanisms that regulate luminal pH may be key to identifying new targets for managing these disorders. Meta-analysis of yeast microarray databases revealed that nutrient-limiting conditions inhibited the histone deacetylase (HDAC) Rpd3 and thereby up-regulated transcription of the endosomal Na+/H+ exchanger Nhx1, resulting in vacuolar alkalinization. Consistent with these findings, Rpd3 inhibition by the HDAC inhibitor and antifungal drug trichostatin A induced Nhx1 expression and vacuolar alkalinization. Bioinformatics analysis of Drosophila and mouse databases revealed that caloric control of the Nhx1 orthologs DmNHE3 and NHE6, respectively, is also mediated by HDACs. We show that NHE6 is a target of the transcription factor cAMP-response element-binding protein (CREB), a known regulator of cellular responses to low-nutrient conditions, providing a molecular mechanism for nutrient- and HDAC-dependent regulation of endosomal pH. Of note, pharmacological targeting of the CREB pathway to increase NHE6 expression helped regulate endosomal pH and correct defective clearance of amyloid Aβ in an apoE4 astrocyte model of Alzheimer's disease. These observations from yeast, fly, mouse, and cell culture models point to an evolutionarily conserved mechanism for HDAC-mediated regulation of endosomal NHE expression. Our insights offer new therapeutic strategies for modulation of endolysosomal pH in fungal infection and human disease.
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Affiliation(s)
- Hari Prasad
- From the Department of Physiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Rajini Rao
- From the Department of Physiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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21
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Compensatory Internalization of Pma1 in V-ATPase Mutants in Saccharomyces cerevisiae Requires Calcium- and Glucose-Sensitive Phosphatases. Genetics 2017; 208:655-672. [PMID: 29254995 PMCID: PMC5788529 DOI: 10.1534/genetics.117.300594] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 12/09/2017] [Indexed: 11/23/2022] Open
Abstract
Loss of V-ATPase activity in organelles triggers compensatory endocytic downregulation of the plasma membrane proton pump Pma1. Here, Velivela and Kane... Loss of V-ATPase activity in organelles, whether through V-ATPase inhibition or V-ATPase (vma) mutations, triggers a compensatory downregulation of the essential plasma membrane proton pump Pma1 in Saccharomyces cerevisiae. We have previously determined that the α-arrestin Rim8 and ubiquitin ligase Rsp5 are essential for Pma1 ubiquination and endocytosis in response to loss of V-ATPase activity. Here, we show that Pma1 endocytosis in V-ATPase mutants does not require Rim101 pathway components upstream and downstream of Rim8, indicating that Rim8 is acting independently in Pma1 internalization. We find that two phosphatases, the calcium-responsive phosphatase calcineurin and the glucose-sensitive phosphatase Glc7 (PP1), and one of the Glc7 regulatory subunits Reg1, exhibit negative synthetic genetic interactions with vma mutants, and demonstrate that both phosphatases are essential for ubiquitination and endocytic downregulation of Pma1 in these mutants. Although both acute and chronic loss of V-ATPase activity trigger the internalization of ∼50% of surface Pma1, a comparable reduction in Pma1 expression in a pma1-007 mutant neither compensates for loss of V-ATPase activity nor stops further Pma1 endocytosis. The results indicate that the cell surface level of Pma1 is not directly sensed and that internalized Pma1 may play a role in compensating for loss of V-ATPase-dependent acidification. Taken together, these results provide new insights into cross talk between two major proton pumps central to cellular pH control.
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22
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Ghanegolmohammadi F, Yoshida M, Ohnuki S, Sukegawa Y, Okada H, Obara K, Kihara A, Suzuki K, Kojima T, Yachie N, Hirata D, Ohya Y. Systematic analysis of Ca 2+ homeostasis in Saccharomyces cerevisiae based on chemical-genetic interaction profiles. Mol Biol Cell 2017; 28:3415-3427. [PMID: 28566553 PMCID: PMC5687040 DOI: 10.1091/mbc.e17-04-0216] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 05/23/2017] [Accepted: 05/24/2017] [Indexed: 12/20/2022] Open
Abstract
We investigated the global landscape of Ca2+ homeostasis in budding yeast based on high-dimensional chemical-genetic interaction profiles. The morphological responses of 62 Ca2+-sensitive (cls) mutants were quantitatively analyzed with the image processing program CalMorph after exposure to a high concentration of Ca2+ After a generalized linear model was applied, an analysis of covariance model was used to detect significant Ca2+-cls interactions. We found that high-dimensional, morphological Ca2+-cls interactions were mixed with positive (86%) and negative (14%) chemical-genetic interactions, whereas one-dimensional fitness Ca2+-cls interactions were all negative in principle. Clustering analysis with the interaction profiles revealed nine distinct gene groups, six of which were functionally associated. In addition, characterization of Ca2+-cls interactions revealed that morphology-based negative interactions are unique signatures of sensitized cellular processes and pathways. Principal component analysis was used to discriminate between suppression and enhancement of the Ca2+-sensitive phenotypes triggered by inactivation of calcineurin, a Ca2+-dependent phosphatase. Finally, similarity of the interaction profiles was used to reveal a connected network among the Ca2+ homeostasis units acting in different cellular compartments. Our analyses of high-dimensional chemical-genetic interaction profiles provide novel insights into the intracellular network of yeast Ca2+ homeostasis.
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Affiliation(s)
| | - Mitsunori Yoshida
- Department of Integrated Biosciences, University of Tokyo, Kashiwa 277-8562, Japan
| | - Shinsuke Ohnuki
- Department of Integrated Biosciences, University of Tokyo, Kashiwa 277-8562, Japan
| | - Yuko Sukegawa
- Department of Integrated Biosciences, University of Tokyo, Kashiwa 277-8562, Japan
- AIST-UTokyo Advanced Operand-Measurement Technology Open Innovation Laboratory, Kashiwa 277-0882, Japan
| | - Hiroki Okada
- Department of Integrated Biosciences, University of Tokyo, Kashiwa 277-8562, Japan
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058
| | - Keisuke Obara
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Akio Kihara
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Kuninori Suzuki
- Department of Integrated Biosciences, University of Tokyo, Kashiwa 277-8562, Japan
- Bioimaging Center, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa 277-8562, Japan
| | - Tetsuya Kojima
- Department of Integrated Biosciences, University of Tokyo, Kashiwa 277-8562, Japan
| | - Nozomu Yachie
- Synthetic Biology Division, Research Center for Advanced Science and Technology, University of Tokyo, Tokyo 153-8904, Japan
- PRESTO, Japan Science and Technology Agency, Tokyo 102-0076, Japan
| | - Dai Hirata
- Research and Development Department, Asahi Sake Brewing Co., Nagaoka 949-5494, Japan
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
| | - Yoshikazu Ohya
- Department of Integrated Biosciences, University of Tokyo, Kashiwa 277-8562, Japan
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Nguyen TD, Walker ME, Gardner JM, Jiranek V. Appropriate vacuolar acidification in Saccharomyces cerevisiae is associated with efficient high sugar fermentation. Food Microbiol 2017; 70:262-268. [PMID: 29173635 DOI: 10.1016/j.fm.2017.09.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 08/05/2017] [Accepted: 09/29/2017] [Indexed: 01/01/2023]
Abstract
Vacuolar acidification serves as a homeostatic mechanism to regulate intracellular pH, ion and chemical balance, as well as trafficking and recycling of proteins and nutrients, critical for normal cellular function. This study reports on the importance of vacuole acidification during wine-like fermentation. Ninety-three mutants (homozygous deletions in lab yeast strain, BY4743), which result in protracted fermentation when grown in a chemically defined grape juice with 200 g L-1 sugar (pH 3.5), were examined to determine whether fermentation protraction was in part due to a dysfunction in vacuolar acidification (VA) during the early stages of fermentation, and whether VA was responsive to the initial sugar concentration in the medium. Cells after 24 h growth were dual-labelled with propidium iodide and vacuolar specific probe 6-carboxyfluorescein diacetate (6-CFDA) and examined with a FACS analyser for viability and impaired VA, respectively. Twenty mutants showed a greater than two-fold increase in fluorescence intensity; the experimental indicator for vacuolar dysfunction; 10 of which have not been previously annotated to this process. With the exception of Δhog1, Δpbs2 and Δvph1 mutants, where dysfunction was directly related to osmolality; the remainder exhibited increased CF-fluorescence, independent of sugar concentration at 20 g L-1 or 200 g L-1. These findings offer insight to the importance of VA to cell growth in high sugar media.
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Affiliation(s)
- Trung D Nguyen
- School of Agriculture, Food and Wine, The University of Adelaide, PMB 1 Glen Osmond, SA 5064, Australia; Wine Innovation Cluster, Adelaide, South Australia, Australia
| | - Michelle E Walker
- School of Agriculture, Food and Wine, The University of Adelaide, PMB 1 Glen Osmond, SA 5064, Australia; Wine Innovation Cluster, Adelaide, South Australia, Australia
| | - Jennifer M Gardner
- School of Agriculture, Food and Wine, The University of Adelaide, PMB 1 Glen Osmond, SA 5064, Australia; Wine Innovation Cluster, Adelaide, South Australia, Australia
| | - Vladimir Jiranek
- School of Agriculture, Food and Wine, The University of Adelaide, PMB 1 Glen Osmond, SA 5064, Australia; Wine Innovation Cluster, Adelaide, South Australia, Australia; Australian Research Council Training Centre for Innovative Wine Production, Australia.
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24
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Phosphate Acquisition and Virulence in Human Fungal Pathogens. Microorganisms 2017; 5:microorganisms5030048. [PMID: 28829379 PMCID: PMC5620639 DOI: 10.3390/microorganisms5030048] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 08/15/2017] [Accepted: 08/16/2017] [Indexed: 01/23/2023] Open
Abstract
The ability of pathogenic fungi to acquire essential macro and micronutrients during infection is a well-established virulence trait. Recent studies in the major human fungal pathogens Candida albicans and Cryptococcus neoformans have revealed that acquisition of the essential macronutrient, phosphate, is essential for virulence. The phosphate sensing and acquisition pathway in fungi, known as the PHO pathway, has been extensively characterized in the model yeast Saccharomyces cerevisiae. In this review, we highlight recent advances in phosphate sensing and signaling mechanisms, and use the S. cerevisiae PHO pathway as a platform from which to compare the phosphate acquisition and storage strategies employed by several human pathogenic fungi. We also explore the multi-layered roles of phosphate acquisition in promoting fungal stress resistance to pH, cationic, and oxidative stresses, and describe emerging roles for the phosphate storage molecule polyphosphate (polyP). Finally, we summarize the recent studies supporting the necessity of phosphate acquisition in mediating the virulence of human fungal pathogens, highlighting the concept that this requirement is intimately linked to promoting resistance to host-imposed stresses.
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25
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Mülleder M, Calvani E, Alam MT, Wang RK, Eckerstorfer F, Zelezniak A, Ralser M. Functional Metabolomics Describes the Yeast Biosynthetic Regulome. Cell 2016; 167:553-565.e12. [PMID: 27693354 PMCID: PMC5055083 DOI: 10.1016/j.cell.2016.09.007] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 06/23/2016] [Accepted: 09/02/2016] [Indexed: 11/16/2022]
Abstract
Genome-metabolism interactions enable cell growth. To probe the extent of these interactions and delineate their functional contributions, we quantified the Saccharomyces amino acid metabolome and its response to systematic gene deletion. Over one-third of coding genes, in particular those important for chromatin dynamics, translation, and transport, contribute to biosynthetic metabolism. Specific amino acid signatures characterize genes of similar function. This enabled us to exploit functional metabolomics to connect metabolic regulators to their effectors, as exemplified by TORC1, whose inhibition in exponentially growing cells is shown to match an interruption in endomembrane transport. Providing orthogonal information compared to physical and genetic interaction networks, metabolomic signatures cluster more than half of the so far uncharacterized yeast genes and provide functional annotation for them. A major part of coding genes is therefore participating in gene-metabolism interactions that expose the metabolism regulatory network and enable access to an underexplored space in gene function. One-third of coding genes significantly impact yeast biosynthetic metabolism The amino acid metabolome is most sensitive to chromatin and transport proteins TORC1 affects biosynthetic amino acid metabolism via vesicle-mediated transport Metabolic signatures are gene specific and cluster 3,923 genes according to function
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Affiliation(s)
- Michael Mülleder
- Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, Cambridge CB2 1GA, UK; The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London NW7 1AA, UK
| | - Enrica Calvani
- Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, Cambridge CB2 1GA, UK; The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London NW7 1AA, UK
| | - Mohammad Tauqeer Alam
- Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, Cambridge CB2 1GA, UK
| | - Richard Kangda Wang
- Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, Cambridge CB2 1GA, UK
| | - Florian Eckerstorfer
- Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, Cambridge CB2 1GA, UK
| | - Aleksej Zelezniak
- Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, Cambridge CB2 1GA, UK; The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London NW7 1AA, UK
| | - Markus Ralser
- Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, Cambridge CB2 1GA, UK; The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London NW7 1AA, UK.
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26
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Ikeh MAC, Kastora SL, Day AM, Herrero-de-Dios CM, Tarrant E, Waldron KJ, Banks AP, Bain JM, Lydall D, Veal EA, MacCallum DM, Erwig LP, Brown AJP, Quinn J. Pho4 mediates phosphate acquisition in Candida albicans and is vital for stress resistance and metal homeostasis. Mol Biol Cell 2016; 27:2784-801. [PMID: 27385340 PMCID: PMC5007097 DOI: 10.1091/mbc.e16-05-0266] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 06/23/2016] [Indexed: 12/02/2022] Open
Abstract
This study provides the first evidence that the phosphate-responsive transcription factor Pho4 is vital for survival of Candida albicans to diverse and physiologically relevant stresses. Pho4 is important for C. albicans pathogenesis, and thus these findings illustrate how metabolic adaptation promotes C. albicans survival in the host. During interactions with its mammalian host, the pathogenic yeast Candida albicans is exposed to a range of stresses such as superoxide radicals and cationic fluxes. Unexpectedly, a nonbiased screen of transcription factor deletion mutants revealed that the phosphate-responsive transcription factor Pho4 is vital for the resistance of C. albicans to these diverse stresses. RNA-Seq analysis indicated that Pho4 does not induce stress-protective genes directly. Instead, we show that loss of Pho4 affects metal cation toxicity, accumulation, and bioavailability. We demonstrate that pho4Δ cells are sensitive to metal and nonmetal cations and that Pho4-mediated polyphosphate synthesis mediates manganese resistance. Significantly, we show that Pho4 is important for mediating copper bioavailability to support the activity of the copper/zinc superoxide dismutase Sod1 and that loss of Sod1 activity contributes to the superoxide sensitivity of pho4Δ cells. Consistent with the key role of fungal stress responses in countering host phagocytic defenses, we also report that C. albicans pho4Δ cells are acutely sensitive to macrophage-mediated killing and display attenuated virulence in animal infection models. The novel connections between phosphate metabolism, metal homeostasis, and superoxide stress resistance presented in this study highlight the importance of metabolic adaptation in promoting C. albicans survival in the host.
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Affiliation(s)
- Mélanie A C Ikeh
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Stavroula L Kastora
- School of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom
| | - Alison M Day
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | | | - Emma Tarrant
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Kevin J Waldron
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - A Peter Banks
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Judith M Bain
- School of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom
| | - David Lydall
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Elizabeth A Veal
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Donna M MacCallum
- School of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom
| | - Lars P Erwig
- School of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom
| | - Alistair J P Brown
- School of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom
| | - Janet Quinn
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
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27
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Tatjer L, González A, Serra-Cardona A, Barceló A, Casamayor A, Ariño J. The Saccharomyces cerevisiae Ptc1 protein phosphatase attenuates G2-M cell cycle blockage caused by activation of the cell wall integrity pathway. Mol Microbiol 2016; 101:671-87. [PMID: 27169355 DOI: 10.1111/mmi.13416] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/05/2016] [Indexed: 01/24/2023]
Abstract
Lack of the yeast Ptc1 Ser/Thr protein phosphatase results in numerous phenotypic defects. A parallel search for high-copy number suppressors of three of these phenotypes (sensitivity to Calcofluor White, rapamycin and alkaline pH), allowed the isolation of 25 suppressor genes, which could be assigned to three main functional categories: maintenance of cell wall integrity (CWI), vacuolar function and protein sorting, and cell cycle regulation. The characterization of these genetic interactions strengthens the relevant role of Ptc1 in downregulating the Slt2-mediated CWI pathway. We show that under stress conditions activating the CWI pathway the ptc1 mutant displays hyperphosphorylated Cdc28 kinase and that these cells accumulate with duplicated DNA content, indicative of a G2-M arrest. Clb2-associated Cdc28 activity was also reduced in ptc1 cells. These alterations are attenuated by mutation of the MKK1 gene, encoding a MAP kinase kinase upstream Slt2. Therefore, our data show that Ptc1 is required for proper G2-M cell cycle transition after activation of the CWI pathway.
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Affiliation(s)
- Laura Tatjer
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
| | - Asier González
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
| | - Albert Serra-Cardona
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
| | - Anna Barceló
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
| | - Antonio Casamayor
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
| | - Joaquín Ariño
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
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28
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Vacuolar H+-ATPase Protects Saccharomyces cerevisiae Cells against Ethanol-Induced Oxidative and Cell Wall Stresses. Appl Environ Microbiol 2016; 82:3121-3130. [PMID: 26994074 DOI: 10.1128/aem.00376-16] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 03/11/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED During fermentation, increased ethanol concentration is a major stress for yeast cells. Vacuolar H(+)-ATPase (V-ATPase), which plays an important role in the maintenance of intracellular pH homeostasis through vacuolar acidification, has been shown to be required for tolerance to straight-chain alcohols, including ethanol. Since ethanol is known to increase membrane permeability to protons, which then promotes intracellular acidification, it is possible that the V-ATPase is required for recovery from alcohol-induced intracellular acidification. In this study, we show that the effects of straight-chain alcohols on membrane permeabilization and acidification of the cytosol and vacuole are strongly dependent on their lipophilicity. These findings suggest that the membrane-permeabilizing effect of straight-chain alcohols induces cytosolic and vacuolar acidification in a lipophilicity-dependent manner. Surprisingly, after ethanol challenge, the cytosolic pH in Δvma2 and Δvma3 mutants lacking V-ATPase activity was similar to that of the wild-type strain. It is therefore unlikely that the ethanol-sensitive phenotype of vma mutants resulted from severe cytosolic acidification. Interestingly, the vma mutants exposed to ethanol exhibited a delay in cell wall remodeling and a significant increase in intracellular reactive oxygen species (ROS). These findings suggest a role for V-ATPase in the regulation of the cell wall stress response and the prevention of endogenous oxidative stress in response to ethanol. IMPORTANCE The yeast Saccharomyces cerevisiae has been widely used in the alcoholic fermentation industry. Among the environmental stresses that yeast cells encounter during the process of alcoholic fermentation, ethanol is a major stress factor that inhibits yeast growth and viability, eventually leading to fermentation arrest. This study provides evidence for the molecular mechanisms of ethanol tolerance, which is a desirable characteristic for yeast strains used in alcoholic fermentation. The results revealed that straight-chain alcohols induced cytosolic and vacuolar acidification through their membrane-permeabilizing effects. Contrary to expectations, a role for V-ATPase in the regulation of the cell wall stress response and the prevention of endogenous oxidative stress, but not in the maintenance of intracellular pH, seems to be important for protecting yeast cells against ethanol stress. These findings will expand our understanding of the mechanisms of ethanol tolerance and provide promising clues for the development of ethanol-tolerant yeast strains.
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29
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Liu J, Ji Y, Zhou J, Xing D. Phosphatidylinositol 3-Kinase Promotes Activation and Vacuolar Acidification and Delays Methyl Jasmonate-Induced Leaf Senescence. PLANT PHYSIOLOGY 2016; 170:1714-31. [PMID: 26739232 PMCID: PMC4775102 DOI: 10.1104/pp.15.00744] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 01/05/2016] [Indexed: 05/09/2023]
Abstract
PI3K and its product PI3P are both involved in plant development and stress responses. In this study, the down-regulation of PI3K activity accelerated leaf senescence induced by methyl jasmonate (MeJA) and suppressed the activation of vacuolar H(+)-ATPase (V-ATPase). Yeast two-hybrid analyses indicated that PI3K bound to the V-ATPase B subunit (VHA-B). Analysis of bimolecular fluorescence complementation in tobacco guard cells showed that PI3K interacted with VHA-B2 in the tonoplasts. Through the use of pharmacological and genetic tools, we found that PI3K and V-ATPase promoted vacuolar acidification and stomatal closure during leaf senescence. Vacuolar acidification was suppressed by the PIKfyve inhibitor in 35S:AtVPS34-YFP Arabidopsis during MeJA-induced leaf senescence, but the decrease was lower than that in YFP-labeled Arabidopsis. These results suggest that PI3K promotes V-ATPase activation and consequently induces vacuolar acidification and stomatal closure, thereby delaying MeJA-induced leaf senescence.
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Affiliation(s)
- Jian Liu
- MOE Key Laboratory of Laser Life Science, and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, China (J.L., Y.J., J.Z., D. X.)
| | - Yingbin Ji
- MOE Key Laboratory of Laser Life Science, and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, China (J.L., Y.J., J.Z., D. X.)
| | - Jun Zhou
- MOE Key Laboratory of Laser Life Science, and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, China (J.L., Y.J., J.Z., D. X.)
| | - Da Xing
- MOE Key Laboratory of Laser Life Science, and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, China (J.L., Y.J., J.Z., D. X.).
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30
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Bernard D, Gebbia M, Prabha S, Gronda M, MacLean N, Wang X, Hurren R, Sukhai MA, Cho EE, Manolson MF, Datti A, Wrana J, Minden MD, Al-Awar R, Aman A, Nislow C, Giaever G, Schimmer AD. Select microtubule inhibitors increase lysosome acidity and promote lysosomal disruption in acute myeloid leukemia (AML) cells. Apoptosis 2016; 20:948-59. [PMID: 25832785 DOI: 10.1007/s10495-015-1123-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
To identify new biological vulnerabilities in acute myeloid leukemia, we screened a library of natural products for compounds cytotoxic to TEX leukemia cells. This screen identified the novel small molecule Deoxysappanone B 7,4' dimethyl ether (Deox B 7,4), which possessed nanomolar anti-leukemic activity. To determine the anti-leukemic mechanism of action of Deox B 7,4, we conducted a genome-wide screen in Saccharomyces cerevisiae and identified enrichment of genes related to mitotic cell cycle as well as vacuolar acidification, therefore pointing to microtubules and vacuolar (V)-ATPase as potential drug targets. Further investigations into the mechanisms of action of Deox B 7,4 and a related analogue revealed that these compounds were reversible microtubule inhibitors that bound near the colchicine site. In addition, Deox B 7,4 and its analogue increased lysosomal V-ATPase activity and lysosome acidity. The effects on microtubules and lysosomes were functionally important for the anti-leukemic effects of these drugs. The lysosomal effects were characteristic of select microtubule inhibitors as only the Deox compounds and nocodazole, but not colchicine, vinca alkaloids or paclitaxel, altered lysosome acidity and induced lysosomal disruption. Thus, our data highlight a new mechanism of action of select microtubule inhibitors on lysosomal function.
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Affiliation(s)
- Dannie Bernard
- Princess Margaret Cancer Centre, University Health Network, Rm 9-516, 610 University Ave, Toronto, ON, M5G 2M9, Canada
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31
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Norlin S, Parekh VS, Naredi P, Edlund H. Asna1/TRC40 Controls β-Cell Function and Endoplasmic Reticulum Homeostasis by Ensuring Retrograde Transport. Diabetes 2016; 65:110-9. [PMID: 26438609 DOI: 10.2337/db15-0699] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 09/28/2015] [Indexed: 11/13/2022]
Abstract
Type 2 diabetes (T2D) is characterized by insulin resistance and β-cell failure. Insulin resistance per se, however, does not provoke overt diabetes as long as compensatory β-cell function is maintained. The increased demand for insulin stresses the β-cell endoplasmic reticulum (ER) and secretory pathway, and ER stress is associated with β-cell failure in T2D. The tail recognition complex (TRC) pathway, including Asna1/TRC40, is implicated in the maintenance of endomembrane trafficking and ER homeostasis. To gain insight into the role of Asna1/TRC40 in maintaining endomembrane homeostasis and β-cell function, we inactivated Asna1 in β-cells of mice. We show that Asna1(β-/-) mice develop hypoinsulinemia, impaired insulin secretion, and glucose intolerance that rapidly progresses to overt diabetes. Loss of Asna1 function leads to perturbed plasma membrane-to-trans Golgi network and Golgi-to-ER retrograde transport as well as to ER stress in β-cells. Of note, pharmacological inhibition of retrograde transport in isolated islets and insulinoma cells mimicked the phenotype of Asna1(β-/-) β-cells and resulted in reduced insulin content and ER stress. These data support a model where Asna1 ensures retrograde transport and, hence, ER and insulin homeostasis in β-cells.
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Affiliation(s)
- Stefan Norlin
- Umeå Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Vishal S Parekh
- Umeå Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Peter Naredi
- Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg
| | - Helena Edlund
- Umeå Centre for Molecular Medicine, Umeå University, Umeå, Sweden
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32
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Tatjer L, Sacristán-Reviriego A, Casado C, González A, Rodríguez-Porrata B, Palacios L, Canadell D, Serra-Cardona A, Martín H, Molina M, Ariño J. Wide-Ranging Effects of the Yeast Ptc1 Protein Phosphatase Acting Through the MAPK Kinase Mkk1. Genetics 2016; 202:141-56. [PMID: 26546002 PMCID: PMC4701081 DOI: 10.1534/genetics.115.183202] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 11/02/2015] [Indexed: 11/18/2022] Open
Abstract
The Saccharomyces cerevisiae type 2C protein phosphatase Ptc1 is required for a wide variety of cellular functions, although only a few cellular targets have been identified. A genetic screen in search of mutations in protein kinase-encoding genes able to suppress multiple phenotypic traits caused by the ptc1 deletion yielded a single gene, MKK1, coding for a MAPK kinase (MAPKK) known to activate the cell-wall integrity (CWI) Slt2 MAPK. In contrast, mutation of the MKK1 paralog, MKK2, had a less significant effect. Deletion of MKK1 abolished the increased phosphorylation of Slt2 induced by the absence of Ptc1 both under basal and CWI pathway stimulatory conditions. We demonstrate that Ptc1 acts at the level of the MAPKKs of the CWI pathway, but only the Mkk1 kinase activity is essential for ptc1 mutants to display high Slt2 activation. We also show that Ptc1 is able to dephosphorylate Mkk1 in vitro. Our results reveal the preeminent role of Mkk1 in signaling through the CWI pathway and strongly suggest that hyperactivation of Slt2 caused by upregulation of Mkk1 is at the basis of most of the phenotypic defects associated with lack of Ptc1 function.
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Affiliation(s)
- Laura Tatjer
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra 08193, Barcelona, Spain
| | - Almudena Sacristán-Reviriego
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense and Instituto Ramón y Cajal de Investigaciones Sanitarias (IRYCIS), 28040 Madrid, Spain
| | - Carlos Casado
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra 08193, Barcelona, Spain
| | - Asier González
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra 08193, Barcelona, Spain
| | - Boris Rodríguez-Porrata
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra 08193, Barcelona, Spain
| | - Lorena Palacios
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense and Instituto Ramón y Cajal de Investigaciones Sanitarias (IRYCIS), 28040 Madrid, Spain
| | - David Canadell
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra 08193, Barcelona, Spain
| | - Albert Serra-Cardona
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra 08193, Barcelona, Spain
| | - Humberto Martín
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense and Instituto Ramón y Cajal de Investigaciones Sanitarias (IRYCIS), 28040 Madrid, Spain
| | - María Molina
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense and Instituto Ramón y Cajal de Investigaciones Sanitarias (IRYCIS), 28040 Madrid, Spain
| | - Joaquín Ariño
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra 08193, Barcelona, Spain
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33
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Ho CY, Choy CH, Wattson CA, Johnson DE, Botelho RJ. The Fab1/PIKfyve phosphoinositide phosphate kinase is not necessary to maintain the pH of lysosomes and of the yeast vacuole. J Biol Chem 2015; 290:9919-28. [PMID: 25713145 DOI: 10.1074/jbc.m114.613984] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Indexed: 12/30/2022] Open
Abstract
Lysosomes and the yeast vacuole are degradative and acidic organelles. Phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P2), a master architect of endolysosome and vacuole identity, is thought to be necessary for vacuolar acidification in yeast. There is also evidence that PtdIns(3,5)P2 may play a role in lysosomal acidification in higher eukaryotes. Nevertheless, these conclusions rely on qualitative assays of lysosome/vacuole pH. For example, quinacrine, an acidotropic fluorescent base, does not accumulate in the vacuoles of fab1Δ yeast. Fab1, along with its mammalian ortholog PIKfyve, is the lipid kinase responsible for synthesizing PtdIns(3,5)P2. In this study, we employed several assays that quantitatively assessed the lysosomal and vacuolar pH in PtdIns(3,5)P2-depleted cells. Using ratiometric imaging, we conclude that lysosomes retain a pH < 5 in PIKfyve-inhibited mammalian cells. In addition, quantitative fluorescence microscopy of vacuole-targeted pHluorin, a pH-sensitive GFP variant, indicates that fab1Δ vacuoles are as acidic as wild-type yeast. Importantly, we also employed fluorimetry of vacuoles loaded with cDCFDA, a pH-sensitive dye, to show that both wild-type and fab1Δ vacuoles have a pH < 5.0. In comparison, the vacuolar pH of the V-ATPase mutant vph1Δ or vph1Δ fab1Δ double mutant was 6.1. Although the steady-state vacuolar pH is not affected by PtdIns(3,5)P2 depletion, it may have a role in stabilizing the vacuolar pH during salt shock. Overall, we propose a model in which PtdIns(3,5)P2 does not govern the steady-state pH of vacuoles or lysosomes.
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Affiliation(s)
- Cheuk Y Ho
- From the Department of Chemistry and Biology and the Molecular Science Program, Ryerson University, Toronto, Ontario M5B2K3, Canada and
| | - Christopher H Choy
- From the Department of Chemistry and Biology and the Molecular Science Program, Ryerson University, Toronto, Ontario M5B2K3, Canada and
| | | | - Danielle E Johnson
- the Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G1X8, Canada
| | - Roberto J Botelho
- From the Department of Chemistry and Biology and the Molecular Science Program, Ryerson University, Toronto, Ontario M5B2K3, Canada and the Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G1X8, Canada
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Mir SUR, Schwarze SR, Jin L, Zhang J, Friend W, Miriyala S, St Clair D, Craven RJ. Progesterone receptor membrane component 1/Sigma-2 receptor associates with MAP1LC3B and promotes autophagy. Autophagy 2014; 9:1566-78. [DOI: 10.4161/auto.25889] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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Pérez-Sampietro M, Herrero E. The PacC-family protein Rim101 prevents selenite toxicity in Saccharomyces cerevisiae by controlling vacuolar acidification. Fungal Genet Biol 2014; 71:76-85. [PMID: 25239548 DOI: 10.1016/j.fgb.2014.09.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 09/02/2014] [Accepted: 09/06/2014] [Indexed: 01/10/2023]
Abstract
Saccharomyces cerevisiae Rim101 is a member of the fungal PacC family of transcription factors involved in the response to alkaline pH stress. Further studies have also implicated Rim101 in the responses to other stresses, and have shown its genetic interaction with the iron deprivation-responsive factor Aft1. The present study shows that the absence of Rim101 leads to hypersensitivity to oxidants such as t-butyl hydroperoxide and diamide, and also to the prooxidant agent selenite. The protective role of Rim101 against selenite requires the sensing complex component Rim8, the ESCRT-I/II/III complexes and the Rim13 protease involved in proteolytic activation of Rim101. The Nrg1 transcriptional repressor is a downstream effector of Rim101 in this response to selenite, as occurs in the responses to alkaline pH, Na(+) and Li(+) stresses. Deletion of RIM101 causes downregulation of the vacuolar ATPase genes VMA2 and VMA4, which becomes accentuated compared to wild type cells upon selenite stress, and activation of the Rim101 protein prevents inhibition of vacuolar acidification caused by selenite. These observations therefore support a role of Rim101 in modulation of vacuolar acidity necessary for selenite detoxification. In addition, a parallel Rim101-independent pathway requiring the complete ESCRT machinery (including the ESCRT-0 complex) also participates in protection against selenite.
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Affiliation(s)
- Maria Pérez-Sampietro
- Departament de Ciències Mèdiques Bàsiques, Universitat de Lleida, IRBLleida, Edifici Biomedicina I, Rovira Roure 198, 25198-Lleida, Spain
| | - Enrique Herrero
- Departament de Ciències Mèdiques Bàsiques, Universitat de Lleida, IRBLleida, Edifici Biomedicina I, Rovira Roure 198, 25198-Lleida, Spain.
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Li SC, Diakov TT, Xu T, Tarsio M, Zhu W, Couoh-Cardel S, Weisman LS, Kane PM. The signaling lipid PI(3,5)P₂ stabilizes V₁-V(o) sector interactions and activates the V-ATPase. Mol Biol Cell 2014; 25:1251-62. [PMID: 24523285 PMCID: PMC3982991 DOI: 10.1091/mbc.e13-10-0563] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Vacuolar proton-translocating ATPases (V-ATPases) are highly conserved, ATP-driven proton pumps regulated by reversible dissociation of its cytosolic, peripheral V1 domain from the integral membrane V(o) domain. Multiple stresses induce changes in V1-V(o) assembly, but the signaling mechanisms behind these changes are not understood. Here we show that certain stress-responsive changes in V-ATPase activity and assembly require the signaling lipid phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2). V-ATPase activation through V1-V(o) assembly in response to salt stress is strongly dependent on PI(3,5)P2 synthesis. Purified V(o) complexes preferentially bind to PI(3,5)P2 on lipid arrays, suggesting direct binding between the lipid and the membrane sector of the V-ATPase. Increasing PI(3,5)P2 levels in vivo recruits the N-terminal domain of V(o)-sector subunit Vph1p from cytosol to membranes, independent of other subunits. This Vph1p domain is critical for V1-V(o) interaction, suggesting that interaction of Vph1p with PI(3,5)P2-containing membranes stabilizes V1-V(o) assembly and thus increases V-ATPase activity. These results help explain the previously described vacuolar acidification defect in yeast fab1 and vac14 mutants and suggest that human disease phenotypes associated with PI(3,5)P2 loss may arise from compromised V-ATPase stability and regulation.
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Affiliation(s)
- Sheena Claire Li
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13219 Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor MI 48109
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Endolysosomal membrane trafficking complexes drive nutrient-dependent TORC1 signaling to control cell growth in Saccharomyces cerevisiae. Genetics 2014; 196:1077-89. [PMID: 24514902 DOI: 10.1534/genetics.114.161646] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The rapamycin-sensitive and endomembrane-associated TORC1 pathway controls cell growth in response to nutrients in eukaryotes. Mutations in class C Vps (Vps-C) complexes are synthetically lethal with tor1 mutations and confer rapamycin hypersensitivity in Saccharomyces cerevisiae, suggesting a role for these complexes in TORC1 signaling. Vps-C complexes are required for vesicular trafficking and fusion and comprise four distinct complexes: HOPS and CORVET and their minor intermediaries (i)-CORVET and i-HOPS. We show that at least one Vps-C complex is required to promote TORC1 activity, with the HOPS complex having the greatest input. The vps-c mutants fail to recover from rapamycin-induced growth arrest and show low levels of TORC1 activity. TORC1 promotes cell growth via Sch9, a p70(S6) kinase ortholog. Constitutively active SCH9 or hyperactive TOR1 alleles restored rapamycin recovery and TORC1 activity of vps-c mutants, supporting a role for the Vps-C complexes upstream of TORC1. The EGO GTPase complex Exit from G0 Complex (EGOC) and its homologous Rag-GTPase complex convey amino acid signals to TORC1 in yeast and mammals, respectively. Expression of the activated EGOC GTPase subunits Gtr1(GTP) and Gtr2(GDP) partially suppressed vps-c mutant rapamycin recovery defects, and this suppression was enhanced by increased amino acid concentrations. Moreover, vps-c mutations disrupted EGOC-TORC1 interactions. TORC1 defects were more severe for vps-c mutants than those observed in EGOC mutants. Taken together, our results support a model in which distinct endolysosomal trafficking Vps-C complexes promote rapamycin-sensitive TORC1 activity via multiple inputs, one of which involves maintenance of amino acid homeostasis that is sensed and transmitted to TORC1 via interactions with EGOC.
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Montefusco DJ, Chen L, Matmati N, Lu S, Newcomb B, Cooper GF, Hannun YA, Lu X. Distinct signaling roles of ceramide species in yeast revealed through systematic perturbation and systems biology analyses. Sci Signal 2013; 6:rs14. [PMID: 24170935 PMCID: PMC3974757 DOI: 10.1126/scisignal.2004515] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Ceramide, the central molecule of sphingolipid metabolism, is an important bioactive molecule that participates in various cellular regulatory events and that has been implicated in disease. Deciphering ceramide signaling is challenging because multiple ceramide species exist, and many of them may have distinct functions. We applied systems biology and molecular approaches to perturb ceramide metabolism in the yeast Saccharomyces cerevisiae and inferred causal relationships between ceramide species and their potential targets by combining lipidomic, genomic, and transcriptomic analyses. We found that during heat stress, distinct metabolic mechanisms controlled the abundance of different groups of ceramide species and provided experimental support for the importance of the dihydroceramidase Ydc1 in mediating the decrease in dihydroceramides during heat stress. Additionally, distinct groups of ceramide species, with different N-acyl chains and hydroxylations, regulated different sets of functionally related genes, indicating that the structural complexity of these lipids produces functional diversity. The transcriptional modules that we identified provide a resource to begin to dissect the specific functions of ceramides.
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Affiliation(s)
- David J. Montefusco
- Dept. Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina
| | - Lujia Chen
- Dept. Biomedical Informatics, University of Pittsburgh, Pittsburgh, PA 15232
| | - Nabil Matmati
- Dept. Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina
- Department of Medicine and the Stony Brook Cancer Center at Stony Brook University, Stony Brook, NY, 11794
| | - Songjian Lu
- Dept. Biomedical Informatics, University of Pittsburgh, Pittsburgh, PA 15232
| | - Benjamin Newcomb
- Dept. Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina
- Department of Medicine and the Stony Brook Cancer Center at Stony Brook University, Stony Brook, NY, 11794
| | - Gregory F. Cooper
- Dept. Biomedical Informatics, University of Pittsburgh, Pittsburgh, PA 15232
| | - Yusuf A. Hannun
- Dept. Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina
- Department of Medicine and the Stony Brook Cancer Center at Stony Brook University, Stony Brook, NY, 11794
| | - Xinghua Lu
- Dept. Biomedical Informatics, University of Pittsburgh, Pittsburgh, PA 15232
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Styles E, Youn JY, Mattiazzi Usaj M, Andrews B. Functional genomics in the study of yeast cell polarity: moving in the right direction. Philos Trans R Soc Lond B Biol Sci 2013; 368:20130118. [PMID: 24062589 PMCID: PMC3785969 DOI: 10.1098/rstb.2013.0118] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The budding yeast Saccharomyces cerevisiae has been used extensively for the study of cell polarity, owing to both its experimental tractability and the high conservation of cell polarity and other basic biological processes among eukaryotes. The budding yeast has also served as a pioneer model organism for virtually all genome-scale approaches, including functional genomics, which aims to define gene function and biological pathways systematically through the analysis of high-throughput experimental data. Here, we outline the contributions of functional genomics and high-throughput methodologies to the study of cell polarity in the budding yeast. We integrate data from published genetic screens that use a variety of functional genomics approaches to query different aspects of polarity. Our integrated dataset is enriched for polarity processes, as well as some processes that are not intrinsically linked to cell polarity, and may provide new areas for future study.
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Affiliation(s)
- Erin Styles
- The Donnelly Centre, University of Toronto, 160 College St., Toronto, Ontario, CanadaM5S 3E1
- Department of Molecular Genetics, University of Toronto, 160 College St., Toronto, Ontario, CanadaM5S 3E1
| | - Ji-Young Youn
- The Donnelly Centre, University of Toronto, 160 College St., Toronto, Ontario, CanadaM5S 3E1
| | - Mojca Mattiazzi Usaj
- The Donnelly Centre, University of Toronto, 160 College St., Toronto, Ontario, CanadaM5S 3E1
| | - Brenda Andrews
- The Donnelly Centre, University of Toronto, 160 College St., Toronto, Ontario, CanadaM5S 3E1
- Department of Molecular Genetics, University of Toronto, 160 College St., Toronto, Ontario, CanadaM5S 3E1
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Jiménez J, Ricco N, Grijota-Martínez C, Fadó R, Clotet J. Redundancy or specificity? The role of the CDK Pho85 in cell cycle control. INTERNATIONAL JOURNAL OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 4:140-149. [PMID: 24049669 PMCID: PMC3776146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 08/31/2013] [Indexed: 06/02/2023]
Abstract
It is generally accepted that progression through the eukaryotic cell cycle is driven by cyclin-dependent kinases (CDKs), which are regulated by interaction with oscillatory expressed proteins called cyclins. CDKs may be separated into 2 categories: essential and non-essential. Understandably, more attention has been focused on essential CDKs because they are shown to control cell cycle progression to a greater degree. After clearly determining the basic and "core" mechanisms of essential CDKs, several questions arise. What role do non-essential CDKs play? Are these CDKs functionally redundant and do they serve as a mere backup? Or might they be responsible for some accessory tasks in cell cycle progression or control? In the present review we will try to answer these questions based on recent findings on the involvement of non-essential CDKs in cell cycle progression. We will analyse the most recent information with regard to these questions in the yeast Saccharomyces cerevisiae, a well-established eukaryotic model, and in its unique non-essential CDK involved in the cell cycle, Pho85. We will also briefly extend our discussion to higher eukaryotic systems.
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Affiliation(s)
- Javier Jiménez
- Department of Basic Sciences, Faculty of Medicine and Health Sciences, International University of Catalonia Barcelona, Catalonia
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Saccharomyces cerevisiae Mutants Affected in Vacuole Assembly or Vacuolar H+-ATPase are Hypersensitive to Lead (Pb) Toxicity. Curr Microbiol 2013; 68:113-9. [DOI: 10.1007/s00284-013-0438-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 07/01/2013] [Indexed: 10/26/2022]
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Chen G, Liu X, Zhang L, Cao H, Lu J, Lin F. Involvement of MoVMA11, a Putative Vacuolar ATPase c' Subunit, in Vacuolar Acidification and Infection-Related Morphogenesis of Magnaporthe oryzae. PLoS One 2013; 8:e67804. [PMID: 23826342 PMCID: PMC3694887 DOI: 10.1371/journal.pone.0067804] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 05/27/2013] [Indexed: 11/18/2022] Open
Abstract
Many functions of vacuole depend on the activity of vacuolar ATPase which is essential to maintain an acidic lumen and create the driving forces for massive fluxes of ions and metabolites through vacuolar membrane. In filamentous fungus Magnaportheoryzae, subcellular colocalization and quinacrine staining suggested that the V1V0 domains of V-ATPase were fully assembled and the vacuoles were kept acidic during infection-related developments. Targeted gene disruption of MoVMA11 gene, encoding the putative c' subunit of V-ATPase, impaired vacuolar acidification and mimicked the phenotypes of yeast V-ATPase mutants in the poor colony morphology, abolished asexual and sexual reproductions, selective carbon source utilization, and increased calcium and heavy metals sensitivities, however, not in the typical pH conditional lethality. Strikingly, aerial hyphae of the MoVMA11 null mutant intertwined with each other to form extremely thick filamentous structures. The results also implicated that MoVMA11 was involved in cell wall integrity and appressorium formation. Abundant non-melanized swollen structures and rare, small appressoria without penetration ability were produced at the hyphal tips of the ΔMovma11 mutant on onion epidermal cells. Finally, the MoVMA11 null mutant lost pathogenicity on both intact and wounded host leaves. Overall, our data indicated that MoVMA11, like other fungal VMA genes, is associated with numerous cellular functions and highlighted that V-ATPase is essential for infection-related morphogenesis and pathogenesis in M. oryzae.
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Affiliation(s)
- Guoqing Chen
- State Key Laboratory for Rice Biology, Biotechnology Institute, Zhejiang University, Hangzhou, China
| | - Xiaohong Liu
- State Key Laboratory for Rice Biology, Biotechnology Institute, Zhejiang University, Hangzhou, China
| | - Lilin Zhang
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Huijuan Cao
- State Key Laboratory for Rice Biology, Biotechnology Institute, Zhejiang University, Hangzhou, China
| | - Jianping Lu
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Fucheng Lin
- State Key Laboratory for Rice Biology, Biotechnology Institute, Zhejiang University, Hangzhou, China
- China Tobacco Gene Research Center, Zhengzhou Tobacco Institute of CNTC, Zhengzhou, China
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Smith RP, Wellman K, Smith ML. Trans-species activity of a nonself recognition domain. BMC Microbiol 2013; 13:63. [PMID: 23517247 PMCID: PMC3618301 DOI: 10.1186/1471-2180-13-63] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 02/07/2013] [Indexed: 11/18/2022] Open
Abstract
Background The ability to distinguish nonself from self is a fundamental characteristic of biological systems. In the filamentous fungus Neurospora crassa, multiple incompatibility genes mediate nonself recognition during vegetative growth. One of these genes, un-24, encodes both nonself recognition function and the large subunit of a type I ribonucleotide reductase, an evolutionarily conserved enzyme that is essential for the conversion of NDP precursors into dNDPs for use in DNA synthesis. Previous studies have shown that co-expression of the two allelic forms of un-24, Oakridge (OR) and Panama (PA), in the same cell results in cell death. Results We identify a 135 amino acid nonself recognition domain in the C-terminus region of UN-24 that confers an incompatibility-like phenotype when expressed in the yeast, Saccharomyces cerevisiae. Low-level expression of this domain results in several cytological and phenotypic characteristics consistent with an incompatibility reaction in filamentous fungi. These incompatibility phenotypes are correlated with the presence of a non-reducible complex consisting of the PA incompatibility domain and Rnr1p, a large subunit of ribonucleotide reductase in yeast. When the PA incompatibility domain is switched to high-level expression, the incompatibility phenotype transitions to wild-type concomitant with the appearance of a complex containing the PA incompatibility domain and Ssa1p, an Hsp70 homolog. Conclusions Results from this study provide insights into the mechanism and control of vegetative nonself recognition mediated by ribonucleotide reductase in N. crassa, thus establishing the yeast system as a powerful tool to study fungal nonself recognition. Our work shows that heat shock proteins may function to deactivate vegetative incompatibility systems, as required for entry into the sexual cycle. Finally, our results suggest that variations on the PA incompatibility domain may serve as novel and specific antimicrobial peptides.
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Böhm S, Buchberger A. The budding yeast Cdc48(Shp1) complex promotes cell cycle progression by positive regulation of protein phosphatase 1 (Glc7). PLoS One 2013; 8:e56486. [PMID: 23418575 PMCID: PMC3572051 DOI: 10.1371/journal.pone.0056486] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 01/10/2013] [Indexed: 12/11/2022] Open
Abstract
The conserved, ubiquitin-selective AAA ATPase Cdc48 regulates numerous cellular processes including protein quality control, DNA repair and the cell cycle. Cdc48 function is tightly controlled by a multitude of cofactors mediating substrate specificity and processing. The UBX domain protein Shp1 is a bona fide substrate-recruiting cofactor of Cdc48 in the budding yeast S. cerevisiae. Even though Shp1 has been proposed to be a positive regulator of Glc7, the catalytic subunit of protein phosphatase 1 in S. cerevisiae, its cellular functions in complex with Cdc48 remain largely unknown. Here we show that deletion of the SHP1 gene results in severe growth defects and a cell cycle delay at the metaphase to anaphase transition caused by reduced Glc7 activity. Using an engineered Cdc48 binding-deficient variant of Shp1, we establish the Cdc48Shp1 complex as a critical regulator of mitotic Glc7 activity. We demonstrate that shp1 mutants possess a perturbed balance of Glc7 phosphatase and Ipl1 (Aurora B) kinase activities and show that hyper-phosphorylation of the kinetochore protein Dam1, a key mitotic substrate of Glc7 and Ipl1, is a critical defect in shp1. We also show for the first time a physical interaction between Glc7 and Shp1 in vivo. Whereas loss of Shp1 does not significantly affect Glc7 protein levels or localization, it causes reduced binding of the activator protein Glc8 to Glc7. Our data suggest that the Cdc48Shp1 complex controls Glc7 activity by regulating its interaction with Glc8 and possibly further regulatory subunits.
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Affiliation(s)
- Stefanie Böhm
- Department of Biochemistry, Biocenter, University of Würzburg, Würzburg, Germany
| | - Alexander Buchberger
- Department of Biochemistry, Biocenter, University of Würzburg, Würzburg, Germany
- * E-mail:
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Abstract
The chaperone-related, ubiquitin-selective AAA (ATPase associated with a variety of cellular activities) protein Cdc48 (also known as TER94, p97 and VCP) is a key regulator of intracellular proteolysis in eukaryotes. It uses the energy derived from ATP hydrolysis to segregate ubiquitylated proteins from stable assemblies with proteins, membranes and chromatin. Originally characterized as essential factor in proteasomal degradation pathways, Cdc48 was recently found to control lysosomal protein degradation as well. Moreover, impaired lysosomal proteolysis due to mutational inactivation of Cdc48 causes protein aggregation diseases in humans. This review introduces the major systems of intracellular proteolysis in eukaryotes and the role of protein ubiquitylation. It then discusses in detail structure, mechanism and cellular functions of Cdc48 with an emphasis on protein degradation pathways in yeast.
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Affiliation(s)
- Alexander Buchberger
- Department of Biochemistry, Biocenter, University of Würzburg, Am Hubland, 97074, Würzburg, Germany,
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Saccharomyces cerevisiae Env7 is a novel serine/threonine kinase 16-related protein kinase and negatively regulates organelle fusion at the lysosomal vacuole. Mol Cell Biol 2012; 33:526-42. [PMID: 23166297 DOI: 10.1128/mcb.01303-12] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Membrane fusion depends on conserved components and is responsible for organelle biogenesis and vesicular trafficking. Yeast vacuoles are dynamic structures analogous to mammalian lysosomes. We report here that yeast Env7 is a novel palmitoylated protein kinase ortholog that negatively regulates vacuolar membrane fusion. Microscopic and biochemical studies confirmed the localization of tagged Env7 at the vacuolar membrane and implicated membrane association via the palmitoylation of its N-terminal Cys13 to -15. In vitro kinase assays established Env7 as a protein kinase. Site-directed mutagenesis of the Env7 alanine-proline-glutamic acid (APE) motif Glu269 to alanine results in an unstable kinase-dead allele that is stabilized and redistributed to the detergent-resistant fraction by interruption of the proteasome system in vivo. Palmitoylation-deficient Env7C13-15S is also kinase dead and mislocalizes to the cytoplasm. Microscopy studies established that env7Δ is defective in maintaining fragmented vacuoles during hyperosmotic response and in buds. ENV7 function is not redundant with a similar role of vacuolar membrane kinase Yck3, as the two do not share a substrate, and ENV7 is not a suppressor of yck3Δ. Bayesian phylogenetic analyses strongly support ENV7 as an ortholog of the gene encoding human STK16, a Golgi apparatus protein kinase with undefined function. We propose that Env7 function in fusion/fission dynamics may be conserved within the endomembrane system.
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Orij R, Urbanus ML, Vizeacoumar FJ, Giaever G, Boone C, Nislow C, Brul S, Smits GJ. Genome-wide analysis of intracellular pH reveals quantitative control of cell division rate by pH(c) in Saccharomyces cerevisiae. Genome Biol 2012; 13:R80. [PMID: 23021432 PMCID: PMC3506951 DOI: 10.1186/gb-2012-13-9-r80] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 09/10/2012] [Accepted: 09/26/2012] [Indexed: 01/20/2023] Open
Abstract
Background Because protonation affects the properties of almost all molecules in cells, cytosolic pH (pHc) is usually assumed to be constant. In the model organism yeast, however, pHc changes in response to the presence of nutrients and varies during growth. Since small changes in pHc can lead to major changes in metabolism, signal transduction, and phenotype, we decided to analyze pHc control. Results Introducing a pH-sensitive reporter protein into the yeast deletion collection allowed quantitative genome-wide analysis of pHc in live, growing yeast cultures. pHc is robust towards gene deletion; no single gene mutation led to a pHc of more than 0.3 units lower than that of wild type. Correct pHc control required not only vacuolar proton pumps, but also strongly relied on mitochondrial function. Additionally, we identified a striking relationship between pHc and growth rate. Careful dissection of cause and consequence revealed that pHc quantitatively controls growth rate. Detailed analysis of the genetic basis of this control revealed that the adequate signaling of pHc depended on inositol polyphosphates, a set of relatively unknown signaling molecules with exquisitely pH sensitive properties. Conclusions While pHc is a very dynamic parameter in the normal life of yeast, genetically it is a tightly controlled cellular parameter. The coupling of pHc to growth rate is even more robust to genetic alteration. Changes in pHc control cell division rate in yeast, possibly as a signal. Such a signaling role of pHc is probable, and may be central in development and tumorigenesis.
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Affiliation(s)
- Rick Orij
- Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, the Netherlands
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Richards A, Gow NAR, Veses V. Identification of vacuole defects in fungi. J Microbiol Methods 2012; 91:155-63. [PMID: 22902527 DOI: 10.1016/j.mimet.2012.08.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2012] [Revised: 07/30/2012] [Accepted: 08/02/2012] [Indexed: 11/25/2022]
Abstract
Fungal vacuoles are involved in a diverse range of cellular functions, participating in cellular homeostasis, degradation of intracellular components, and storage of ions and molecules. In recent years there has been a significant increase in the number of studies linking these organelles with the regulation of growth and control of cellular morphology, particularly in those fungal species able to undergo yeast-hypha morphogenetic transitions. This has contributed to the refinement of previously published protocols and the development of new techniques, particularly in the area of live-cell imaging of membrane trafficking events and vacuolar dynamics. The current review outlines recent advances in the imaging of fungal vacuoles and assays for characterization of trafficking pathways, and other physiological activities of this important cell organelle.
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Affiliation(s)
- Andrea Richards
- The Aberdeen Fungal Group, School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom
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Vacuolar H+-ATPase plays a key role in cell wall biosynthesis of Aspergillus niger. Fungal Genet Biol 2012; 49:284-93. [DOI: 10.1016/j.fgb.2011.12.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 12/15/2011] [Accepted: 12/16/2011] [Indexed: 11/21/2022]
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Kane PM. Targeting reversible disassembly as a mechanism of controlling V-ATPase activity. Curr Protein Pept Sci 2012; 13:117-23. [PMID: 22044153 PMCID: PMC3536023 DOI: 10.2174/138920312800493142] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 08/05/2011] [Accepted: 08/06/2011] [Indexed: 11/22/2022]
Abstract
Vacuolar proton-translocating ATPases (V-ATPases) are highly conserved proton pumps consisting of a peripheral membrane subcomplex called V1, which contains the sites of ATP hydrolysis, attached to an integral membrane subcomplex called Vo, which encompasses the proton pore. V-ATPase regulation by reversible dissociation, characterized by release of assembled V1 sectors into the cytosol and inhibition of both ATPase and proton transport activities, was first identified in tobacco hornworm and yeast. It has since become clear that modulation of V-ATPase assembly level is also a regulatory mechanism in mammalian cells. In this review, the implications of reversible disassembly for V-ATPase structure are discussed, along with insights into underlying subunit-subunit interactions provided by recent structural work. Although initial experiments focused on glucose deprivation as a trigger for disassembly, it is now clear that V-ATPase assembly can be regulated by other extracellular conditions. Consistent with a complex, integrated response to extracellular signals, a number of different regulatory proteins, including RAVE/rabconnectin, aldolase and other glycolytic enzymes, and protein kinase A have been suggested to control V-ATPase assembly and disassembly. It is likely that multiple signaling pathways dictate the ultimate level of assembly and activity. Tissue-specific V-ATPase inhibition is a potential therapy for osteoporosis and cancer; the possibility of exploiting reversible disassembly in design of novel V-ATPase inhibitors is discussed.
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Affiliation(s)
- Patricia M Kane
- Dept. of Biochemistry and Molecular Biology, SUNY Upstate Medical University, 750 East Adams St., Syracuse, NY 13210, USA.
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