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Hashmi F, Kane PM. V-ATPase Disassembly at the Yeast Lysosome-Like Vacuole Is a Phenotypic Driver of Lysosome Dysfunction in Replicative Aging. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.23.604825. [PMID: 39091794 PMCID: PMC11291124 DOI: 10.1101/2024.07.23.604825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
Declines in lysosomal acidification and function with aging are observed in organisms ranging from yeast to humans. V-ATPases play a central role in organelle acidification and V-ATPase activity is regulated by reversible disassembly in many different settings. Using the yeast Saccharomyces cerevisiae as a replicative aging model, we demonstrate that V-ATPases disassemble into their V1 and V0 subcomplexes in aging cells, with release of V1 subunit C (Vma5) from the lysosome-like vacuole into the cytosol. Disassembly is observed after ≥5 cell divisions and results in overall vacuole alkalinization. Caloric restriction, an established mechanism for reversing many age-related outcomes, prevents V-ATPase disassembly in older cells and preserves vacuolar pH homeostasis. Reversible disassembly is controlled in part by the activity of two opposing and conserved factors, the RAVE complex and Oxr1. The RAVE complex promotes V-ATPase assembly and a rav1Δ mutant shortens replicative lifespan; Oxr1 promotes disassembly and an oxr1Δ mutation extends lifespan. Importantly, the level of Rav2, a key subunit of the RAVE complex, declines in aged cells. These data indicate that reduced V-ATPase assembly contributes to the loss of lysosome acidification with age, which affects replicative lifespan.
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Affiliation(s)
- Fiza Hashmi
- Department of Biochemistry and Molecular Biology , SUNY Upstate Medical University, Syracuse, NY USA
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology , SUNY Upstate Medical University, Syracuse, NY USA
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2
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Zhang C, Balutowski A, Feng Y, Calderin JD, Fratti RA. High throughput analysis of vacuolar acidification. Anal Biochem 2022; 658:114927. [PMID: 36167157 DOI: 10.1016/j.ab.2022.114927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 09/09/2022] [Accepted: 09/20/2022] [Indexed: 11/15/2022]
Abstract
Eukaryotic cells are compartmentalized into membrane-bound organelles, allowing each organelle to maintain the specialized conditions needed for their specific functions. One of the features that change between organelles is lumenal pH. In the endocytic and secretory pathways, lumenal pH is controlled by isoforms and concentration of the vacuolar-type H+-ATPase (V-ATPase). In the endolysosomal pathway, copies of complete V-ATPase complexes accumulate as membranes mature from early endosomes to late endosomes and lysosomes. Thus, each compartment becomes more acidic as maturation proceeds. Lysosome acidification is essential for the breakdown of macromolecules delivered from endosomes as well as cargo from different autophagic pathways, and dysregulation of this process is linked to various diseases. Thus, it is important to understand the regulation of the V-ATPase. Here we describe a high-throughput method for screening inhibitors/activators of V-ATPase activity using Acridine Orange (AO) as a fluorescent reporter for acidified yeast vacuolar lysosomes. Through this method, the acidification of purified vacuoles can be measured in real-time in half-volume 96-well plates or a larger 384-well format. This not only reduces the cost of expensive low abundance reagents, but it drastically reduces the time needed to measure individual conditions in large volume cuvettes.
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Affiliation(s)
- Chi Zhang
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | - Adam Balutowski
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | - Yilin Feng
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | - Jorge D Calderin
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | - Rutilio A Fratti
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA; Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA.
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3
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Liu NN, Zhou J, Jiang T, Tarsio M, Yu F, Zheng X, Qi W, Liu L, Tan JC, Wei L, Ding J, Li J, Zeng L, Ren B, Huang X, Peng Y, Cao YB, Zhao Y, Zhang XY, Kane PM, Chen C, Wang H. A dual action small molecule enhances azoles and overcomes resistance through co-targeting Pdr5 and Vma1. Transl Res 2022; 247:39-57. [PMID: 35452875 DOI: 10.1016/j.trsl.2022.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 02/26/2022] [Accepted: 04/12/2022] [Indexed: 11/19/2022]
Abstract
Fungal infection threatens human health worldwide due to the limited arsenal of antifungals and the rapid emergence of resistance. Epidermal growth factor receptor (EGFR) is demonstrated to mediate epithelial cell endocytosis of the leading human fungal pathogen, Candida albicans. However, whether EGFR inhibitors act on fungal cells remains unknown. Here, we discovered that the specific EGFR inhibitor osimertinib mesylate (OSI) potentiates azole efficacy against diverse fungal pathogens and overcomes azole resistance. Mechanistic investigation revealed a conserved activity of OSI by promoting intracellular fluconazole accumulation via inhibiting Pdr5 and disrupting V-ATPase function via targeting Vma1 at serine 274, eventually leading to inactivation of the global regulator TOR. Evaluation of the in vivo efficacy and toxicity of OSI demonstrated its potential clinical application in impeding fluconazole resistance. Thus, the identification of OSI as a dual action antifungal with co-targeting activity proposes a potentially effective therapeutic strategy to treat life-threatening fungal infection and overcome antifungal resistance.
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Affiliation(s)
- Ning-Ning Liu
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Jia Zhou
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Tong Jiang
- The Center for Microbes, Development and Health, Key Laboratory of Molecular Virology and Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Maureen Tarsio
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Feifei Yu
- Institute of Environmental Pollution and Health, School of Environmental and Chemical Engineering, Shanghai University, Shanghai, China
| | - Xuehan Zheng
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Wanjun Qi
- Division of Infectious Diseases, Boston Children's Hospital/Harvard Medical School, Boston, MA, USA
| | - Lin Liu
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jing-Cong Tan
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Luqi Wei
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jun Ding
- Computational biology department, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Jingquan Li
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Lingbing Zeng
- Department of Laboratory Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Biao Ren
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, Sichuan, China
| | - Xiaotian Huang
- Department of Medical Microbiology, School of Medicine, Nanchang University, Nanchang, Jiangxi, China
| | - Yibing Peng
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Faculty of Medical Laboratory Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yong-Bing Cao
- Department of Vascular Disease, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China; Shanghai TCM-Integrated Institute of Vascular Disease, Shanghai, China
| | - Yanbin Zhao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, China
| | - Xin-Yu Zhang
- School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Changbin Chen
- The Center for Microbes, Development and Health, Key Laboratory of Molecular Virology and Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China.
| | - Hui Wang
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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4
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Gutierrez JI, Brittingham GP, Karadeniz YB, Tran KD, Dutta A, Holehouse AS, Peterson CL, Holt LJ. SWI/SNF senses carbon starvation with a pH-sensitive low complexity sequence. eLife 2022; 11:70344. [PMID: 35129437 PMCID: PMC8890752 DOI: 10.7554/elife.70344] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 02/06/2022] [Indexed: 11/16/2022] Open
Abstract
It is increasingly appreciated that intracellular pH changes are important biological signals. This motivates the elucidation of molecular mechanisms of pH sensing. We determined that a nucleocytoplasmic pH oscillation was required for the transcriptional response to carbon starvation in Saccharomyces cerevisiae. The SWI/SNF chromatin remodeling complex is a key mediator of this transcriptional response. A glutamine-rich low-complexity domain (QLC) in the SNF5 subunit of this complex, and histidines within this sequence, was required for efficient transcriptional reprogramming. Furthermore, the SNF5 QLC mediated pH-dependent recruitment of SWI/SNF to an acidic transcription factor in a reconstituted nucleosome remodeling assay. Simulations showed that protonation of histidines within the SNF5 QLC leads to conformational expansion, providing a potential biophysical mechanism for regulation of these interactions. Together, our results indicate that pH changes are a second messenger for transcriptional reprogramming during carbon starvation and that the SNF5 QLC acts as a pH sensor.
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Affiliation(s)
| | - Gregory P Brittingham
- Institute for Systems Genetics, New York University Langone Health, New York, United States
| | - Yonca B Karadeniz
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, United States
| | - Kathleen D Tran
- Department of Cell and Molecular Biology, University of Rhode Island, South Kingstown, United States
| | - Arnob Dutta
- Department of Cell and Molecular Biology, University of Rhode Island, South Kingstown, United States
| | - Alex S Holehouse
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis, St Louis, United States
| | - Craig L Peterson
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, United States
| | - Liam J Holt
- Institute for Systems Genetics, New York University Langone Health, New York, United States
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5
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Salsaa M, Aziz K, Lazcano P, Schmidtke MW, Tarsio M, Hüttemann M, Reynolds CA, Kane PM, Greenberg ML. Valproate activates the Snf1 kinase in Saccharomyces cerevisiae by decreasing the cytosolic pH. J Biol Chem 2021; 297:101110. [PMID: 34428448 PMCID: PMC8449051 DOI: 10.1016/j.jbc.2021.101110] [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: 03/30/2021] [Revised: 08/19/2021] [Accepted: 08/20/2021] [Indexed: 11/27/2022] Open
Abstract
Valproate (VPA) is a widely used mood stabilizer, but its therapeutic mechanism of action is not understood. This knowledge gap hinders the development of more effective drugs with fewer side effects. Using the yeast model to elucidate the effects of VPA on cellular metabolism, we determined that the drug upregulated expression of genes normally repressed during logarithmic growth on glucose medium and increased levels of activated (phosphorylated) Snf1 kinase, the major metabolic regulator of these genes. VPA also decreased the cytosolic pH (pHc) and reduced glycolytic production of 2/3-phosphoglycerate. ATP levels and mitochondrial membrane potential were increased, and glucose-mediated extracellular acidification decreased in the presence of the drug, as indicated by a smaller glucose-induced shift in pH, suggesting that the major P-type proton pump Pma1 was inhibited. Interestingly, decreasing the pHc by omeprazole-mediated inhibition of Pma1 led to Snf1 activation. We propose a model whereby VPA lowers the pHc causing a decrease in glycolytic flux. In response, Pma1 is inhibited and Snf1 is activated, resulting in increased expression of normally repressed metabolic genes. These findings suggest a central role for pHc in regulating the metabolic program of yeast cells.
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Affiliation(s)
- Michael Salsaa
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Kerestin Aziz
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Pablo Lazcano
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Michael W Schmidtke
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Maureen Tarsio
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, USA
| | - Maik Hüttemann
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, Michigan, USA
| | - Christian A Reynolds
- Department of Emergency Medicine, School of Medicine, Wayne State University, Detroit, Michigan, USA; Department of Biotechnology, University of Rijeka, Rijeka, Croatia
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, USA
| | - Miriam L Greenberg
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA.
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6
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Investigating the Antifungal Mechanism of Action of Polygodial by Phenotypic Screening in Saccharomyces cerevisiae. Int J Mol Sci 2021; 22:ijms22115756. [PMID: 34071169 PMCID: PMC8198865 DOI: 10.3390/ijms22115756] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/19/2021] [Accepted: 05/25/2021] [Indexed: 11/17/2022] Open
Abstract
Polygodial is a "hot" peppery-tasting sesquiterpenoid that was first described for its anti-feedant activity against African armyworms. Using the haploid deletion mutant library of Saccharomyces cerevisiae, a genome-wide mutant screen was performed to shed more light on polygodial's antifungal mechanism of action. We identified 66 deletion strains that were hypersensitive and 47 that were highly resistant to polygodial treatment. Among the hypersensitive strains, an enrichment was found for genes required for vacuolar acidification, amino acid biosynthesis, nucleosome mobilization, the transcription mediator complex, autophagy and vesicular trafficking, while the resistant strains were enriched for genes encoding cytoskeleton-binding proteins, ribosomal proteins, mitochondrial matrix proteins, components of the heme activator protein (HAP) complex, and known regulators of the target of rapamycin complex 1 (TORC1) signaling. WE confirm that polygodial triggers a dose-dependent vacuolar alkalinization and that it increases Ca2+ influx and inhibits glucose-induced Ca2+ signaling. Moreover, we provide evidence suggesting that TORC1 signaling and its protective agent ubiquitin play a central role in polygodial resistance, suggesting that they can be targeted by polygodial either directly or via altered Ca2+ homeostasis.
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7
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Garza NM, Griffin AT, Zulkifli M, Qiu C, Kaplan CD, Gohil VM. A genome-wide copper-sensitized screen identifies novel regulators of mitochondrial cytochrome c oxidase activity. J Biol Chem 2021; 296:100485. [PMID: 33662401 PMCID: PMC8027276 DOI: 10.1016/j.jbc.2021.100485] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/22/2021] [Accepted: 02/25/2021] [Indexed: 11/30/2022] Open
Abstract
Copper is essential for the activity and stability of cytochrome c oxidase (CcO), the terminal enzyme of the mitochondrial respiratory chain. Loss-of-function mutations in genes required for copper transport to CcO result in fatal human disorders. Despite the fundamental importance of copper in mitochondrial and organismal physiology, systematic identification of genes that regulate mitochondrial copper homeostasis is lacking. To discover these genes, we performed a genome-wide screen using a library of DNA-barcoded yeast deletion mutants grown in copper-supplemented media. Our screen recovered a number of genes known to be involved in cellular copper homeostasis as well as genes previously not linked to mitochondrial copper biology. These newly identified genes include the subunits of the adaptor protein 3 complex (AP-3) and components of the cellular pH-sensing pathway Rim20 and Rim21, both of which are known to affect vacuolar function. We find that AP-3 and Rim mutants exhibit decreased vacuolar acidity, which in turn perturbs mitochondrial copper homeostasis and CcO function. CcO activity of these mutants could be rescued by either restoring vacuolar pH or supplementing growth media with additional copper. Consistent with these genetic data, pharmacological inhibition of the vacuolar proton pump leads to decreased mitochondrial copper content and a concomitant decrease in CcO abundance and activity. Taken together, our study uncovered novel genetic regulators of mitochondrial copper homeostasis and provided a mechanism by which vacuolar pH impacts mitochondrial respiration through copper homeostasis.
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Affiliation(s)
- Natalie M Garza
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Aaron T Griffin
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Mohammad Zulkifli
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Chenxi Qiu
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Craig D Kaplan
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Vishal M Gohil
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.
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8
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Yang M, Zhu Z, Bai Y, Zhuang Z, Ge F, Li M, Wang S. A novel phosphoinositide kinase Fab1 regulates biosynthesis of pathogenic aflatoxin in Aspergillus flavus. Virulence 2020; 12:96-113. [PMID: 33315533 PMCID: PMC7781676 DOI: 10.1080/21505594.2020.1859820] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Aspergillus flavus (A. flavus) is one of the most important model environmental fungi which can produce a potent toxin and carcinogen known as aflatoxin. Aflatoxin contamination causes massive agricultural economic loss and a critical human health issue each year. Although a functional vacuole has been highlighted for its fundamental importance in fungal virulence, the molecular mechanisms of the vacuole in regulating the virulence of A. flavus remain largely unknown. Here, we identified a novel vacuole-related protein in A. flavus, the ortholog of phosphatidylinositol-3-phosphate-5-kinase (Fab1) in Saccharomyces cerevisiae. This kinase was located at the vacuolar membrane, and loss of fab1 function was found to affect the growth, conidia and sclerotial development, cellular acidification and metal ion homeostasis, aflatoxin production and pathogenicity of A. flavus. Further functional analysis revealed that Fab1 was required to maintain the vacuole size and cell morphology. Additional quantitative proteomic analysis suggested that Fab1 was likely to play an important role in maintaining vacuolar/cellular homeostasis, with vacuolar dysregulation upon fab1 deletion leading to impaired aflatoxin synthesis in this fungus. Together, these results provide insight into the molecular mechanisms by which this pathogen produces aflatoxin and mediates its pathogenicity, and may facilitate dissection of the vacuole-mediated regulatory network in A. flavus.
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Affiliation(s)
- Mingkun Yang
- School of Life Sciences, and Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Fujian Agriculture and Forestry University , Fuzhou, China.,State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences , Wuhan, China
| | - Zhuo Zhu
- School of Life Sciences, and Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Fujian Agriculture and Forestry University , Fuzhou, China
| | - Youhuang Bai
- School of Life Sciences, and Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Fujian Agriculture and Forestry University , Fuzhou, China
| | - Zhenhong Zhuang
- School of Life Sciences, and Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Fujian Agriculture and Forestry University , Fuzhou, China
| | - Feng Ge
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences , Wuhan, China
| | - Mingzhu Li
- School of Life Sciences, and Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Fujian Agriculture and Forestry University , Fuzhou, China
| | - Shihua Wang
- School of Life Sciences, and Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Fujian Agriculture and Forestry University , Fuzhou, China
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9
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Mou YN, Gao BJ, Ren K, Tong SM, Ying SH, Feng MG. P-type Na +/K + ATPases essential and nonessential for cellular homeostasis and insect pathogenicity of Beauveria bassiana. Virulence 2020; 11:1415-1431. [PMID: 33103596 PMCID: PMC7588218 DOI: 10.1080/21505594.2020.1836903] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 08/11/2020] [Accepted: 10/11/2020] [Indexed: 02/06/2023] Open
Abstract
ENA1 and ENA2 are P-type IID/ENA Na+/K+-ATPases required for cellular homeostasis in yeasts but remain poorly understood in filamentous fungal insect pathogens. Here, we characterized seven genes encoding five ENA1/2 homologues (ENA1a-c and ENA2a/b) and two P-type IIC/NK Na+/K+-ATPases (NK1/2) in Beauveria bassiana, an insect-pathogenic fungus serving as a main source of fungal insecticides worldwide. Most of these genes were highly responsive to alkaline pH and Na+/K+ cues at transcription level. Cellular Na+, K+ and H+ homeostasis was disturbed only in the absence of ena1a or ena2b. The disturbed homeostasis featured acceleration of vacuolar acidification, elevation of cytosolic Na+/K+ level at pH 5.0 to 9.0, and stabilization of extracellular H+ level to initial pH 7.5 during a 5-day period of submerged incubation. Despite little defect in hyphal growth and asexual development, the Δena1a and Δena2b mutants were less tolerant to metal cations (Na+, K+, Li+, Zn2+, Mn2+ and Fe3+), cell wall perturbation, oxidation, non-cation hyperosmolarity and UVB irradiation, severely compromised in insect pathogenicity via normal cuticle infection, and attenuated in virulence via hemocoel injection. The deletion mutants of five other ENA and NK genes showed little change in vacuolar pH and all examined phenotypes. Therefore, only ENA1a and ENA2b evidently involved in both transmembrane and vacuolar activities are essential for cellular cation homeostasis, insect pathogenicity and multiple stress tolerance in B. bassiana. These findings provide a novel insight into ENA1a- and ENA2b-dependent vacuolar pH stability, cation-homeostatic process and fungal fitness to host insect and environment.
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Affiliation(s)
- Ya-Ni Mou
- MOE Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Ben-Jie Gao
- MOE Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Kang Ren
- MOE Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Sen-Miao Tong
- College of Agricultural and Food Science, Zhejiang A&F University, Lin’an, Zhejiang, China
| | - Sheng-Hua Ying
- MOE Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Ming-Guang Feng
- MOE Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
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10
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ATP hydrolysis by yeast Hsp104 determines protein aggregate dissolution and size in vivo. Nat Commun 2020; 11:5226. [PMID: 33067463 PMCID: PMC7568574 DOI: 10.1038/s41467-020-19104-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 09/28/2020] [Indexed: 12/23/2022] Open
Abstract
Signs of proteostasis failure often entwine with those of metabolic stress at the cellular level. Here, we study protein sequestration during glucose deprivation-induced ATP decline in Saccharomyces cerevisiae. Using live-cell imaging, we find that sequestration of misfolded proteins and nascent polypeptides into two distinct compartments, stress granules, and Q-bodies, is triggered by the exhaustion of ATP. Both compartments readily dissolve in a PKA-dependent manner within minutes of glucose reintroduction and ATP level restoration. We identify the ATP hydrolase activity of Hsp104 disaggregase as the critical ATP-consuming process determining compartments abundance and size, even in optimal conditions. Sequestration of proteins into distinct compartments during acute metabolic stress and their retrieval during the recovery phase provide a competitive fitness advantage, likely promoting cell survival during stress. The sequestration of misfolded protein into insoluble aggregates occurs under conditions of proteotoxic stress. Here the authors observe that a reduction in cellular ATP promotes protein sequestration into two separate compartments: Q-bodies and stress granules; and identify Hsp104 as a critical ATP-consuming process that determines those compartments abundance and size.
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11
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Mouton SN, Thaller DJ, Crane MM, Rempel IL, Terpstra OT, Steen A, Kaeberlein M, Lusk CP, Boersma AJ, Veenhoff LM. A physicochemical perspective of aging from single-cell analysis of pH, macromolecular and organellar crowding in yeast. eLife 2020; 9:e54707. [PMID: 32990592 PMCID: PMC7556870 DOI: 10.7554/elife.54707] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 09/28/2020] [Indexed: 01/03/2023] Open
Abstract
Cellular aging is a multifactorial process that is characterized by a decline in homeostatic capacity, best described at the molecular level. Physicochemical properties such as pH and macromolecular crowding are essential to all molecular processes in cells and require maintenance. Whether a drift in physicochemical properties contributes to the overall decline of homeostasis in aging is not known. Here, we show that the cytosol of yeast cells acidifies modestly in early aging and sharply after senescence. Using a macromolecular crowding sensor optimized for long-term FRET measurements, we show that crowding is rather stable and that the stability of crowding is a stronger predictor for lifespan than the absolute crowding levels. Additionally, in aged cells, we observe drastic changes in organellar volume, leading to crowding on the micrometer scale, which we term organellar crowding. Our measurements provide an initial framework of physicochemical parameters of replicatively aged yeast cells.
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Affiliation(s)
- Sara N Mouton
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center GroningenGroningenNetherlands
| | - David J Thaller
- Department of Cell Biology, Yale School of MedicineNew HavenUnited States
| | - Matthew M Crane
- Department of Pathology, School of Medicine, University of WashingtonSeattleUnited States
| | - Irina L Rempel
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center GroningenGroningenNetherlands
| | - Owen T Terpstra
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center GroningenGroningenNetherlands
| | - Anton Steen
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center GroningenGroningenNetherlands
| | - Matt Kaeberlein
- Department of Pathology, School of Medicine, University of WashingtonSeattleUnited States
| | - C Patrick Lusk
- Department of Cell Biology, Yale School of MedicineNew HavenUnited States
| | | | - Liesbeth M Veenhoff
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center GroningenGroningenNetherlands
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Nüske E, Marini G, Richter D, Leng W, Bogdanova A, Franzmann TM, Pigino G, Alberti S. Filament formation by the translation factor eIF2B regulates protein synthesis in starved cells. Biol Open 2020; 9:bio046391. [PMID: 32554487 PMCID: PMC7358136 DOI: 10.1242/bio.046391] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 05/26/2020] [Indexed: 12/11/2022] Open
Abstract
Cells exposed to starvation have to adjust their metabolism to conserve energy and protect themselves. Protein synthesis is one of the major energy-consuming processes and as such has to be tightly controlled. Many mechanistic details about how starved cells regulate the process of protein synthesis are still unknown. Here, we report that the essential translation initiation factor eIF2B forms filaments in starved budding yeast cells. We demonstrate that filamentation is triggered by starvation-induced acidification of the cytosol, which is caused by an influx of protons from the extracellular environment. We show that filament assembly by eIF2B is necessary for rapid and efficient downregulation of translation. Importantly, this mechanism does not require the kinase Gcn2. Furthermore, analysis of site-specific variants suggests that eIF2B assembly results in enzymatically inactive filaments that promote stress survival and fast recovery of cells from starvation. We propose that translation regulation through filament assembly is an efficient mechanism that allows yeast cells to adapt to fluctuating environments.
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Affiliation(s)
- Elisabeth Nüske
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Guendalina Marini
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Doris Richter
- Department of Cellular Biochemistry Biotechnology Center (BIOTEC), Center for Molecular and Cellular Bioengineering (CMCB), Technische Universität Dresden, Tatzberg 47/49, 01307 Dresden, Germany
| | - Weihua Leng
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Aliona Bogdanova
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Titus M Franzmann
- Department of Cellular Biochemistry Biotechnology Center (BIOTEC), Center for Molecular and Cellular Bioengineering (CMCB), Technische Universität Dresden, Tatzberg 47/49, 01307 Dresden, Germany
| | - Gaia Pigino
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Simon Alberti
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
- Department of Cellular Biochemistry Biotechnology Center (BIOTEC), Center for Molecular and Cellular Bioengineering (CMCB), Technische Universität Dresden, Tatzberg 47/49, 01307 Dresden, Germany
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13
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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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14
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Struyfs C, Cools TL, De Cremer K, Sampaio-Marques B, Ludovico P, Wasko BM, Kaeberlein M, Cammue BPA, Thevissen K. The antifungal plant defensin HsAFP1 induces autophagy, vacuolar dysfunction and cell cycle impairment in yeast. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183255. [PMID: 32145284 DOI: 10.1016/j.bbamem.2020.183255] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 02/28/2020] [Accepted: 03/02/2020] [Indexed: 12/19/2022]
Abstract
The plant defensin HsAFP1 is characterized by broad-spectrum antifungal activity and induces apoptosis in Candida albicans. In this study, we performed a transcriptome analysis on C. albicans cultures treated with HsAFP1 to gain further insight in the antifungal mode of action of HsAFP1. Various genes coding for cell surface proteins, like glycosylphosphatidylinositol (GPI)-anchored proteins, and proteins involved in cation homeostasis, autophagy and in cell cycle were differentially expressed upon HsAFP1 treatment. The biological validation of these findings was performed in the model yeast Saccharomyces cerevisiae. To discriminate between events linked to HsAFP1's antifungal activity and those that are not, we additionally used an inactive HsAFP1 mutant. We demonstrated that (i) HsAFP1-resistent S. cerevisiae mutants that are characterized by a defect in processing GPI-anchors are unable to internalize HsAFP1, and (ii) moderate doses (FC50, fungicidal concentration resulting in 50% killing) of HsAFP1 induce autophagy in S. cerevisiae, while high HsAFP1 doses result in vacuolar dysfunction. Vacuolar function is an important determinant of replicative lifespan (RLS) under dietary restriction (DR). In line, HsAFP1 specifically reduces RLS under DR. Lastly, (iii) HsAFP1 affects S. cerevisiae cell cycle in the G2/M phase. However, the latter HsAFP1-induced event is not linked to its antifungal activity, as the inactive HsAFP1 mutant also impairs the G2/M phase. In conclusion, we demonstrated that GPI-anchored proteins are involved in HsAFP1's internalization, and that HsAFP1 induces autophagy, vacuolar dysfunction and impairment of the cell cycle. Collectively, all these data provide novel insights in the mode of action of HsAFP1 as well as in S. cerevisiae tolerance mechanisms against this peptide.
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Affiliation(s)
- Caroline Struyfs
- Centre of Microbial and Plant Genetics, KU Leuven, 3001 Leuven, Belgium; VIB Center for Plant Systems Biology, 9052 Ghent, Belgium
| | - Tanne L Cools
- Centre of Microbial and Plant Genetics, KU Leuven, 3001 Leuven, Belgium
| | - Kaat De Cremer
- Centre of Microbial and Plant Genetics, KU Leuven, 3001 Leuven, Belgium
| | - Belém Sampaio-Marques
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga, Portugal; ICVS/3B's-PT Government Associate Laboratory, 4700 Braga/Guimarães, Portugal
| | - Paula Ludovico
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga, Portugal; ICVS/3B's-PT Government Associate Laboratory, 4700 Braga/Guimarães, Portugal
| | - Brian M Wasko
- Department of Pathology, University of Washington, 98195 Seattle, USA
| | - Matt Kaeberlein
- Department of Pathology, University of Washington, 98195 Seattle, USA
| | - Bruno P A Cammue
- Centre of Microbial and Plant Genetics, KU Leuven, 3001 Leuven, Belgium; VIB Center for Plant Systems Biology, 9052 Ghent, Belgium
| | - Karin Thevissen
- Centre of Microbial and Plant Genetics, KU Leuven, 3001 Leuven, Belgium.
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15
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A new pH sensor localized in the Golgi apparatus of Saccharomyces cerevisiae reveals unexpected roles of Vph1p and Stv1p isoforms. Sci Rep 2020; 10:1881. [PMID: 32024908 PMCID: PMC7002768 DOI: 10.1038/s41598-020-58795-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 01/21/2020] [Indexed: 12/22/2022] Open
Abstract
The gradual acidification of the secretory pathway is conserved and extremely important for eukaryotic cells, but until now there was no pH sensor available to monitor the pH of the early Golgi apparatus in Saccharomyces cerevisiae. Therefore, we developed a pHluorin-based sensor for in vivo measurements in the lumen of the Golgi. By using this new tool we show that the cis- and medial-Golgi pH is equal to 6.6–6.7 in wild type cells during exponential phase. As expected, V-ATPase inactivation results in a near neutral Golgi pH. We also uncover that surprisingly Vph1p isoform of the V-ATPase is prevalent to Stv1p for Golgi acidification. Additionally, we observe that during changes of the cytosolic pH, the Golgi pH is kept relatively stable, mainly thanks to the V-ATPase. Eventually, this new probe will allow to better understand the mechanisms involved in the acidification and the pH control within the secretory pathway.
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Cytosolic Acidification Is the First Transduction Signal of Lactoferrin-induced Regulated Cell Death Pathway. Int J Mol Sci 2019; 20:ijms20235838. [PMID: 31757076 PMCID: PMC6928705 DOI: 10.3390/ijms20235838] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 11/18/2019] [Accepted: 11/19/2019] [Indexed: 01/04/2023] Open
Abstract
In yeast, we reported the critical role of K+-efflux for the progress of the regulated cell death (RCD) induced by human lactoferrin (hLf), an antimicrobial protein of the innate immune system that blocks Pma1p H+-ATPase. In the present study, the K+ channel Tok1p was identified as the K+ channel-mediating K+-efflux, as indicated by the protective effect of extracellular K+ (30 mM), K+-channel blockers, and the greater hLf-resistance of TOK1-disrupted strains. K+-depletion was necessary but not sufficient to induce RCD as inferred from the effects of valinomycin, NH4Cl or nigericin which released a percentage of K+ similar to that released by lactoferrin without affecting cell viability. Cytosolic pH of hLf-treated cells decreased transiently (0.3 pH units) and its inhibition prevented the RCD process, indicating that cytosolic acidification was a necessary and sufficient triggering signal. The blocking effect of lactoferrin on Pma1p H+-ATPase caused a transitory decrease of cytosolic pH, and the subsequent membrane depolarization activated the voltage-gated K+ channel, Tok1p, allowing an electrogenic K+-efflux. These ionic events, cytosolic accumulation of H+ followed by K+-efflux, constituted the initiating signals of this mitochondria-mediated cell death. These findings suggest, for the first time, the existence of an ionic signaling pathway in RCD.
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17
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Rane HS, Hayek SR, Frye JE, Abeyta EL, Bernardo SM, Parra KJ, Lee SA. Candida albicans Pma1p Contributes to Growth, pH Homeostasis, and Hyphal Formation. Front Microbiol 2019; 10:1012. [PMID: 31143168 PMCID: PMC6521590 DOI: 10.3389/fmicb.2019.01012] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 04/24/2019] [Indexed: 12/30/2022] Open
Abstract
Candida albicans occupies diverse ecological niches within the host and must tolerate a wide range of environmental pH. The plasma membrane H+-ATPase Pma1p is the major regulator of cytosolic pH in fungi. Pma1p extrudes protons from the cytosol to maintain neutral-to-alkaline pH and is a potential drug target due to its essentiality and fungal specificity. We characterized mutants in which one allele of PMA1 has been deleted and the other truncated by 18–38 amino acids. Increasing C-terminal truncation caused corresponding decreases in plasma membrane ATPase-specific activity and cytosolic pH. Pma1p is regulated by glucose: glucose rapidly activates the ATPase, causing a sharp increase in cytosolic pH. Increasing Pma1p truncation severely impaired this glucose response. Pma1p truncation also altered cation responses, disrupted vacuolar morphology and pH, and reduced filamentation competence. Early studies of cytosolic pH and filamentation have described a rapid, transient alkalinization of the cytosol preceding germ tube formation; Pma1p has been proposed as a regulator of this process. We find Pma1p plays a role in the establishment of cell polarity, and distribution of Pma1p is non-homogenous in emerging hyphae. These findings suggest a role of PMA1 in cytosolic alkalinization and in the specialized form of polarized growth that is filamentation.
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Affiliation(s)
- Hallie S Rane
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Science Center, Albuquerque, NM, United States
| | - Summer R Hayek
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Science Center, Albuquerque, NM, United States
| | - Jillian E Frye
- Section of Infectious Diseases, New Mexico VA Healthcare System, Albuquerque, NM, United States
| | - Esteban L Abeyta
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Science Center, Albuquerque, NM, United States
| | - Stella M Bernardo
- Division of Infectious Diseases, University of New Mexico Health Science Center, Albuquerque, NM, United States
| | - Karlett J Parra
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Science Center, Albuquerque, NM, United States
| | - Samuel A Lee
- Medicine Service, White River Junction VA Medical Center, White River Junction, VT, United States.,Infectious Disease Section, Department of Medicine, Geisel School of Medicine at Dartmouth, Dartmouth College, Hanover, NH, United States
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18
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Reifenrath M, Boles E. A superfolder variant of pH-sensitive pHluorin for in vivo pH measurements in the endoplasmic reticulum. Sci Rep 2018; 8:11985. [PMID: 30097598 PMCID: PMC6086885 DOI: 10.1038/s41598-018-30367-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 07/27/2018] [Indexed: 11/09/2022] Open
Abstract
Many cellular processes are regulated via pH, and maintaining the pH of different organelles is crucial for cell survival. A pH-sensitive GFP variant, the so-called pHluorin, has proven to be a valuable tool to study the pH of the cytosol, mitochondria and other organelles in vivo. We found that the fluorescence intensity of Endoplasmic Reticulum (ER)-targeted pHluorin in the yeast Saccharomyces cerevisiae was very low and barely showed pH sensitivity, probably due to misfolding in the oxidative environment of the ER. We therefore developed a superfolder variant of pHluorin which enabled us to monitor pH changes in the ER and the cytosol of S. cerevisiae in vivo. The superfolder pHluorin variant is likely to be functional in cells of different organisms as well as in additional compartments that originate from the secretory pathway like the Golgi apparatus and pre-vacuolar compartments, and therefore has a broad range of possible future applications.
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Affiliation(s)
- Mara Reifenrath
- Institute of Molecular Biosciences, Faculty of Biological Sciences, Goethe University Frankfurt, Max-von-Laue Straße 9, 60438, Frankfurt am Main, Germany
| | - Eckhard Boles
- Institute of Molecular Biosciences, Faculty of Biological Sciences, Goethe University Frankfurt, Max-von-Laue Straße 9, 60438, Frankfurt am Main, Germany.
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19
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Henderson R, Poolman B. Proton-solute coupling mechanism of the maltose transporter from Saccharomyces cerevisiae. Sci Rep 2017; 7:14375. [PMID: 29084970 PMCID: PMC5662749 DOI: 10.1038/s41598-017-14438-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 10/10/2017] [Indexed: 12/12/2022] Open
Abstract
Mal11 catalyzes proton-coupled maltose transport across the plasma membrane of Saccharomyces cerevisiae. We used structure-based design of mutants and a kinetic analysis of maltose transport to determine the energy coupling mechanism of transport. We find that wildtype Mal11 is extremely well coupled and allows yeast to rapidly accumulate maltose to dangerous levels, resulting under some conditions in self-lysis. Three protonatable residues lining the central membrane-embedded cavity of Mal11 were identified as having potential roles in proton translocation. We probed the mechanistic basis for proton coupling with uphill and downhill transport assays and found that single mutants can still accumulate maltose but with a lower coupling efficiency than the wildtype. Next, we combined the individual mutations and created double and triple mutants. We found some redundancy in the functions of the acidic residues in proton coupling and that no single residue is most critical for proton coupling to maltose uptake, unlike what is usually observed in related transporters. Importantly, the triple mutants were completely uncoupled but still fully active in downhill efflux and equilibrium exchange. Together, these results depict a concerted mechanism of proton transport in Mal11 involving multiple charged residues.
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Affiliation(s)
- Ryan Henderson
- Department of Biochemistry Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials University of Groningen Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Bert Poolman
- Department of Biochemistry Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials University of Groningen Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
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20
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Abstract
Heat tolerance is well known to be key to fungal survival in many habitats, but our mechanistic understanding of how organisms adapt to heat stress is still incomplete. Using Metarhizium robertsii, an emerging model organism for assessing evolutionary processes, we report that pyruvate is in the vanguard of molecules that scavenge heat-induced reactive oxygen species (ROS). We show that, as well as inducing a rapid burst of ROS production, heat stress also downregulates genes for pyruvate consumption. The accumulating pyruvate is the fastest acting of several M. robertsii ROS scavengers, efficiently reducing protein carbonylation, stabilizing mitochondrial membrane potential, and promoting fungal growth. The acetate produced from pyruvate-ROS reactions itself causes acid stress, tolerance to which is regulated by Hog1 mitogen-activated protein kinase. Heat stress also induces pyruvate accumulation in several other fungi, suggesting that scavenging of heat-induced ROS by pyruvate is widespread. Heat is a dangerous challenge for most organisms, as it denatures proteins and induces the production of ROS that inactivate proteins, lipid membranes, and DNA. How organisms respond to this stress is not fully understood. Using the experimentally tractable insect pathogen Metarhizium robertsii as a model organism, we show for the first time that heat stress induces pyruvate production and that this functions as the first line of defense against heat-induced ROS. Heat stress also induces rapid pyruvate accumulation in other fungi, suggesting that pyruvate is a common but unappreciated defense against stress.
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21
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Banerjee S, Kane PM. Direct interaction of the Golgi V-ATPase a-subunit isoform with PI(4)P drives localization of Golgi V-ATPases in yeast. Mol Biol Cell 2017; 28:2518-2530. [PMID: 28720663 PMCID: PMC5597324 DOI: 10.1091/mbc.e17-05-0316] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 07/03/2017] [Accepted: 07/14/2017] [Indexed: 12/11/2022] Open
Abstract
PI(4)P directly interacts with the cytosolic domain of yeast Golgi vacuolar H+-ATPase (V-ATPase) a-isoform, Stv1, and the human Golgi a-subunit isoform. Lys-84 of Stv1 is essential for PI(4)P interaction, and localization of Stv1-containing V-ATPases in vivo requires the PI(4)P interaction. We propose that phosphatidylinositol binding exerts organelle-specific control over V-ATPases. Luminal pH and phosphoinositide content are fundamental features of organelle identity. Vacuolar H+-ATPases (V-ATPases) drive organelle acidification in all eukaryotes, and membrane-bound a-subunit isoforms of the V-ATPase are implicated in organelle-specific targeting and regulation. Earlier work demonstrated that the endolysosomal lipid PI(3,5)P2 activates V-ATPases containing the vacuolar a-subunit isoform in Saccharomyces cerevisiae. Here we demonstrate that PI(4)P, the predominant Golgi phosphatidylinositol (PI) species, directly interacts with the cytosolic amino terminal (NT) domain of the yeast Golgi V-ATPase a-isoform Stv1. Lysine-84 of Stv1NT is essential for interaction with PI(4)P in vitro and in vivo, and interaction with PI(4)P is required for efficient localization of Stv1-containing V-ATPases. The cytosolic NT domain of the human V-ATPase a2 isoform specifically interacts with PI(4)P in vitro, consistent with its Golgi localization and function. We propose that NT domains of Vo a-subunit isoforms interact specifically with PI lipids in their organelles of residence. These interactions can transmit organelle-specific targeting or regulation information to V-ATPases.
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Affiliation(s)
- Subhrajit Banerjee
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210
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22
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Abstract
Despite diverse and changing extracellular environments, fungi maintain a relatively constant cytosolic pH and numerous organelles of distinct lumenal pH. Key players in fungal pH control are V-ATPases and the P-type proton pump Pma1. These two proton pumps act in concert with a large array of other transporters and are highly regulated. The activities of Pma1 and the V-ATPase are coordinated under some conditions, suggesting that pH in the cytosol and organelles is not controlled independently. Genomic studies, particularly in the highly tractable S. cerevisiae, are beginning to provide a systems-level view of pH control, including transcriptional responses to acid or alkaline ambient pH and definition of the full set of regulators required to maintain pH homeostasis. Genetically encoded pH sensors have provided new insights into localized mechanisms of pH control, as well as highlighting the dynamic nature of pH responses to the extracellular environment. Recent studies indicate that cellular pH plays a genuine signaling role that connects nutrient availability and growth rate through a number of mechanisms. Many of the pH control mechanisms found in S. cerevisiae are shared with other fungi, with adaptations for their individual physiological contexts. Fungi deploy certain proton transport and pH control mechanisms not shared with other eukaryotes; these regulators of cellular pH are potential antifungal targets. This review describes current and emerging knowledge proton transport and pH control mechanisms in S. cerevisiae and briefly discusses how these mechanisms vary among fungi.
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23
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Antagonism of Fluconazole and a Proton Pump Inhibitor against Candida albicans. Antimicrob Agents Chemother 2015; 60:1145-7. [PMID: 26596946 DOI: 10.1128/aac.02043-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 11/17/2015] [Indexed: 01/09/2023] Open
Abstract
Hospitalized ill patients, at risk for invasive candidiasis, often receive multiple medications, including proton pump inhibitors (PPIs). The antifungal fluconazole perturbs the vacuolar proton ATPase. The PPI omeprazole antagonized Candida albicans growth inhibition by fluconazole. A C. albicans codon-adapted pHluorin, Ca.pHluorin, was generated to measure cytosolic pH. The fungal cytosol was acidified by omeprazole and realkalinized by coexposure to fluconazole. Vacuolar pH was alkalinized by fluconazole. Off-target effects of any medication on fungal pathogens may occur.
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24
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ALL2, a Homologue of ALL1, Has a Distinct Role in Regulating pH Homeostasis in the Pathogen Cryptococcus neoformans. Infect Immun 2015; 84:439-51. [PMID: 26597983 DOI: 10.1128/iai.01046-15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 11/13/2015] [Indexed: 12/30/2022] Open
Abstract
Cryptococcus neoformans is a facultative intracellular fungal pathogen that has a polysaccharide capsule and causes life-threatening meningoencephalitis. Its capsule, as well as its ability to survive in the acidic environment of the phagolysosome, contributes to the pathogen's resilience in the host environment. Previously, we reported that downregulation of allergen 1 (ALL1) results in the secretion of a shorter, more viscous exopolysaccharide with less branching and structural complexity, as well as altered iron homeostasis. Now, we report on a homologous coregulated gene, allergen 2 (ALL2). ALL2's function was characterized by generating null mutants in C. neoformans. In contrast to ALL1, loss of ALL2 attenuated virulence in the pulmonary infection model. The all2Δ mutant shed a less viscous exopolysaccharide and exhibited higher sensitivity to hydrogen peroxide than the wild type, and as a result, the all2Δ mutant was more resistant to macrophage-mediated killing. Transcriptome analysis further supported the distinct function of these two genes. Unlike ALL1's involvement in iron homeostasis, we now present data on ALL2's unique function in maintaining intracellular pH in low-pH conditions. Thus, our data highlight that C. neoformans, a human-pathogenic basidiomycete, has evolved a unique set of virulence-associated genes that contributes to its resilience in the human niche.
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25
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Deranieh RM, Shi Y, Tarsio M, Chen Y, McCaffery JM, Kane PM, Greenberg ML. Perturbation of the Vacuolar ATPase: A NOVEL CONSEQUENCE OF INOSITOL DEPLETION. J Biol Chem 2015; 290:27460-72. [PMID: 26324718 DOI: 10.1074/jbc.m115.683706] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Indexed: 11/06/2022] Open
Abstract
Depletion of inositol has profound effects on cell function and has been implicated in the therapeutic effects of drugs used to treat epilepsy and bipolar disorder. We have previously shown that the anticonvulsant drug valproate (VPA) depletes inositol by inhibiting myo-inositol-3-phosphate synthase, the enzyme that catalyzes the first and rate-limiting step of inositol biosynthesis. To elucidate the cellular consequences of inositol depletion, we screened the yeast deletion collection for VPA-sensitive mutants and identified mutants in vacuolar sorting and the vacuolar ATPase (V-ATPase). Inositol depletion caused by starvation of ino1Δ cells perturbed the vacuolar structure and decreased V-ATPase activity and proton pumping in isolated vacuolar vesicles. VPA compromised the dynamics of phosphatidylinositol 3,5-bisphosphate (PI3,5P2) and greatly reduced V-ATPase proton transport in inositol-deprived wild-type cells. Osmotic stress, known to increase PI3,5P2 levels, did not restore PI3,5P2 homeostasis nor did it induce vacuolar fragmentation in VPA-treated cells, suggesting that perturbation of the V-ATPase is a consequence of altered PI3,5P2 homeostasis under inositol-limiting conditions. This study is the first to demonstrate that inositol depletion caused by starvation of an inositol synthesis mutant or by the inositol-depleting drug VPA leads to perturbation of the V-ATPase.
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Affiliation(s)
- Rania M Deranieh
- From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202
| | - Yihui Shi
- From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202
| | - Maureen Tarsio
- the Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, New York 13210, and
| | - Yan Chen
- From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202
| | - J Michael McCaffery
- the Integrated Imaging Center, Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218
| | - Patricia M Kane
- the Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, New York 13210, and
| | - Miriam L Greenberg
- From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202,
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PEP3 overexpression shortens lag phase but does not alter growth rate in Saccharomyces cerevisiae exposed to acetic acid stress. Appl Microbiol Biotechnol 2015; 99:8667-80. [PMID: 26051671 DOI: 10.1007/s00253-015-6708-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Revised: 04/22/2015] [Accepted: 05/19/2015] [Indexed: 12/12/2022]
Abstract
In fungi, two recognized mechanisms contribute to pH homeostasis: the plasma membrane proton-pumping ATPase that exports excess protons and the vacuolar proton-pumping ATPase (V-ATPase) that mediates vacuolar proton uptake. Here, we report that overexpression of PEP3 which encodes a component of the HOPS and CORVET complexes involved in vacuolar biogenesis, shortened lag phase in Saccharomyces cerevisiae exposed to acetic acid stress. By confocal microscopy, PEP3-overexpressing cells stained with the vacuolar membrane-specific dye, FM4-64 had more fragmented vacuoles than the wild-type control. The stained overexpression mutant was also found to exhibit about 3.6-fold more FM4-64 fluorescence than the wild-type control as determined by flow cytometry. While the vacuolar pH of the wild-type strain grown in the presence of 80 mM acetic acid was significantly higher than in the absence of added acid, no significant difference was observed in vacuolar pH of the overexpression strain grown either in the presence or absence of 80 mM acetic acid. Based on an indirect growth assay, the PEP3-overexpression strain exhibited higher V-ATPase activity. We hypothesize that PEP3 overexpression provides protection from acid stress by increasing vacuolar surface area and V-ATPase activity and, hence, proton-sequestering capacity.
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Smardon AM, Kane PM. Loss of vacuolar H+-ATPase activity in organelles signals ubiquitination and endocytosis of the yeast plasma membrane proton pump Pma1p. J Biol Chem 2014; 289:32316-32326. [PMID: 25271159 DOI: 10.1074/jbc.m114.574442] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Yeast mutants lacking the intracellular V-ATPase proton pump (vma mutants) have reduced levels of the Pma1p proton pump at the plasma membrane and increased levels in organelles including the vacuolar lumen. We examined the mechanism and physiological consequences of Pma1p mislocalization. Pma1p is ubiquitinated in vma mutants, and ubiquitination depends on the ubiquitin ligase Rsp5p and the arrestin-related adaptor protein Rim8p. vma mutant strains containing rsp5 or rim8 mutations maintain Pma1p at the plasma membrane, suggesting that ubiquitination is required for Pma1p internalization. Acute inhibition of V-ATPase activity with concanamycin A triggers Pma1p ubiquitination and internalization. In an endocytosis-deficient mutant (end4Δ) Pma1p is ubiquitinated but retained at the plasma membrane during concanamycin A treatment. Consistent with specificity in signaling loss of V-ATPase activity to Pma1p, another plasma membrane transporter, Mup1p, is not internalized in a vma mutant, and loss of the Mup1p adaptor Art1p does not prevent Pma1p internalization in a vma mutant. Very poor growth of vma2 rsp5-1 and vma2 rim8Δ double mutants suggests that Pma1p internalization benefits the vma mutants. We hypothesize that loss of V-ATPase-mediated organelle acidification signals ubiquitination, internalization, and degradation of a portion of Pma1p as a means of balancing overall pH homeostasis.
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Affiliation(s)
- Anne M Smardon
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210.
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Homotypic vacuole fusion in yeast requires organelle acidification and not the V-ATPase membrane domain. Dev Cell 2014; 27:462-8. [PMID: 24286827 DOI: 10.1016/j.devcel.2013.10.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 07/23/2013] [Accepted: 10/17/2013] [Indexed: 11/23/2022]
Abstract
Studies of homotypic vacuole-vacuole fusion in the yeast Saccharomyces cerevisiae have been instrumental in determining the cellular machinery required for eukaryotic membrane fusion and have implicated the vacuolar H(+)-ATPase (V-ATPase). The V-ATPase is a multisubunit, rotary proton pump whose precise role in homotypic fusion is controversial. Models formulated from in vitro studies suggest that it is the proteolipid proton-translocating pore of the V-ATPase that functions in fusion, with further studies in worms, flies, zebrafish, and mice appearing to support this model. We present two in vivo assays and use a mutant V-ATPase subunit to establish that it is the H(+)-translocation/vacuole acidification function, rather than the physical presence of the V-ATPase, that promotes homotypic vacuole fusion in yeast. Furthermore, we show that acidification of the yeast vacuole in the absence of the V-ATPase rescues vacuole-fusion defects. Our results clarify the in vivo requirements of acidification for membrane fusion.
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