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Peterson A, Baskett C, Ratcliff WC, Burnetti A. Transforming yeast into a facultative photoheterotroph via expression of vacuolar rhodopsin. Curr Biol 2024; 34:648-654.e3. [PMID: 38218181 DOI: 10.1016/j.cub.2023.12.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 11/03/2023] [Accepted: 12/13/2023] [Indexed: 01/15/2024]
Abstract
Phototrophic metabolism, the capture of light for energy, was a pivotal biological innovation that greatly increased the total energy available to the biosphere. Chlorophyll-based photosynthesis is the most familiar phototrophic metabolism, but retinal-based microbial rhodopsins transduce nearly as much light energy as chlorophyll does,1 via a simpler mechanism, and are found in far more taxonomic groups. Although this system has apparently spread widely via horizontal gene transfer,2,3,4 little is known about how rhodopsin genes (with phylogenetic origins within prokaryotes5,6) are horizontally acquired by eukaryotic cells with complex internal membrane architectures or the conditions under which they provide a fitness advantage. To address this knowledge gap, we sought to determine whether Saccharomyces cerevisiae, a heterotrophic yeast with no known evolutionary history of phototrophy, can function as a facultative photoheterotroph after acquiring a single rhodopsin gene. We inserted a rhodopsin gene from Ustilago maydis,7 which encodes a proton pump localized to the vacuole, an organelle normally acidified via a V-type rotary ATPase, allowing the rhodopsin to supplement heterotrophic metabolism. Probes of the physiology of modified cells show that they can deacidify the cytoplasm using light energy, demonstrating the ability of rhodopsins to ameliorate the effects of starvation and quiescence. Further, we show that yeast-bearing rhodopsins gain a selective advantage when illuminated, proliferating more rapidly than their non-phototrophic ancestor or rhodopsin-bearing yeast cultured in the dark. These results underscore the ease with which rhodopsins may be horizontally transferred even in eukaryotes, providing novel biological function without first requiring evolutionary optimization.
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Affiliation(s)
- Autumn Peterson
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30309, USA; Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA 30309, USA
| | - Carina Baskett
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30309, USA; Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA 30309, USA
| | - William C Ratcliff
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30309, USA; Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA 30309, USA.
| | - Anthony Burnetti
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30309, USA; Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA 30309, USA.
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2
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Umeda C, Nakajima T, Maruhashi T, Tanigawa M, Maeda T, Mukai Y. Overexpression of polyphosphate polymerases and deletion of polyphosphate phosphatases shorten the replicative lifespan in yeast. FEBS Lett 2023; 597:2316-2333. [PMID: 37574219 DOI: 10.1002/1873-3468.14715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 07/29/2023] [Accepted: 08/03/2023] [Indexed: 08/15/2023]
Abstract
We previously found that overexpression of phosphate starvation-responsive genes by disrupting PHO80 led to a shortened replicative lifespan in yeast. To identify lifespan-related genes, we screened upregulated genes in the pho80Δ mutant and focused on the VTC genes, which encode the vacuolar polyphosphate (polyP) polymerase complex. VTC1/VTC2/VTC4 deletion restored the lifespan and intracellular polyP levels in pho80Δ. In the wild type, overexpression of VTC5 or a combination of the other VTCs caused high polyP accumulation and shortened lifespan. Similar phenotypes were caused by the deletion of polyP phosphatase genes-vacuolar PPN1 and cytosolic PPX1. The polyP-accumulating strains exhibited stress sensitivities. Thus, we demonstrated that polyP metabolic enzymes participate in replicative lifespan, and extreme polyP accumulation shortens the lifespan.
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Affiliation(s)
- Chiharu Umeda
- Department of Frontier Bioscience, Nagahama Institute of Bio-Science and Technology, Shiga, Japan
| | - Toshio Nakajima
- Department of Frontier Bioscience, Nagahama Institute of Bio-Science and Technology, Shiga, Japan
| | - Tsubasa Maruhashi
- Department of Frontier Bioscience, Nagahama Institute of Bio-Science and Technology, Shiga, Japan
| | - Mirai Tanigawa
- Department of Biology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Tatsuya Maeda
- Department of Biology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Yukio Mukai
- Department of Frontier Bioscience, Nagahama Institute of Bio-Science and Technology, Shiga, Japan
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3
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Liu W, Wang J, Comte‐Miserez V, Zhang M, Yu X, Chen Q, Jessen HJ, Mayer A, Wu S, Ye S. Cryo-EM structure of the polyphosphate polymerase VTC reveals coupling of polymer synthesis to membrane transit. EMBO J 2023; 42:e113320. [PMID: 37066886 PMCID: PMC10183816 DOI: 10.15252/embj.2022113320] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 03/18/2023] [Accepted: 03/27/2023] [Indexed: 04/18/2023] Open
Abstract
The eukaryotic vacuolar transporter chaperone (VTC) complex acts as a polyphosphate (polyP) polymerase that synthesizes polyP from adenosine triphosphate (ATP) and translocates polyP across the vacuolar membrane to maintain an intracellular phosphate (Pi ) homeostasis. To discover how the VTC complex performs its function, we determined a cryo-electron microscopy structure of an endogenous VTC complex (Vtc4/Vtc3/Vtc1) purified from Saccharomyces cerevisiae at 3.1 Å resolution. The structure reveals a heteropentameric architecture of one Vtc4, one Vtc3, and three Vtc1 subunits. The transmembrane region forms a polyP-selective channel, likely adopting a resting state conformation, in which a latch-like, horizontal helix of Vtc4 limits the entrance. The catalytic Vtc4 central domain is located on top of the pseudo-symmetric polyP channel, creating a strongly electropositive pathway for nascent polyP that can couple synthesis to translocation. The SPX domain of the catalytic Vtc4 subunit positively regulates polyP synthesis by the VTC complex. The noncatalytic Vtc3 regulates VTC through a phosphorylatable loop. Our findings, along with the functional data, allow us to propose a mechanism of polyP channel gating and VTC complex activation.
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Affiliation(s)
- Wei Liu
- Frontiers Science Center for Synthetic Biology (Ministry of Education), Tianjin Key Laboratory of Function and Application of Biological Macromolecular Structures, School of Life SciencesTianjin UniversityTianjinChina
| | - Jiening Wang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative Innovation Center for Green Transformation of Bio‐Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life SciencesHubei UniversityWuhanChina
| | | | - Mengyu Zhang
- Frontiers Science Center for Synthetic Biology (Ministry of Education), Tianjin Key Laboratory of Function and Application of Biological Macromolecular Structures, School of Life SciencesTianjin UniversityTianjinChina
| | - Xuejing Yu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative Innovation Center for Green Transformation of Bio‐Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life SciencesHubei UniversityWuhanChina
| | - Qingfeng Chen
- School of Life SciencesYunnan UniversityKunmingChina
| | - Henning Jacob Jessen
- Institute of Organic ChemistryUniversity of FreiburgFreiburgGermany
- CIBSS – Centre for Integrative Biological Signalling StudiesUniversity of FreiburgFreiburgGermany
| | - Andreas Mayer
- Département d'ImmunobiologieUniversité de LausanneEpalingesSwitzerland
| | - Shan Wu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative Innovation Center for Green Transformation of Bio‐Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life SciencesHubei UniversityWuhanChina
| | - Sheng Ye
- Frontiers Science Center for Synthetic Biology (Ministry of Education), Tianjin Key Laboratory of Function and Application of Biological Macromolecular Structures, School of Life SciencesTianjin UniversityTianjinChina
- Life Sciences Institute, Zhejiang UniversityHangzhouChina
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4
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Pipercevic J, Kohl B, Gerasimaite R, Comte-Miserez V, Hostachy S, Müntener T, Agustoni E, Jessen HJ, Fiedler D, Mayer A, Hiller S. Inositol pyrophosphates activate the vacuolar transport chaperone complex in yeast by disrupting a homotypic SPX domain interaction. Nat Commun 2023; 14:2645. [PMID: 37156835 PMCID: PMC10167327 DOI: 10.1038/s41467-023-38315-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Accepted: 04/25/2023] [Indexed: 05/10/2023] Open
Abstract
Many proteins involved in eukaryotic phosphate homeostasis are regulated by SPX domains. In yeast, the vacuolar transporter chaperone (VTC) complex contains two such domains, but mechanistic details of its regulation are not well understood. Here, we show at the atomic level how inositol pyrophosphates interact with SPX domains of subunits Vtc2 and Vtc3 to control the activity of the VTC complex. Vtc2 inhibits the catalytically active VTC subunit Vtc4 by homotypic SPX-SPX interactions via the conserved helix α1 and the previously undescribed helix α7. Binding of inositol pyrophosphates to Vtc2 abrogates this interaction, thus activating the VTC complex. Accordingly, VTC activation is also achieved by site-specific point mutations that disrupt the SPX-SPX interface. Structural data suggest that ligand binding induces reorientation of helix α1 and exposes the modifiable helix α7, which might facilitate its post-translational modification in vivo. The variable composition of these regions within the SPX domain family might contribute to the diversified SPX functions in eukaryotic phosphate homeostasis.
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Affiliation(s)
- Joka Pipercevic
- Biozentrum, University of Basel, Spitalstrasse 41, 4056, Basel, Switzerland
| | - Bastian Kohl
- Biozentrum, University of Basel, Spitalstrasse 41, 4056, Basel, Switzerland
| | - Ruta Gerasimaite
- Department of Immunobiology, University of Lausanne, Chemin des Boveresses 155, CP51 1066, Epalinges, Switzerland
- Max-Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Véronique Comte-Miserez
- Department of Immunobiology, University of Lausanne, Chemin des Boveresses 155, CP51 1066, Epalinges, Switzerland
| | - Sarah Hostachy
- Department of Chemical Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Straße 10, 13125, Berlin, Germany
| | - Thomas Müntener
- Biozentrum, University of Basel, Spitalstrasse 41, 4056, Basel, Switzerland
| | - Elia Agustoni
- Biozentrum, University of Basel, Spitalstrasse 41, 4056, Basel, Switzerland
| | - Henning Jacob Jessen
- Institute of Organic Chemistry, University of Freiburg, Albertstraße 21, 79104, Freiburg, Germany
| | - Dorothea Fiedler
- Department of Chemical Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Straße 10, 13125, Berlin, Germany
| | - Andreas Mayer
- Department of Immunobiology, University of Lausanne, Chemin des Boveresses 155, CP51 1066, Epalinges, Switzerland
| | - Sebastian Hiller
- Biozentrum, University of Basel, Spitalstrasse 41, 4056, Basel, Switzerland.
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Guan Z, Chen J, Liu R, Chen Y, Xing Q, Du Z, Cheng M, Hu J, Zhang W, Mei W, Wan B, Wang Q, Zhang J, Cheng P, Cai H, Cao J, Zhang D, Yan J, Yin P, Hothorn M, Liu Z. The cytoplasmic synthesis and coupled membrane translocation of eukaryotic polyphosphate by signal-activated VTC complex. Nat Commun 2023; 14:718. [PMID: 36759618 PMCID: PMC9911596 DOI: 10.1038/s41467-023-36466-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 02/01/2023] [Indexed: 02/11/2023] Open
Abstract
Inorganic polyphosphate (polyP) is an ancient energy metabolite and phosphate store that occurs ubiquitously in all organisms. The vacuolar transporter chaperone (VTC) complex integrates cytosolic polyP synthesis from ATP and polyP membrane translocation into the vacuolar lumen. In yeast and in other eukaryotes, polyP synthesis is regulated by inositol pyrophosphate (PP-InsP) nutrient messengers, directly sensed by the VTC complex. Here, we report the cryo-electron microscopy structure of signal-activated VTC complex at 3.0 Å resolution. Baker's yeast VTC subunits Vtc1, Vtc3, and Vtc4 assemble into a 3:1:1 complex. Fifteen trans-membrane helices form a novel membrane channel enabling the transport of newly synthesized polyP into the vacuolar lumen. PP-InsP binding orients the catalytic polymerase domain at the entrance of the trans-membrane channel, both activating the enzyme and coupling polyP synthesis and membrane translocation. Together with biochemical and cellular studies, our work provides mechanistic insights into the biogenesis of an ancient energy metabolite.
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Affiliation(s)
- Zeyuan Guan
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Juan Chen
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Ruiwen Liu
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yanke Chen
- Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Qiong Xing
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, 430062, China
| | - Zhangmeng Du
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Meng Cheng
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jianjian Hu
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Wenhui Zhang
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Wencong Mei
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Beijing Wan
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Qiang Wang
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jie Zhang
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Peng Cheng
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Huanyu Cai
- College of Science, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jianbo Cao
- Public Laboratory of Electron Microscopy, Huazhong Agricultural University, Wuhan, 430070, China
| | - Delin Zhang
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Junjie Yan
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Ping Yin
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Michael Hothorn
- Structural Plant Biology Laboratory, Department of Plant Scienes, University of Geneva, Geneva, 1211, Switzerland
| | - Zhu Liu
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China.
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6
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PHM6 and PHM7 genes are essential for phosphate surplus in the cells of Saccharomyces cerevisiae. Arch Microbiol 2023; 205:47. [PMID: 36592238 DOI: 10.1007/s00203-022-03394-8] [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: 10/18/2022] [Revised: 12/26/2022] [Accepted: 12/28/2022] [Indexed: 01/03/2023]
Abstract
The cells of Saccharomyces cerevisiae are capable for phosphate surplus: the increased uptake of phosphate (Pi) and accumulation of inorganic polyphosphate (polyP) occur when the cells after Pi limitation were cultivated in a medium supplemented with Pi. We demonstrated that single knockout mutations in the PHO84, PHO87, and PHO89 genes encoding plasma membrane phosphate transporters suppressed the Pi uptake and polyP accumulation under phosphate surplus at nitrogen starvation. The knockout strains in the PHM6 and PHM7 genes encoding unannotated PHO-proteins showed decreased polyP accumulation under Pi surplus both at nitrogen starvation and in complete YPD medium. This is due to the suppression of Pi uptake in the cells of these mutant strains. We speculate that Pi transporters of plasma membrane, and Phm6 and Phm7 proteins function in concert providing increased Pi uptake at phosphate surplus conditions.
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7
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Shi X, Liu X, Cooper AM, Silver K, Merzendorfer H, Zhu KY, Zhang J. Vacuolar (H + )-ATPase subunit c is essential for the survival and systemic RNA interference response in Locusta migratoria. PEST MANAGEMENT SCIENCE 2022; 78:1555-1566. [PMID: 34981606 DOI: 10.1002/ps.6774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/19/2021] [Accepted: 01/03/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND Vacuolar (H+ )-ATPase (V-ATPase) is a multi-subunit enzyme that hydrolyzes adenosine triphosphate (ATP) to transport protons across a cellular membrane, and it plays an important role in numerous biological processes, including in growth, development and immune responses. The c subunit of V-ATPase is a highly conserved subunit of the rotatory proteolipid ring that is required for binding and transporting protons. To date, there are only a few published reports on V-ATPase-c functions in insects. RESULTS We identified and characterized the V-ATPase-c gene in Locusta migratoria, one of the most destructive agricultural insect pests in the world. LmV-ATPase-c was predominately expressed in Malpighian tubules of nymphs, followed by the hindgut and ovary, while the other tissues showed relatively low expression levels. Silencing of LmV-ATPase-c caused severe molting defects in nymphs and a high mortality rate of > 90%. Histological staining and microscopic examination of sections from the abdominal cuticle revealed the absence of newly formed cuticle in nymphs that were injected with dsLmV-ATPase-c. In addition, silencing of LmV-ATPase-c transcript levels significantly impaired RNA interference (RNAi) efficiency of a reporter gene. By quantifying double-stranded RNA (dsRNA) amounts by quantitative polymerase chain reaction (PCR), we found that RNAi against LmV-ATPase-c provoked a dramatic accumulation of dsRNA in the endosomes of epidermal and midgut cells of Locusta migratoria. CONCLUSION Our results indicate that LmV-ATPase-c is indispensable for the formation of new cuticle during the molting process and has pivotal functions in dsRNA escape from endosomes. LmV-ATPase-c might be a valuable target for developing new strategies for insect pest management. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Xuekai Shi
- Institute of Applied Biology, Shanxi University, Taiyuan, China
- College of Life Sciences, Shanxi University, Taiyuan, China
| | - Xiaojian Liu
- Institute of Applied Biology, Shanxi University, Taiyuan, China
| | | | - Kristopher Silver
- Department of Entomology, Kansas State University, Manhattan, KS, USA
| | | | - Kun Yan Zhu
- Department of Entomology, Kansas State University, Manhattan, KS, USA
| | - Jianzhen Zhang
- Institute of Applied Biology, Shanxi University, Taiyuan, China
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Vtc5 Is Localized to the Vacuole Membrane by the Conserved AP-3 Complex to Regulate Polyphosphate Synthesis in Budding Yeast. mBio 2021; 12:e0099421. [PMID: 34544285 PMCID: PMC8510523 DOI: 10.1128/mbio.00994-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Polyphosphates (polyP) are energy-rich polymers of inorganic phosphates assembled into chains ranging from 3 residues to thousands of residues in length. They are thought to exist in all cells on earth and play roles in an eclectic mix of functions ranging from phosphate homeostasis to cell signaling, infection control, and blood clotting. In the budding yeast Saccharomyces cerevisiae, polyP chains are synthesized by the vacuole-bound vacuolar transporter chaperone (VTC) complex, which synthesizes polyP while simultaneously translocating it into the vacuole lumen, where it is stored at high concentrations. VTC’s activity is promoted by an accessory subunit called Vtc5. In this work, we found that the conserved AP-3 complex is required for proper Vtc5 localization to the vacuole membrane. In human cells, previous work has demonstrated that mutation of AP-3 subunits gives rise to Hermansky-Pudlak syndrome, a rare disease with molecular phenotypes that include decreased polyP accumulation in platelet dense granules. In yeast AP-3 mutants, we found that Vtc5 is rerouted to the vacuole lumen by the endosomal sorting complex required for transport (ESCRT), where it is degraded by the vacuolar protease Pep4. Cells lacking functional AP-3 have decreased levels of polyP, demonstrating that membrane localization of Vtc5 is required for its VTC stimulatory activity in vivo. Our work provides insight into the molecular trafficking of a critical regulator of polyP metabolism in yeast. We speculate that AP-3 may also be responsible for the delivery of polyP regulatory proteins to platelet dense granules in higher eukaryotes.
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Lemus L, Matić Z, Gal L, Fadel A, Schuldiner M, Goder V. Post-ER degradation of misfolded GPI-anchored proteins is linked with microautophagy. Curr Biol 2021; 31:4025-4037.e5. [PMID: 34314677 DOI: 10.1016/j.cub.2021.06.078] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 06/07/2021] [Accepted: 06/25/2021] [Indexed: 01/08/2023]
Abstract
Glycosylphosphatidylinositol-anchored proteins (GPI-APs) are membrane-conjugated cell-surface proteins with diverse structural, developmental, and signaling functions and clinical relevance. Typically, after biosynthesis and attachment to the preassembled GPI anchor, GPI-APs rapidly leave the endoplasmic reticulum (ER) and rely on post-ER quality control. Terminally misfolded GPI-APs end up inside the vacuole/lysosome for degradation, but their trafficking itinerary to this organelle and the processes linked to their uptake by the vacuole/lysosome remain uncharacterized. In a yeast mutant that is lacking Pep4, a key vacuolar protease, several misfolded model GPI-APs accumulated in the vacuolar membrane. In the same mutant, macroautophagy and the multi-vesicular body (MVB) pathway were intact, hinting at a hitherto-unknown trafficking pathway for the degradation of misfolded GPI-APs. To unravel it, we used a genome-wide screen coupled to high-throughput fluorescence microscopy and followed the fate of the misfolded GPI-AP: Gas1∗. We found that components of the early secretory and endocytic pathways are involved in its targeting to the vacuole and that vacuolar transporter chaperones (VTCs), with roles in microautophagy, negatively affect the vacuolar uptake of Gas1∗. In support, we demonstrate that Gas1∗ internalizes from vacuolar membranes into membrane-bound intravacuolar vesicles prior to degradation. Our data link post-ER degradation with microautophagy.
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Affiliation(s)
- Leticia Lemus
- Department of Genetics, University of Seville, Ave Reina Mercedes, 6, 41012 Seville, Spain.
| | - Zrinka Matić
- Department of Genetics, University of Seville, Ave Reina Mercedes, 6, 41012 Seville, Spain
| | - Lihi Gal
- Department of Molecular Genetics, Meyer Bldg. Room 122, Weizmann Institute of Sciences, 76100 Rehovot, Israel
| | - Amir Fadel
- Department of Molecular Genetics, Meyer Bldg. Room 122, Weizmann Institute of Sciences, 76100 Rehovot, Israel
| | - Maya Schuldiner
- Department of Molecular Genetics, Meyer Bldg. Room 122, Weizmann Institute of Sciences, 76100 Rehovot, Israel
| | - Veit Goder
- Department of Genetics, University of Seville, Ave Reina Mercedes, 6, 41012 Seville, Spain.
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10
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Regulation of inorganic polyphosphate is required for proper vacuolar proteolysis in fission yeast. J Biol Chem 2021; 297:100891. [PMID: 34147496 PMCID: PMC8294586 DOI: 10.1016/j.jbc.2021.100891] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 06/07/2021] [Accepted: 06/16/2021] [Indexed: 02/08/2023] Open
Abstract
Regulation of cellular proliferation and quiescence is a central issue in biology that has been studied using model unicellular eukaryotes, such as the fission yeast Schizosaccharomyces pombe. We previously reported that the ubiquitin/proteasome pathway and autophagy are essential to maintain quiescence induced by nitrogen deprivation in S. pombe; however, specific ubiquitin ligases that maintain quiescence are not fully understood. Here we investigated the SPX-RING-type ubiquitin ligase Pqr1, identified as required for quiescence in a genetic screen. Pqr1 is found to be crucial for vacuolar proteolysis, the final step of autophagy, through proper regulation of phosphate and its polymer polyphosphate. Pqr1 restricts phosphate uptake into the cell through ubiquitination and subsequent degradation of phosphate transporters on plasma membranes. We hypothesized that Pqr1 may act as the central regulator for phosphate control in S. pombe, through the function of the SPX domain involved in phosphate sensing. Deletion of pqr1+ resulted in hyperaccumulation of intracellular phosphate and polyphosphate and in improper autophagy-dependent proteolysis under conditions of nitrogen starvation. Polyphosphate hyperaccumulation in pqr1+-deficient cells was mediated by the polyphosphate synthase VTC complex in vacuoles. Simultaneous deletion of VTC complex subunits rescued Pqr1 mutant phenotypes, including defects in proteolysis and loss of viability during quiescence. We conclude that excess polyphosphate may interfere with proteolysis in vacuoles by mechanisms that as yet remain unknown. The present results demonstrate a connection between polyphosphate metabolism and vacuolar functions for proper autophagy-dependent proteolysis, and we propose that polyphosphate homeostasis contributes to maintenance of cellular viability during quiescence.
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11
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Tomashevsky A, Kulakovskaya E, Trilisenko L, Kulakovskiy IV, Kulakovskaya T, Fedorov A, Eldarov M. VTC4 Polyphosphate Polymerase Knockout Increases Stress Resistance of Saccharomyces cerevisiae Cells. BIOLOGY 2021; 10:487. [PMID: 34070801 PMCID: PMC8227513 DOI: 10.3390/biology10060487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 05/26/2021] [Accepted: 05/27/2021] [Indexed: 11/17/2022]
Abstract
Inorganic polyphosphate (polyP) is an important factor of alkaline, heavy metal, and oxidative stress resistance in microbial cells. In yeast, polyP is synthesized by Vtc4, a subunit of the vacuole transporter chaperone complex. Here, we report reduced but reliably detectable amounts of acid-soluble and acid-insoluble polyPs in the Δvtc4 strain of Saccharomyces cerevisiae, reaching 10% and 20% of the respective levels of the wild-type strain. The Δvtc4 strain has decreased resistance to alkaline stress but, unexpectedly, increased resistance to oxidation and heavy metal excess. We suggest that increased resistance is achieved through elevated expression of DDR2, which is implicated in stress response, and reduced expression of PHO84 encoding a phosphate and divalent metal transporter. The decreased Mg2+-dependent phosphate accumulation in Δvtc4 cells is consistent with reduced expression of PHO84. We discuss a possible role that polyP level plays in cellular signaling of stress response mobilization in yeast.
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Affiliation(s)
- Alexander Tomashevsky
- Federal Scientific Center, Pushchino Research Center for Biology of the Russian Academy of Sciences, Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, pr. Nauki 5, 142290 Pushchino, Russia; (A.T.); (E.K.); (L.T.)
| | - Ekaterina Kulakovskaya
- Federal Scientific Center, Pushchino Research Center for Biology of the Russian Academy of Sciences, Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, pr. Nauki 5, 142290 Pushchino, Russia; (A.T.); (E.K.); (L.T.)
| | - Ludmila Trilisenko
- Federal Scientific Center, Pushchino Research Center for Biology of the Russian Academy of Sciences, Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, pr. Nauki 5, 142290 Pushchino, Russia; (A.T.); (E.K.); (L.T.)
| | - Ivan V. Kulakovskiy
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia;
- Vavilov Institute of General Genetics, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Tatiana Kulakovskaya
- Federal Scientific Center, Pushchino Research Center for Biology of the Russian Academy of Sciences, Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, pr. Nauki 5, 142290 Pushchino, Russia; (A.T.); (E.K.); (L.T.)
| | - Alexey Fedorov
- Federal Scientific Center for Biotechnology of the Russian Academy of Sciences, Institute of Bioengineering, Russian Academy of Sciences, Leninsky prosp. 33-2, 119071 Moscow, Russia; (A.F.); (M.E.)
| | - Mikhail Eldarov
- Federal Scientific Center for Biotechnology of the Russian Academy of Sciences, Institute of Bioengineering, Russian Academy of Sciences, Leninsky prosp. 33-2, 119071 Moscow, Russia; (A.F.); (M.E.)
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12
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Kulakovskaya TV, Andreeva NA, Ledova LA, Ryazanova LP, Trilisenko LV, Eldarov MA. Enzymes of Polyphosphate Metabolism in Yeast: Properties, Functions, Practical Significance. BIOCHEMISTRY (MOSCOW) 2021; 86:S96-S108. [PMID: 33827402 DOI: 10.1134/s0006297921140078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Inorganic polyphosphates (polyP) are the linear polymers of orthophosphoric acid varying in the number of phosphate residues linked by the energy-rich phosphoanhydride bonds. PolyP is an essential component in living cells. Knowledge of polyP metabolizing enzymes in eukaryotes is necessary for understanding molecular mechanisms of polyP metabolism in humans and development of new approaches for treating bone and cardiovascular diseases associated with impaired mineral phosphorus metabolism. Yeast cells represent a rational experimental model for this research due to availability of the methods for studying phosphorus metabolism and construction of knockout mutants and strains overexpressing target proteins. Multicomponent system of polyP metabolism in Saccharomyces cerevisiae cells is presented in this review discussing properties, functioning, and practical significance of the enzymes involved in the synthesis and degradation of this important metabolite.
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Affiliation(s)
- Tatiana V Kulakovskaya
- Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino Research Center for Biology, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
| | - Nadezhda A Andreeva
- Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino Research Center for Biology, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Larisa A Ledova
- Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino Research Center for Biology, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Lubov P Ryazanova
- Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino Research Center for Biology, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Ludmila V Trilisenko
- Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino Research Center for Biology, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Michail A Eldarov
- Institute of Bioengineering, Federal Scientific Center for Biotechnology, Russian Academy of Sciences, Moscow, 117312, Russia
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13
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Stasic AJ, Dykes EJ, Cordeiro CD, Vella SA, Fazli MS, Quinn S, Docampo R, Moreno SNJ. Ca 2+ entry at the plasma membrane and uptake by acidic stores is regulated by the activity of the V-H + -ATPase in Toxoplasma gondii. Mol Microbiol 2021; 115:1054-1068. [PMID: 33793004 DOI: 10.1111/mmi.14722] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 03/21/2021] [Accepted: 03/26/2021] [Indexed: 12/14/2022]
Abstract
Ca2+ is a universal intracellular signal that regulates many cellular functions. In Toxoplasma gondii, the controlled influx of extracellular and intracellular Ca2+ into the cytosol initiates a signaling cascade that promotes pathogenic processes like tissue destruction and dissemination. In this work, we studied the role of proton transport in cytosolic Ca2+ homeostasis and the initiation of Ca2+ signaling. We used a T. gondii mutant of the V-H+ -ATPase, a pump previously shown to transport protons to the extracellular medium, and to control intracellular pH and membrane potential and we show that proton gradients are important for maintaining resting cytosolic Ca2+ at physiological levels and for Ca2+ influx. Proton transport was also important for Ca2+ storage by acidic stores and, unexpectedly, the endoplasmic reticulum. Proton transport impacted the amount of polyphosphate (polyP), a phosphate polymer that binds Ca2+ and concentrates in acidocalcisomes. This was supported by the co-localization of the vacuolar transporter chaperone 4 (VTC4), the catalytic subunit of the VTC complex that synthesizes polyP, with the V-ATPase in acidocalcisomes. Our work shows that proton transport regulates plasma membrane Ca2+ transport and control acidocalcisome polyP and Ca2+ content, impacting Ca2+ signaling and downstream stimulation of motility and egress in T. gondii.
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Affiliation(s)
- Andrew J Stasic
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, GA, USA
| | - Eric J Dykes
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, GA, USA.,Department of Cellular Biology, University of Georgia, Athens, GA, USA
| | - Ciro D Cordeiro
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, GA, USA.,Department of Cellular Biology, University of Georgia, Athens, GA, USA
| | - Stephen A Vella
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, GA, USA
| | - Mojtaba S Fazli
- Department of Computer Sciences, University of Georgia, Athens, GA, USA
| | - Shannon Quinn
- Department of Cellular Biology, University of Georgia, Athens, GA, USA.,Department of Computer Sciences, University of Georgia, Athens, GA, USA
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, GA, USA.,Department of Cellular Biology, University of Georgia, Athens, GA, USA
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, GA, USA.,Department of Cellular Biology, University of Georgia, Athens, GA, USA
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14
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Single-cell visualization and quantification of trace metals in Chlamydomonas lysosome-related organelles. Proc Natl Acad Sci U S A 2021; 118:2026811118. [PMID: 33879572 DOI: 10.1073/pnas.2026811118] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The acidocalcisome is an acidic organelle in the cytosol of eukaryotes, defined by its low pH and high calcium and polyphosphate content. It is visualized as an electron-dense object by transmission electron microscopy (TEM) or described with mass spectrometry (MS)-based imaging techniques or multimodal X-ray fluorescence microscopy (XFM) based on its unique elemental composition. Compared with MS-based imaging techniques, XFM offers the additional advantage of absolute quantification of trace metal content, since sectioning of the cell is not required and metabolic states can be preserved rapidly by either vitrification or chemical fixation. We employed XFM in Chlamydomonas reinhardtii to determine single-cell and organelle trace metal quotas within algal cells in situations of trace metal overaccumulation (Fe and Cu). We found up to 70% of the cellular Cu and 80% of Fe sequestered in acidocalcisomes in these conditions and identified two distinct populations of acidocalcisomes, defined by their unique trace elemental makeup. We utilized the vtc1 mutant, defective in polyphosphate synthesis and failing to accumulate Ca, to show that Fe sequestration is not dependent on either. Finally, quantitation of the Fe and Cu contents of individual cells and compartments via XFM, over a range of cellular metal quotas created by nutritional and genetic perturbations, indicated excellent correlation with bulk data from corresponding cell cultures, establishing a framework to distinguish the nutritional status of single cells.
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15
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Austin S, Mayer A. Phosphate Homeostasis - A Vital Metabolic Equilibrium Maintained Through the INPHORS Signaling Pathway. Front Microbiol 2020; 11:1367. [PMID: 32765429 PMCID: PMC7381174 DOI: 10.3389/fmicb.2020.01367] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 05/27/2020] [Indexed: 12/12/2022] Open
Abstract
Cells face major changes in demand for and supply of inorganic phosphate (Pi). Pi is often a limiting nutrient in the environment, particularly for plants and microorganisms. At the same time, the need for phosphate varies, establishing conflicts of goals. Cells experience strong peaks of Pi demand, e.g., during the S-phase, when DNA, a highly abundant and phosphate-rich compound, is duplicated. While cells must satisfy these Pi demands, they must safeguard themselves against an excess of Pi in the cytosol. This is necessary because Pi is a product of all nucleotide-hydrolyzing reactions. An accumulation of Pi shifts the equilibria of these reactions and reduces the free energy that they can provide to drive endergonic metabolic reactions. Thus, while Pi starvation may simply retard growth and division, an elevated cytosolic Pi concentration is potentially dangerous for cells because it might stall metabolism. Accordingly, the consequences of perturbed cellular Pi homeostasis are severe. In eukaryotes, they range from lethality in microorganisms such as yeast (Sethuraman et al., 2001; Hürlimann, 2009), severe growth retardation and dwarfism in plants (Puga et al., 2014; Liu et al., 2015; Wild et al., 2016) to neurodegeneration or renal Fanconi syndrome in humans (Legati et al., 2015; Ansermet et al., 2017). Intracellular Pi homeostasis is thus not only a fundamental topic of cell biology but also of growing interest for medicine and agriculture.
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Affiliation(s)
- Sisley Austin
- Département de Biochimie, Université de Lausanne, Lausanne, Switzerland
| | - Andreas Mayer
- Département de Biochimie, Université de Lausanne, Lausanne, Switzerland
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16
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Identification of the Genetic Requirements for Zinc Tolerance and Toxicity in Saccharomyces cerevisiae. G3-GENES GENOMES GENETICS 2020; 10:479-488. [PMID: 31836620 PMCID: PMC7003084 DOI: 10.1534/g3.119.400933] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Zinc is essential for almost all living organisms, since it serves as a crucial cofactor for transcription factors and enzymes. However, it is toxic to cell growth when present in excess. The present work aims to investigate the toxicity mechanisms induced by zinc stress in yeast cells. To this end, 108 yeast single-gene deletion mutants were identified sensitive to 6 mM ZnCl2 through a genome-wide screen. These genes were predominantly related to the biological processes of vacuolar acidification and transport, polyphosphate metabolic process, cytosolic transport, the process utilizing autophagic mechanism. A result from the measurement of intracellular zinc content showed that 64 mutants accumulated higher intracellular zinc under zinc stress than the wild-type cells. We further measured the intracellular ROS (reactive oxygen species) levels of 108 zinc-sensitive mutants treated with 3 mM ZnCl2. We showed that the intracellular ROS levels in 51 mutants were increased by high zinc stress, suggesting their possible involvement in regulating ROS homeostasis in response to high zinc. The results also revealed that excess zinc could generate oxidative damage and then activate the expression of several antioxidant defenses genes. Taken together, the data obtained indicated that excess zinc toxicity might be mainly due to the high intracellular zinc levels and ROS levels induced by zinc stress in yeast cells. Our current findings would provide a basis to understand the molecular mechanisms of zinc toxicity in yeast cells.
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17
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Müller WE, Schröder HC, Wang X. Inorganic Polyphosphates As Storage for and Generator of Metabolic Energy in the Extracellular Matrix. Chem Rev 2019; 119:12337-12374. [PMID: 31738523 PMCID: PMC6935868 DOI: 10.1021/acs.chemrev.9b00460] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Indexed: 12/14/2022]
Abstract
Inorganic polyphosphates (polyP) consist of linear chains of orthophosphate residues, linked by high-energy phosphoanhydride bonds. They are evolutionarily old biopolymers that are present from bacteria to man. No other molecule concentrates as much (bio)chemically usable energy as polyP. However, the function and metabolism of this long-neglected polymer are scarcely known, especially in higher eukaryotes. In recent years, interest in polyP experienced a renaissance, beginning with the discovery of polyP as phosphate source in bone mineralization. Later, two discoveries placed polyP into the focus of regenerative medicine applications. First, polyP shows morphogenetic activity, i.e., induces cell differentiation via gene induction, and, second, acts as an energy storage and donor in the extracellular space. Studies on acidocalcisomes and mitochondria provided first insights into the enzymatic basis of eukaryotic polyP formation. In addition, a concerted action of alkaline phosphatase and adenylate kinase proved crucial for ADP/ATP generation from polyP. PolyP added extracellularly to mammalian cells resulted in a 3-fold increase of ATP. The importance and mechanism of this phosphotransfer reaction for energy-consuming processes in the extracellular matrix are discussed. This review aims to give a critical overview about the formation and function of this unique polymer that is capable of storing (bio)chemically useful energy.
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Affiliation(s)
- Werner E.G. Müller
- ERC Advanced Investigator
Grant Research
Group at the Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Duesbergweg 6, D-55128 Mainz, Germany
| | - Heinz C. Schröder
- ERC Advanced Investigator
Grant Research
Group at the Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Duesbergweg 6, D-55128 Mainz, Germany
| | - Xiaohong Wang
- ERC Advanced Investigator
Grant Research
Group at the Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Duesbergweg 6, D-55128 Mainz, Germany
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18
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Cruz MD, Kim K. The inner workings of intracellular heterotypic and homotypic membrane fusion mechanisms. J Biosci 2019; 44:91. [PMID: 31502569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Intracellular trafficking is a field that has been intensively studied for years and yet there remains much to be learned. Part of the reason that there is so much obscurity remaining in this field is due to all the pathways and the stages that define cellular trafficking. One of the major steps in cellular trafficking is fusion. Fusion is defined as the terminal step that occurs when a cargo-laden vesicle arrives at the proper destination. There are two types of fusion within a cell: homotypic and heterotypic fusion. Homotypic fusion occurs when the two membranes merging together are of the same type such as vacuole to vacuole fusion. Heterotypic fusion occurs when the two membranes at play are of different types such as when an endosomal membrane fuses with a Golgi membrane. In this review, we will focus on all the protein components - Rabs, Golgins, Multisubunit tethers, GTPases, protein phosphatases and SNAREs - that have been known to function in both of these types of fusion. We hope to develop a model of how all of these constituents function together to achieve membrane fusion. Membrane fusion is a biological process absolutely necessary for proper intracellular trafficking. Due to the degree of importance multiple proteins are required for it to be properly carried through. Whether we are talking about heterotypic or homotypic fusion, any defects in the fusion machinery can result in disease states such as Parkinson's and Alzheimer's disease. Although much research has significantly expanded our knowledge of fusion, there is still much more to be learned.
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19
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Delgado Cruz M, Kim K. The inner workings of intracellular heterotypic and homotypic membrane fusion mechanisms. J Biosci 2019. [DOI: 10.1007/s12038-019-9913-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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20
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Chia SZ, Lai YW, Yagoub D, Lev S, Hamey JJ, Pang CNI, Desmarini D, Chen Z, Djordjevic JT, Erce MA, Hart-Smith G, Wilkins MR. Knockout of the Hmt1p Arginine Methyltransferase in Saccharomyces cerevisiae Leads to the Dysregulation of Phosphate-associated Genes and Processes. Mol Cell Proteomics 2018; 17:2462-2479. [PMID: 30206180 DOI: 10.1074/mcp.ra117.000214] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 08/14/2018] [Indexed: 11/06/2022] Open
Abstract
Hmt1p is the predominant arginine methyltransferase in Saccharomyces cerevisiae Its substrate proteins are involved in transcription, transcriptional regulation, nucleocytoplasmic transport and RNA splicing. Hmt1p-catalyzed methylation can also modulate protein-protein interactions. Hmt1p is conserved from unicellular eukaryotes through to mammals where its ortholog, PRMT1, is lethal upon knockout. In yeast, however, the effect of knockout on the transcriptome and proteome has not been described. Transcriptome analysis revealed downregulation of phosphate-responsive genes in hmt1Δ, including acid phosphatases PHO5, PHO11, and PHO12, phosphate transporters PHO84 and PHO89 and the vacuolar transporter chaperone VTC3 Analysis of the hmt1Δ proteome revealed decreased abundance of phosphate-associated proteins including phosphate transporter Pho84p, vacuolar alkaline phosphatase Pho8p, acid phosphatase Pho3p and subunits of the vacuolar transporter chaperone complex Vtc1p, Vtc3p and Vtc4p. Consistent with this, phosphate homeostasis was dysregulated in hmt1Δ cells, showing decreased extracellular phosphatase levels and decreased total Pi in phosphate-depleted medium. In vitro, we showed that transcription factor Pho4p can be methylated at Arg-241, which could explain phosphate dysregulation in hmt1Δ if interplay exists with phosphorylation at Ser-242 or Ser-243, or if Arg-241 methylation affects the capacity of Pho4p to homodimerize or interact with Pho2p. However, the Arg-241 methylation site was not validated in vivo and the localization of a Pho4p-GFP fusion in hmt1Δ was not different from wild type. To our knowledge, this is the first study to reveal an association between Hmt1p and phosphate homeostasis and one which suggests a regulatory link between S-adenosyl methionine and intracellular phosphate.
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Affiliation(s)
- Samantha Z Chia
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Yu-Wen Lai
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Daniel Yagoub
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Sophie Lev
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute and Sydney Medical School, University of Sydney at Westmead Hospital, Westmead, New South Wales, Australia
| | - Joshua J Hamey
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Chi Nam Ignatius Pang
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Desmarini Desmarini
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute and Sydney Medical School, University of Sydney at Westmead Hospital, Westmead, New South Wales, Australia
| | - Zhiliang Chen
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Julianne T Djordjevic
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute and Sydney Medical School, University of Sydney at Westmead Hospital, Westmead, New South Wales, Australia
| | - Melissa A Erce
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Gene Hart-Smith
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Marc R Wilkins
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
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21
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Kohl K, Zangger H, Rossi M, Isorce N, Lye LF, Owens KL, Beverley SM, Mayer A, Fasel N. Importance of polyphosphate in the Leishmania life cycle. MICROBIAL CELL 2018; 5:371-384. [PMID: 30175107 PMCID: PMC6116282 DOI: 10.15698/mic2018.08.642] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Protozoan parasites contain negatively charged polymers of a few up to several hundreds of phosphate residues. In other organisms, these poly-phosphate (polyP) chains serve as an energy source and phosphate reservoir, and have been implicated in adaptation to stress and virulence of pathogenic organisms. In this study, we confirmed first that the polyP polymerase vacuolar transporter chaperone 4 (VTC4) is responsible for polyP synthesis in Leishmania parasites. During Leishmaniain vitro culture, polyP is accumulated in logarithmic growth phase and subsequently consumed once stationary phase is reached. However, polyP is not essential since VTC4-deficient (vtc4-) Leishmania proliferated normally in culture and differentiated into infective metacyclic parasites and into intracellular and axenic amastigotes. In in vivo mouse infections, L. majorVTC4 knockout showed a delay in lesion formation but ultimately gave rise to strong pathology, although we were unable to restore virulence by complementation to confirm this phenotype. Knockdown of VTC4 did not alter the course of L. guyanensis infections in mice, suggesting that polyP was not required for infection, or that very low levels of it suffice for lesion development. At higher temperatures, Leishmania promastigotes highly consumed polyP, and both knockdown or deletion of VTC4 diminished parasite survival. Thus, although polyP was not essential in the life cycle of the parasite, our data suggests a role for polyP in increasing parasite survival at higher temperatures, a situation faced by the parasite when transmitted to humans.
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Affiliation(s)
- Kid Kohl
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | - Haroun Zangger
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | - Matteo Rossi
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | - Nathalie Isorce
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | - Lon-Fye Lye
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Katherine L Owens
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Stephen M Beverley
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Andreas Mayer
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | - Nicolas Fasel
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
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22
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Zientara-Rytter K, Subramani S. AIM/LIR-based fluorescent sensors-new tools to monitor mAtg8 functions. Autophagy 2018; 14:1074-1078. [PMID: 29749795 DOI: 10.1080/15548627.2018.1454238] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022] Open
Abstract
Macroautophagy/autophagy, a catabolic process by which cytoplasmic materials are degraded and recycled in lysosomes/vacuoles, remains a rapidly expanding research topic with the need for constantly improved methodologies to study each step of this pathway. Recently Lee and colleagues, as well as Stolz et al., independently reported the development of new AIM/LIR-based fluorescent sensors, which mark individual endogenous mammalian Atg8-family (mAtg8) proteins without affecting the autophagic flux. When expressed in cells, each sensor selectively recognizes individual mAtg8 isoforms and distinguishes mammalian MAP1LC3/LC3 proteins from the related GABARAPs. Such selectivity was achieved by using various LC3-interacting regions with high binding affinity to either a subgroup, or a specific, mAtg8 isoform as part of the sensor. Here we discuss the utility of these sensors in autophagy research and highlight their strengths, weaknesses and future directions.
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Affiliation(s)
- Katarzyna Zientara-Rytter
- a Section of Molecular Biology, Division of Biological Sciences , University of California San Diego , La Jolla , CA , USA
| | - Suresh Subramani
- a Section of Molecular Biology, Division of Biological Sciences , University of California San Diego , La Jolla , CA , USA
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23
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Eskes E, Deprez MA, Wilms T, Winderickx J. pH homeostasis in yeast; the phosphate perspective. Curr Genet 2017; 64:155-161. [PMID: 28856407 PMCID: PMC5778149 DOI: 10.1007/s00294-017-0743-2] [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: 08/10/2017] [Revised: 08/21/2017] [Accepted: 08/22/2017] [Indexed: 12/22/2022]
Abstract
Recent research further clarified the molecular mechanisms that link nutrient signaling and pH homeostasis with the regulation of growth and survival of the budding yeast Saccharomyces cerevisiae. The central nutrient signaling kinases PKA, TORC1, and Sch9 are intimately associated to pH homeostasis, presumably allowing them to concert far-reaching phenotypical repercussions of nutritional cues. To exemplify such repercussions, we briefly describe consequences for phosphate uptake and signaling and outline interactions between phosphate homeostasis and the players involved in intra- and extracellular pH control. Inorganic phosphate uptake, its subcellular distribution, and its conversion into polyphosphates are dependent on the proton gradients created over different membranes. Conversely, polyphosphate metabolism appears to contribute in determining the intracellular pH. Additionally, inositol pyrophosphates are emerging as potent determinants of growth potential, in this way providing feedback from phosphate metabolism onto the central nutrient signaling kinases. All these data point towards the importance of phosphate metabolism in the reciprocal regulation of nutrient signaling and pH homeostasis.
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Affiliation(s)
- Elja Eskes
- Functional Biology, KU Leuven, Kasteelpark Arenberg 31 box 2433, 3001, Heverlee, Belgium
| | - Marie-Anne Deprez
- Functional Biology, KU Leuven, Kasteelpark Arenberg 31 box 2433, 3001, Heverlee, Belgium
| | - Tobias Wilms
- Functional Biology, KU Leuven, Kasteelpark Arenberg 31 box 2433, 3001, Heverlee, Belgium
| | - Joris Winderickx
- Functional Biology, KU Leuven, Kasteelpark Arenberg 31 box 2433, 3001, Heverlee, Belgium.
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24
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Yang SY, Huang TK, Kuo HF, Chiou TJ. Role of vacuoles in phosphorus storage and remobilization. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3045-3055. [PMID: 28077447 DOI: 10.1093/jxb/erw481] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Vacuoles play a fundamental role in storage and remobilization of various nutrients, including phosphorus (P), an essential element for cell growth and development. Cells acquire P primarily in the form of inorganic orthophosphate (Pi). However, the form of P stored in vacuoles varies by organism and tissue. Algae and yeast store polyphosphates (polyPs), whereas plants store Pi and inositol phosphates (InsPs) in vegetative tissues and seeds, respectively. In this review, we summarize how vacuolar P molecules are stored and reallocated and how these processes are regulated and co-ordinated. The roles of SYG1/PHO81/XPR1 (SPX)-domain-containing membrane proteins in allocating vacuolar P are outlined. We also highlight the importance of vacuolar P in buffering the cytoplasmic Pi concentration to maintain cellular homeostasis when the external P supply fluctuates, and present additional roles for vacuolar polyP and InsP besides being a P reserve. Furthermore, we discuss the possibility of alternative pathways to recycle Pi from other P metabolites in vacuoles. Finally, future perspectives for researching this topic and its potential application in agriculture are proposed.
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Affiliation(s)
- Shu-Yi Yang
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Teng-Kuei Huang
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Hui-Fen Kuo
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Tzyy-Jen Chiou
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan
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25
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Shebanova A, Ismagulova T, Solovchenko A, Baulina O, Lobakova E, Ivanova A, Moiseenko A, Shaitan K, Polshakov V, Nedbal L, Gorelova O. Versatility of the green microalga cell vacuole function as revealed by analytical transmission electron microscopy. PROTOPLASMA 2017; 254:1323-1340. [PMID: 27677801 DOI: 10.1007/s00709-016-1024-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 09/08/2016] [Indexed: 05/22/2023]
Abstract
Vacuole is a multifunctional compartment central to a large number of functions (storage, catabolism, maintenance of the cell homeostasis) in oxygenic phototrophs including microalgae. Still, microalgal cell vacuole is much less studied than that of higher plants although knowledge of the vacuolar structure and function is essential for understanding physiology of nutrition and stress tolerance of microalgae. Here, we combined the advanced analytical and conventional transmission electron microscopy methods to obtain semi-quantitative, spatially resolved at the subcellular level information on elemental composition of the cell vacuoles in several free-living and symbiotic chlorophytes. We obtained a detailed record of the changes in cell and vacuolar ultrastructure in response to environmental stimuli under diverse conditions. We suggested that the vacuolar inclusions could be divided into responsible for storage of phosphorus (mainly in form of polyphosphate) and those accommodating non-protein nitrogen (presumably polyamine) reserves, respectively.The ultrastructural findings, together with the data on elemental composition of different cell compartments, allowed us to speculate on the role of the vacuolar membrane in the biosynthesis and sequestration of polyphosphate. We also describe the ultrastructural evidence of possible involvement of the tonoplast in the membrane lipid turnover and exchange of energy and metabolites between chloroplasts and mitochondria. These processes might play a significant role in acclimation in different stresses including nitrogen starvation and extremely high level of CO2 and might also be of importance for microalgal biotechnology. Advantages and limitations of application of analytical electron microscopy to biosamples such as microalgal cells are discussed.
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Affiliation(s)
| | | | - Alexei Solovchenko
- Lomonosov Moscow State University, Moscow, Russia.
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia.
- Faculty of Biology, Moscow State University, Leninskie Gori 1/12, 119234, GSP-1 Moscow, Russia.
| | - Olga Baulina
- Lomonosov Moscow State University, Moscow, Russia
| | | | - Alexandra Ivanova
- Komarov Botanical Institute, Russian Academy of Sciences, St. Petersburg, Russia
- St. Petersburg State University, St. Petersburg, Russia
| | | | | | - Vladimir Polshakov
- Faculty of fundamental medicine, Lomonosov Moscow State University, Moscow, Russia
| | - Ladislav Nedbal
- Institute of Bio- and Geosciences / Plant Sciences (IBG-2), Forschungszentrum Jülich, Jülich, Germany
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26
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Schreiber V, Dersch J, Puzik K, Bäcker O, Liu X, Stork S, Schulz J, Heimerl T, Klingl A, Zauner S, Maier UG. The Central Vacuole of the Diatom Phaeodactylum tricornutum: Identification of New Vacuolar Membrane Proteins and of a Functional Di-leucine-based Targeting Motif. Protist 2017; 168:271-282. [PMID: 28495413 DOI: 10.1016/j.protis.2017.03.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 02/24/2017] [Accepted: 03/04/2017] [Indexed: 01/22/2023]
Abstract
Diatoms are unicellular organisms evolved by secondary endosymbiosis. Although studied in many aspects, the functions of vacuolar-like structures of these organisms are rarely investigated. One of these structures is a dominant central vacuole-like compartment with a marbled phenotype, which is supposed to represent a chrysolaminarin-storing and carbohydrate mobilization compartment. However, other functions as well as targeting of proteins to this compartment are not shown experimentally. In order to study trafficking of membrane proteins to the vacuolar membrane, we scanned the genome for intrinsic vacuolar membrane proteins and used one representative for targeting studies. Our work led to the identification of several proteins located in the vacuolar membrane as well as the sub-compartmentalized localization of one protein. In addition, we show that a di-leucine-based motif is an important signal for correct targeting to the central vacuole of diatoms, like it is in plants.
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Affiliation(s)
| | - Josefine Dersch
- Laboratory for Cell Biology, Philipps-Universität Marburg, Germany
| | - Katharina Puzik
- Laboratory for Cell Biology, Philipps-Universität Marburg, Germany
| | - Oliver Bäcker
- Laboratory for Cell Biology, Philipps-Universität Marburg, Germany
| | - Xiaojuan Liu
- Laboratory for Cell Biology, Philipps-Universität Marburg, Germany
| | - Simone Stork
- Laboratory for Cell Biology, Philipps-Universität Marburg, Germany
| | - Julian Schulz
- Laboratory for Cell Biology, Philipps-Universität Marburg, Germany
| | - Thomas Heimerl
- LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, Germany
| | - Andreas Klingl
- LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, Germany
| | - Stefan Zauner
- Laboratory for Cell Biology, Philipps-Universität Marburg, Germany
| | - Uwe G Maier
- Laboratory for Cell Biology, Philipps-Universität Marburg, Germany; LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, Germany.
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27
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Gerasimaitė R, Mayer A. Ppn2, a novel Zn2+-dependent polyphosphatase in the acidocalcisome-like yeast vacuole. J Cell Sci 2017; 130:1625-1636. [DOI: 10.1242/jcs.201061] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 03/13/2017] [Indexed: 12/12/2022] Open
Abstract
Acidocalcisome-like organelles are found in all kingdoms of life. Many of their functions, such as the accumulation and storage of metal ions, nitrogen and phosphate, the activation of blood clotting and inflammation, depend on the controlled synthesis and turnover of polyphosphate (polyP), a polymer of inorganic phosphate linked by phosphoric anhydride bonds. The exploration of the role of acidocalcisomes in metabolism and physiology requires manipulation of polyP turnover, yet the complete set of proteins responsible for this turnover is unknown. Here, we identify a novel type of polyphosphatase operating in the acidocalcisome-like vacuoles of yeast, Ppn2. Ppn2 belongs to the PPP-superfamily of metallo-phosphatases, is activated by Zn2+ ions and exclusively shows endopolyphosphatase activity. It is sorted to vacuoles via the multivesicular body pathway. Together with Ppn1, Ppn2 constitutes a major fraction of polyphosphatase activity that is necessary to mobilize polyP stores, for example in response to phosphate scarcity. This finding opens the way to manipulating polyP metabolism more profoundly and deciphering its roles in phosphate and energy homeostasis, as well as in signaling.
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Affiliation(s)
- Rūta Gerasimaitė
- Department of Biochemistry, University of Lausanne, Ch. des Boveresses 155, 1066 Epalinges, Switzerland
| | - Andreas Mayer
- Department of Biochemistry, University of Lausanne, Ch. des Boveresses 155, 1066 Epalinges, Switzerland
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28
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Wild R, Hothorn M. The macro domain as fusion tag for carrier-driven crystallization. Protein Sci 2016; 26:365-374. [PMID: 27774698 DOI: 10.1002/pro.3073] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 09/27/2016] [Accepted: 10/20/2016] [Indexed: 12/16/2022]
Abstract
Obtaining well-ordered crystals remains a significant challenge in protein X-ray crystallography. Carrier-driven crystallization can facilitate crystal formation and structure solution of difficult target proteins. We obtained crystals of the small and highly flexible SPX domain from the yeast vacuolar transporter chaperone 4 (Vtc4) when fused to a C-terminal, non-cleavable macro tag derived from human histone macroH2A1.1. Initial crystals diffracted to 3.3 Å resolution. Reductive protein methylation of the fusion protein yielded a new crystal form diffracting to 2.1 Å. The structures were solved by molecular replacement, using isolated macro domain structures as search models. Our findings suggest that macro domain tags can be employed in recombinant protein expression in E. coli, and in carrier-driven crystallization.
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Affiliation(s)
- Rebekka Wild
- Structural Plant Biology Laboratory, Department of Botany and Plant Biology, University of Geneva, Switzerland
| | - Michael Hothorn
- Structural Plant Biology Laboratory, Department of Botany and Plant Biology, University of Geneva, Switzerland
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29
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Enzymes of yeast polyphosphate metabolism: structure, enzymology and biological roles. Biochem Soc Trans 2016; 44:234-9. [PMID: 26862210 DOI: 10.1042/bst20150213] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Inorganic polyphosphate (polyP) is found in all living organisms. The known polyP functions in eukaryotes range from osmoregulation and virulence in parasitic protozoa to modulating blood coagulation, inflammation, bone mineralization and cellular signalling in mammals. However mechanisms of regulation and even the identity of involved proteins in many cases remain obscure. Most of the insights obtained so far stem from studies in the yeast Saccharomyces cerevisiae. Here, we provide a short overview of the properties and functions of known yeast polyP metabolism enzymes and discuss future directions for polyP research.
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30
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Desfougères Y, Gerasimaitė RU, Jessen HJ, Mayer A. Vtc5, a Novel Subunit of the Vacuolar Transporter Chaperone Complex, Regulates Polyphosphate Synthesis and Phosphate Homeostasis in Yeast. J Biol Chem 2016; 291:22262-22275. [PMID: 27587415 PMCID: PMC5064005 DOI: 10.1074/jbc.m116.746784] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 09/01/2016] [Indexed: 12/23/2022] Open
Abstract
SPX domains control phosphate homeostasis in eukaryotes. Ten genes in yeast encode SPX-containing proteins, among which YDR089W is the only one of unknown function. Here, we show that YDR089W encodes a novel subunit of the vacuole transporter chaperone (VTC) complex that produces inorganic polyphosphate (polyP). The polyP synthesis transfers inorganic phosphate (Pi) from the cytosol into the acidocalcisome- and lysosome-related vacuoles of yeast, where it can be released again. It was therefore proposed for buffer changes in cytosolic Pi concentration (Thomas, M. R., and O'Shea, E. K. (2005) Proc. Natl. Acad. Sci. U.S.A. 102, 9565-9570). Vtc5 physically interacts with the VTC complex and accelerates the accumulation of polyP synthesized by it. Deletion of VTC5 reduces polyP accumulation in vivo and in vitro Its overexpression hyperactivates polyP production and triggers the phosphate starvation response via the PHO pathway. Because this Vtc5-induced starvation response can be reverted by shutting down polyP synthesis genetically or pharmacologically, we propose that polyP synthesis rather than Vtc5 itself is a regulator of the PHO pathway. Our observations suggest that polyP synthesis not only serves to establish a buffer for transient drops in cytosolic Pi levels but that it can actively decrease or increase the steady state of cytosolic Pi.
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Affiliation(s)
- Yann Desfougères
- From the Department of Biochemistry, University of Lausanne, Chemin des Boveresses 155, 1066 Epalinges, Switzerland and
| | - R Uta Gerasimaitė
- From the Department of Biochemistry, University of Lausanne, Chemin des Boveresses 155, 1066 Epalinges, Switzerland and
| | - Henning Jacob Jessen
- the Institute of Organic Chemistry, Albert-Ludwigs-University, 79104 Freiburg, Germany
| | - Andreas Mayer
- From the Department of Biochemistry, University of Lausanne, Chemin des Boveresses 155, 1066 Epalinges, Switzerland and
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31
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Desfougères Y, Neumann H, Mayer A. Organelle size control - increasing vacuole content activates SNAREs to augment organelle volume through homotypic fusion. J Cell Sci 2016; 129:2817-28. [PMID: 27252384 DOI: 10.1242/jcs.184382] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 05/26/2016] [Indexed: 11/20/2022] Open
Abstract
Cells control the size of their compartments relative to cell volume, but there is also size control within each organelle. Yeast vacuoles neither burst nor do they collapse into a ruffled morphology, indicating that the volume of the organellar envelope is adjusted to the amount of content. It is poorly understood how this adjustment is achieved. We show that the accumulating content of yeast vacuoles activates fusion of other vacuoles, thus increasing the volume-to-surface ratio. Synthesis of the dominant compound stored inside vacuoles, polyphosphate, stimulates binding of the chaperone Sec18/NSF to vacuolar SNAREs, which activates them and triggers fusion. SNAREs can only be activated by lumenal, not cytosolic, polyphosphate (polyP). Control of lumenal polyP over SNARE activation in the cytosol requires the cytosolic cyclin-dependent kinase Pho80-Pho85 and the R-SNARE Nyv1. These results suggest that cells can adapt the volume of vacuoles to their content through feedback from the vacuole lumen to the SNAREs on the cytosolic surface of the organelle.
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Affiliation(s)
- Yann Desfougères
- Département de Biochimie, Université de Lausanne, Chemin des Boveresses 155, Epalinges 1066, Switzerland
| | - Heinz Neumann
- GZMB, Institut für Molekulare Strukturbiologie, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
| | - Andreas Mayer
- Département de Biochimie, Université de Lausanne, Chemin des Boveresses 155, Epalinges 1066, Switzerland
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32
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Inorganic polyphosphate in the microbial world. Emerging roles for a multifaceted biopolymer. World J Microbiol Biotechnol 2016; 32:27. [DOI: 10.1007/s11274-015-1983-2] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 11/05/2015] [Indexed: 10/22/2022]
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33
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Zhu S, Rea SL, Cheng T, Feng HT, Walsh JP, Ratajczak T, Tickner J, Pavlos N, Xu HZ, Xu J. Bafilomycin A1 Attenuates Osteoclast Acidification and Formation, Accompanied by Increased Levels of SQSTM1/p62 Protein. J Cell Biochem 2015; 117:1464-70. [PMID: 27043248 DOI: 10.1002/jcb.25442] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 11/11/2015] [Indexed: 12/14/2022]
Abstract
Vacuolar proton pump H(+)-adenosine triphosphatases (V-ATPases) play an important role in osteoclast function. Further understanding of the cellular and molecular mechanisms of V-ATPase inhibition is vital for the development of anti-resorptive drugs specifically targeting osteoclast V-ATPases. In this study, we observed that bafilomycin A1, a naturally-occurring inhibitor of V-ATPases, increased the protein level of SQSTM1/p62, a known negative regulator of osteoclast formation. Consistently, we found that bafilomycin A1 diminishes the intracellular accumulation of the acidotropic probe lysotracker in osteoclast-like cells; indicative of reduced acidification. Further, bafilomycin A1 inhibits osteoclast formation with attenuation of cell fusion and multi-nucleation of osteoclast-like cells during osteoclast differentiation. Taken together, these data indicate that bafilomycin A1 attenuates osteoclast differentiation in part via increased levels of SQSTM1/p62 protein, providing further mechanistic insight into the effect of V-ATPase inhibition in osteoclasts.
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Affiliation(s)
- Sipin Zhu
- Department of Orthopaedics, The Second Affiliated Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China.,School of Pathology and Laboratory Medicine, The University of Western Australia, Crawley, WA, Australia
| | - Sarah L Rea
- Laboratory for Molecular Endocrinology, Harry Perkins Institute of Medical Research and UWA Centre for Medical Research, The University of Western Australia, Crawley, WA, 6009, Australia.,Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Nedlands, WA, 6009, Australia
| | - Taksum Cheng
- School of Surgery, Centre of Orthopaedic Research, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Hao Tian Feng
- School of Pathology and Laboratory Medicine, The University of Western Australia, Crawley, WA, Australia
| | - John P Walsh
- Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Nedlands, WA, 6009, Australia.,School of Medicine and Pharmacology, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Thomas Ratajczak
- Laboratory for Molecular Endocrinology, Harry Perkins Institute of Medical Research and UWA Centre for Medical Research, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Jennifer Tickner
- School of Pathology and Laboratory Medicine, The University of Western Australia, Crawley, WA, Australia
| | - Nathan Pavlos
- School of Surgery, Centre of Orthopaedic Research, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Hua-Zi Xu
- Department of Orthopaedics, The Second Affiliated Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Jiake Xu
- Department of Orthopaedics, The Second Affiliated Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China.,School of Pathology and Laboratory Medicine, The University of Western Australia, Crawley, WA, Australia
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34
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Sun-Wada GH, Wada Y. Role of vacuolar-type proton ATPase in signal transduction. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:1166-72. [PMID: 26072192 DOI: 10.1016/j.bbabio.2015.06.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 06/01/2015] [Accepted: 06/03/2015] [Indexed: 12/21/2022]
Abstract
The vacuolar H(+)-ATPase (V-ATPase) was first identified as an electrogenic proton pump that acidifies the lumen of intra- and extracellular compartments. The acidic pH generated by V-ATPase is important for a wide range of cellular processes as well as acidification-independent processes such as secretion and membrane fusion. In addition to these housekeeping functions, recent studies implicate V-ATPase in the direct regulation and function of signaling pathways. In this review, we describe recent findings on the functions of V-ATPase in growth regulation and tissue physiology.
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Affiliation(s)
- Ge-Hong Sun-Wada
- Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts, Kohdo, Kyotanabe, Kyoto 610-0395, Japan.
| | - Yoh Wada
- Division of Biological Science, Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
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35
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Lucena MN, Pinto MR, Garçon DP, McNamara JC, Leone FA. A kinetic characterization of the gill V(H+)-ATPase in juvenile and adult Macrobrachium amazonicum, a diadromous palaemonid shrimp. Comp Biochem Physiol B Biochem Mol Biol 2015; 181:15-25. [DOI: 10.1016/j.cbpb.2014.11.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 09/05/2014] [Accepted: 11/07/2014] [Indexed: 10/24/2022]
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36
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Aksoy M, Pootakham W, Grossman AR. Critical function of a Chlamydomonas reinhardtii putative polyphosphate polymerase subunit during nutrient deprivation. THE PLANT CELL 2014; 26:4214-29. [PMID: 25281687 PMCID: PMC4247568 DOI: 10.1105/tpc.114.129270] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 08/25/2014] [Accepted: 09/09/2014] [Indexed: 05/20/2023]
Abstract
Forward genetics was used to isolate Chlamydomonas reinhardtii mutants with altered abilities to acclimate to sulfur (S) deficiency. The ars76 mutant has a deletion that eliminates several genes, including VACUOLAR TRANSPORTER CHAPERONE1 (VTC1), which encodes a component of a polyphosphate polymerase complex. The ars76 mutant cannot accumulate arylsulfatase protein or mRNA and shows marked alterations in levels of many transcripts encoded by genes induced during S deprivation. The mutant also shows little acidocalcisome formation compared with wild-type, S-deprived cells and dies more rapidly than wild-type cells following exposure to S-, phosphorus-, or nitrogen (N)-deficient conditions. Furthermore, the mutant does not accumulate periplasmic L-amino acid oxidase during N deprivation. Introduction of the VTC1 gene specifically complements the ars76 phenotypes, suggesting that normal acidocalcisome formation in cells deprived of S requires VTC1. Our data also indicate that a deficiency in acidocalcisome function impacts trafficking of periplasmic proteins, which can then feed back on the transcription of the genes encoding these proteins. These results and the reported function of vacuoles in degradation processes suggest a major role of the acidocalcisome in reshaping the cell during acclimation to changing environmental conditions.
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Affiliation(s)
- Munevver Aksoy
- The Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305
| | - Wirulda Pootakham
- The Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305 National Center for Genetic Engineering and Biotechnology, Pathum Thani 12120, Thailand
| | - Arthur R Grossman
- The Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305
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37
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Gerasimaitė R, Sharma S, Desfougères Y, Schmidt A, Mayer A. Coupled synthesis and translocation restrains polyphosphate to acidocalcisome-like vacuoles and prevents its toxicity. J Cell Sci 2014; 127:5093-104. [DOI: 10.1242/jcs.159772] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Eukaryotes contain inorganic polyphosphate (polyP) and acidocalcisomes, which sequester polyP and store amino acids and divalent cations. Why polyP is sequestered in dedicated organelles has been unknown. We show that polyP produced in the cytosol of yeast becomes toxic. Reconstitution of polyP translocation with purified vacuoles, the acidocalcisomes of yeast, showed that cytosolic polyP cannot be imported whereas polyP produced by the VTC complex, an endogenous vacuolar polyP polymerase, is efficiently imported and does not interfere with growth. PolyP synthesis and import require an electrochemical gradient, probably as a driving force for polyP translocation. VTC exposes its catalytic domain to the cytosol and carries nine vacuolar transmembrane domains. Mutations in the VTC transmembrane regions, which likely constitute the translocation channel, block not only polyP translocation but also synthesis. Since they are far from the cytosolic catalytic domain of VTC, this suggests that the VTC complex obligatorily couples synthesis of polyP to its import in order to avoid toxic intermediates in the cytosol. Sequestration of otherwise toxic polyP may be one reason for the existence of acidocalcisomes in eukaryotes.
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38
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Lander N, Ulrich PN, Docampo R. Trypanosoma brucei vacuolar transporter chaperone 4 (TbVtc4) is an acidocalcisome polyphosphate kinase required for in vivo infection. J Biol Chem 2013; 288:34205-34216. [PMID: 24114837 DOI: 10.1074/jbc.m113.518993] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Polyphosphate (polyP) is an anionic polymer of orthophosphate groups linked by high energy bonds that typically accumulates in acidic, calcium-rich organelles known as acidocalcisomes. PolyP synthesis in eukaryotes was unclear until it was demonstrated that the protein named Vtc4p (vacuolar transporter chaperone 4) is a long chain polyP kinase that localizes to the yeast vacuole. Here, we report that TbVtc4 (Vtc4 ortholog of Trypanosoma brucei) encodes, in contrast, a short chain polyP kinase that localizes to acidocalcisomes. The subcellular localization of TbVtc4 was demonstrated by fluorescence and electron microscopy of cell lines expressing TbVtc4 in its endogenous locus fused to an epitope tag and by purified polyclonal antibodies against TbVtc4. Recombinant TbVtc4 was expressed in bacteria, and polyP kinase activity was assayed in vitro. The in vitro growth of conditional knock-out bloodstream form trypanosomes (TbVtc4-KO) was significantly affected relative to the parental cell line. This mutant had reduced polyP kinase activity and short chain polyP content and was considerably less virulent in mice. The wild-type phenotype was recovered when an ectopic copy of the TbVtc4 gene was expressed in the presence of doxycycline. The mutant also exhibited a defect in volume recovery under osmotic stress conditions in vitro, underscoring the relevance of polyP in osmoregulation.
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Affiliation(s)
- Noelia Lander
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
| | - Paul N Ulrich
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia 30602.
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39
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Lü P, Xia H, Gao L, Pan Y, Wang Y, Cheng X, Lü H, Lin F, Chen L, Yao Q, Liu X, Tang Q, Chen K. V-ATPase Is Involved in Silkworm Defense Response against Bombyx mori Nucleopolyhedrovirus. PLoS One 2013; 8:e64962. [PMID: 23823190 PMCID: PMC3688796 DOI: 10.1371/journal.pone.0064962] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 04/23/2013] [Indexed: 11/29/2022] Open
Abstract
Silkworms are usually susceptible to the infection of Bombyx mori (B. mori) nucleopolyhedrovirus (BmNPV), which can cause significant economic loss. However, some silkworm strains are identified to be highly resistant to BmNPV. To explore the silkworm genes involved in this resistance in the present study, we performed comparative real-time PCR, ATPase assay, over-expression and sub-cellular localization experiments. We found that when inoculated with BmNPV both the expression and activity of V-ATPase were significantly up-regulated in the midgut column cells (not the goblet cells) of BmNPV-resistant strains (NB and BC8), the main sites for the first step of BmNPV invasion, but not in those of a BmNPV-susceptible strain 306. Furthermore, this up-regulation mainly took place during the first 24 hours post inoculation (hpi), the essential period required for establishment of virus infection, and then was down-regulated to normal levels. Amazingly, transient over-expression of V-ATPase c subunit in BmNPV-infected silkworm cells could significantly inhibit BmNPV proliferation. To our knowledge this is the first report demonstrating clearly that V-ATPase is indeed involved in the defense response against BmNPV. Our data further suggests that prompt and potent regulation of V-ATPase may be essential for execution of this response, which may enable fast acidification of endosomes and/or lysosomes to render them competent for degradation of invading viruses.
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Affiliation(s)
- Peng Lü
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, Jiangsu, PR China
- Institute of Life Sciences, Jiangsu University, Zhenjiang, Jiangsu, PR China
| | - Hengchuan Xia
- Institute of Life Sciences, Jiangsu University, Zhenjiang, Jiangsu, PR China
| | - Lu Gao
- School of Medical Science and Laboratory Medicine, Jiangsu University, Zhenjiang, Jiangsu, PR China
| | - Ye Pan
- The Laboratory Animal Research Center, Jiangsu University, Zhenjiang, Jiangsu, PR China
| | - Yong Wang
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, Jiangsu, PR China
| | - Xin Cheng
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, Jiangsu, PR China
- Nanchang Key Laboratory of Applied Fermentation Technology, Jiangxi Agricultural University, Nanchang, PR China
| | - Honggang Lü
- Institute of Life Sciences, Jiangsu University, Zhenjiang, Jiangsu, PR China
| | - Feng Lin
- Zhejiang Institute of Freshwater Fisheries, Huzhou, Zhejiang, PR China
| | - Liang Chen
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, Jiangsu, PR China
| | - Qin Yao
- Institute of Life Sciences, Jiangsu University, Zhenjiang, Jiangsu, PR China
| | - Xiaoyong Liu
- Institute of Life Sciences, Jiangsu University, Zhenjiang, Jiangsu, PR China
| | - Qi Tang
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, Jiangsu, PR China
| | - Keping Chen
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, Jiangsu, PR China
- Institute of Life Sciences, Jiangsu University, Zhenjiang, Jiangsu, PR China
- * E-mail:
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40
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Zieger M, Mayer A. Yeast vacuoles fragment in an asymmetrical two-phase process with distinct protein requirements. Mol Biol Cell 2012; 23:3438-49. [PMID: 22787281 PMCID: PMC3431934 DOI: 10.1091/mbc.e12-05-0347] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Yeast vacuoles fragment and fuse in response to environmental conditions, such as changes in osmotic conditions or nutrient availability. Here we analyze osmotically induced vacuole fragmentation by time-lapse microscopy. Small fragmentation products originate directly from the large central vacuole. This happens by asymmetrical scission rather than by consecutive equal divisions. Fragmentation occurs in two distinct phases. Initially, vacuoles shrink and generate deep invaginations that leave behind tubular structures in their vicinity. Already this invagination requires the dynamin-like GTPase Vps1p and the vacuolar proton gradient. Invaginations are stabilized by phosphatidylinositol 3-phosphate (PI(3)P) produced by the phosphoinositide 3-kinase complex II. Subsequently, vesicles pinch off from the tips of the tubular structures in a polarized manner, directly generating fragmentation products of the final size. This phase depends on the production of phosphatidylinositol-3,5-bisphosphate and the Fab1 complex. It is accelerated by the PI(3)P- and phosphatidylinositol 3,5-bisphosphate-binding protein Atg18p. Thus vacuoles fragment in two steps with distinct protein and lipid requirements.
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Affiliation(s)
- Martin Zieger
- Département de Biochimie, Université de Lausanne, 1066 Epalinges, Switzerland
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41
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Qiu QS. V-ATPase, ScNhx1p and Yeast Vacuole Fusion. J Genet Genomics 2012; 39:167-71. [DOI: 10.1016/j.jgg.2012.02.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 02/02/2012] [Accepted: 02/02/2012] [Indexed: 01/07/2023]
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42
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Chesi A, Kilaru A, Fang X, Cooper AA, Gitler AD. The role of the Parkinson's disease gene PARK9 in essential cellular pathways and the manganese homeostasis network in yeast. PLoS One 2012; 7:e34178. [PMID: 22457822 PMCID: PMC3311584 DOI: 10.1371/journal.pone.0034178] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Accepted: 02/27/2012] [Indexed: 02/01/2023] Open
Abstract
YPK9 (Yeast PARK9; also known as YOR291W) is a non-essential yeast gene predicted by sequence to encode a transmembrane P-type transport ATPase. However, its substrate specificity is unknown. Mutations in the human homolog of YPK9, ATP13A2/PARK9, have been linked to genetic forms of early onset parkinsonism. We previously described a strong genetic interaction between Ypk9 and another Parkinson's disease (PD) protein α-synuclein in multiple model systems, and a role for Ypk9 in manganese detoxification in yeast. In humans, environmental exposure to toxic levels of manganese causes a syndrome similar to PD and is thus an environmental risk factor for the disease. How manganese contributes to neurodegeneration is poorly understood. Here we describe multiple genome-wide screens in yeast aimed at defining the cellular function of Ypk9 and the mechanisms by which it protects cells from manganese toxicity. In physiological conditions, we found that Ypk9 genetically interacts with essential genes involved in cellular trafficking and the cell cycle. Deletion of Ypk9 sensitizes yeast cells to exposure to excess manganese. Using a library of non-essential gene deletions, we screened for additional genes involved in tolerance to excess manganese exposure, discovering several novel pathways involved in manganese homeostasis. We defined the dependence of the deletion strain phenotypes in the presence of manganese on Ypk9, and found that Ypk9 deletion modifies the manganese tolerance of only a subset of strains. These results confirm a role for Ypk9 in manganese homeostasis and illuminates cellular pathways and biological processes in which Ypk9 likely functions.
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Affiliation(s)
- Alessandra Chesi
- Department of Genetics, Stanford University School of Medicine, Stanford University, Stanford, California, United States of America
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Austin Kilaru
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Xiaodong Fang
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Antony A. Cooper
- Garvan Institute of Medical Research, University of New South Wales, Sydney, New South Wales, Australia
| | - Aaron D. Gitler
- Department of Genetics, Stanford University School of Medicine, Stanford University, Stanford, California, United States of America
- * E-mail:
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43
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Qiu QS. Plant and yeast NHX antiporters: roles in membrane trafficking. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2012; 54:66-72. [PMID: 22222113 DOI: 10.1111/j.1744-7909.2012.01097.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The plant NHX gene family encodes Na(+)/H(+) antiporters which are crucial for salt tolerance, potassium homeostasis and cellular pH regulation. Understanding the role of NHX antiporters in membrane trafficking is becoming an increasingly interesting subject of study. Membrane trafficking is a central cellular process during which proteins, lipids and polysaccharides are continuously exchanged among membrane compartments. Yeast ScNhx1p, a prevacuole/ vacuolar Na(+)/H(+) antiporter, plays an important role in regulating pH to control trafficking out of the endosome. Evidence begins to accumulate that plant NHX antiporters might function in regulating membrane trafficking in plants.
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Affiliation(s)
- Quan-Sheng Qiu
- School of Life Sciences, Lanzhou University, 222 South Tianshui Rd., Lanzhou 730000, China.
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44
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Phosphate homeostasis in the yeast Saccharomyces cerevisiae, the key role of the SPX domain-containing proteins. FEBS Lett 2012; 586:289-95. [PMID: 22285489 DOI: 10.1016/j.febslet.2012.01.036] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 01/11/2012] [Accepted: 01/16/2012] [Indexed: 12/27/2022]
Abstract
In the yeast Saccharomyces cerevisiae, a working model for nutrient homeostasis in eukaryotes, inorganic phosphate (Pi) homeostasis is regulated by the PHO pathway, a set of phosphate starvation induced genes, acting to optimize Pi uptake and utilization. Among these, a subset of proteins containing the SPX domain has been shown to be key regulators of Pi homeostasis. In this review, we summarize the recent progresses in elucidating the mechanisms controlling Pi homeostasis in yeast, focusing on the key roles of the SPX domain-containing proteins in these processes, as well as describing the future challenges and opportunities in this fast-moving field.
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Alpadi K, Kulkarni A, Comte V, Reinhardt M, Schmidt A, Namjoshi S, Mayer A, Peters C. Sequential analysis of trans-SNARE formation in intracellular membrane fusion. PLoS Biol 2012; 10:e1001243. [PMID: 22272185 PMCID: PMC3260307 DOI: 10.1371/journal.pbio.1001243] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 12/01/2011] [Indexed: 11/19/2022] Open
Abstract
SNARE complexes are required for membrane fusion in the endomembrane system. They contain coiled-coil bundles of four helices, three (Q(a), Q(b), and Q(c)) from target (t)-SNAREs and one (R) from the vesicular (v)-SNARE. NSF/Sec18 disrupts these cis-SNARE complexes, allowing reassembly of their subunits into trans-SNARE complexes and subsequent fusion. Studying these reactions in native yeast vacuoles, we found that NSF/Sec18 activates the vacuolar cis-SNARE complex by selectively displacing the vacuolar Q(a) SNARE, leaving behind a Q(bc)R subcomplex. This subcomplex serves as an acceptor for a Q(a) SNARE from the opposite membrane, leading to Q(a)-Q(bc)R trans-complexes. Activity tests of vacuoles with diagnostic distributions of inactivating mutations over the two fusion partners confirm that this distribution accounts for a major share of the fusion activity. The persistence of the Q(bc)R cis-complex and the formation of the Q(a)-Q(bc)R trans-complex are both sensitive to the Rab-GTPase inhibitor, GDI, and to mutations in the vacuolar tether complex, HOPS (HOmotypic fusion and vacuolar Protein Sorting complex). This suggests that the vacuolar Rab-GTPase, Ypt7, and HOPS restrict cis-SNARE disassembly and thereby bias trans-SNARE assembly into a preferred topology.
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Affiliation(s)
- Kannan Alpadi
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Aditya Kulkarni
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Veronique Comte
- Département de Biochimie, Université de Lausanne, Epalinges, Switzerland
| | - Monique Reinhardt
- Département de Biochimie, Université de Lausanne, Epalinges, Switzerland
| | - Andrea Schmidt
- Département de Biochimie, Université de Lausanne, Epalinges, Switzerland
| | - Sarita Namjoshi
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Andreas Mayer
- Département de Biochimie, Université de Lausanne, Epalinges, Switzerland
| | - Christopher Peters
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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46
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The V-ATPase proteolipid cylinder promotes the lipid-mixing stage of SNARE-dependent fusion of yeast vacuoles. EMBO J 2011; 30:4126-41. [PMID: 21934648 DOI: 10.1038/emboj.2011.335] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Accepted: 08/19/2011] [Indexed: 01/13/2023] Open
Abstract
The V-ATPase V(0) sector associates with the peripheral V(1) sector to form a proton pump. V(0) alone has an additional function, facilitating membrane fusion in the endocytic and late exocytic pathways. V(0) contains a hexameric proteolipid cylinder, which might support fusion as proposed in proteinaceous pore models. To test this, we randomly mutagenized proteolipids. We recovered alleles that preserve proton translocation, normal SNARE activation and trans-SNARE pairing but that impair lipid and content mixing. Critical residues were found in all subunits of the proteolipid ring. They concentrate within the bilayer, close to the ring subunit interfaces. The fusion-impairing proteolipid substitutions stabilize the interaction of V(0) with V(1). Deletion of the vacuolar v-SNARE Nyv1 has the same effect, suggesting that both types of mutations similarly alter the conformation of V(0). Also covalent linkage of subunits in the proteolipid cylinder blocks vacuole fusion. We propose that a SNARE-dependent conformational change in V(0) proteolipids might stimulate fusion by creating a hydrophobic crevice that promotes lipid reorientation and formation of a lipidic fusion pore.
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Arlt H, Perz A, Ungermann C. An Overexpression Screen in Saccharomyces cerevisiae Identifies Novel Genes that Affect Endocytic Protein Trafficking. Traffic 2011; 12:1592-603. [DOI: 10.1111/j.1600-0854.2011.01252.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Sambuk EV, Fizikova AY, Savinov VA, Padkina MV. Acid phosphatases of budding yeast as a model of choice for transcription regulation research. Enzyme Res 2011; 2011:356093. [PMID: 21785706 PMCID: PMC3137970 DOI: 10.4061/2011/356093] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 04/26/2011] [Indexed: 11/20/2022] Open
Abstract
Acid phosphatases of budding yeast have been studied for more than forty years. This paper covers biochemical characteristics of acid phosphatases and different aspects in expression regulation of eukaryotic genes, which were researched using acid phosphatases model. A special focus is devoted to cyclin-dependent kinase Pho85p, a negative transcriptional regulator, and its role in maintaining mitochondrial genome stability and to pleiotropic effects of pho85 mutations.
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Affiliation(s)
- Elena V Sambuk
- Genetics and Breeding Department, Biology and Soil Sciences Faculty, Saint Petersburg State University, Universitetskaya emb. 7-9, Saint Petersburg 199034, Russia
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Rooney PJ, Ayong L, Tobin CM, Moreno SNJ, Knoll LJ. TgVTC2 is involved in polyphosphate accumulation in Toxoplasma gondii. Mol Biochem Parasitol 2010; 176:121-6. [PMID: 21195114 DOI: 10.1016/j.molbiopara.2010.12.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 12/20/2010] [Accepted: 12/22/2010] [Indexed: 10/18/2022]
Abstract
Polyphosphate is found in every cell, having roles in diverse processes, including differentiation and response to stress. In this study, we characterize a Toxoplasma gondii mutant containing an insertion within the carboxy-terminal end of a homolog of Saccharomyces cerevisiae Vtc2p, a component of the polyphosphate synthetic machinery. Locus TgVTC2 encodes a 140kDa protein containing conserved SPX, VTC and transmembrane domains. TgVTC2 localizes in punctate spots within the cytoplasm that do not co-localize with known markers. The TgVTC2 mutant showed dramatically reduced polyphosphate accumulation, a defect restored by introduction of TgVTC2 to the mutant. Insertion within TgVTC2 resulted in increased transcript levels for two loci, including a putative FIKK kinase. These transcript levels were restored to wild-type levels upon complementation with the TgVTC2 locus. The TgVTC2 locus was refractory to knockout, and may be essential. Analysis of this TgVTC2 mutant will facilitate dissection of the T. gondii polyphosphate synthesis pathway.
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Affiliation(s)
- Peggy J Rooney
- Department of Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Microbial Sciences Building Room 3345, 1550 Linden Drive, Madison, WI 53706, USA
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50
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Wickner W. Membrane fusion: five lipids, four SNAREs, three chaperones, two nucleotides, and a Rab, all dancing in a ring on yeast vacuoles. Annu Rev Cell Dev Biol 2010; 26:115-36. [PMID: 20521906 DOI: 10.1146/annurev-cellbio-100109-104131] [Citation(s) in RCA: 217] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Although fusion mechanisms are highly conserved in evolution and among organelles of the exocytic and endocytic pathways, yeast vacuole homotypic fusion offers unique technical advantages: excellent genetics, clear organelle cytology, in vitro colorimetric fusion assays, and reconstitution of fusion from all-pure components, including a Rab GTPase, HOPS (homotypic fusion and vacuole protein sorting complex), four SNAREs [soluble N-ethylmaleimide-sensitive factor (NSF) attachment receptors] that snare (bind) each other, SNARE-complex disassembly chaperones, and vacuolar lipids. Vacuole fusion studies offer paradigms of the interdependence of lipids and fusion proteins to assemble a fusion microdomain, distinct lipid functions, SNARE complex proofreading through the synergy between HOPS and the SNARE disassembly chaperones, and the role of each fusion protein in promoting radical bilayer restructuring for fusion without lysis.
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Affiliation(s)
- William Wickner
- Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755-3844, USA.
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