1
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Gokbayrak ZD, Patel D, Brett CL. Acetate and hypertonic stress stimulate vacuole membrane fission using distinct mechanisms. PLoS One 2022; 17:e0271199. [PMID: 35834522 PMCID: PMC9282455 DOI: 10.1371/journal.pone.0271199] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 06/25/2022] [Indexed: 11/19/2022] Open
Abstract
Vacuoles in plants and fungi play critical roles in cell metabolism and osmoregulation. To support these functions, vacuoles change their morphology, e.g. they fragment when these organisms are challenged with draught, high salinity or metabolic stress (e.g. acetate accumulation). In turn, morphology reflects an equilibrium between membrane fusion and fission that determines size, shape and copy number. By studying Saccharomyces cerevisiae and its vacuole as models, conserved molecular mechanisms responsible for fusion have been revealed. However, a detailed understanding of vacuole fission and how these opposing processes respond to metabolism or osmoregulation remain elusive. Herein we describe a new fluorometric assay to measure yeast vacuole fission in vitro. For proof–of–concept, we use this assay to confirm that acetate, a metabolic stressor, triggers vacuole fission and show it blocks homotypic vacuole fusion in vitro. Similarly, hypertonic stress induced by sorbitol or glucose caused robust vacuole fission in vitro whilst inhibiting fusion. Using wortmannin to inhibit phosphatidylinositol (PI) -kinases or rGyp1-46 to inactivate Rab–GTPases, we show that acetate stress likely targets PI signaling, whereas osmotic stress affects Rab signaling on vacuole membranes to stimulate fission. This study sets the stage for further investigation into the mechanisms that change vacuole morphology to support cell metabolism and osmoregulation.
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Affiliation(s)
| | - Dipti Patel
- Department of Biology, Concordia University, Montreal, Quebec, Canada
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2
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de Araujo MEG, Liebscher G, Hess MW, Huber LA. Lysosomal size matters. Traffic 2019; 21:60-75. [PMID: 31808235 PMCID: PMC6972631 DOI: 10.1111/tra.12714] [Citation(s) in RCA: 105] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 10/30/2019] [Accepted: 10/31/2019] [Indexed: 12/25/2022]
Abstract
Lysosomes are key cellular catabolic centers that also perform fundamental metabolic, signaling and quality control functions. Lysosomes are not static and they respond dynamically to intra‐ and extracellular stimuli triggering changes in organelle numbers, size and position. Such physical changes have a strong impact on lysosomal activity ultimately influencing cellular homeostasis. In this review, we summarize the current knowledge on lysosomal size regulation, on its physiological role(s) and association to several disease conditions.
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Affiliation(s)
- Mariana E G de Araujo
- Institute of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Gudrun Liebscher
- Institute of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Michael W Hess
- Institute of Histology and Embryology, Medical University of Innsbruck, Innsbruck, Austria
| | - Lukas A Huber
- Institute of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria.,Austrian Drug Screening Institute, ADSI, Innsbruck, Austria
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3
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Xia Y, Liu N, Xie X, Bi G, Ba H, Li L, Zhang J, Deng X, Yao Y, Tang Z, Yin B, Wang J, Jiang K, Li Z, Choi Y, Gong F, Cheng X, O'Shea JJ, Chae JJ, Laurence A, Yang XP. The macrophage-specific V-ATPase subunit ATP6V0D2 restricts inflammasome activation and bacterial infection by facilitating autophagosome-lysosome fusion. Autophagy 2019; 15:960-975. [PMID: 30681394 DOI: 10.1080/15548627.2019.1569916] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Macroautophagy/autophagy is a conserved ubiquitous pathway that performs diverse roles in health and disease. Although many key, widely expressed proteins that regulate autophagosome formation followed by lysosomal fusion have been identified, the possibilities of cell-specific elements that contribute to the autophagy fusion machinery have not been explored. Here we show that a macrophage-specific isoform of the vacuolar ATPase protein ATP6V0D2/subunit d2 is dispensable for lysosome acidification, but promotes the completion of autophagy via promotion of autophagosome-lysosome fusion through its interaction with STX17 and VAMP8. Atp6v0d2-deficient macrophages have augmented mitochondrial damage, enhanced inflammasome activation and reduced clearance of Salmonella typhimurium. The susceptibility of atp6v0d2 knockout mice to DSS-induced colitis and Salmonella typhimurium-induced death, highlights the in vivo significance of ATP6V0D2-mediated autophagosome-lysosome fusion. Together, our data identify ATP6V0D2 as a key component of macrophage-specific autophagosome-lysosome fusion machinery maintaining macrophage organelle homeostasis and, in turn, limiting both inflammation and bacterial infection. Abbreviations: ACTB/β-actin: actin, beta; ATG14: autophagy related 14; ATG16L1: autophagy related 16-like 1 (S. cerevisiae); ATP6V0D1/2: ATPase, H+ transporting, lysosomal V0 subunit D1/2; AIM2: absent in melanoma 2; BMDM: bone marrow-derived macrophage; CASP1: caspase 1; CGD: chronic granulomatous disease; CSF1/M-CSF: colony stimulating factor 1 (macrophage); CTSB: cathepsin B; DSS: dextran sodium sulfate; IL1B: interleukin 1 beta; IL6: interleukin 6; IRGM: immunity-related GTPase family M member; KO: knockout; LAMP1: lysosomal-associated membrane protein 1; LC3: microtubule-associated protein 1 light chain 3; LPS: lipo-polysaccaride; NLRP3: NLR family, pyrin domain containing 3; PYCARD/ASC: PYD and CARD domain containing; SNARE: soluble N-ethylmaleimide-sensitive factor attachment protein receptor; SNAP29: synaptosomal-associated protein 29; SQSTM1/p62: sequestosome 1; STX17: syntaxin 17; TLR: toll-like receptor; TNF: tumor necrosis factor ; TOMM20: translocase of outer mitochondrial membrane 20; ULK1: unc-51 like kinase 1; VAMP8: vesicle-associated membrane protein 8; WT: wild type; 3-MA: 3-methyladenine.
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Affiliation(s)
- Yu Xia
- a Department of Immunology , School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology , Wuhan , China
| | - Na Liu
- a Department of Immunology , School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology , Wuhan , China
| | - Xiuxiu Xie
- a Department of Immunology , School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology , Wuhan , China
| | - Guoyu Bi
- a Department of Immunology , School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology , Wuhan , China
| | - Hongping Ba
- a Department of Immunology , School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology , Wuhan , China
| | - Lin Li
- a Department of Immunology , School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology , Wuhan , China
| | - Jinxia Zhang
- a Department of Immunology , School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology , Wuhan , China
| | - Xiaofei Deng
- a Department of Immunology , School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology , Wuhan , China
| | - Yao Yao
- b Department of Surgery, Tongji Hospital , Huazhong University of Science and Technology , Wuhan , China
| | - Zhaohui Tang
- b Department of Surgery, Tongji Hospital , Huazhong University of Science and Technology , Wuhan , China
| | - Binjiao Yin
- a Department of Immunology , School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology , Wuhan , China
| | - Jing Wang
- a Department of Immunology , School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology , Wuhan , China
| | - Kan Jiang
- c Lymphocyte Cell Biology Section , NIAMS, NIH , Bethesda , MD , USA
| | - Zhuoya Li
- a Department of Immunology , School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology , Wuhan , China
| | - Yongwon Choi
- d Perelman School of Medicine , University of Pennsylvania , Philadelphia , PA , USA
| | - Feili Gong
- a Department of Immunology , School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology , Wuhan , China
| | - Xiang Cheng
- e Laboratory of Cardiovascular Immunology, Institute of Cardiology, Union Hospital , Tongji Medical College, Huazhong University of Science and Technology , Wuhan , China
| | - John J O'Shea
- c Lymphocyte Cell Biology Section , NIAMS, NIH , Bethesda , MD , USA
| | - Jae Jin Chae
- f Inflammatory Disease Section , NHGRI, NIH , Bethesda , MD , USA
| | - Arian Laurence
- g Translational Gastroentology Unit, Nuffield department of medicine, John Radcliffe Hospital , University of Oxford , Oxford , UK
| | - Xiang-Ping Yang
- a Department of Immunology , School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology , Wuhan , China
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4
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Sreelatha A, Yee SS, Lopez VA, Park BC, Kinch LN, Pilch S, Servage KA, Zhang J, Jiou J, Karasiewicz-Urbańska M, Łobocka M, Grishin NV, Orth K, Kucharczyk R, Pawłowski K, Tomchick DR, Tagliabracci VS. Protein AMPylation by an Evolutionarily Conserved Pseudokinase. Cell 2018; 175:809-821.e19. [PMID: 30270044 DOI: 10.1016/j.cell.2018.08.046] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 07/19/2018] [Accepted: 08/17/2018] [Indexed: 02/06/2023]
Abstract
Approximately 10% of human protein kinases are believed to be inactive and named pseudokinases because they lack residues required for catalysis. Here, we show that the highly conserved pseudokinase selenoprotein-O (SelO) transfers AMP from ATP to Ser, Thr, and Tyr residues on protein substrates (AMPylation), uncovering a previously unrecognized activity for a member of the protein kinase superfamily. The crystal structure of a SelO homolog reveals a protein kinase-like fold with ATP flipped in the active site, thus providing a structural basis for catalysis. SelO pseudokinases localize to the mitochondria and AMPylate proteins involved in redox homeostasis. Consequently, SelO activity is necessary for the proper cellular response to oxidative stress. Our results suggest that AMPylation may be a more widespread post-translational modification than previously appreciated and that pseudokinases should be analyzed for alternative transferase activities.
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Affiliation(s)
- Anju Sreelatha
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Samantha S Yee
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Victor A Lopez
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Brenden C Park
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Lisa N Kinch
- Howard Hughes Medical Institute, Dallas, TX 75390, USA
| | - Sylwia Pilch
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw 02-106, Poland
| | - Kelly A Servage
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Junmei Zhang
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jenny Jiou
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | | | - Małgorzata Łobocka
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw 02-106, Poland; Faculty of Agriculture and Biology, Warsaw University of Life Sciences, Warsaw 02-776, Poland
| | - Nick V Grishin
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Howard Hughes Medical Institute, Dallas, TX 75390, USA; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Howard Hughes Medical Institute, Dallas, TX 75390, USA; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Roza Kucharczyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw 02-106, Poland
| | - Krzysztof Pawłowski
- Faculty of Agriculture and Biology, Warsaw University of Life Sciences, Warsaw 02-776, Poland
| | - Diana R Tomchick
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Vincent S Tagliabracci
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA; Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
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5
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Xu Y, Quan H, Wang Y, Zhong H, Sun J, Xu J, Jia N, Jiang Y. Requirement for Ergosterol in Berberine Tolerance Underlies Synergism of Fluconazole and Berberine against Fluconazole-Resistant Candida albicans Isolates. Front Cell Infect Microbiol 2017; 7:491. [PMID: 29238700 PMCID: PMC5712545 DOI: 10.3389/fcimb.2017.00491] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 11/15/2017] [Indexed: 12/19/2022] Open
Abstract
Candida albicans is one of the most common fungal pathogens. Our previous study demonstrated that concomitant use of berberine (BBR) and fluconazole (FLC) showed a synergistic action against FLC-resistant C. albicans in vitro and BBR had a major antifungal effect in the synergism, while FLC played a role of increasing the intracellular BBR concentration. Since the antifungal activity of BBR alone is very weak (MIC > 128 μg/mL), it was assumed that FLC-resistant C. albicans was naturally tolerant to BBR, and this tolerance could be reversed by FLC. The present study aimed to elucidate the mechanism underlying BBR tolerance in FLC-resistant C. albicans and its disruption by FLC. The ergosterol quantitative analysis showed that the BBR monotreatment could increase the content of cellular ergosterol. Real-time RT-PCR revealed a global upregulation of ergosterol synthesis genes in response to BBR exposure. In addition, exogenous ergosterol could decrease intracellular BBR concentration and increase the expression of drug efflux pump genes, further reducing the susceptibility of C. albicans to BBR. Similar to FLC, other antifungal agents acting on ergosterol were able to synergize with BBR against FLC-resistant C. albicans. However, the antifungal agents not acting on ergosterol were not synergistic with BBR. These results suggested that ergosterol was required for BBR tolerance, and FLC could enhance the susceptibility of FLC-resistant C. albicans to BBR by inhibiting ergosterol synthesis.
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Affiliation(s)
- Yi Xu
- Department of Pharmacy, Jinan Military General Hospital, Jinan, China
| | - Hua Quan
- New Drug Research and Development Center, School of Pharmacy, Second Military Medical University, Shanghai, China.,Shanghai Pudong Institute for Food and Drug Control, Shanghai, China
| | - Yan Wang
- New Drug Research and Development Center, School of Pharmacy, Second Military Medical University, Shanghai, China
| | - Hua Zhong
- New Drug Research and Development Center, School of Pharmacy, Second Military Medical University, Shanghai, China
| | - Jun Sun
- Department of Pharmacy, Jinan Military General Hospital, Jinan, China
| | - Jianjiang Xu
- Department of Pharmacy, Jinan Military General Hospital, Jinan, China
| | - Nuan Jia
- Department of Pharmacy, Jinan Military General Hospital, Jinan, China
| | - Yuanying Jiang
- New Drug Research and Development Center, School of Pharmacy, Second Military Medical University, Shanghai, China
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6
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Liu Z, Wang Z, Huang M, Yan L, Ma Z, Yin Y. The FgSsb-FgZuo-FgSsz complex regulates multiple stress responses and mycotoxin production via folding the soluble SNARE Vam7 and β2-tubulin in Fusarium graminearum. Environ Microbiol 2017; 19:5040-5059. [PMID: 29076607 DOI: 10.1111/1462-2920.13968] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 10/16/2017] [Accepted: 10/19/2017] [Indexed: 11/28/2022]
Abstract
Hsp70 proteins play important roles in protein folding in the budding yeast, but their functions in pathogenic fungi are largely unknown. Here, we found that Fusarium graminearum Hsp70 proteins FgSsb, FgSsz and their cochaperone FgZuo formed a complex. This complex was required for microtubule morphology, vacuole fusion and endocytosis. More importantly, the β2-tubulin FgTub2 and SNARE protein FgVam7 were identified as targeting proteins of this complex. We further found that the complex FgSsb-FgZuo-FgSsz controlled sensitivity of F. graminearum to the antimicrotubule drug carbendazim and cold stress via regulating the folding of FgTub2. Moreover, this complex assisted the folding of FgVam7, subsequently modulated vacuole fusion and responses to heavy metal, osmotic and oxidative stresses. In addition, the deletion of this complex led to dramatically decreased deoxynivalenol biosynthesis. This study uncovers a novel regulating mechanism of Hsp70 in multiple stress responses in a filamentous fungus.
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Affiliation(s)
- Zunyong Liu
- Institute of Biotechnology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Zhihui Wang
- Institute of Biotechnology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Mengmeng Huang
- Institute of Biotechnology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Leiyan Yan
- Ningbo Academy of Agricultural Sciences, Ningbo, 315040, China
| | - Zhonghua Ma
- Institute of Biotechnology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China.,State Key Laboratory of Rice Biology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Yanni Yin
- Institute of Biotechnology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
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7
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Organelle acidification negatively regulates vacuole membrane fusion in vivo. Sci Rep 2016; 6:29045. [PMID: 27363625 PMCID: PMC4929563 DOI: 10.1038/srep29045] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 06/10/2016] [Indexed: 12/13/2022] Open
Abstract
The V-ATPase is a proton pump consisting of a membrane-integral V0 sector and a peripheral V1 sector, which carries the ATPase activity. In vitro studies of yeast vacuole fusion and evidence from worms, flies, zebrafish and mice suggested that V0 interacts with the SNARE machinery for membrane fusion, that it promotes the induction of hemifusion and that this activity requires physical presence of V0 rather than its proton pump activity. A recent in vivo study in yeast has challenged these interpretations, concluding that fusion required solely lumenal acidification but not the V0 sector itself. Here, we identify the reasons for this discrepancy and reconcile it. We find that acute pharmacological or physiological inhibition of V-ATPase pump activity de-acidifies the vacuole lumen in living yeast cells within minutes. Time-lapse microscopy revealed that de-acidification induces vacuole fusion rather than inhibiting it. Cells expressing mutated V0 subunits that maintain vacuolar acidity were blocked in this fusion. Thus, proton pump activity of the V-ATPase negatively regulates vacuole fusion in vivo. Vacuole fusion in vivo does, however, require physical presence of a fusion-competent V0 sector.
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8
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Stauffer B, Powers T. Target of rapamycin signaling mediates vacuolar fission caused by endoplasmic reticulum stress in Saccharomyces cerevisiae. Mol Biol Cell 2015; 26:4618-30. [PMID: 26466677 PMCID: PMC4678019 DOI: 10.1091/mbc.e15-06-0344] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 10/07/2015] [Indexed: 01/15/2023] Open
Abstract
The yeast vacuole is equivalent to the mammalian lysosome and, in response to diverse physiological and environmental stimuli, undergoes alterations both in size and number. Here we demonstrate that vacuoles fragment in response to stress within the endoplasmic reticulum (ER) caused by chemical or genetic perturbations. We establish that this response does not involve known signaling pathways linked previously to ER stress but instead requires the rapamycin-sensitive TOR Complex 1 (TORC1), a master regulator of cell growth, together with its downstream effectors, Tap42/Sit4 and Sch9. To identify additional factors required for ER stress-induced vacuolar fragmentation, we conducted a high-throughput, genome-wide visual screen for yeast mutants that are refractory to ER stress-induced changes in vacuolar morphology. We identified several genes shown previously to be required for vacuolar fusion and/or fission, validating the utility of this approach. We also identified a number of new components important for fragmentation, including a set of proteins involved in assembly of the V-ATPase. Remarkably, we find that one of these, Vph2, undergoes a change in intracellular localization in response to ER stress and, moreover, in a manner that requires TORC1 activity. Together these results reveal a new role for TORC1 in the regulation of vacuolar behavior.
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Affiliation(s)
- Bobbiejane Stauffer
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, Davis, CA 95616
| | - Ted Powers
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, Davis, CA 95616 )
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9
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Maxson ME, Grinstein S. The vacuolar-type H⁺-ATPase at a glance - more than a proton pump. J Cell Sci 2015; 127:4987-93. [PMID: 25453113 DOI: 10.1242/jcs.158550] [Citation(s) in RCA: 171] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The vacuolar H(+)-ATPase (V-ATPase) has long been appreciated to function as an electrogenic H(+) pump. By altering the pH of intracellular compartments, the V-ATPase dictates enzyme activity, governs the dissociation of ligands from receptors and promotes the coupled transport of substrates across membranes, a role often aided by the generation of a transmembrane electrical potential. In tissues where the V-ATPase is expressed at the plasma membrane, it can serve to acidify the extracellular microenvironment. More recently, however, the V-ATPase has been implicated in a bewildering variety of additional roles that seem independent of its ability to translocate H(+). These non-canonical functions, which include fusogenicity, cytoskeletal tethering and metabolic sensing, are described in this Cell Science at a Glance article and accompanying poster, together with a brief overview of the conventional functions of the V-ATPase.
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Affiliation(s)
- Michelle E Maxson
- Program in Cell Biology, Hospital for Sick Children, 686 Bay Street, Toronto, ON, M5G 0A4, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, 686 Bay Street, Toronto, ON, M5G 0A4, Canada Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, 290 Victoria Street, Toronto, ON, M5C 1N8, Canada
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10
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Morel N, Poëa-Guyon S. The membrane domain of vacuolar H(+)ATPase: a crucial player in neurotransmitter exocytotic release. Cell Mol Life Sci 2015; 72:2561-73. [PMID: 25795337 PMCID: PMC11113229 DOI: 10.1007/s00018-015-1886-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 03/10/2015] [Accepted: 03/12/2015] [Indexed: 12/31/2022]
Abstract
V-ATPases are multimeric enzymes made of two sectors, a V1 catalytic domain and a V0 membrane domain. They accumulate protons in various intracellular organelles. Acidification of synaptic vesicles by V-ATPase energizes the accumulation of neurotransmitters in these storage organelles and is therefore required for efficient synaptic transmission. In addition to this well-accepted role, functional studies have unraveled additional hidden roles of V0 in neurotransmitter exocytosis that are independent of the transport of protons. V0 interacts with SNAREs and calmodulin, and perturbing these interactions affects neurotransmitter release. Here, we discuss these data in relation with previous results obtained in reconstituted membranes and on yeast vacuole fusion. We propose that V0 could be a sensor of intra-vesicular pH that controls the exocytotic machinery, probably regulating SNARE complex assembly during the synaptic vesicle priming step, and that, during the membrane fusion step, V0 might favor lipid mixing and fusion pore stability.
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Affiliation(s)
- Nicolas Morel
- Centre de Neurosciences Paris-Sud, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8195 and Université Paris-Sud, 91405, Orsay, France,
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11
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Abstract
Neurons fire by releasing neurotransmitters via fusion of synaptic vesicles with the plasma membrane. Fusion can be evoked by an incoming signal from a preceding neuron or can occur spontaneously. Synaptic vesicle fusion requires the formation of trans complexes between SNAREs as well as Ca(2+) ions. Wang et al. (2014. J. Cell Biol. http://dx.doi.org/jcb.201312109) now find that the Ca(2+)-binding protein Calmodulin promotes spontaneous release and SNARE complex formation via its interaction with the V0 sector of the V-ATPase.
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Affiliation(s)
- Stefano Vavassori
- Département de Biochimie, Université de Lausanne, 1066 Epalinges, Switzerland
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12
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Schulze U, Vollenbröker B, Braun DA, Van Le T, Granado D, Kremerskothen J, Fränzel B, Klosowski R, Barth J, Fufezan C, Wolters DA, Pavenstädt H, Weide T. The Vac14-interaction network is linked to regulators of the endolysosomal and autophagic pathway. Mol Cell Proteomics 2014; 13:1397-411. [PMID: 24578385 DOI: 10.1074/mcp.m113.034108] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The scaffold protein Vac14 acts in a complex with the lipid kinase PIKfyve and its counteracting phosphatase FIG4, regulating the interconversion of phosphatidylinositol-3-phosphate to phosphatidylinositol-3,5-bisphosphate. Dysfunctional Vac14 mutants, a deficiency of one of the Vac14 complex components, or inhibition of PIKfyve enzymatic activity results in the formation of large vacuoles in cells. How these vacuoles are generated and which processes are involved are only poorly understood. Here we show that ectopic overexpression of wild-type Vac14 as well as of the PIKfyve-binding deficient Vac14 L156R mutant causes vacuoles. Vac14-dependent vacuoles and PIKfyve inhibitor-dependent vacuoles resulted in elevated levels of late endosomal, lysosomal, and autophagy-associated proteins. However, only late endosomal marker proteins were bound to the membranes of these enlarged vacuoles. In order to decipher the linkage between the Vac14 complex and regulators of the endolysosomal pathway, a protein affinity approach combined with multidimensional protein identification technology was conducted, and novel molecular links were unraveled. We found and verified the interaction of Rab9 and the Rab7 GAP TBC1D15 with Vac14. The identified Rab-related interaction partners support the theory that the regulation of vesicular transport processes and phosphatidylinositol-modifying enzymes are tightly interconnected.
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Affiliation(s)
- Ulf Schulze
- From the ‡Department of Internal Medicine D, Molecular Nephrology, University Hospital of Muenster, Albert-Schweitzer Campus 1, A14, D-48149 Muenster, Germany
| | - Beate Vollenbröker
- From the ‡Department of Internal Medicine D, Molecular Nephrology, University Hospital of Muenster, Albert-Schweitzer Campus 1, A14, D-48149 Muenster, Germany
| | - Daniela A Braun
- From the ‡Department of Internal Medicine D, Molecular Nephrology, University Hospital of Muenster, Albert-Schweitzer Campus 1, A14, D-48149 Muenster, Germany
| | - Truc Van Le
- From the ‡Department of Internal Medicine D, Molecular Nephrology, University Hospital of Muenster, Albert-Schweitzer Campus 1, A14, D-48149 Muenster, Germany
| | - Daniel Granado
- From the ‡Department of Internal Medicine D, Molecular Nephrology, University Hospital of Muenster, Albert-Schweitzer Campus 1, A14, D-48149 Muenster, Germany
| | - Joachim Kremerskothen
- From the ‡Department of Internal Medicine D, Molecular Nephrology, University Hospital of Muenster, Albert-Schweitzer Campus 1, A14, D-48149 Muenster, Germany
| | - Benjamin Fränzel
- ‖Analytical Chemistry NC4/72, Biomolecular Mass Spectrometry/Proteincenter, Ruhr-University Bochum, Universitätsstr. 150, D-44801 Bochum, Germany
| | - Rafael Klosowski
- ‖Analytical Chemistry NC4/72, Biomolecular Mass Spectrometry/Proteincenter, Ruhr-University Bochum, Universitätsstr. 150, D-44801 Bochum, Germany
| | - Johannes Barth
- ‡‡Institute of Plant Biology and Biotechnology, University of Muenster, Schlossplatz 8, D-48143 Muenster, Germany
| | - Christian Fufezan
- ‡‡Institute of Plant Biology and Biotechnology, University of Muenster, Schlossplatz 8, D-48143 Muenster, Germany
| | - Dirk A Wolters
- ‖Analytical Chemistry NC4/72, Biomolecular Mass Spectrometry/Proteincenter, Ruhr-University Bochum, Universitätsstr. 150, D-44801 Bochum, Germany
| | - Hermann Pavenstädt
- From the ‡Department of Internal Medicine D, Molecular Nephrology, University Hospital of Muenster, Albert-Schweitzer Campus 1, A14, D-48149 Muenster, Germany;
| | - Thomas Weide
- From the ‡Department of Internal Medicine D, Molecular Nephrology, University Hospital of Muenster, Albert-Schweitzer Campus 1, A14, D-48149 Muenster, Germany;
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Homotypic vacuole fusion in yeast requires organelle acidification and not the V-ATPase membrane domain. Dev Cell 2014; 27:462-8. [PMID: 24286827 DOI: 10.1016/j.devcel.2013.10.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 07/23/2013] [Accepted: 10/17/2013] [Indexed: 11/23/2022]
Abstract
Studies of homotypic vacuole-vacuole fusion in the yeast Saccharomyces cerevisiae have been instrumental in determining the cellular machinery required for eukaryotic membrane fusion and have implicated the vacuolar H(+)-ATPase (V-ATPase). The V-ATPase is a multisubunit, rotary proton pump whose precise role in homotypic fusion is controversial. Models formulated from in vitro studies suggest that it is the proteolipid proton-translocating pore of the V-ATPase that functions in fusion, with further studies in worms, flies, zebrafish, and mice appearing to support this model. We present two in vivo assays and use a mutant V-ATPase subunit to establish that it is the H(+)-translocation/vacuole acidification function, rather than the physical presence of the V-ATPase, that promotes homotypic vacuole fusion in yeast. Furthermore, we show that acidification of the yeast vacuole in the absence of the V-ATPase rescues vacuole-fusion defects. Our results clarify the in vivo requirements of acidification for membrane fusion.
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14
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Solinger JA, Spang A. Tethering complexes in the endocytic pathway: CORVET and HOPS. FEBS J 2013; 280:2743-57. [PMID: 23351085 DOI: 10.1111/febs.12151] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2012] [Revised: 01/10/2013] [Accepted: 01/23/2013] [Indexed: 12/21/2022]
Abstract
Endocytosis describes the processes by which proteins, peptides and solutes, and also pathogens, enter the cell. Endocytosed material progresses to endosomes. Genetic studies in yeast, worms, flies and mammals have identified a set of universally conserved proteins that are essential for early-to-late endosome transition and lysosome biogenesis, and for endolysosomal trafficking pathways, including autophagy. The two Vps-C complexes CORVET (class C core vacuole/endosome tethering) and HOPS (homotypic fusion and vacuole protein sorting) perform diverse biochemical functions in endocytosis: they tether membranes, interact with Rab GTPases, activate and proof-read SNARE assembly to drive membrane fusion, and possibly attach endosomes to the cytoskeleton. In addition, several of the CORVET and HOPS subunits have diversified in metazoans, and probably form additional specialized complexes to accomodate the higher complexity of trafficking pathways in these cells. Recent studies offer new insights into the complex relationships between CORVET and HOPS complexes and other factors of the endolysosomal pathway. Interactions with V-ATPase, the ESCRT machinery, phosphoinositides, the cytoskeleton and the Rab switch suggest an intricate cooperative network for endosome maturation. Accumulating evidence supports the view that endosomal tethering complexes implement a regulatory logic that governs endomembrane identity and dynamics.
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15
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Wong D, Chao JD, Av-Gay Y. Mycobacterium tuberculosis-secreted phosphatases: from pathogenesis to targets for TB drug development. Trends Microbiol 2013; 21:100-9. [DOI: 10.1016/j.tim.2012.09.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 09/10/2012] [Accepted: 09/14/2012] [Indexed: 01/02/2023]
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16
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Mycobacterium tuberculosis protein tyrosine phosphatase (PtpA) excludes host vacuolar-H+-ATPase to inhibit phagosome acidification. Proc Natl Acad Sci U S A 2011; 108:19371-6. [PMID: 22087003 DOI: 10.1073/pnas.1109201108] [Citation(s) in RCA: 274] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Mycobacterium tuberculosis (Mtb) pathogenicity depends on its ability to inhibit phagosome acidification and maturation processes after engulfment by macrophages. Here, we show that the secreted Mtb protein tyrosine phosphatase (PtpA) binds to subunit H of the macrophage vacuolar-H(+)-ATPase (V-ATPase) machinery, a multisubunit protein complex in the phagosome membrane that drives luminal acidification. Furthermore, we show that the macrophage class C vacuolar protein sorting complex, a key regulator of endosomal membrane fusion, associates with V-ATPase in phagosome maturation, suggesting a unique role for V-ATPase in coordinating phagosome-lysosome fusion. PtpA interaction with host V-ATPase is required for the previously reported dephosphorylation of VPS33B and subsequent exclusion of V-ATPase from the phagosome during Mtb infection. These findings show that inhibition of phagosome acidification in the mycobacterial phagosome is directly attributed to PtpA, a key protein needed for Mtb survival and pathogenicity within host macrophages.
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17
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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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18
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Cabrera M, Langemeyer L, Mari M, Rethmeier R, Orban I, Perz A, Bröcker C, Griffith J, Klose D, Steinhoff HJ, Reggiori F, Engelbrecht-Vandré S, Ungermann C. Phosphorylation of a membrane curvature-sensing motif switches function of the HOPS subunit Vps41 in membrane tethering. ACTA ACUST UNITED AC 2011; 191:845-59. [PMID: 21079247 PMCID: PMC2983053 DOI: 10.1083/jcb.201004092] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An AP-3–binding site required for vesicle–vacuole fusion is masked when Vps41 is associated with highly curved membranes, such as endosomes, but is exposed at membranes with lower curvature, such as vacuoles, because of phosphorylation of the membrane-binding motif. Tethering factors are organelle-specific multisubunit protein complexes that identify, along with Rab guanosine triphosphatases, transport vesicles and trigger their SNARE-mediated fusion of specific transport vesicles with the target membranes. Little is known about how tethering factors discriminate between different trafficking pathways, which may converge at the same organelle. In this paper, we describe a phosphorylation-based switch mechanism, which allows the homotypic vacuole fusion protein sorting effector subunit Vps41 to operate in two distinct fusion events, namely endosome–vacuole and AP-3 vesicle–vacuole fusion. Vps41 contains an amphipathic lipid-packing sensor (ALPS) motif, which recognizes highly curved membranes. At endosomes, this motif is inserted into the lipid bilayer and masks the binding motif for the δ subunit of the AP-3 complex, Apl5, without affecting the Vps41 function in endosome–vacuole fusion. At the much less curved vacuole, the ALPS motif becomes available for phosphorylation by the resident casein kinase Yck3. As a result, the Apl5-binding site is exposed and allows AP-3 vesicles to bind to Vps41, followed by specific fusion with the vacuolar membrane. This multifunctional tethering factor thus discriminates between trafficking routes by switching from a curvature-sensing to a coat recognition mode upon phosphorylation.
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Affiliation(s)
- Margarita Cabrera
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, 49076 Osnabrück, Germany
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19
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Balderhaar HJK, Arlt H, Ostrowicz C, Bröcker C, Sündermann F, Brandt R, Babst M, Ungermann C. The Rab GTPase Ypt7 is linked to retromer-mediated receptor recycling and fusion at the yeast late endosome. J Cell Sci 2010; 123:4085-94. [PMID: 21062894 DOI: 10.1242/jcs.071977] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Organelles of the endomembrane system need to counterbalance fission and fusion events to maintain their surface-to-volume ratio. At the late mammalian endosome, the Rab GTPase Rab7 is a major regulator of fusion, whereas the homologous yeast protein Ypt7 seems to be restricted to the vacuole surface. Here, we present evidence that Ypt7 is recruited to and acts on late endosomes, where it affects multiple trafficking reactions. We show that overexpression of Ypt7 results in expansion and massive invagination of the vacuolar membrane, which requires cycling of Ypt7 between GDP- and GTP-bound states. Invaginations are blocked by ESCRT, CORVET and retromer mutants, but not by autophagy or AP-3 mutants. We also show that Ypt7-GTP specifically binds to the retromer cargo-recognition subcomplex, which--like its cargo Vps10--is found on the vacuole upon Ypt7 overproduction. Our data suggest that Ypt7 functions at the late endosome to coordinate retromer-mediated recycling with the fusion of late endosomes with vacuoles.
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Affiliation(s)
- Henning J Kleine Balderhaar
- University of Osnabrück, Department of Biology and Chemistry, Biochemistry section, Barbarastrasse 13, 49076 Osnabrück, Germany
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20
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Navarro RE, Ramos-Balderas JL, Guerrero I, Pelcastre V, Maldonado E. Pigment dilution mutants from fish models with connection to lysosome-related organelles and vesicular traffic genes. Zebrafish 2009; 5:309-18. [PMID: 19133829 DOI: 10.1089/zeb.2008.0549] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
An interesting question in developmental biology is why mutations in genes with functions essential for the majority of cells produce diseases affecting only specific tissues. For example, pigment dilution disorders are often the consequence of mutations in conserved vesicular traffic genes. In Hermansky-Pudlak, Griscelli, and Chediak-Higashi pigment dilution syndromes, vesicular traffic mutations affect several organs with one characteristic in common: to carry out their functions they depend to a great extent on lysosome-related organelles (LROs), such as the melanosomes in melanocytes. Conserved multimeric complexes, present in most cell types, target proteins to lysosomes or selected LROs using transport vesicles. By studying these diseases or the model organisms that are defective in these processes, we have learned that every cell type possesses a unique way to regulate its vesicular traffic machinery and to assemble its multimeric complexes. This is accomplished by subunits from these multimeric complexes acting in a cell-specific manner. Here, we review several fish pigment dilution mutants that represent models for human vesicular traffic diseases.
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Affiliation(s)
- Rosa E Navarro
- Departamento de Biología Celular, Instituto de Fisiología Celular , Universidad Nacional Autónoma de México, UNAM, México City, México
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21
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Current awareness on yeast. Yeast 2009. [DOI: 10.1002/yea.1618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Valluru R, Lammens W, Claupein W, Van den Ende W. Freezing tolerance by vesicle-mediated fructan transport. TRENDS IN PLANT SCIENCE 2008; 13:409-14. [PMID: 18619894 DOI: 10.1016/j.tplants.2008.05.008] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Revised: 04/28/2008] [Accepted: 05/30/2008] [Indexed: 05/04/2023]
Abstract
Fructans are fructose-based polymers associated with freezing tolerance. They might act directly via membrane stabilization or indirectly by stimulating alternative cryoprotectants. Fructans and fructan biosynthetic enzymes, in general, are believed to be present in the vacuole. This paper draws particular attention to the surprising presence of fructans and fructan exohydrolase activity in the apoplast of cold-stressed plants. This observation raises questions concerning the origin of apoplastic fructans and suggests that fructans are transported to the apoplast by post-synthesis mechanisms, perhaps induced by cold. We propose a conceptual vesicle-mediated transport model for the movement of vacuolar fructans to the apoplast, where they could assist in stabilizing the plasma membrane.
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Affiliation(s)
- Ravi Valluru
- Institute for Crop Production and Grassland Research, University of Hohenheim, D-70599 Stuttgart, Germany
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23
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Zabrocki P, Bastiaens I, Delay C, Bammens T, Ghillebert R, Pellens K, De Virgilio C, Van Leuven F, Winderickx J. Phosphorylation, lipid raft interaction and traffic of alpha-synuclein in a yeast model for Parkinson. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:1767-80. [PMID: 18634833 DOI: 10.1016/j.bbamcr.2008.06.010] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2007] [Revised: 05/08/2008] [Accepted: 06/02/2008] [Indexed: 01/04/2023]
Abstract
Parkinson's disease is a neurodegenerative disorder characterized by the formation of Lewy bodies containing aggregated alpha-synuclein. We used a yeast model to screen for deletion mutants with mislocalization and enhanced inclusion formation of alpha-synuclein. Many of the mutants were affected in functions related to vesicular traffic but especially mutants in endocytosis and vacuolar degradation combined inclusion formation with enhanced alpha-synuclein-mediated toxicity. The screening also allowed for identification of casein kinases responsible for alpha-synuclein phosphorylation at the plasma membrane as well as transacetylases that modulate the alpha-synuclein membrane interaction. In addition, alpha-synuclein was found to associate with lipid rafts, a phenomenon dependent on the ergosterol content. Together, our data suggest that toxicity of alpha-synuclein in yeast is at least in part associated with endocytosis of the protein, vesicular recycling back to the plasma membrane and vacuolar fusion defects, each contributing to the obstruction of different vesicular trafficking routes.
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Affiliation(s)
- Piotr Zabrocki
- Laboratory of Functional Biology, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
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