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Khakurel A, Lupashin VV. Role of GARP Vesicle Tethering Complex in Golgi Physiology. Int J Mol Sci 2023; 24:6069. [PMID: 37047041 PMCID: PMC10094427 DOI: 10.3390/ijms24076069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 03/17/2023] [Accepted: 03/19/2023] [Indexed: 04/14/2023] Open
Abstract
The Golgi associated retrograde protein complex (GARP) is an evolutionarily conserved component of Golgi membrane trafficking machinery that belongs to the Complexes Associated with Tethering Containing Helical Rods (CATCHR) family. Like other multisubunit tethering complexes such as COG, Dsl1, and Exocyst, the GARP is believed to function by tethering and promoting fusion of the endosome-derived small trafficking intermediate. However, even twenty years after its discovery, the exact structure and the functions of GARP are still an enigma. Recent studies revealed novel roles for GARP in Golgi physiology and identified human patients with mutations in GARP subunits. In this review, we summarized our knowledge of the structure of the GARP complex, its protein partners, GARP functions related to Golgi physiology, as well as cellular defects associated with the dysfunction of GARP subunits.
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Affiliation(s)
| | - Vladimir V. Lupashin
- Department of Physiology and Cell Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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2
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Garcia JM, Schwabe MJ, Voelker DR, Riekhof WR. A functional genomic screen in Saccharomyces cerevisiae reveals divergent mechanisms of resistance to different alkylphosphocholine chemotherapeutic agents. G3-GENES GENOMES GENETICS 2021; 11:6347582. [PMID: 34568930 PMCID: PMC8496327 DOI: 10.1093/g3journal/jkab233] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 05/03/2021] [Indexed: 11/12/2022]
Abstract
The alkylphosphocholine (APC) class of antineoplastic and antiprotozoal drugs, such as edelfosine and miltefosine, are structural mimics of lyso-phosphatidylcholine (lyso-PC), and are inhibitory to the yeast Saccharomyces cerevisiae at low micromolar concentrations. Cytotoxic effects related to inhibition of phospholipid synthesis, induction of an unfolded protein response, inhibition of oxidative phosphorylation, and disruption of lipid rafts have been attributed to members of this drug class, however, the molecular mechanisms of action of these drugs remain incompletely understood. Cytostatic and cytotoxic effects of the APCs exhibit variability with regard to chemical structure, leading to differences in effectiveness against different organisms or cell types. We now report the comprehensive identification of S. cerevisiae titratable-essential gene and haploid nonessential gene deletion mutants that are resistant to the APC drug miltefosine (hexadecyl-O-phosphocholine). Fifty-eight strains out of ∼5600 tested displayed robust and reproducible resistance to miltefosine. This gene set was heavily enriched in functions associated with vesicular transport steps, especially those involving endocytosis and retrograde transport of endosome derived vesicles to the Golgi or vacuole, suggesting a role for these trafficking pathways in transport of miltefosine to potential sites of action in the endoplasmic reticulum and mitochondrion. In addition, we identified mutants with defects in phosphatidylinositol-4-phosphate synthesis (TetO::STT4) and hydrolysis (sac1Δ), an oxysterol binding protein homolog (osh2Δ), a number of ER-resident proteins, and multiple components of the eisosome. These findings suggest that ER-plasma membrane contact sites and retrograde vesicle transport are involved in the interorganelle transport of lyso-PtdCho and related lyso-phospholipid-like analogs to their intracellular sites of cytotoxic activity.
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Affiliation(s)
- Jaquelin M Garcia
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Michael J Schwabe
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Dennis R Voelker
- Department of Medicine, National Jewish Health, Denver, CO 80206, USA
| | - Wayne R Riekhof
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
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3
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Shi Z, Chen S, Han X, Peng R, Luo J, Yang L, Zheng Y, Wang H. The rare mutation in the endosome-associated recycling protein gene VPS50 is associated with human neural tube defects. Mol Cytogenet 2019; 12:8. [PMID: 30828385 PMCID: PMC6381738 DOI: 10.1186/s13039-019-0421-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 02/04/2019] [Indexed: 12/22/2022] Open
Abstract
Background Tight control of endosome trafficking is essential for the generation of a normally patterned embryo. Recent studies have found that VPS50 is a key ingredient in EARP which is required for recycling of internalized TfRs to the cell surface and dense-core vesicle maturation. However, the role of VPS50 in embryogenesis and human physiology are poorly understood. Results We identified a rare missense heterozygous VPS50 mutation (p. Gly169Val) in NTDs by high-throughput sequencing. In vitro functional analysis demonstrated that the p. Gly169Val was a loss-of-function mutation, delaying transferrin recycling and altering its interaction with VPS53. Using WISH during zebrafish embryogenesis, we demonstrated that vps50 gene was expressed throughout the early embryo, especially in the head. Abnormal body axis phenotypes were observed in those vps50 knock-down zebrafishes. Further rescue study in zebrafish suggested that the mutation displayed loss-of-function effects comparing with wild-type VPS50. Conclusions These findings thus demonstrated that the functional mutations in VPS50 might contribute to neurodevelopmental disorder and highlighted the critical importance of VPS50 function in cellular and organismal physiology. Electronic supplementary material The online version of this article (10.1186/s13039-019-0421-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Zhiwen Shi
- 1Obstetrics and Gynecology Hospital, State Key Laboratory of Genetic Engineering at School of Life Sciences, Institute of Reproduction and Development, Fudan University, Shanghai, 200011 China.,2Key Laboratory of Reproduction Regulation of NPFPC, Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai, 200032 China
| | - Shuxia Chen
- 1Obstetrics and Gynecology Hospital, State Key Laboratory of Genetic Engineering at School of Life Sciences, Institute of Reproduction and Development, Fudan University, Shanghai, 200011 China.,2Key Laboratory of Reproduction Regulation of NPFPC, Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai, 200032 China
| | - Xiao Han
- 1Obstetrics and Gynecology Hospital, State Key Laboratory of Genetic Engineering at School of Life Sciences, Institute of Reproduction and Development, Fudan University, Shanghai, 200011 China.,2Key Laboratory of Reproduction Regulation of NPFPC, Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai, 200032 China
| | - Rui Peng
- 1Obstetrics and Gynecology Hospital, State Key Laboratory of Genetic Engineering at School of Life Sciences, Institute of Reproduction and Development, Fudan University, Shanghai, 200011 China.,2Key Laboratory of Reproduction Regulation of NPFPC, Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai, 200032 China
| | - Jin Luo
- 1Obstetrics and Gynecology Hospital, State Key Laboratory of Genetic Engineering at School of Life Sciences, Institute of Reproduction and Development, Fudan University, Shanghai, 200011 China.,2Key Laboratory of Reproduction Regulation of NPFPC, Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai, 200032 China
| | - Luming Yang
- 2Key Laboratory of Reproduction Regulation of NPFPC, Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai, 200032 China
| | - Yufang Zheng
- 2Key Laboratory of Reproduction Regulation of NPFPC, Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai, 200032 China.,1Obstetrics and Gynecology Hospital, State Key Laboratory of Genetic Engineering at School of Life Sciences, Institute of Reproduction and Development, Fudan University, Shanghai, 200011 China.,3Institute of Developmental Biology & Molecular Medicine, Fudan University, Shanghai, 200433 China
| | - Hongyan Wang
- 2Key Laboratory of Reproduction Regulation of NPFPC, Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai, 200032 China.,1Obstetrics and Gynecology Hospital, State Key Laboratory of Genetic Engineering at School of Life Sciences, Institute of Reproduction and Development, Fudan University, Shanghai, 200011 China.,4Children's Hospital and Institutes of Biomedical Sciences of Fudan University, 399 Wanyuan Road, Shanghai, 201102 China
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4
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Schultzhaus Z, Cunningham GA, Mouriño-Pérez RR, Shaw BD. The phospholipid flippase DnfD localizes to late Golgi and is involved in asexual differentiation in Aspergillus nidulans. Mycologia 2019; 111:13-25. [PMID: 30699058 DOI: 10.1080/00275514.2018.1543927] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The maintenance of cell shape requires finely tuned and robust vesicle trafficking in order to provide sufficient plasma membrane materials. The hyphal cells of filamentous fungi are an extreme example of cell shape maintenance due to their ability to grow rapidly and respond to the environment while keeping a relatively consistent shape. We have previously shown that two phospholipid flippases, which regulate the asymmetry of specific phospholipids within the plasma membrane, are important for hyphal growth in Aspergillus nidulans. Here, we examine the rest of the phospholipid flippases encoded by A. nidulans by obtaining single and double deletions of all four family members, dnfA, dnfB, dnfC, and dnfD. We find that deleting dnfC does not impart a noticeable phenotype, by itself or with other deletions, but that dnfD, the homolog of the essential yeast gene neo1, is important for conidiation. dnfD deletion mutants form misshapen conidiophore vesicles that are defective in metulae formation. We localize DnfD to late Golgi equivalents, where it appears just before dissociation of this organelle. We propose that DnfD functions in a trafficking process that is specifically required for the morphological changes that take place during conidiation.
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Affiliation(s)
- Z Schultzhaus
- a Department of Plant Pathology and Microbiology , Texas A&M University , 2132 TAMU , College Station , Texas 77845.,b Center for Biomolecular Science and Engineering , Naval Research laboratory , Washington , District of Columbia 20375
| | - G A Cunningham
- a Department of Plant Pathology and Microbiology , Texas A&M University , 2132 TAMU , College Station , Texas 77845
| | - R R Mouriño-Pérez
- c Departamento de Microbiología , Centro de Investigación Científica y de Educación Superior de Ensenada , Ensenada , Baja California , México
| | - B D Shaw
- a Department of Plant Pathology and Microbiology , Texas A&M University , 2132 TAMU , College Station , Texas 77845
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Eising S, Thiele L, Fröhlich F. A systematic approach to identify recycling endocytic cargo depending on the GARP complex. eLife 2019; 8:42837. [PMID: 30694181 PMCID: PMC6374077 DOI: 10.7554/elife.42837] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 01/29/2019] [Indexed: 12/14/2022] Open
Abstract
Proteins and lipids of the plasma membrane underlie constant remodeling via a combination of the secretory- and the endocytic pathway. In the yeast endocytic pathway, cargo is sorted for recycling to the plasma membrane or degradation in vacuoles. Previously we have shown a role for the GARP complex in sphingolipid sorting and homeostasis (Fröhlich et al. 2015). However, the majority of cargo sorted in a GARP dependent process remain largely unknown. Here we use auxin induced degradation of GARP combined with mass spectrometry based vacuolar proteomics and lipidomics to show that recycling of two specific groups of proteins, the amino-phospholipid flippases and cell wall synthesis proteins depends on a functional GARP complex. Our results suggest that mis-sorting of flippases and remodeling of the lipid composition are the first occurring defects in GARP mutants. Our assay can be adapted to systematically map cargo of the entire endocytic pathway.
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Affiliation(s)
- Sebastian Eising
- Department of Biology/Chemistry, Molecular Membrane Biology Group, University of Osnabrück, Osnabrück, Germany.,Center of Cellular Nanoanalytics, University of Osnabrück, Osnabrück, Germany
| | - Lisa Thiele
- Department of Biology/Chemistry, Molecular Membrane Biology Group, University of Osnabrück, Osnabrück, Germany.,Center of Cellular Nanoanalytics, University of Osnabrück, Osnabrück, Germany
| | - Florian Fröhlich
- Center of Cellular Nanoanalytics, University of Osnabrück, Osnabrück, Germany
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6
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Mioka T, Fujimura-Kamada K, Mizugaki N, Kishimoto T, Sano T, Nunome H, Williams DE, Andersen RJ, Tanaka K. Phospholipid flippases and Sfk1p, a novel regulator of phospholipid asymmetry, contribute to low permeability of the plasma membrane. Mol Biol Cell 2018. [PMID: 29540528 PMCID: PMC5935070 DOI: 10.1091/mbc.e17-04-0217] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Phospholipid flippase (type 4 P-type ATPase) plays a major role in the generation of phospholipid asymmetry in eukaryotic cell membranes. Loss of Lem3p-Dnf1/2p flippases leads to the exposure of phosphatidylserine (PS) and phosphatidylethanolamine (PE) on the cell surface in yeast, resulting in sensitivity to PS- or PE-binding peptides. We isolated Sfk1p, a conserved membrane protein in the TMEM150/FRAG1/DRAM family, as a multicopy suppressor of this sensitivity. Overexpression of SFK1 decreased PS/PE exposure in lem3Δ mutant cells. Consistent with this, lem3Δ sfk1Δ double mutant cells exposed more PS/PE than the lem3Δ mutant. Sfk1p was previously implicated in the regulation of the phosphatidylinositol-4 kinase Stt4p, but the effect of Sfk1p on PS/PE exposure in lem3Δ was independent of Stt4p. Surprisingly, Sfk1p did not facilitate phospholipid flipping but instead repressed it, even under ATP-depleted conditions. We propose that Sfk1p negatively regulates transbilayer movement of phospholipids irrespective of directions. In addition, we showed that the permeability of the plasma membrane was dramatically elevated in the lem3Δ sfk1Δ double mutant in comparison with the corresponding single mutants. Interestingly, total ergosterol was decreased in the lem3Δ sfk1Δ mutant. Our results suggest that phospholipid asymmetry is required for the maintenance of low plasma membrane permeability.
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Affiliation(s)
- Tetsuo Mioka
- Division of Molecular Interaction, Institute for Genetic Medicine, Hokkaido University Graduate School of Life Science, Kita-ku, Sapporo 060-0815, Japan
| | - Konomi Fujimura-Kamada
- Division of Molecular Interaction, Institute for Genetic Medicine, Hokkaido University Graduate School of Life Science, Kita-ku, Sapporo 060-0815, Japan
| | - Nahiro Mizugaki
- Division of Molecular Interaction, Institute for Genetic Medicine, Hokkaido University Graduate School of Life Science, Kita-ku, Sapporo 060-0815, Japan
| | - Takuma Kishimoto
- Division of Molecular Interaction, Institute for Genetic Medicine, Hokkaido University Graduate School of Life Science, Kita-ku, Sapporo 060-0815, Japan
| | - Takamitsu Sano
- Division of Molecular Interaction, Institute for Genetic Medicine, Hokkaido University Graduate School of Life Science, Kita-ku, Sapporo 060-0815, Japan
| | - Hitoshi Nunome
- Division of Molecular Interaction, Institute for Genetic Medicine, Hokkaido University Graduate School of Life Science, Kita-ku, Sapporo 060-0815, Japan
| | - David E Williams
- Departments of Chemistry and Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Raymond J Andersen
- Departments of Chemistry and Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Kazuma Tanaka
- Division of Molecular Interaction, Institute for Genetic Medicine, Hokkaido University Graduate School of Life Science, Kita-ku, Sapporo 060-0815, Japan
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7
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Dalton LE, Bean BDM, Davey M, Conibear E. Quantitative high-content imaging identifies novel regulators of Neo1 trafficking at endosomes. Mol Biol Cell 2017; 28:1539-1550. [PMID: 28404745 PMCID: PMC5449152 DOI: 10.1091/mbc.e16-11-0772] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 04/05/2017] [Accepted: 04/06/2017] [Indexed: 12/21/2022] Open
Abstract
P4-ATPases are a family of putative phospholipid flippases that regulate lipid membrane asymmetry, which is important for vesicle formation. Two yeast flippases, Drs2 and Neo1, have nonredundant functions in the recycling of the synaptobrevin-like v-SNARE Snc1 from early endosomes. Drs2 activity is needed to form vesicles and regulate its own trafficking, suggesting that flippase activity and localization are linked. However, the role of Neo1 in endosomal recycling is not well characterized. To identify novel regulators of Neo1 trafficking and activity at endosomes, we first identified mutants with impaired recycling of a Snc1-based reporter and subsequently used high-content microscopy to classify these mutants based on the localization of Neo1 or its binding partners, Mon2 and Dop1. This analysis identified a role for Arl1 in stabilizing the Mon2/Dop1 complex and uncovered a new function for Vps13 in early endosome recycling and Neo1 localization. We further showed that the cargo-selective sorting nexin Snx3 is required for Neo1 trafficking and identified an Snx3 sorting motif in the Neo1 N-terminus. Of importance, the Snx3-dependent sorting of Neo1 was required for the correct sorting of another Snx3 cargo protein, suggesting that the incorporation of Neo1 into recycling tubules may influence their formation.
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Affiliation(s)
- Lauren E Dalton
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Björn D M Bean
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Michael Davey
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Elizabeth Conibear
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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8
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Schultzhaus Z, Yan H, Shaw BD. Aspergillus nidulansflippase DnfA is cargo of the endocytic collar and plays complementary roles in growth and phosphatidylserine asymmetry with another flippase, DnfB. Mol Microbiol 2015; 97:18-32. [DOI: 10.1111/mmi.13019] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/31/2015] [Indexed: 12/22/2022]
Affiliation(s)
- Zachary Schultzhaus
- Department of Plant Pathology and Microbiology; Texas A&M University; College Station TX USA
| | - Huijuan Yan
- Department of Plant Protection; Fujian Agricultural and Forestry University; Fuzhou Fujian China
| | - Brian D. Shaw
- Department of Plant Pathology and Microbiology; Texas A&M University; College Station TX USA
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9
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Takeda M, Yamagami K, Tanaka K. Role of phosphatidylserine in phospholipid flippase-mediated vesicle transport in Saccharomyces cerevisiae. EUKARYOTIC CELL 2014; 13:363-75. [PMID: 24390140 PMCID: PMC3957583 DOI: 10.1128/ec.00279-13] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 12/26/2013] [Indexed: 02/07/2023]
Abstract
Phospholipid flippases translocate phospholipids from the exoplasmic to the cytoplasmic leaflet of cell membranes to generate and maintain phospholipid asymmetry. The genome of budding yeast encodes four heteromeric flippases (Drs2p, Dnf1p, Dnf2p, and Dnf3p), which associate with the Cdc50 family noncatalytic subunit, and one monomeric flippase Neo1p. Flippases have been implicated in the formation of transport vesicles, but the underlying mechanisms are largely unknown. We show here that overexpression of the phosphatidylserine synthase gene CHO1 suppresses defects in the endocytic recycling pathway in flippase mutants. This suppression seems to be mediated by increased cellular phosphatidylserine. Two models can be envisioned for the suppression mechanism: (i) phosphatidylserine in the cytoplasmic leaflet recruits proteins for vesicle formation with its negative charge, and (ii) phosphatidylserine flipping to the cytoplasmic leaflet induces membrane curvature that supports vesicle formation. In a mutant depleted for flippases, a phosphatidylserine probe GFP-Lact-C2 was still localized to endosomal membranes, suggesting that the mere presence of phosphatidylserine in the cytoplasmic leaflet is not enough for vesicle formation. The CHO1 overexpression did not suppress the growth defect in a mutant depleted or mutated for all flippases, suggesting that the suppression was dependent on flippase-mediated phospholipid flipping. Endocytic recycling was not blocked in a mutant lacking phosphatidylserine or depleted in phosphatidylethanolamine, suggesting that a specific phospholipid is not required for vesicle formation. These results suggest that flippase-dependent vesicle formation is mediated by phospholipid flipping, not by flipped phospholipids.
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Affiliation(s)
- Miyoko Takeda
- Division of Molecular Interaction, Institute for Genetic Medicine, Hokkaido University, Graduate School of Life Science, Kita-ku, Sapporo, Japan
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10
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Xu P, Baldridge RD, Chi RJ, Burd CG, Graham TR. Phosphatidylserine flipping enhances membrane curvature and negative charge required for vesicular transport. ACTA ACUST UNITED AC 2013; 202:875-86. [PMID: 24019533 PMCID: PMC3776346 DOI: 10.1083/jcb.201305094] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Drs2 flippase increases membrane curvature and anionic phospholipid composition of the membrane by flipping phosphatidylserine, which is critical for vesicular transport between the trans-Golgi network and early endosomes. Vesicle-mediated protein transport between organelles of the secretory and endocytic pathways is strongly influenced by the composition and organization of membrane lipids. In budding yeast, protein transport between the trans-Golgi network (TGN) and early endosome (EE) requires Drs2, a phospholipid translocase in the type IV P-type ATPase family. However, downstream effectors of Drs2 and specific phospholipid substrate requirements for protein transport in this pathway are unknown. Here, we show that the Arf GTPase-activating protein (ArfGAP) Gcs1 is a Drs2 effector that requires a variant of the ArfGAP lipid packing sensor (+ALPS) motif for localization to TGN/EE membranes. Drs2 increases membrane curvature and anionic phospholipid composition of the cytosolic leaflet, both of which are sensed by the +ALPS motif. Using mutant forms of Drs2 and the related protein Dnf1, which alter their ability to recognize phosphatidylserine, we show that translocation of this substrate to the cytosolic leaflet is essential for +ALPS binding and vesicular transport between the EE and the TGN.
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Affiliation(s)
- Peng Xu
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235
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11
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Hachiro T, Yamamoto T, Nakano K, Tanaka K. Phospholipid flippases Lem3p-Dnf1p and Lem3p-Dnf2p are involved in the sorting of the tryptophan permease Tat2p in yeast. J Biol Chem 2012; 288:3594-608. [PMID: 23250744 DOI: 10.1074/jbc.m112.416263] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The type 4 P-type ATPases are flippases that generate phospholipid asymmetry in membranes. In budding yeast, heteromeric flippases, including Lem3p-Dnf1p and Lem3p-Dnf2p, translocate phospholipids to the cytoplasmic leaflet of membranes. Here, we report that Lem3p-Dnf1/2p are involved in transport of the tryptophan permease Tat2p to the plasma membrane. The lem3Δ mutant exhibited a tryptophan requirement due to the mislocalization of Tat2p to intracellular membranes. Tat2p was relocalized to the plasma membrane when trans-Golgi network (TGN)-to-endosome transport was inhibited. Inhibition of ubiquitination by mutations in ubiquitination machinery also rerouted Tat2p to the plasma membrane. Lem3p-Dnf1/2p are localized to endosomal/TGN membranes in addition to the plasma membrane. Endocytosis mutants, in which Lem3p-Dnf1/2p are sequestered to the plasma membrane, also exhibited the ubiquitination-dependent missorting of Tat2p. These results suggest that Tat2p is ubiquitinated at the TGN and missorted to the vacuolar pathway in the lem3Δ mutant. The NH(2)-terminal cytoplasmic region of Tat2p containing ubiquitination acceptor lysines interacted with liposomes containing acidic phospholipids, including phosphatidylserine. This interaction was abrogated by alanine substitution mutations in the basic amino acids downstream of the ubiquitination sites. Interestingly, a mutant Tat2p containing these substitutions was missorted in a ubiquitination-dependent manner. We propose the following model based on these results; Tat2p is not ubiquitinated when the NH(2)-terminal region is bound to membrane phospholipids, but if it dissociates from the membrane due to a low level of phosphatidylserine caused by perturbation of phospholipid asymmetry in the lem3Δ mutant, Tat2p is ubiquitinated and then transported from the TGN to the vacuole.
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Affiliation(s)
- Takeru Hachiro
- Division of Molecular Interaction, Institute for Genetic Medicine, Hokkaido University Graduate School of Life Science, N15 W7, Kita-ku, Sapporo 060-0815, Japan
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