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Ma X, Li X, Wang W, Zhang M, Yang B, Miao Z. Phosphatidylserine, inflammation, and central nervous system diseases. Front Aging Neurosci 2022; 14:975176. [PMID: 35992593 PMCID: PMC9382310 DOI: 10.3389/fnagi.2022.975176] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 07/15/2022] [Indexed: 11/13/2022] Open
Abstract
Phosphatidylserine (PS) is an anionic phospholipid in the eukaryotic membrane and is abundant in the brain. Accumulated studies have revealed that PS is involved in the multiple functions of the brain, such as activation of membrane signaling pathways, neuroinflammation, neurotransmission, and synaptic refinement. Those functions of PS are related to central nervous system (CNS) diseases. In this review, we discuss the metabolism of PS, the anti-inflammation function of PS in the brain; the alterations of PS in different CNS diseases, and the possibility of PS to serve as a therapeutic agent for diseases. Clinical studies have showed that PS has no side effects and is well tolerated. Therefore, PS and PS liposome could be a promising supplementation for these neurodegenerative and neurodevelopmental diseases.
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Affiliation(s)
- Xiaohua Ma
- Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, China
- Institute of Neuroscience, Soochow University, Suzhou, China
| | - Xiaojing Li
- Suzhou Science and Technology Town Hospital, Suzhou, China
| | - Wenjuan Wang
- Institute of Neuroscience, Soochow University, Suzhou, China
| | - Meng Zhang
- Institute of Neuroscience, Soochow University, Suzhou, China
| | - Bo Yang
- Department of Anesthesiology, The Second Affiliated Hospital of Soochow University, Suzhou, China
- *Correspondence: Bo Yang,
| | - Zhigang Miao
- Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, China
- Institute of Neuroscience, Soochow University, Suzhou, China
- Zhigang Miao,
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2
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Rodríguez LR, Lapeña-Luzón T, Benetó N, Beltran-Beltran V, Pallardó FV, Gonzalez-Cabo P, Navarro JA. Therapeutic Strategies Targeting Mitochondrial Calcium Signaling: A New Hope for Neurological Diseases? Antioxidants (Basel) 2022; 11:antiox11010165. [PMID: 35052668 PMCID: PMC8773297 DOI: 10.3390/antiox11010165] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/12/2022] [Accepted: 01/13/2022] [Indexed: 12/13/2022] Open
Abstract
Calcium (Ca2+) is a versatile secondary messenger involved in the regulation of a plethora of different signaling pathways for cell maintenance. Specifically, intracellular Ca2+ homeostasis is mainly regulated by the endoplasmic reticulum and the mitochondria, whose Ca2+ exchange is mediated by appositions, termed endoplasmic reticulum-mitochondria-associated membranes (MAMs), formed by proteins resident in both compartments. These tethers are essential to manage the mitochondrial Ca2+ influx that regulates the mitochondrial function of bioenergetics, mitochondrial dynamics, cell death, and oxidative stress. However, alterations of these pathways lead to the development of multiple human diseases, including neurological disorders, such as amyotrophic lateral sclerosis, Friedreich's ataxia, and Charcot-Marie-Tooth. A common hallmark in these disorders is mitochondrial dysfunction, associated with abnormal mitochondrial Ca2+ handling that contributes to neurodegeneration. In this work, we highlight the importance of Ca2+ signaling in mitochondria and how the mechanism of communication in MAMs is pivotal for mitochondrial maintenance and cell homeostasis. Lately, we outstand potential targets located in MAMs by addressing different therapeutic strategies focused on restoring mitochondrial Ca2+ uptake as an emergent approach for neurological diseases.
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Affiliation(s)
- Laura R. Rodríguez
- Department of Physiology, Faculty of Medicine and Dentistry, Universitat de València-INCLIVA, 46010 Valencia, Spain; (T.L.-L.); (N.B.); (V.B.-B.); (F.V.P.)
- Associated Unit for Rare Diseases INCLIVA-CIPF, 46010 Valencia, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 46010 Valencia, Spain
- Correspondence: (L.R.R.); (P.G.-C.); (J.A.N.)
| | - Tamara Lapeña-Luzón
- Department of Physiology, Faculty of Medicine and Dentistry, Universitat de València-INCLIVA, 46010 Valencia, Spain; (T.L.-L.); (N.B.); (V.B.-B.); (F.V.P.)
- Associated Unit for Rare Diseases INCLIVA-CIPF, 46010 Valencia, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 46010 Valencia, Spain
| | - Noelia Benetó
- Department of Physiology, Faculty of Medicine and Dentistry, Universitat de València-INCLIVA, 46010 Valencia, Spain; (T.L.-L.); (N.B.); (V.B.-B.); (F.V.P.)
- Associated Unit for Rare Diseases INCLIVA-CIPF, 46010 Valencia, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 46010 Valencia, Spain
| | - Vicent Beltran-Beltran
- Department of Physiology, Faculty of Medicine and Dentistry, Universitat de València-INCLIVA, 46010 Valencia, Spain; (T.L.-L.); (N.B.); (V.B.-B.); (F.V.P.)
| | - Federico V. Pallardó
- Department of Physiology, Faculty of Medicine and Dentistry, Universitat de València-INCLIVA, 46010 Valencia, Spain; (T.L.-L.); (N.B.); (V.B.-B.); (F.V.P.)
- Associated Unit for Rare Diseases INCLIVA-CIPF, 46010 Valencia, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 46010 Valencia, Spain
| | - Pilar Gonzalez-Cabo
- Department of Physiology, Faculty of Medicine and Dentistry, Universitat de València-INCLIVA, 46010 Valencia, Spain; (T.L.-L.); (N.B.); (V.B.-B.); (F.V.P.)
- Associated Unit for Rare Diseases INCLIVA-CIPF, 46010 Valencia, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 46010 Valencia, Spain
- Correspondence: (L.R.R.); (P.G.-C.); (J.A.N.)
| | - Juan Antonio Navarro
- Department of Genetics, Universitat de València-INCLIVA, 46100 Valencia, Spain
- INCLIVA Biomedical Research Institute, 46010 Valencia, Spain
- Correspondence: (L.R.R.); (P.G.-C.); (J.A.N.)
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3
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Wang Y, Zhang X, Wen Y, Li S, Lu X, Xu R, Li C. Endoplasmic Reticulum-Mitochondria Contacts: A Potential Therapy Target for Cardiovascular Remodeling-Associated Diseases. Front Cell Dev Biol 2021; 9:774989. [PMID: 34858991 PMCID: PMC8631538 DOI: 10.3389/fcell.2021.774989] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/08/2021] [Indexed: 12/14/2022] Open
Abstract
Cardiovascular remodeling occurs in cardiomyocytes, collagen meshes, and vascular beds in the progress of cardiac insufficiency caused by a variety of cardiac diseases such as chronic ischemic heart disease, chronic overload heart disease, myocarditis, and myocardial infarction. The morphological changes that occur as a result of remodeling are the critical pathological basis for the occurrence and development of serious diseases and also determine morbidity and mortality. Therefore, the inhibition of remodeling is an important approach to prevent and treat heart failure and other related diseases. The endoplasmic reticulum (ER) and mitochondria are tightly linked by ER-mitochondria contacts (ERMCs). ERMCs play a vital role in different signaling pathways and provide a satisfactory structural platform for the ER and mitochondria to interact and maintain the normal function of cells, mainly by involving various cellular life processes such as lipid metabolism, calcium homeostasis, mitochondrial function, ER stress, and autophagy. Studies have shown that abnormal ERMCs may promote the occurrence and development of remodeling and participate in the formation of a variety of cardiovascular remodeling-associated diseases. This review focuses on the structure and function of the ERMCs, and the potential mechanism of ERMCs involved in cardiovascular remodeling, indicating that ERMCs may be a potential target for new therapeutic strategies against cardiovascular remodeling-induced diseases.
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Affiliation(s)
- Yu Wang
- Innovation Research Institute of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China.,Emergency Department, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Xinrong Zhang
- Innovation Research Institute of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Ya Wen
- Innovation Research Institute of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Sixuan Li
- Innovation Research Institute of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Xiaohui Lu
- Emergency Department, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Ran Xu
- Jinan Tianqiao People's Hospital, Jinan, China
| | - Chao Li
- Innovation Research Institute of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China
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4
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Ristovski M, Farhat D, Bancud SEM, Lee JY. Lipid Transporters Beam Signals from Cell Membranes. MEMBRANES 2021; 11:562. [PMID: 34436325 PMCID: PMC8399137 DOI: 10.3390/membranes11080562] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 07/21/2021] [Accepted: 07/22/2021] [Indexed: 12/12/2022]
Abstract
Lipid composition in cellular membranes plays an important role in maintaining the structural integrity of cells and in regulating cellular signaling that controls functions of both membrane-anchored and cytoplasmic proteins. ATP-dependent ABC and P4-ATPase lipid transporters, two integral membrane proteins, are known to contribute to lipid translocation across the lipid bilayers on the cellular membranes. In this review, we will highlight current knowledge about the role of cholesterol and phospholipids of cellular membranes in regulating cell signaling and how lipid transporters participate this process.
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Affiliation(s)
- Miliça Ristovski
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada; (M.R.); (D.F.); (S.E.M.B.)
- Translational and Molecular Medicine Program, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Danny Farhat
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada; (M.R.); (D.F.); (S.E.M.B.)
- Biomedical Sciences Program, Faculty of Science, University of Ottawa, Ottawa, ON K1H 6N5, Canada
| | - Shelly Ellaine M. Bancud
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada; (M.R.); (D.F.); (S.E.M.B.)
- Translational and Molecular Medicine Program, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Jyh-Yeuan Lee
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada; (M.R.); (D.F.); (S.E.M.B.)
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5
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Giamogante F, Poggio E, Barazzuol L, Covallero A, Calì T. Apoptotic signals at the endoplasmic reticulum-mitochondria interface. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2021; 126:307-343. [PMID: 34090618 DOI: 10.1016/bs.apcsb.2021.02.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The maintenance of cellular homeostasis involves the participation of multiple organelles, such as the endoplasmic reticulum (ER) and mitochondria. Specifically, ER plays a key role in calcium (Ca2+) storage, lipid synthesis, protein folding, and assembly, while mitochondria are the "energy factories" and provide energy to drive intracellular processes. Hence, alteration in ER or mitochondrial homeostasis has detrimental effects on cell survival, being linked to the triggering of apoptosis, a programmed form of cell death. Besides, ER stress conditions affect mitochondria functionality and vice-versa, as ER and mitochondria communicate via mitochondria-associated ER membranes (MAMs) to carry out a number of fundamental cellular functions. It is not surprising, thus, that also MAMs perturbations are involved in the regulation of apoptosis. This chapter intends to accurately discuss the involvement of MAMs in apoptosis, highlighting their crucial role in controlling this delicate cellular process.
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Affiliation(s)
- Flavia Giamogante
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Elena Poggio
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Lucia Barazzuol
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Alberto Covallero
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Tito Calì
- Department of Biomedical Sciences, University of Padova, Padova, Italy.
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6
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Pera M, Montesinos J, Larrea D, Agrawal RR, Velasco KR, Stavrovskaya IG, Yun TD, Area-Gomez E. MAM and C99, key players in the pathogenesis of Alzheimer's disease. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2020; 154:235-278. [PMID: 32739006 DOI: 10.1016/bs.irn.2020.03.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Inter-organelle communication is a rapidly-expanding field that has transformed our understanding of cell biology and pathology. Organelle-organelle contact sites can generate transient functional domains that act as enzymatic hubs involved in the regulation of cellular metabolism and intracellular signaling. One of these hubs is located in areas of the endoplasmic reticulum (ER) connected to mitochondria, called mitochondria-associated ER membranes (MAM). These MAM are transient lipid rafts intimately involved in cholesterol and phospholipid metabolism, calcium homeostasis, and mitochondrial function and dynamics. In addition, γ-secretase-mediated proteolysis of the amyloid precursor protein 99-aa C-terminal fragment (C99) to form amyloid β also occurs at the MAM. Our most recent data indicates that in Alzheimer's disease, increases in uncleaved C99 levels at the MAM provoke the upregulation of MAM-resident functions, resulting in the loss of lipid homeostasis, and mitochondrial dysfunction. Here, we discuss the relevance of these findings in the field, and the contribution of C99 and MAM dysfunction to Alzheimer's disease neuropathology.
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Affiliation(s)
- Marta Pera
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, United States; Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Sant Cugat del Vallés, Barcelona, Spain.
| | - Jorge Montesinos
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, United States; Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Irving Medical Center, New York, NY, United States
| | - Delfina Larrea
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, United States
| | - Rishi R Agrawal
- Institute of Human Nutrition, Columbia University Irving Medical Center, New York, NY, United States
| | - Kevin R Velasco
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, United States
| | - Irina G Stavrovskaya
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, United States
| | - Taekyung D Yun
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, United States
| | - Estela Area-Gomez
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, United States; Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Irving Medical Center, New York, NY, United States; Institute of Human Nutrition, Columbia University Irving Medical Center, New York, NY, United States.
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7
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Filadi R, Theurey P, Pizzo P. The endoplasmic reticulum-mitochondria coupling in health and disease: Molecules, functions and significance. Cell Calcium 2017; 62:1-15. [PMID: 28108029 DOI: 10.1016/j.ceca.2017.01.003] [Citation(s) in RCA: 154] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 01/09/2017] [Accepted: 01/09/2017] [Indexed: 12/14/2022]
Abstract
The close apposition between endoplasmic reticulum (ER) and mitochondria represents a key platform, capable to regulate different fundamental cellular pathways. Among these, Ca2+ signaling and lipid homeostasis have been demonstrated over the last years to be deeply modulated by ER-mitochondria cross-talk. Given its importance in cell life/death decisions, increasing evidence suggests that alterations of the ER-mitochondria axis could be responsible for the onset and progression of several diseases, including neurodegeneration, cancer and obesity. However, the molecular identity of the proteins controlling this inter-organelle apposition is still debated. In this review, we summarize the main cellular pathways controlled by ER-mitochondria appositions, focusing on the principal molecules reported to be involved in this interplay and on those diseases for which alterations in organelles communication have been reported.
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Affiliation(s)
- Riccardo Filadi
- Department of Biomedical Sciences, University of Padova, Italy
| | - Pierre Theurey
- Department of Biomedical Sciences, University of Padova, Italy
| | - Paola Pizzo
- Department of Biomedical Sciences, University of Padova, Italy; Neuroscience Institute, National Research Council (CNR), Padova, Italy.
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8
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Gsell M, Fankl A, Klug L, Mascher G, Schmidt C, Hrastnik C, Zellnig G, Daum G. A Yeast Mutant Deleted of GPH1 Bears Defects in Lipid Metabolism. PLoS One 2015; 10:e0136957. [PMID: 26327557 PMCID: PMC4556709 DOI: 10.1371/journal.pone.0136957] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 08/10/2015] [Indexed: 11/18/2022] Open
Abstract
In a previous study we demonstrated up-regulation of the yeast GPH1 gene under conditions of phosphatidylethanolamine (PE) depletion caused by deletion of the mitochondrial (M) phosphatidylserine decarboxylase 1 (PSD1) (Gsell et al., 2013, PLoS One. 8(10):e77380. doi: 10.1371/journal.pone.0077380). Gph1p has originally been identified as a glycogen phosphorylase catalyzing degradation of glycogen to glucose in the stationary growth phase of the yeast. Here we show that deletion of this gene also causes decreased levels of phosphatidylcholine (PC), triacylglycerols and steryl esters. Depletion of the two non-polar lipids in a Δgph1 strain leads to lack of lipid droplets, and decrease of the PC level results in instability of the plasma membrane. In vivo labeling experiments revealed that formation of PC via both pathways of biosynthesis, the cytidine diphosphate (CDP)-choline and the methylation route, is negatively affected by a Δgph1 mutation, although expression of genes involved is not down regulated. Altogether, Gph1p besides its function as a glycogen mobilizing enzyme appears to play a regulatory role in yeast lipid metabolism.
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Affiliation(s)
- Martina Gsell
- Institute of Biochemistry, Graz University of Technology, NaWi Graz, Petersgasse 12/2, 8010, Graz, Austria
| | - Ariane Fankl
- Institute of Biochemistry, Graz University of Technology, NaWi Graz, Petersgasse 12/2, 8010, Graz, Austria
| | - Lisa Klug
- Institute of Biochemistry, Graz University of Technology, NaWi Graz, Petersgasse 12/2, 8010, Graz, Austria
| | - Gerald Mascher
- Institute of Biochemistry, Graz University of Technology, NaWi Graz, Petersgasse 12/2, 8010, Graz, Austria
| | - Claudia Schmidt
- Institute of Biochemistry, Graz University of Technology, NaWi Graz, Petersgasse 12/2, 8010, Graz, Austria
| | - Claudia Hrastnik
- Institute of Biochemistry, Graz University of Technology, NaWi Graz, Petersgasse 12/2, 8010, Graz, Austria
| | - Günther Zellnig
- Institute of Plant Sciences, Karl Franzens University Graz, NaWi Graz, Austria
| | - Günther Daum
- Institute of Biochemistry, Graz University of Technology, NaWi Graz, Petersgasse 12/2, 8010, Graz, Austria
- * E-mail:
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9
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Flis VV, Fankl A, Ramprecht C, Zellnig G, Leitner E, Hermetter A, Daum G. Phosphatidylcholine Supply to Peroxisomes of the Yeast Saccharomyces cerevisiae. PLoS One 2015; 10:e0135084. [PMID: 26241051 PMCID: PMC4524607 DOI: 10.1371/journal.pone.0135084] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 07/17/2015] [Indexed: 12/23/2022] Open
Abstract
In the yeast Saccharomyces cerevisiae, phosphatidylcholine (PC), the major phospholipid (PL) of all organelle membranes, is synthesized via two different pathways. Methylation of phosphatidylethanolamine (PE) catalyzed by the methyl transferases Cho2p/Pem1p and Opi3p/Pem2p as well as incorporation of choline through the CDP (cytidine diphosphate)-choline branch of the Kennedy pathway lead to PC formation. To determine the contribution of these two pathways to the supply of PC to peroxisomes (PX), yeast mutants bearing defects in the two pathways were cultivated under peroxisome inducing conditions, i.e. in the presence of oleic acid, and subjected to biochemical and cell biological analyses. Phenotype studies revealed compromised growth of both the cho20Δopi3Δ (mutations in the methylation pathway) and the cki1Δdpl1Δeki1Δ (mutations in the CDP-choline pathway) mutant when grown on oleic acid. Analysis of peroxisomes from the two mutant strains showed that both pathways produce PC for the supply to peroxisomes, although the CDP-choline pathway seemed to contribute with higher efficiency than the methylation pathway. Changes in the peroxisomal lipid pattern of mutants caused by defects in the PC biosynthetic pathways resulted in changes of membrane properties as shown by anisotropy measurements with fluorescent probes. In summary, our data define the origin of peroxisomal PC and demonstrate the importance of PC for peroxisome membrane formation and integrity.
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Affiliation(s)
- Vid V. Flis
- Institute of Biochemistry, Graz University of Technology, NAWI Graz, Graz, Austria
| | - Ariane Fankl
- Institute of Biochemistry, Graz University of Technology, NAWI Graz, Graz, Austria
| | - Claudia Ramprecht
- Institute of Biochemistry, Graz University of Technology, NAWI Graz, Graz, Austria
| | - Günther Zellnig
- Institute of Plant Sciences, University of Graz, NAWI Graz, Graz, Austria
| | - Erich Leitner
- Institute of Analytical Chemistry and Food Technology, Graz University of Technology, NAWI Graz, Graz, Austria
| | - Albin Hermetter
- Institute of Biochemistry, Graz University of Technology, NAWI Graz, Graz, Austria
| | - Günther Daum
- Institute of Biochemistry, Graz University of Technology, NAWI Graz, Graz, Austria
- * E-mail:
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10
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Yin C, Andersson MX, Zhang H, Aronsson H. Phosphatidylcholine is transferred from chemically-defined liposomes to chloroplasts through proteins of the chloroplast outer envelope membrane. FEBS Lett 2015; 589:177-81. [PMID: 25479091 DOI: 10.1016/j.febslet.2014.11.044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 11/24/2014] [Accepted: 11/24/2014] [Indexed: 10/24/2022]
Abstract
Chloroplasts maintain their lipid balance through a tight interplay with the endoplasmic reticulum (ER). The outer envelope membrane of chloroplasts contains a large proportion of the phospholipid phosphatidylcholine (PC), which is synthesized in the ER and also a possible precursor for thylakoid galactolipids. The mechanism for PC transport from the ER to chloroplasts is not known. Using isolated chloroplasts and liposomes containing radiolabeled PC we investigated non-vesicular transport of PC in vitro. PC uptake in chloroplasts was time and temperature dependent, but nucleotide independent. Increased radius of liposomes stimulated PC uptake, and protease treatment of the chloroplasts impaired PC uptake. This implies that the chloroplast outer envelopes contains an exposed proteinaceous machinery for the uptake of PC from closely apposed membranes.
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Affiliation(s)
- Congfei Yin
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, People's Republic of China; Department of Biological and Environmental Sciences, University of Gothenburg, SE-405 30 Gothenburg, Sweden
| | - Mats X Andersson
- Department of Biological and Environmental Sciences, University of Gothenburg, SE-405 30 Gothenburg, Sweden
| | - Hongsheng Zhang
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, People's Republic of China.
| | - Henrik Aronsson
- Department of Biological and Environmental Sciences, University of Gothenburg, SE-405 30 Gothenburg, Sweden.
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11
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Kannan M, Riekhof WR, Voelker DR. Transport of Phosphatidylserine from the Endoplasmic Reticulum to the Site of Phosphatidylserine Decarboxylase2 in Yeast. Traffic 2014; 16:123-34. [DOI: 10.1111/tra.12236] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 10/17/2014] [Accepted: 10/28/2014] [Indexed: 02/03/2023]
Affiliation(s)
- Muthukumar Kannan
- Department of Medicine and Program in Cell Biology; National Jewish Health; Denver CO 80206 USA
| | - Wayne R. Riekhof
- School of Biological Sciences; University of Nebraska; Lincoln NE 68588 USA
| | - Dennis R. Voelker
- Department of Medicine and Program in Cell Biology; National Jewish Health; Denver CO 80206 USA
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12
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Baldridge RD, Xu P, Graham TR. Type IV P-type ATPases distinguish mono- versus diacyl phosphatidylserine using a cytofacial exit gate in the membrane domain. J Biol Chem 2013; 288:19516-27. [PMID: 23709217 PMCID: PMC3707653 DOI: 10.1074/jbc.m113.476911] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 05/09/2013] [Indexed: 12/22/2022] Open
Abstract
Type IV P-type ATPases (P4-ATPases) use the energy from ATP to "flip" phospholipid across a lipid bilayer, facilitating membrane trafficking events and maintaining the characteristic plasma membrane phospholipid asymmetry. Preferred translocation substrates for the budding yeast P4-ATPases Dnf1 and Dnf2 include lysophosphatidylcholine, lysophosphatidylethanolamine, derivatives of phosphatidylcholine and phosphatidylethanolamine containing a 7-nitro-2-1,3-benzoxadiazol-4-yl (NBD) group on the sn-2 C6 position, and were presumed to include phosphatidylcholine and phosphatidylethanolamine species with two intact acyl chains. We previously identified several mutations in Dnf1 transmembrane (TM) segments 1 through 4 that greatly enhance recognition and transport of NBD phosphatidylserine (NBD-PS). Here we show that most of these Dnf1 mutants cannot flip diacylated PS to the cytosolic leaflet to establish PS asymmetry. However, mutation of a highly conserved asparagine (Asn-550) in TM3 allowed Dnf1 to restore plasma membrane PS asymmetry in a strain deficient for the P4-ATPase Drs2, the primary PS flippase. Moreover, Dnf1 N550 mutants could replace the Drs2 requirement for growth at low temperature. A screen for additional Dnf1 mutants capable of replacing Drs2 function identified substitutions of TM1 and 2 residues, within a region called the exit gate, that permit recognition of dually acylated PS. These TM1, 2, and 3 residues coordinate with the "proline + 4" residue within TM4 to determine substrate preference at the exit gate. Moreover, residues from Atp8a1, a mammalian ortholog of Drs2, in these positions allow PS recognition by Dnf1. These studies indicate that Dnf1 poorly recognizes diacylated phospholipid and define key substitutions enabling recognition of endogenous PS.
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Affiliation(s)
- Ryan D. Baldridge
- From the Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235
| | - Peng Xu
- From the Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235
| | - Todd R. Graham
- From the Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235
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13
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English AR, Voeltz GK. Endoplasmic reticulum structure and interconnections with other organelles. Cold Spring Harb Perspect Biol 2013; 5:a013227. [PMID: 23545422 DOI: 10.1101/cshperspect.a013227] [Citation(s) in RCA: 226] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The endoplasmic reticulum (ER) is a large, continuous membrane-bound organelle comprised of functionally and structurally distinct domains including the nuclear envelope, peripheral tubular ER, peripheral cisternae, and numerous membrane contact sites at the plasma membrane, mitochondria, Golgi, endosomes, and peroxisomes. These domains are required for multiple cellular processes, including synthesis of proteins and lipids, calcium level regulation, and exchange of macromolecules with various organelles at ER-membrane contact sites. The ER maintains its unique overall structure regardless of dynamics or transfer at ER-organelle contacts. In this review, we describe the numerous factors that contribute to the structure of the ER.
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Affiliation(s)
- Amber R English
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
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14
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Abstract
The most well-characterized organelle contact sites are those between the endoplasmic reticulum (ER) and mitochondria. Increased understanding is being gained of how ER-mitochondria contact sites are organized and which factors converge at this interface, some of which may provide a tethering function. The role of the ER-mitochondria junction in coordinating the functions of these two organelles is also becoming clearer, and it has been shown to be involved in the regulation of lipid synthesis, Ca(2+) signalling and the control of mitochondrial biogenesis and intracellular trafficking.
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15
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Singh A, Yadav V, Prasad R. Comparative lipidomics in clinical isolates of Candida albicans reveal crosstalk between mitochondria, cell wall integrity and azole resistance. PLoS One 2012; 7:e39812. [PMID: 22761908 PMCID: PMC3384591 DOI: 10.1371/journal.pone.0039812] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 05/26/2012] [Indexed: 11/19/2022] Open
Abstract
Prolonged usage of antifungal azoles which target enzymes involved in lipid biosynthesis invariably leads to the development of multi-drug resistance (MDR) in Candida albicans. We had earlier shown that membrane lipids and their fluidity are closely linked to the MDR phenomenon. In one of our recent studies involving comparative lipidomics between azole susceptible (AS) and azole resistant (AR) matched pair clinical isolates of C. albicans, we could not see consistent differences in the lipid profiles of AS and AR strains because they came from different patients and so in this study, we have used genetically related variant recovered from the same patient collected over a period of 2-years. During this time, the levels of fluconazole (FLC) resistance of the strain increased by over 200-fold. By comparing the lipid profiles of select isolates, we were able to observe gradual and statistically significant changes in several lipid classes, particularly in plasma membrane microdomain specific lipids such as mannosylinositolphosphorylceramides and ergosterol, and in a mitochondrial specific phosphoglyceride, phosphatidyl glycerol. Superimposed with these quantitative and qualitative changes in the lipid profiles, were simultaneous changes at the molecular lipid species levels which again coincided with the development of resistance to FLC. Reverse transcriptase-PCR of the key genes of the lipid metabolism validated lipidomic picture. Taken together, this study illustrates how the gradual corrective changes in Candida lipidome correspond to the development of FLC tolerance. Our study also shows a first instance of the mitochondrial membrane dysfunction and defective cell wall (CW) in clinical AR isolates of C. albicans, and provides evidence of a cross-talk between mitochondrial lipid homeostasis, CW integrity and azole tolerance.
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Affiliation(s)
- Ashutosh Singh
- Membrane Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Vipin Yadav
- Membrane Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Rajendra Prasad
- Membrane Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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16
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Berry KAZ, Hankin JA, Barkley RM, Spraggins JM, Caprioli RM, Murphy RC. MALDI imaging of lipid biochemistry in tissues by mass spectrometry. Chem Rev 2011; 111:6491-512. [PMID: 21942646 PMCID: PMC3199966 DOI: 10.1021/cr200280p] [Citation(s) in RCA: 277] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Karin A. Zemski Berry
- Department of Pharmacology, University of Colorado Denver, Mail Stop 8303, 12801 E. 17 Ave., Aurora, CO 80045
| | - Joseph A. Hankin
- Department of Pharmacology, University of Colorado Denver, Mail Stop 8303, 12801 E. 17 Ave., Aurora, CO 80045
| | - Robert M. Barkley
- Department of Pharmacology, University of Colorado Denver, Mail Stop 8303, 12801 E. 17 Ave., Aurora, CO 80045
| | - Jeffrey M. Spraggins
- Department of Biochemistry and Mass Spectrometry Research Center, Vanderbilt University, 9160 MRB 3, 465 21 Ave. S., Nashville, TN 37232
| | - Richard M. Caprioli
- Department of Biochemistry and Mass Spectrometry Research Center, Vanderbilt University, 9160 MRB 3, 465 21 Ave. S., Nashville, TN 37232
| | - Robert C. Murphy
- Department of Pharmacology, University of Colorado Denver, Mail Stop 8303, 12801 E. 17 Ave., Aurora, CO 80045
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17
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Mitochondria and fungal pathogenesis: drug tolerance, virulence, and potential for antifungal therapy. EUKARYOTIC CELL 2011; 10:1376-83. [PMID: 21926328 DOI: 10.1128/ec.05184-11] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Recently, mitochondria have been identified as important contributors to the virulence and drug tolerance of human fungal pathogens. In different scenarios, either hypo- or hypervirulence can result from changes in mitochondrial function. Similarly, specific mitochondrial mutations lead to either sensitivity or resistance to antifungal drugs. Here, we provide a synthesis of this emerging field, proposing that mitochondrial function in membrane lipid homeostasis is the common denominator underlying the observed effects of mitochondria in drug tolerance (both sensitivity and resistance). We discuss how the contrasting effects of mitochondrial dysfunction on fungal drug tolerance and virulence could be explained and the potential for targeting mitochondrial factors for future antifungal drug development.
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18
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Fujimoto M, Hayashi T. New Insights into the Role of Mitochondria-Associated Endoplasmic Reticulum Membrane. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 292:73-117. [DOI: 10.1016/b978-0-12-386033-0.00002-5] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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19
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Dagley MJ, Gentle IE, Beilharz TH, Pettolino FA, Djordjevic JT, Lo TL, Uwamahoro N, Rupasinghe T, Tull DL, McConville M, Beaurepaire C, Nantel A, Lithgow T, Mitchell AP, Traven A. Cell wall integrity is linked to mitochondria and phospholipid homeostasis in Candida albicans through the activity of the post-transcriptional regulator Ccr4-Pop2. Mol Microbiol 2010; 79:968-89. [PMID: 21299651 DOI: 10.1111/j.1365-2958.2010.07503.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The cell wall is essential for viability of fungi and is an effective drug target in pathogens such as Candida albicans. The contribution of post-transcriptional gene regulators to cell wall integrity in C. albicans is unknown. We show that the C. albicans Ccr4-Pop2 mRNA deadenylase, a regulator of mRNA stability and translation, is required for cell wall integrity. The ccr4/pop2 mutants display reduced wall β-glucans and sensitivity to the echinocandin caspofungin. Moreover, the deadenylase mutants are compromised for filamentation and virulence. We demonstrate that defective cell walls in the ccr4/pop2 mutants are linked to dysfunctional mitochondria and phospholipid imbalance. To further understand mitochondrial function in cell wall integrity, we screened a Saccharomyces cerevisiae collection of mitochondrial mutants. We identify several mitochondrial proteins required for caspofungin tolerance and find a connection between mitochondrial phospholipid homeostasis and caspofungin sensitivity. We focus on the mitochondrial outer membrane SAM complex subunit Sam37, demonstrating that it is required for both trafficking of phospholipids between the ER and mitochondria and cell wall integrity. Moreover, in C. albicans also Sam37 is essential for caspofungin tolerance. Our study provides the basis for an integrative view of mitochondrial function in fungal cell wall biogenesis and resistance to echinocandin antifungal drugs.
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Affiliation(s)
- Michael J Dagley
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
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20
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Hayashi T, Su TP. Cholesterol at the endoplasmic reticulum: roles of the sigma-1 receptor chaperone and implications thereof in human diseases. Subcell Biochem 2010; 51:381-98. [PMID: 20213551 PMCID: PMC3155710 DOI: 10.1007/978-90-481-8622-8_13] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Despite substantial data elucidating the roles of cholesterol in lipid rafts at the plasma membrane, the roles of cholesterol and related lipids in lipid raft microdomains at the level of subcellular membrane, such as the endoplasmic reticulum (ER) membrane, remain less understood. Growing evidence, however, begins to unveil the importance of cholesterol and lipids on the lipid raft at the ER membrane. A few ER proteins including the sigma-1 receptor chaperone were identified at lipid raft-like microdomains of the ER membrane. The sigma-1 receptor, which is highly expressed at a subdomain of ER membrane directly apposing mitochondria and known as the mitochondria-associated ER membrane or MAM, has been shown to associate with steroids as well as cholesterol. The sigma-1 receptor has been implicated in ER lipid metabolisms/transports, lipid raft reconstitution at the plasma membrane, trophic factor signalling, cellular differentiation, and cellular protection against beta-amyloid-induced neurotoxicity. Recent studies on sigma-1 receptor chaperones and other ER proteins clearly suggest that cholesterol, in concert with those ER proteins, may regulate several important functions of the ER including folding, degradation, compartmentalization, and segregation of ER proteins, and the biosynthesis of sphingolipids.
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Affiliation(s)
- Teruo Hayashi
- National Institute on Drug Abuse, Department of Health and Human Services, National Institutes of Health, Baltimore, MD 21224, USA.
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21
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Rajakumari S, Daum G. Janus-faced enzymes yeast Tgl3p and Tgl5p catalyze lipase and acyltransferase reactions. Mol Biol Cell 2009; 21:501-10. [PMID: 20016004 PMCID: PMC2820416 DOI: 10.1091/mbc.e09-09-0775] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The yeast triacylglycerol (TAG) lipases Tgl3p and Tgl5p not only contain a TAG lipase, but also an acyltransferase motif. We show that purified Tgl3p and Tgl5p indeed exhibit lysophospholipid acyltransferase activity. Both Tgl3p and Tgl5p affect the level of glycerophospholipids, and Tgl3p is also important for efficient sporulation of yeast. In the yeast, mobilization of triacylglycerols (TAGs) is facilitated by the three TAG lipases Tgl3p, Tgl4p, and Tgl5p. Motif search analysis, however, indicated that Tgl3p and Tgl5p do not only contain the TAG lipase motif GXSXG but also an H-(X)4-D acyltransferase motif. Interestingly, lipid analysis revealed that deletion of TGL3 resulted in a decrease and overexpression of TGL3 in an increase of glycerophospholipids. Similar results were obtained with TGL5. Therefore, we tested purified Tgl3p and Tgl5p for acyltransferase activity. Indeed, both enzymes not only exhibited lipase activity but also catalyzed acylation of lysophosphatidylethanolamine and lysophosphatidic acid, respectively. Experiments using variants of Tgl3p created by site-directed mutagenesis clearly demonstrated that the two enzymatic activities act independently of each other. We also showed that Tgl3p is important for efficient sporulation of yeast cells, but rather through its acyltransferase than lipase activity. In summary, our results demonstrate that yeast Tgl3p and Tgl5p play a dual role in lipid metabolism contributing to both anabolic and catabolic processes.
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Affiliation(s)
- Sona Rajakumari
- Institute of Biochemistry, Graz University of Technology, A-8010 Graz, Austria
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22
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Zehmer JK, Huang Y, Peng G, Pu J, Anderson RGW, Liu P. A role for lipid droplets in inter-membrane lipid traffic. Proteomics 2009; 9:914-21. [PMID: 19160396 DOI: 10.1002/pmic.200800584] [Citation(s) in RCA: 205] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
All cells have the capacity to accumulate neutral lipids and package them into lipid droplets. Recent proteomic analyses indicate that lipid droplets are not simple lipid storage depots, but rather complex organelles that have multiple cellular functions. One of these proposed functions is to distribute neutral lipids as well as phospholipids to various membrane-bound organelles within the cell. Here, we summarize the lipid droplet-associated membrane-trafficking proteins and review the evidence that lipid droplets interact with endoplasmic reticulum, endosomes, peroxisomes, and mitochondria. Based on this evidence, we present a model for how lipid droplets can distribute lipids to specific membrane compartments.
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Affiliation(s)
- John K Zehmer
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
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23
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Mitochondrial-morphology-targeted breeding of industrial yeast strains for alcohol fermentation. Biotechnol Appl Biochem 2009; 53:145-53. [DOI: 10.1042/ba20090032] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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24
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Schuiki I, Daum G. Phosphatidylserine decarboxylases, key enzymes of lipid metabolism. IUBMB Life 2009; 61:151-62. [PMID: 19165886 DOI: 10.1002/iub.159] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Phosphatidylserine decarboxylases (PSDs) (E.C. 4.1.1.65) are enzymes which catalyze the formation of phosphatidylethanolamine (PtdEtn) by decarboxylation of phosphatidylserine (PtdSer). This enzymatic activity has been identified in both prokaryotic and eukaryotic organisms. PSDs occur as two types of proteins depending on their localization and the sequence of a conserved motif. Type I PSDs include enzymes of eukaryotic mitochondria and bacterial origin which contain the amino acid sequence LGST as a characteristic motif. Type II PSDs are found in the endomembrane system of eukaryotes and contain a typical GGST motif. These characteristic motifs are considered as autocatalytic cleavage sites where proenzymes are split into alpha- and beta-subunits. The S-residue set free by this cleavage serves as an attachment site of a pyruvoyl group which is required for the activity of the enzymes. Moreover, PSDs harbor characteristic binding sites for the substrate PtdSer. Substrate supply to eukaryotic PSDs requires lipid transport because PtdSer synthesis and decarboxylation are spatially separated. Targeting of PSDs to their proper locations requires additional intramolecular domains. Mitochondrially localized type I PSDs are directed to the inner mitochondrial membrane by N-terminal targeting sequences. Type II PSDs also contain sequences in their N-terminal extensions which might be required for subcellular targeting. Lack of PSDs causes various defects in different cell types. The physiological relevance of these findings and the central role of PSDs in lipid metabolism will be discussed in this review.
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Affiliation(s)
- Irmgard Schuiki
- Institute of Biochemistry, Graz University of Technology, Graz, Austria
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25
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Mitchell KAP, Szabo G, de S Otero A. Direct binding of cytosolic NDP kinases to membrane lipids is regulated by nucleotides. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1793:469-76. [PMID: 19146889 DOI: 10.1016/j.bbamcr.2008.12.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2008] [Revised: 11/30/2008] [Accepted: 12/03/2008] [Indexed: 11/19/2022]
Abstract
In spite of their complete lack of any structural features that characterize membrane proteins, cytosolic nucleoside-diphosphate kinases (NDPKs) have been found repeatedly to associate with membranes. In some instances the recruitment of cytosolic NDPKs to membranes was attributed to interactions with peripheral or integral membrane proteins, but in many cases the mechanism underlying the association of NDPKs with membranes remained unknown. We show here that cytosolic NDPKs bind directly to membrane lipids in a dynamic process that is controlled by its substrates, nucleoside tri- and diphosphates, and can be fully reconstituted with chemically defined, protein-free phospholipids and recombinant NDPK, or with purified NDPK. Our results uncover a novel mechanism for the reversible targeting of soluble NDPKs to membranes, where they may act as a reservoir of high energy phosphate, supporting the operation of membrane-based processes that utilize nucleotides other than ATP, such as intracellular traffic and phospholipid biosynthesis.
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Affiliation(s)
- Kimberly A P Mitchell
- Department of Molecular Physiology and Biological Physics, University of Virginia Medical School, P.O. Box 800736, Charlottesville, VA 22908-0736, USA
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26
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Federovitch CM, Jones YZ, Tong AH, Boone C, Prinz WA, Hampton RY. Genetic and structural analysis of Hmg2p-induced endoplasmic reticulum remodeling in Saccharomyces cerevisiae. Mol Biol Cell 2008; 19:4506-20. [PMID: 18667535 DOI: 10.1091/mbc.e07-11-1188] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The endoplasmic reticulum (ER) is highly plastic, and increased expression of distinct single ER-resident membrane proteins, such as HMG-CoA reductase (HMGR), can induce a dramatic restructuring of ER membranes into highly organized arrays. Studies on the ER-remodeling behavior of the two yeast HMGR isozymes, Hmg1p and Hmg2p, suggest that they could be mechanistically distinct. We examined the features of Hmg2p required to generate its characteristic structures, and we found that the molecular requirements are similar to those of Hmg1p. However, the structures generated by Hmg1p and Hmg2p have distinct cell biological features determined by the transmembrane regions of the proteins. In parallel, we conducted a genetic screen to identify HER genes (required for Hmg2p-induced ER Remodeling), further confirming that the mechanisms of membrane reorganization by these two proteins are distinct because most of the HER genes were required for Hmg2p but not Hmg1p-induced ER remodeling. One of the HER genes identified was PSD1, which encodes the phospholipid biosynthetic enzyme phosphatidylserine decarboxylase. This direct connection to phospholipid biosynthesis prompted a more detailed examination of the effects of Hmg2p on phospholipid mutants and composition. Our analysis revealed that overexpression of Hmg2p caused significant and specific growth defects in nulls of the methylation pathway for phosphatidylcholine biosynthesis that includes the Psd1p enzyme. Furthermore, increased expression of Hmg2p altered the composition of cellular phospholipids in a manner that implied a role for PSD1. These phospholipid effects, unlike Hmg2p-induced ER remodeling, required the enzymatic activity of Hmg2p. Together, our results indicate that, although related, Hmg2p- and Hmg1p-induced ER remodeling are mechanistically distinct.
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Affiliation(s)
- Christine M Federovitch
- UCSD Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093-0347, USA
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27
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Rajakumari S, Grillitsch K, Daum G. Synthesis and turnover of non-polar lipids in yeast. Prog Lipid Res 2008; 47:157-71. [DOI: 10.1016/j.plipres.2008.01.001] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Revised: 01/08/2008] [Accepted: 01/09/2008] [Indexed: 11/25/2022]
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28
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Bakovic M, Fullerton MD, Michel V. Metabolic and molecular aspects of ethanolamine phospholipid biosynthesis: the role of CTP:phosphoethanolamine cytidylyltransferase (Pcyt2). Biochem Cell Biol 2007; 85:283-300. [PMID: 17612623 DOI: 10.1139/o07-006] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The CDP-ethanolamine branch of the Kennedy pathway is the major route for the formation of ethanolamine-derived phospholipids, including diacyl phosphatidylethanolamine and alkenylacyl phosphatidylethanolamine derivatives, known as plasmalogens. Ethanolamine phospholipids are essential structural components of the cell membranes and play regulatory roles in cell division, cell signaling, activation, autophagy, and phagocytosis. The physiological importance of plasmalogens has not been not fully elucidated, although they are known for their antioxidant properties and deficiencies in a number of inherited peroxisomal disorders. This review highlights important aspects of ethanolamine phospholipid metabolism and reports current molecular information on 1 of the regulatory enzymes in their synthesis, CTP:phosphoethanolamine cytidylyltransferase (Pcyt2). Pcyt2 is encoded by a single, nonredundant gene in animal species that could be alternatively spliced into 2 potential protein products. We describe properties of the mouse and human Pcyt2 genes and their regulatory promoters and provide molecular evidence for the existence of 2 distinct Pcyt2 proteins. The goal is to obtain more insight into Pcyt2 catalytic function and regulation to facilitate a better understanding of the production of ethanolamine phospholipids via the CDP-ethanolamine branch of the Kennedy pathway.
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Affiliation(s)
- Marica Bakovic
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada.
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29
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Daum G, Wagner A, Czabany T, Athenstaedt K. Dynamics of neutral lipid storage and mobilization in yeast. Biochimie 2007; 89:243-8. [PMID: 16919863 DOI: 10.1016/j.biochi.2006.06.018] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2006] [Accepted: 06/16/2006] [Indexed: 11/28/2022]
Abstract
We make use of the yeast Saccharomyces cerevisiae as a flexible experimental system to investigate coordinate pathways of neutral lipid synthesis, storage and mobilization with special emphasis on the role of different organelles in these processes. Recently, a number of new gene products involved in triacylglycerol (TAG) and steryl ester (STE) metabolism were identified in our laboratory and by other groups. STE are synthesized by the two STE synthases Are1p and Are2p, whereas TAG are formed mainly through the action of the two TAG synthases Dga1p and Lro1p with minor contributions of Are1p and Are2p. Once formed, TAG and STE are stored in so-called lipid particles. A dga1Deltalro1Deltaare1Deltaare2Delta quadruple mutant which lacks neutral lipid synthesis and is consequently devoid of lipid particles turned out to be a valuable tool for studying the physiological role of storage lipids and lipid particles. Mobilization of neutral lipid depots occurs through catalysis of TAG lipases and STE hydrolases. Three TAG lipases named Tgl3p, Tgl4p and Tgl5p, and three STE hydrolases named Tgl1p, Yeh1p and Yeh2p were recently identified at the molecular level. Although these hydrolases exhibit overlapping function within the enzyme families, they are specific for TAG and STE, respectively. With the exception of Dga1p, whose activity is partially localized to lipid particles, TAG and STE forming enzymes are restricted to the endoplasmic reticulum. TAG lipases and STE hydrolases are components of lipid particles with the exception of Yeh2p, which is plasma membrane located. Thus, neutral lipid metabolism is not only regulated at the enzyme level but also by the distribution of the components to organelles. The fact that neutral lipid homeostasis is linked to a number of cell biological processes confirms the important role of this class of lipids as cellular modulators or effectors.
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Affiliation(s)
- G Daum
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, 8010 Graz, Austria.
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30
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Jouhet J, Maréchal E, Block MA. Glycerolipid transfer for the building of membranes in plant cells. Prog Lipid Res 2007; 46:37-55. [PMID: 16970991 DOI: 10.1016/j.plipres.2006.06.002] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2006] [Revised: 06/14/2006] [Accepted: 06/20/2006] [Indexed: 01/05/2023]
Abstract
Membranes of plant organelles have specific glycerolipid compositions. Selective distribution of lipids at the levels of subcellular organelles, membrane leaflets and membrane domains reflects a complex and finely tuned lipid homeostasis. Glycerolipid neosynthesis occurs mainly in plastid envelope and endoplasmic reticulum membranes. Since most lipids are not only present in the membranes where they are synthesized, one cannot explain membrane specific lipid distribution by metabolic processes confined in each membrane compartment. In this review, we present our current understanding of glycerolipid trafficking in plant cells. We examine the potential mechanisms involved in lipid transport inside bilayers and from one membrane to another. We survey lipid transfers going through vesicular membrane flow and those dependent on lipid transfer proteins at membrane contact sites. By introducing recently described membrane lipid reorganization during phosphate deprivation and recent developments issued from mutant analyses, we detail the specific lipid transfers towards or outwards the chloroplast envelope.
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Affiliation(s)
- Juliette Jouhet
- Laboratoire de Physiologie, Cellulaire Végétale, UMR 5168 (CNRS/CEA/Université Joseph Fourier/INRA), DRDC/PCV, CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble-cedex 9, France
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31
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Tabak HF, Hoepfner D, Zand AVD, Geuze HJ, Braakman I, Huynen MA. Formation of peroxisomes: present and past. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:1647-54. [PMID: 17030445 DOI: 10.1016/j.bbamcr.2006.08.045] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2006] [Revised: 07/25/2006] [Accepted: 08/18/2006] [Indexed: 11/24/2022]
Abstract
Eukaryotic cells contain functionally distinct, membrane enclosed compartments called organelles. Here we like to address two questions concerning this architectural lay out. How did this membrane complexity arise during evolution and how is this collection of organelles maintained in multiplying cells to ensure that new cells retain a complete set of them. We will try to address these questions with peroxisomes as a focal point of interest.
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Affiliation(s)
- H F Tabak
- Department of Cellular Protein Chemistry, University of Utrecht, Padualaan 8, NL-3548 CH Utrecht, The Netherlands.
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32
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Bleijerveld OB, Houweling M, Thomas MJ, Cui Z. Metabolipidomics: Profiling metabolism of glycerophospholipid species by stable isotopic precursors and tandem mass spectrometry. Anal Biochem 2006; 352:1-14. [PMID: 16564484 DOI: 10.1016/j.ab.2006.02.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Revised: 02/13/2006] [Accepted: 02/15/2006] [Indexed: 10/24/2022]
Affiliation(s)
- Onno B Bleijerveld
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, and Institute of Biomembranes, Utrecht University, P.O. Box 80176, 3508 TD, Utrecht, The Netherlands
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33
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Testet E, Laroche-Traineau J, Noubhani A, Coulon D, Bunoust O, Camougrand N, Manon S, Lessire R, Bessoule JJ. Ypr140wp, 'the yeast tafazzin', displays a mitochondrial lysophosphatidylcholine (lyso-PC) acyltransferase activity related to triacylglycerol and mitochondrial lipid synthesis. Biochem J 2006; 387:617-26. [PMID: 15588229 PMCID: PMC1134991 DOI: 10.1042/bj20041491] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
When the yeast protein Ypr140w was expressed in Escherichia coli, a lyso-PC [lysophosphatidylcholine (1-acylglycerophosphorylcholine)] acyltransferase activity was found associated with the membranes of the bacteria. To our knowledge, this is the first identification of a protein capable of catalysing the acylation of lyso-PC molecules to form PC. Fluorescence microscopy analysis of living yeasts revealed that the fusion protein Ypr140w-green fluorescent protein is targeted to the mitochondria. Moreover, in contrast with wild-type cells, in the absence of acyl-CoA, the yeast mutant deleted for the YPR140w gene has no lyso-PC acyltransferase activity associated with the mitochondrial fraction. When yeast cells were grown in the presence of lactate, the mutant synthesized 2-fold more triacylglycerols when compared with the wild-type. Moreover, its mitochondrial membranes contained a lesser amount of PC and cardiolipin, and the fatty acid composition of these latter was greatly changed. These modifications were accompanied by a 2-fold increase in the respiration rates (states 3 and 4) of the mitochondria. The relationship between the deletion of the YPR140w gene and the lipid composition of the ypr140wDelta cells is discussed.
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Affiliation(s)
- Eric Testet
- Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS-Université Victor Segalen, Bordeaux 2/ESTBB, case 92, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France.
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Estrada de Martin P, Novick P, Ferro-Novick S. The organization, structure, and inheritance of the ER in higher and lower eukaryotes. Biochem Cell Biol 2006; 83:752-61. [PMID: 16333327 DOI: 10.1139/o05-159] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The endoplasmic reticulum (ER) is a fundamental organelle required for protein assembly, lipid biosynthesis, and vesicular traffic, as well as calcium storage and the controlled release of calcium from the ER lumen into the cytosol. Membranes functionally linked to the ER by vesicle-mediated transport, such as the Golgi complex, endosomes, vacuoles-lysosomes, secretory vesicles, and the plasma membrane, originate largely from proteins and lipids synthesized in the ER. In this review we will discuss the structural organization of the ER and its inheritance.
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Affiliation(s)
- Paula Estrada de Martin
- Department of Cell Biology, Yale University School of Medicine, Boyer Center for Molecular Medicine, New Haven, CT 06519, USA
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35
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Abstract
Since energy storage is a basic metabolic process, the synthesis of neutral lipids occurs in all kingdoms of life. The yeast Saccharomyces cerevisiae, widely accepted as a model eukaryotic cell, contains two classes of neutral lipids, namely STEs (steryl esters) and TAGs (triacylglycerols). TAGs are synthesized through two pathways governed by the acyl-CoA diacylglycerol acyltransferase Dga1p and the phospholipid diacylglycerol acyltransferase Lro1p. STEs are formed by two STE synthases Are1p and Are2p, two enzymes with overlapping function, which also catalyse TAG formation, although to a minor extent. Neutral lipids are stored in the so-called lipid particles and can be utilized for membrane formation under conditions of lipid depletion. For this purpose, storage lipids have to be mobilized by TAG lipases and STE hydrolases. A TAG lipase named Tgl3p was identified as a major yeast TAG hydrolytic enzyme in lipid particles. Recently, a new family of hydrolases was detected which is required for STE mobilization in S. cerevisiae. These enzymes, named Yeh1p, Yeh2p and Tgl1p, are paralogues of the mammalian acid lipase family. The role of these proteins in biosynthesis and mobilization of TAG and STE, and the regulation of these processes will be discussed in this minireview.
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Hoepfner D, Schildknegt D, Braakman I, Philippsen P, Tabak HF. Contribution of the endoplasmic reticulum to peroxisome formation. Cell 2005; 122:85-95. [PMID: 16009135 DOI: 10.1016/j.cell.2005.04.025] [Citation(s) in RCA: 353] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2004] [Revised: 03/15/2005] [Accepted: 04/25/2005] [Indexed: 01/07/2023]
Abstract
How peroxisomes are formed in eukaryotic cells is unknown but important for insight into a variety of diseases. Both human and yeast cells lacking peroxisomes due to mutations in PEX3 or PEX19 genes regenerate the organelles upon reintroduction of the corresponding wild-type version. To evaluate how and from where new peroxisomes are formed, we followed the trafficking route of newly made YFP-tagged Pex3 and Pex19 proteins by real-time fluorescence microscopy in Saccharomyces cerevisiae. Remarkably, Pex3 (an integral membrane protein) could first be observed in the endoplasmic reticulum (ER), where it concentrates in foci that then bud off in a Pex19-dependent manner and mature into fully functional peroxisomes. Pex19 (a farnesylated, mostly cytosolic protein) enriches first at the Pex3 foci on the ER and then on the maturing peroxisomes. This trafficking route of Pex3-YFP is the same in wild-type cells. These results demonstrate that peroxisomes are generated from domains in the ER.
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Affiliation(s)
- Dominic Hoepfner
- Department of Cellular Protein Chemistry, University of Utrecht, Padualaan 8, NL-3548 CH Utrecht, The Netherlands
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37
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Vaena de Avalos S, Su X, Zhang M, Okamoto Y, Dowhan W, Hannun YA. The phosphatidylglycerol/cardiolipin biosynthetic pathway is required for the activation of inositol phosphosphingolipid phospholipase C, Isc1p, during growth of Saccharomyces cerevisiae. J Biol Chem 2004; 280:7170-7. [PMID: 15611094 DOI: 10.1074/jbc.m411058200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inositolsphingolipid phospholipase C (Isc1p) is the Saccharomyces cerevisiae member of the extended family of neutral sphingomyelinases that regulates the generation of bioactive ceramides. Recently, we reported that Isc1p is post-translationally activated in the post-diauxic phase of growth and that it localizes to mitochondria (Vaena de Avalos, S., Okamoto, Y., and Hannun, Y. A. (2004) J. Biol. Chem. 279, 11537-11545). In this study the in vivo mechanisms of activation and function of Isc1p were investigated. Deletion of ISC1 resulted in markedly lower growth in non-fermentable carbon sources. Interestingly, the growth defect of isc1Delta strains resembled that of pgs1Delta strains, lacking the committed step in the synthesis of phosphatidylglycerol (PG) and cardiolipin (CL), which were shown to activate Isc1p in vitro. Therefore, the role of Pgs1p in activation of Isc1p in vivo was investigated. The results showed that in the pgs1Delta strain, the growth-dependent activation of Isc1p was impaired as was the ISC1-dependent increase in the levels of phytoceramide during the post-diauxic phase, demonstrating that the activation of Isc1p in vivo is dependent on PGS1 and on the mitochondrial phospholipids PG/CL. Mechanistically, loss of Isc1p resulted in lower levels of mitochondrial cytochrome c oxidase subunits cox3p and cox4p, previously established targets of both PG and CL (Ostrander, D. B., Zhang, M., Mileykovskaya, E., Rho, M., and Dowhan, W. (2001) J. Biol. Chem. 276, 25262-25272), thus suggesting that Isc1p mediates at least some functions downstream of PG/CL. This study provides the first evidence for the mechanism of in vivo activation and function of Isc1p. A model with endogenous PG/CL as the in vivo activator of Isc1p is proposed.
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Affiliation(s)
- Silvia Vaena de Avalos
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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Bürgermeister M, Birner-Grünberger R, Heyn M, Daum G. Contribution of different biosynthetic pathways to species selectivity of aminoglycerophospholipids assembled into mitochondrial membranes of the yeast Saccharomyces cerevisiae. Biochim Biophys Acta Mol Cell Biol Lipids 2004; 1686:148-60. [PMID: 15522831 DOI: 10.1016/j.bbalip.2004.09.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2004] [Revised: 09/08/2004] [Accepted: 09/14/2004] [Indexed: 11/16/2022]
Abstract
In the yeast Saccharomyces cerevisiae, three pathways lead to the formation of cellular phosphatidylethanolamine (PtdEtn), namely the mitochondrial conversion of phosphatidylserine (PtdSer) to PtdEtn catalyzed by phosphatidylserine decarboxylase 1 (Psd1p), the equivalent reaction catalyzed by phosphatidylserine decarboxylase 2 (Psd2p) in the Golgi, and the CDP-ethanolamine branch of the so-called Kennedy pathway which is located to the microsomal fraction. To investigate the contributions of these three pathways to the cellular pattern of PtdEtn species (fatty acid composition) we subjected lipids of wild-type and yeast mutant strains with distinct defects in the respective pathways to mass spectrometric analysis. We also analyzed species of PtdSer and phosphatidylcholine (PtdCho) of these strains because formation of the three aminoglycerophospholipids is linked through their biosynthetic route. We demonstrate that all three pathways involved in PtdEtn synthesis exhibit a preference for the formation of C34:2 and C32:2 species resulting in a high degree of unsaturation in total cellular PtdEtn. In PtdSer, the ratio of unsaturated to saturated fatty acids is much lower than in PtdEtn, suggesting a high species selectivity of PtdSer decarboxylases. Finally, PtdCho is characterized by its higher ratio of C16 to C18 fatty acids compared to PtdSer and PtdEtn. In contrast to biosynthetic steps, import of all three aminoglycerophospholipids into mitochondria of wild-type and mutant cells is not highly specific with respect to species transported. Thus, the species pattern of aminoglycerophospholipids in mitochondria is mainly the result of enzyme specificities, but not of translocation processes involved. Our results support a model that suggests equilibrium transport of aminoglycerophospholipids between mitochondria and microsomes based on membrane contact between the two compartments.
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Affiliation(s)
- Maria Bürgermeister
- Institut für Biochemie, Technische Universität Graz, Petersgasse 12/2, A-8010 Graz, Austria
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Kvam E, Goldfarb DS. Nvj1p is the outer-nuclear-membrane receptor for oxysterol-binding protein homolog Osh1p in Saccharomyces cerevisiae. J Cell Sci 2004; 117:4959-68. [PMID: 15367582 DOI: 10.1242/jcs.01372] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
OSH1 belongs to a seven-member gene family in yeast that is related to mammalian oxysterol-binding protein (OSBP). Here, we investigate the targeting of Osh1p to nucleus-vacuole (NV) junctions in Saccharomyces cerevisiae. NV junctions are interorganelle interfaces mediated by Nvj1p in the nuclear envelope and Vac8p on the vacuole membrane. Together, Nvj1p and Vac8p form Velcro-like patches through which teardrop-like portions of the nucleus are pinched off into the vacuolar lumen and degraded by a process termed piecemeal microautophagy of the nucleus (PMN). Osh1p is targeted to NV junctions proportional to NVJ1 expression through a physical association with Nvj1p. NV junctions per se are not required for this targeting because Osh1p colocalizes with Nvj1p in the absence of Vac8p. NV-junction-associated Osh1p is also a substrate for PMN degradation. Although OSH1 is not required for NV-junction formation or PMN, PMN is defective in cells lacking the yeast OSBP family (Osh1p to Osh7p). By contrast, the vesicular targeting of aminopeptidase I to the vacuole by macroautophagy is not dependent on the Osh protein family. We conclude the formation of nuclear PMN vesicles requires the overlapping activities of Osh1p and other Osh family members.
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Affiliation(s)
- Erik Kvam
- Department of Biology, University of Rochester, 436 Hutchison Hall, NY 14627, USA
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Schwer B, Ren S, Pietschmann T, Kartenbeck J, Kaehlcke K, Bartenschlager R, Yen TSB, Ott M. Targeting of hepatitis C virus core protein to mitochondria through a novel C-terminal localization motif. J Virol 2004; 78:7958-68. [PMID: 15254168 PMCID: PMC446112 DOI: 10.1128/jvi.78.15.7958-7968.2004] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The hepatitis C virus (HCV) core protein represents the first 191 amino acids of the viral precursor polyprotein and is cotranslationally inserted into the membrane of the endoplasmic reticulum (ER). Processing at position 179 by a recently identified intramembrane signal peptide peptidase leads to the generation and potential cytosolic release of a 179-amino-acid matured form of the core protein. Using confocal microscopy, we observed that a fraction of the mature core protein colocalized with mitochondrial markers in core-expressing HeLa cells and in Huh-7 cells containing the full-length HCV replicon. Subcellular fractionation confirmed this observation and showed that the core protein associates with purified mitochondrial fractions devoid of ER contaminants. The core protein also fractionated with mitochondrion-associated membranes, a site of physical contact between the ER and mitochondria. Using immunoelectron microscopy and in vitro mitochondrial import assays, we showed that the core protein is located on the mitochondrial outer membrane. A stretch of 10 amino acids within the hydrophobic C terminus of the processed core protein conferred mitochondrial localization when it was fused to green fluorescent protein. The location of the core protein in the outer mitochondrial membrane suggests that it could modulate apoptosis or lipid transfer, both of which are associated with this subcellular compartment, during HCV infection.
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Affiliation(s)
- Björn Schwer
- Department of Molecular Virology, University of Heidelberg, Heidelberg, Germany
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41
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Birner R, Daum G. Biogenesis and cellular dynamics of aminoglycerophospholipids. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 225:273-323. [PMID: 12696595 DOI: 10.1016/s0074-7696(05)25007-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Aminoglycerophospholipids phosphatidylserine (PtdSer), phosphatidylethanolamine (PtdEtn), and phosphatidylcholine (PtdCho) comprise about 80% of total cellular phospholipids in most cell types. While the major function of PtdCho in eukaryotes and PtdEtn in prokaryotes is that of bulk membrane lipids, PtdSer is a minor component and appears to play a more specialized role in the plasma membrane of eukaryotes, e.g., in cell recognition processes. All three aminoglycerophospholipid classes are essential in mammals, whereas prokaryotes and lower eukaryotes such as yeast appear to be more flexible regarding their aminoglycerophospholipid requirement. Since different subcellular compartments of eukaryotes, namely the endoplasmic reticulum and mitochondria, contribute to the biosynthetic sequence of aminoglycerophospholipid formation, intracellular transport, sorting, and specific function of these lipids in different organelles are of special interest.
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Affiliation(s)
- Ruth Birner
- Institut für Biochemie, Technische Universität Graz, Petersgasse 12/2, A-8010 Graz, Austria
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42
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Fields SD, Arana Q, Heuser J, Clarke M. Mitochondrial membrane dynamics are altered in cluA- mutants of Dictyostelium. J Muscle Res Cell Motil 2003; 23:829-38. [PMID: 12952081 DOI: 10.1023/a:1024492031696] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In cluA- mutants of Dictyostelium, mitochondria are clustered near the cell center rather than being dispersed throughout the cytoplasm. We have examined two possible mechanisms that could account for this phenotype. First, we sought evidence that the cytoskeleton or a presumptive mitochondrion-cytoskeleton linkage was altered in mutant cells. We found that cytoskeletal structures in cluA- cells appeared normal by immunostaining, and that the distribution of peroxisomes in mutant cells was indistinguishable from that in wild type cells. Treatment of wild type cells with drugs that disrupted microtubules or actin filaments did not mimic the cluA- phenotype. Thus, cytoskeletal defects seemed unlikely to account for the mitochondrial clustering in cluA- cells. Observation of the movement of GFP-tagged mitochondria in wild type cells suggested that mitochondria are transported along microtubules, as in mammalian cells, rather than along actin filaments, as in budding yeast. Therefore, the similar phenotypes of cluA- Dictyostelium cells and clu1delta yeast cells argued against CluA/Clu1p acting as a mitochondrion-cytoskeleton linker. We next examined the ultrastructure of mitochondria in freeze-substituted, thin-sectioned cells. We found that the clustered mitochondria in cluA- cells are interconnected. Often, adjacent mitochondria are linked by narrow membranous strands, although sometimes the mitochondria are partially merged. The presence of narrow constrictions at presumptive division sites argues that the constriction step of division proceeds normally. Our data suggest that cluA- cells may be blocked at a very late step in fission of the outer mitochondrial membrane.
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Affiliation(s)
- Stephen D Fields
- Program in Molecular and Cell Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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Abstract
Investigations of peroxisome biogenesis in diverse organisms reveal new details of this unique process and its evolutionary conservation. Interactions among soluble receptors and the membrane peroxins that catalyze protein translocation are being mapped. Ubiquitination is observed. A receptor enters the organelle carrying folded cargo and recycles back to the cytosol. Tiny peroxisome remnants - vesicles and tubules - are discovered in pex3 mutants that lack the organelle. When the mutant is transfected with a good PEX3 gene, these protoperoxisomes acquire additional membrane peroxins and then import the matrix enzymes to reform peroxisomes. Thus, de novo formation need not be postulated. Dynamic imaging of yeast reveals dynamin-dependent peroxisome division and regulated actin-dependent segregation of the organelle before cell division. These results are consistent with biogenesis by growth and division of pre-existing peroxisomes.
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Affiliation(s)
- Paul B Lazarow
- Mount Sinai School of Medicine, 1190 Fifth Avenue, Box 1007, New York, NY 10029-6574, USA.
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Rontein D, Wu WI, Voelker DR, Hanson AD. Mitochondrial phosphatidylserine decarboxylase from higher plants. Functional complementation in yeast, localization in plants, and overexpression in Arabidopsis. PLANT PHYSIOLOGY 2003; 132:1678-87. [PMID: 12857846 PMCID: PMC167104 DOI: 10.1104/pp.103.023242] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2003] [Revised: 04/02/2003] [Accepted: 04/04/2003] [Indexed: 05/19/2023]
Abstract
Plants are known to synthesize ethanolamine (Etn) moieties by decarboxylation of free serine (Ser), but there is also some evidence for phosphatidyl-Ser (Ptd-Ser) decarboxylation. Database searches identified diverse plant cDNAs and an Arabidopsis gene encoding 50-kD proteins homologous to yeast (Saccharomyces cerevisiae) and mammalian mitochondrial Ptd-Ser decarboxylases (PSDs). Like the latter, the plant proteins have putative mitochondrial targeting and inner membrane sorting sequences and contain near the C terminus a Glycine-Serine-Threonine motif corresponding to the site of proteolysis and catalytic pyruvoyl residue formation. A truncated tomato (Lycopersicon esculentum) cDNA lacking the targeting sequence and a chimeric construct in which the targeting and sorting sequences were replaced by those from yeast PSD1 both complemented the Etn requirement of a yeast psd1 psd2 mutant, and PSD activity was detected in the mitochondria of the complemented cells. Immunoblot analysis of potato (Solanum tuberosum) mitochondria demonstrated that PSD is located in mitochondrial membranes, and mRNA analysis in Arabidopsis showed that the mitochondrial PSD gene is expressed at low levels throughout the plant. An Arabidopsis knockup mutant grew normally but had 6- to 13-fold more mitochondrial PSD mRNA and 9-fold more mitochondrial PSD activity. Total membrane PSD activity was, however, unchanged in the mutant, showing mitochondrial activity to be a minor part of the total. These results establish that plants can synthesize Etn moieties via a phospholipid pathway and have both mitochondrial and extramitochondrial PSDs. They also indicate that mitochondrial PSD is an important housekeeping enzyme whose expression is strongly regulated at the transcriptional level.
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Affiliation(s)
- Denis Rontein
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611, USA
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45
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Abstract
Maintenance of membrane lipid asymmetry is a dynamic process that influences many events over the lifespan of the cell. With few exceptions, most cells restrict the bulk of the aminophospholipids to the inner membrane leaflet by means of specific transporters. Working in concert with each other, these proteins correct for sporadic incursions of the aminophospholipids to the outer membrane leaflet as a result of bilayer imbalances created by various cellular events. A shift in the relative contribution in each of these activities can result in sustained exposure of the aminophospholipids at the cell surface, which allows capture of the cells by phagocytes before the integrity of the plasma membrane is compromised. The absence of an efficient recognition and elimination mechanism can result in uncontrolled and persistent presentation of self-antigens to the immune system, with development of autoimmune syndromes. To prevent this, phagocytes have developed a diverse array of distinct and redundant receptor systems that drive the postphagocytic events along pathways that facilitate cross-talk between the homeostatic and the immune systems. In this work, we review the basis for the proposed mechanism(s) by which apoptotic ligands appear on the target cell surface and the phagocyte receptors that recognize these moieties.
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de Kroon AIPM, Koorengevel MC, Vromans TAM, de Kruijff B. Continuous equilibration of phosphatidylcholine and its precursors between endoplasmic reticulum and mitochondria in yeast. Mol Biol Cell 2003; 14:2142-50. [PMID: 12802081 PMCID: PMC165103 DOI: 10.1091/mbc.e02-08-0460] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In Saccharomyces cerevisiae phosphatidylcholine (PC) is synthesized in the ER and transported to mitochondria via an unknown mechanism. The transport of PC synthesized by the triple methylation of phosphatidylethanolamine was investigated by pulsing yeast spheroplasts with l-[methyl-3H]methionine, followed by a chase with unlabeled methionine and subcellular fractionation. During the pulse, increasing amounts of PC and its mono- and dimethylated precursors (PMME and PDME, respectively) appear in similar proportions in both microsomes and mitochondria, with the extent of incorporation in microsomes being twice that in mitochondria. During the chase, the [3H]-methyl label from the precursors accumulates into PC with similar kinetics in both organelles. The results demonstrate that transport of methylated phospholipids from ER to mitochondria is 1) coupled to synthesis, 2) not selective for PC, 3) at least as fast as the fastest step in the methylation of PE, and 4) bidirectional for PMME and PDME. The interorganellar equilibration of methylated phospholipids was reconstituted in vitro and did not depend on ongoing methylation, cytosolic factors, ATP, and energization of the mitochondria, although energization could accelerate the reaction. The exchange of methylated phospholipids was reduced after pretreating both microsomes and mitochondria with trypsin, indicating the involvement of membrane proteins from both organelles.
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Affiliation(s)
- Anton I P M de Kroon
- Department Biochemistry of Membranes, Centre for Biomembranes and Lipid Enzymology, Institute of Biomembranes, Utrecht University, The Netherlands.
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47
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Loewen CJR, Roy A, Levine TP. A conserved ER targeting motif in three families of lipid binding proteins and in Opi1p binds VAP. EMBO J 2003; 22:2025-35. [PMID: 12727870 PMCID: PMC156073 DOI: 10.1093/emboj/cdg201] [Citation(s) in RCA: 462] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2002] [Revised: 02/26/2003] [Accepted: 03/05/2003] [Indexed: 11/13/2022] Open
Abstract
Intracellular lipid traffic is mediated both by membrane vesicles and by a number of non-vesicular pathways facilitated by cytoplasmic lipid binding proteins. For these proteins to act effectively they must be targeted accurately to specific membranes. Here we identify a novel short conserved determinant called the FFAT motif that is shared by several seemingly unrelated lipid binding proteins and is also found in Opi1p, a transcriptional regulator of phospholipid synthesis in yeast. FFAT motifs act as membrane- targeting determinants by their direct interaction with homologues of VAMP-associated protein (VAP), a conserved endoplasmic reticulum (ER) protein. In budding yeast, all four proteins with FFAT motifs interact with Scs2p, a homologue of VAP, to target the ER to some extent. The precise intracellular distribution of each of these proteins depends on the integration of the FFAT-Scs2p interaction with other targeting determinants, and the interaction is functionally significant. We conclude that binding to a VAP homologue is a common mechanism by which proteins with FFAT motifs, most of which are involved in lipid metabolism, target ER membranes.
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Affiliation(s)
- Christopher J R Loewen
- Division of Cell Biology, Institute of Ophthalmology, University College London, Bath Street, London EC1V 9EL, UK
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48
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Sorger D, Daum G. Triacylglycerol biosynthesis in yeast. Appl Microbiol Biotechnol 2003; 61:289-99. [PMID: 12743757 DOI: 10.1007/s00253-002-1212-4] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2002] [Revised: 11/29/2002] [Accepted: 11/29/2002] [Indexed: 10/25/2022]
Abstract
Triacylglycerol (TAG) is the major storage component for fatty acids, and thus for energy, in eukaryotic cells. In this mini-review, we describe recent progress that has been made with the yeast Saccharomyces cerevisiae in understanding formation of TAG and its cell biological role. Formation of TAG involves the synthesis of phosphatidic acid (PA) and diacylglycerol (DAG), two key intermediates of lipid metabolism. De novo formation of PA in yeast as in other types of cells can occur either through the glycerol-3-phosphate- or dihydroxyacetone phosphate-pathways-each named after its respective precursor. PA, formed in two steps of acylation, is converted to DAG by phosphatidate phosphatase. Acylation of DAG to yield TAG is catalyzed mainly by the two yeast proteins Dga1p and Lro1p, which utilize acyl-CoA or phosphatidylcholine, respectively, as acyl donors. In addition, minor alternative routes of DAG acylation appear to exist. Endoplasmic reticulum and lipid particles (LP), the TAG storage compartment in yeast, are the major sites of TAG synthesis. The interplay of these organelles, formation of LP, and enzymatic properties of enzymes catalyzing the synthesis of PA, DAG, and TAG in yeast are discussed in this communication.
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Affiliation(s)
- D Sorger
- Institut für Biochemie, Technische Universität Graz, Petersgasse 12/2, Austria
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49
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Abstract
In eukaryotes, phosphatidylserine (PtdSer) can serve as a precursor of phosphatidylethanolamine (PtdEtn) and phosphatidylcholine (PtdCho), which are the major cellular phospholipids. PtdSer synthesis originates in the endoplasmic reticulum (ER) and its subdomain named the mitochondria-associated membrane (MAM). PtdSer is transported to the mitochondria in mammalian cells and yeast, and decarboxylated by PtdSer decarboxylase 1 (Psd1p) to form PtdEtn. A second decarboxylase, Psd2p, is also found in yeast in the Golgi-vacuole. PtdEtn produced by Psd1p and Psd2p can be transported to the ER, where it is methylated to form PtdCho. Organelle-specific metabolism of the aminoglycerophospholipids is a powerful tool for experimentally following lipid traffic that is now enabling identification of new proteins involved in the regulation of this process. Genetic and biochemical experiments demonstrate that transport of PtdSer between the MAM and mitochondria is regulated by protein ubiquitination, which affects events at both membranes. Similar analyses of PtdSer transport to the locus of Psd2p now indicate that a membrane-bound phosphatidylinositol transfer protein and the C2 domain of Psd2p are both required on the acceptor membrane for efficient transport of PtdSer. Collectively, these recent findings indicate that novel multiprotein assemblies on both donor and acceptor membranes participate in interorganelle phospholipid transport.
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Affiliation(s)
- Dennis R Voelker
- Program in Cell Biology, Department of Medicine, National Jewish Medical and Research Center, 1400 Jackson St., Denver, CO 80206, USA.
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50
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Vance JE. Molecular and cell biology of phosphatidylserine and phosphatidylethanolamine metabolism. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 2003; 75:69-111. [PMID: 14604010 DOI: 10.1016/s0079-6603(03)75003-x] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In this review, the pathways for phosphatidylserine (PS) and phosphatidylethanolamine (PE) biosynthesis, as well as the genes and proteins involved in these pathways, are described in mammalian cells, yeast, and prokaryotes. In mammalian cells, PS is synthesized by a base-exchange reaction in which phosphatidylcholine or PE is substrate for PS synthase-1 or PS synthase-2, respectively. Isolation of Chinese hamster ovary cell mutants led to the cloning of cDNAs and genes encoding these two PS synthases. In yeast and prokaryotes PS is produced by a biosynthetic pathway completely different from that in mammals: from a reaction between CDP-diacylglycerol and serine. The major route for PE synthesis in cultured cells is from the mitochondrial decarboxylation of PS. Alternatively, PE can be synthesized in the endoplasmic reticulum (ER) from the CDP-ethanolamine pathway. Genes and/or cDNAs encoding all the enzymes in these two pathways for PE synthesis have been isolated and characterized. In mammalian cells, PS is synthesized on the ER and/or mitochondria-associated membranes (MAM). PS synthase-1 and -2 are highly enriched in MAM compared to the bulk of ER. Since MAM are a region of the ER that appears to be in close juxtaposition to the mitochondrial outer membrane, it has been proposed that MAM act as a conduit for the transfer of newly synthesized PS into mitochondria. A similar pathway appears to operate in yeast. The use of yeast mutants has led to identification of genes involved in the interorganelle transport of PS and PE in yeast, but so far none of the corresponding genes in mammalian cells has been identified. PS and PE do not act solely as structural components of membranes. Several specific functions have been ascribed to these two aminophospholipids. For example, cell-surface exposure of PS during apoptosis is thought to be the signal by which apoptotic cells are recognized and phagocytosed. Translocation of PS from the inner to outer leaflet of the plasma membrane of platelets initiates the blood-clotting cascade, and PS is an important activator of several enzymes, including protein kinase C. Recently, exposure of PE on the cell surface was identified as a regulator of cytokinesis. In addition, in Escherichia coli, PE appears to be involved in the correct folding of membrane proteins; and in Drosophila, PE regulates lipid homeostasis via the sterol response element-binding protein.
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Affiliation(s)
- Jean E Vance
- Canadian Institutes for Health Research Group on Molecular and Cell Biology of Lipids, Department of Medicine, University of Alberta, 332 HMRC, Edmonton, AB, Canada T6G 2S2
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