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Liu Q, Long R, Lin C, Bi X, Liang Z, Deng YZ. Phosphatidylethanolamines link ferroptosis and autophagy during appressorium formation of rice blast fungus. MOLECULAR PLANT PATHOLOGY 2024; 25:e13489. [PMID: 38956897 PMCID: PMC11219472 DOI: 10.1111/mpp.13489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2024] [Accepted: 06/13/2024] [Indexed: 07/04/2024]
Abstract
A cell death pathway, ferroptosis, occurs in conidial cells and is critical for formation and function of the infection structure, the appressorium, in the rice blast fungus Magnaporthe oryzae. In this study, we identified an orthologous lysophosphatidic acid acyltransferase (Lpaat) acting at upstream of phosphatidylethanolamines (PEs) biosynthesis and which is required for such fungal ferroptosis and pathogenicity. Two PE species, DOPE and SLPE, that depend on Lpaat function for production were sufficient for induction of lipid peroxidation and the consequent ferroptosis, thus positively regulating fungal pathogenicity. On the other hand, both DOPE and SLPE positively regulated autophagy. Loss of the LPAAT gene led to a decrease in the lipidated form of the autophagy protein Atg8, which is probably responsible for the autophagy defect of the lpaatΔ mutant. GFP-Lpaat was mostly localized on the membrane of lipid droplets (LDs) that were stained by the fluorescent dye monodansylpentane (MDH), suggesting that LDs serve as a source of lipids for membrane PE biosynthesis and probably as a membrane source of autophagosome. Overall, our results reveal novel intracellular membrane-bound organelle dynamics based on Lpaat-mediated lipid metabolism, providing a temporal and spatial link of ferroptosis and autophagy.
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Affiliation(s)
- Qiao Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research CentreSouth China Agricultural UniversityGuangzhouChina
| | - Ruhui Long
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research CentreSouth China Agricultural UniversityGuangzhouChina
| | - Chaoxiang Lin
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research CentreSouth China Agricultural UniversityGuangzhouChina
| | - Xinping Bi
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research CentreSouth China Agricultural UniversityGuangzhouChina
| | - Zhibin Liang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research CentreSouth China Agricultural UniversityGuangzhouChina
| | - Yi Zhen Deng
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research CentreSouth China Agricultural UniversityGuangzhouChina
- Guangdong Laboratory for Lingnan Modern AgricultureGuangzhouChina
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2
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Laquel P, Ayciriex S, Doignon F, Camougrand N, Fougère L, Rocher C, Wattelet-Boyer V, Bessoule JJ, Testet E. Mlg1, a yeast acyltransferase located in ER membranes associated with mitochondria (MAMs), is involved in de novo synthesis and remodelling of phospholipids. FEBS J 2024; 291:2683-2702. [PMID: 38297966 DOI: 10.1111/febs.17068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 11/27/2023] [Accepted: 01/17/2024] [Indexed: 02/02/2024]
Abstract
In cells, phospholipids contain acyl chains of variable lengths and saturation, features that affect their functions. Their de novo synthesis in the endoplasmic reticulum takes place via the cytidine diphosphate diacylglycerol (CDP-DAG) and Kennedy pathways, which are conserved in eukaryotes. PA is a key intermediate for all phospholipids (PI, PIPs, PS, PE, PC, PG and CL). The de novo synthesis of PA occurs by acylation of glycerophosphate leading to the synthesis of 1-acyl lysoPA and subsequent acylation of 1-acyl lysoPA at the sn-2 position. Using membranes from Escherichia coli overexpressing MLG1, we showed that the yeast gene MLG1 encodes an acyltransferase, leading specifically to the synthesis of PA from 1-acyl lysoPA. Moreover, after their de novo synthesis, phospholipids can be remodelled by acyl exchange with one and/or two acyl chains exchanged at the sn-1 and/or sn-2 position. Based on shotgun lipidomics of the reference and mlg1Δ strains, as well as biochemical assays for acyltransferase activities, we identified an additional remodelling activity for Mlg1p, namely, incorporation of palmitic acid into the sn-1 position of PS and PE. By using confocal microscopy and subcellular fractionation, we also found that this acyltransferase is located in ER membranes associated with mitochondria, a finding that highlights the importance of these organelles in the global cellular metabolism of lipids.
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Affiliation(s)
- Patricia Laquel
- Univ. Bordeaux, CNRS, LBM, UMR 5200, Villenave d'Ornon, France
| | - Sophie Ayciriex
- Univ. Lyon, CNRS, Université Claude Bernard Lyon 1, ISA, UMR 5280, Villeurbanne, France
| | | | | | - Louise Fougère
- Univ. Bordeaux, CNRS, LBM, UMR 5200, Villenave d'Ornon, France
| | | | | | | | - Eric Testet
- Univ. Bordeaux, CNRS, LBM, UMR 5200, Villenave d'Ornon, France
- Bordeaux INP, LBM, UMR 5200, Villenave d'Ornon, France
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3
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Santoshi M, Bansia H, Hussain M, Jha AK, Nagaraja V. Identification of a 1-acyl-glycerol-3-phosphate acyltransferase from Mycobacterium tuberculosis, a key enzyme involved in triacylglycerol biosynthesis. Mol Microbiol 2024; 121:1164-1181. [PMID: 38676355 DOI: 10.1111/mmi.15265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 04/02/2024] [Accepted: 04/04/2024] [Indexed: 04/28/2024]
Abstract
Latent tuberculosis, caused by dormant Mycobacterium tuberculosis (Mtb), poses a threat to global health through the incubation of undiagnosed infections within the community. Dormant Mtb, which is phenotypically tolerant to antibiotics, accumulates triacylglycerol (TAG) utilizing fatty acids obtained from macrophage lipid droplets. TAG is vital to mycobacteria, serving as a cell envelope component and energy reservoir during latency. TAG synthesis occurs by sequential acylation of glycerol-3-phosphate, wherein the second acylation step is catalyzed by acylglycerol-3-phosphate acyltransferase (AGPAT), resulting in the production of phosphatidic acid (PA), a precursor for the synthesis of TAG and various phospholipids. Here, we have characterized a putative acyltransferase of Mtb encoded by Rv3816c. We found that Rv3816c has all four characteristic motifs of AGPAT, exists as a membrane-bound enzyme, and functions as 1-acylglycerol-3-phosphate acyltransferase. The enzyme could transfer the acyl group to acylglycerol-3-phosphate (LPA) from monounsaturated fatty acyl-coenzyme A of chain length 16 or 18 to produce PA. Complementation of Escherichia coli PlsC mutant in vivo by Rv3816c confirmed that it functions as AGPAT. Its active site mutants, H43A and D48A, were incapable of transferring the acyl group to LPA in vitro and were not able to rescue the growth defect of E. coli PlsC mutant in vivo. Identifying Rv3816c as AGPAT and comparing its properties with other AGPAT homologs is not only a step toward understanding the TAG biosynthesis in mycobacteria but has the potential to explore it as a drug target.
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Affiliation(s)
- Meghna Santoshi
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Harsh Bansia
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Muzammil Hussain
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Abodh Kumar Jha
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Valakunja Nagaraja
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
- Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
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4
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Liu F, Wu R, Ma X, Su E. The Advancements and Prospects of Nervonic Acid Production. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:12772-12783. [PMID: 36166330 DOI: 10.1021/acs.jafc.2c05770] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Nervonic acid (NA) is a monounsaturated very long-chain fatty acid (VLCFA) and has been identified with critical biological functions in medical and health care for brain development and injury repair. Yet, the approaches to producing NA from the sources of plants or animals continue to pose challenges to meet increasing market demand, as they are generally associated with high costs, a lack of natural resources, a long life cycle, and low production efficiency. The recent technological advance in metabolic engineering allows us to precisely engineer oleaginous microbes to develop high-content NA-producing strains, which has the potential to provide a possible solution to produce NA on a commercial fermentation scale. In this Review, the biosynthetic pathway, natural sources, and metabolic engineering of NA are summarized. The strategies of metabolic engineering that could be adopted to modify oleaginous yeast to produce NA are discussed in detail, providing the prospecting views for the microbial cells producing NA.
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Affiliation(s)
- Feixiang Liu
- Co-innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China
- Department of Food Science and Technology, College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing 210037, China
- Department of Biological Science and Food Engineering, Bozhou University, Bozhou 236800, China
| | - Rong Wu
- Co-innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China
- Department of Food Science and Technology, College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing 210037, China
| | - Xiaoqiang Ma
- Department of Food Science and Technology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Erzheng Su
- Co-innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China
- Department of Food Science and Technology, College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing 210037, China
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5
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Chaturvedi S, Bhattacharya A, Rout PK, Nain L, Khare SK. An Overview of Enzymes and Rate-Limiting Steps Responsible for Lipid Production in Oleaginous Yeast. Ind Biotechnol (New Rochelle N Y) 2022. [DOI: 10.1089/ind.2021.0003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Shivani Chaturvedi
- Enzyme and Microbial Biochemistry Laboratory, Department of Chemistry, Indian Institute of Technology, Delhi, India
| | - Amrik Bhattacharya
- Enzyme and Microbial Biochemistry Laboratory, Department of Chemistry, Indian Institute of Technology, Delhi, India
| | - Prasant K. Rout
- Phytochemistry Division, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, Uttar Pradesh, India
| | - Lata Nain
- Division of Microbiology, ICAR- Indian Agricultural Research Institute, New Delhi, India
| | - Sunil K. Khare
- Enzyme and Microbial Biochemistry Laboratory, Department of Chemistry, Indian Institute of Technology, Delhi, India
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6
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Urita A, Ishibashi Y, Kawaguchi R, Yanase Y, Tani M. Crosstalk between protein kinase A and the HOG pathway under impaired biosynthesis of complex sphingolipids in budding yeast. FEBS J 2021; 289:766-786. [PMID: 34492172 DOI: 10.1111/febs.16188] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 07/03/2021] [Accepted: 09/06/2021] [Indexed: 11/28/2022]
Abstract
Complex sphingolipids are important components of the lipid bilayer of budding yeast Saccharomyces cerevisiae, and a defect of the biosynthesis causes widespread cellular dysfunction. In this study, we found that mutations causing upregulation of the cAMP/protein kinase A (PKA) pathway cause hypersensitivity to the defect of complex sphingolipid biosynthesis caused by repression of AUR1 encoding inositol phosphorylceramide synthase, whereas loss of PKA confers resistance to the defect. Loss of PDE2 encoding cAMP phosphodiesterase or PKA did not affect the reduction in complex sphingolipid levels and ceramide accumulation caused by AUR1 repression, suggesting that the change in sensitivity to the AUR1 repression due to the mutation of the cAMP/PKA pathway is not caused by exacerbation or suppression of the abnormal metabolism of sphingolipids. We also identified PBS2 encoding MAPKK in the high-osmolarity glycerol (HOG) pathway as a multicopy suppressor gene that rescues the hypersensitivity to AUR1 repression caused by deletion of IRA2, which causes hyperactivation of the cAMP/PKA pathway. Since the HOG pathway has been identified as one of the rescue systems against the growth defect caused by the impaired biosynthesis of complex sphingolipids, it was assumed that PKA affects activation of the HOG pathway under AUR1-repressive conditions. Under AUR1-repressive conditions, hyperactivation of PKA suppressed the phosphorylation of Hog1, MAPK in the HOG pathway, and transcriptional activation downstream of the HOG pathway. These findings suggested that PKA is possibly involved in the avoidance of excessive activation of the HOG pathway under impaired biosynthesis of complex sphingolipids.
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Affiliation(s)
- Atsuya Urita
- Department of Chemistry, Faculty of Sciences, Kyushu University, Fukuoka, Japan
| | - Yohei Ishibashi
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan
| | - Ryotaro Kawaguchi
- Department of Chemistry, Faculty of Sciences, Kyushu University, Fukuoka, Japan
| | - Yukimi Yanase
- Department of Chemistry, Faculty of Sciences, Kyushu University, Fukuoka, Japan
| | - Motohiro Tani
- Department of Chemistry, Faculty of Sciences, Kyushu University, Fukuoka, Japan
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7
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Athenstaedt K. Phosphatidic acid biosynthesis in the model organism yeast Saccharomyces cerevisiae - a survey. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:158907. [PMID: 33610760 PMCID: PMC7613133 DOI: 10.1016/j.bbalip.2021.158907] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 02/04/2021] [Accepted: 02/11/2021] [Indexed: 01/07/2023]
Abstract
Phosphatidic acid biosynthesis represents the initial part of de novo formation of all glycerophospholipids (membrane lipids) as well as triacylglycerols (storage lipids), and is thus the centerpiece of glycerolipid metabolism. The universal route of phosphatidic acid biosynthesis starts from the precursor glycerol-3-phosphate and comprises two consecutive acylation reactions which are catalyzed by a glycerol-3-phosphate acyltransferase and a 1-acyl glycerol-3-phosphate acyltransferase. In addition, yeast and mammals harbor a set of enzymes which can synthesize phosphatidic acid from the precursor dihydroxyacetone phosphate. In the present review our current knowledge about enzymes contributing to phosphatidic acid biosynthesis in the invaluable model organism yeast, Saccharomyces cerevisiae, is summarized. A special focus is laid upon the regulation and the localization of these enzymes. Furthermore, research needs for a deeper insight into the high complexity of phosphatidic acid biosynthesis and consequently the entire lipid metabolic network is presented.
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Affiliation(s)
- Karin Athenstaedt
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/2, 8010 Graz, Austria.
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8
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Su WC, Lin YH, Pagac M, Wang CW. Seipin negatively regulates sphingolipid production at the ER-LD contact site. J Cell Biol 2019; 218:3663-3680. [PMID: 31594806 PMCID: PMC6829658 DOI: 10.1083/jcb.201902072] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 06/23/2019] [Accepted: 08/08/2019] [Indexed: 01/06/2023] Open
Abstract
Su et al. show that seipin negatively regulates the production of sphingoid intermediates by binding the enzymes serine palmitoyltransferase and fatty acid elongase at discrete regions of the ER in close vicinity to lipid droplets, thereby mediating the synthesis of two major building blocks for sphingolipids. Seipin is known for its critical role in controlling lipid droplet (LD) assembly at the LD-forming subdomain of the endoplasmic reticulum (ER). Here, we identified a new function of seipin as a negative regulator for sphingolipid production. We show that yeast cells lacking seipin displayed altered sensitivity to sphingolipid inhibitors, accumulated sphingoid precursors and intermediates, and increased serine palmitoyltransferase (SPT) and fatty acid (FA) elongase activities. Seipin associated with SPT and FA elongase, and the interaction was reduced by inhibitors for sphingolipid synthesis in a concentration-dependent manner. We further show that the interactions of seipin with SPT and FA elongase occurred at ER–LD contacts and were likely regulated differentially. Further evidence indicated that LD biogenesis was intact when SPT activity was blocked, whereas excess sphingoid intermediates may affect LD morphology. Expression of human seipin rescued the altered sphingolipids in yeast seipin mutants, suggesting that the negative regulation of sphingolipid synthesis by seipin is likely an evolutionarily conserved process.
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Affiliation(s)
- Wei-Cheng Su
- Institute of Plant and Microbial Biology, Academia Sinica, Nangang, Taipei, Taiwan
| | - Yi-Hsiu Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Nangang, Taipei, Taiwan
| | - Martin Pagac
- Institute of Plant and Microbial Biology, Academia Sinica, Nangang, Taipei, Taiwan
| | - Chao-Wen Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Nangang, Taipei, Taiwan
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Campbell AA, Stenback KE, Flyckt K, Hoang T, Perera MADN, Nikolau BJ. A single-cell platform for reconstituting and characterizing fatty acid elongase component enzymes. PLoS One 2019; 14:e0213620. [PMID: 30856216 PMCID: PMC6411113 DOI: 10.1371/journal.pone.0213620] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 02/25/2019] [Indexed: 11/19/2022] Open
Abstract
Fatty acids of more than 18-carbons, generally known as very long chain fatty acids (VLCFAs) are essential for eukaryotic cell viability, and uniquely in terrestrial plants they are the precursors of the cuticular lipids that form the organism's outer barrier to the environment. VLCFAs are synthesized by fatty acid elongase (FAE), which is an integral membrane enzyme system with multiple components. The genetic complexity of the FAE system, and its membrane association has hampered the biochemical characterization of FAE. In this study we computationally identified Zea mays genetic sequences that encode the enzymatic components of FAE and developed a heterologous expression system to evaluate their functionality. The ability of the maize components to genetically complement Saccharomyces cerevisiae lethal mutants confirmed the functionality of ZmKCS4, ZmELO1, ZmKCR1, ZmKCR2, ZmHCD and ZmECR, and the VLCFA profiles of the resulting strains were used to infer the ability of each enzyme component to determine the product profile of FAE. These characterizations indicate that the product profile of the FAE system is an attribute shared among the KCS, ELO, and KCR components of FAE.
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Affiliation(s)
- Alexis A. Campbell
- Roy J Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, United States of America
- Center for Metabolic Biology, Iowa State University, Ames, Iowa, United States of America
- NSF-Engineering Research Center for Biorenewable Chemicals, Iowa State University, Ames, Iowa, United States of America
| | - Kenna E. Stenback
- Roy J Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, United States of America
- NSF-Engineering Research Center for Biorenewable Chemicals, Iowa State University, Ames, Iowa, United States of America
| | - Kayla Flyckt
- Roy J Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, United States of America
- NSF-Engineering Research Center for Biorenewable Chemicals, Iowa State University, Ames, Iowa, United States of America
| | - Trang Hoang
- Roy J Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, United States of America
- NSF-Engineering Research Center for Biorenewable Chemicals, Iowa State University, Ames, Iowa, United States of America
| | - M Ann DN Perera
- W.M. Keck Metabolomics Research Laboratory, Iowa State University, Ames, Iowa, United States of America
| | - Basil J. Nikolau
- Roy J Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, United States of America
- Center for Metabolic Biology, Iowa State University, Ames, Iowa, United States of America
- NSF-Engineering Research Center for Biorenewable Chemicals, Iowa State University, Ames, Iowa, United States of America
- W.M. Keck Metabolomics Research Laboratory, Iowa State University, Ames, Iowa, United States of America
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10
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Genetically Compromising Phospholipid Metabolism Limits Candida albicans' Virulence. Mycopathologia 2019; 184:213-226. [PMID: 30693413 DOI: 10.1007/s11046-019-00320-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 01/19/2019] [Indexed: 01/06/2023]
Abstract
Perturbing ergosterol synthesis has been previously shown to reduce the virulence of Candida albicans. We tested the hypothesis that further altering cell membrane composition by limiting phospholipid synthesis or remodeling will have the same effect. To model partial inhibition, C. albicans strains independently harboring heterozygous deletion of four genes that encode for enzymes that mediate phospholipid synthesis or modification were generated. Quantitative PCR determined that heterozygous deletion routinely caused a nearly 50% reduction in the respective gene's transcript abundance. Compensatory increased transcript abundance was only found with the deletion of LRO1, a homolog of phospholipid diacylglycerol acyltransferases. Virulence of the mutants was assayed in a Caenorhabditis elegans host model. Even modestly reduced expression of LRO1, phosphatidylserine synthase (CHO1), and lysophospholipid acyltransferase (LPT1) significantly reduced virulence by 23-38%. Reintroducing a second functional allele, respectively, to all three mutants restored virulence. Heterozygous deletion of SLC1, a homolog of 1-acylglycerol-3-phosphate O-acyltransferases, did not significantly reduce virulence. Electrospray ionization tandem mass spectrometry analysis of phospholipid composition followed by principal component analysis identified comprehensive changes in the LRO1 and CHO1 deletion heterozygotes. Strikingly (p < 0.001), univariate comparisons found that both deletion heterozygotes had 20% more phosphatidylinositol, 75% less lysophosphatidylcholine, and 35% less lysophosphatidylethanolamine compared to wild type. Heterozygous deletion of LPT1 also significantly increased phosphatidylinositol abundance. No growth phenotype, including filamentation, was affected by any mutation. Together, these data predict that even partial pharmacological inhibition of Lro1p, Cho1p, and Lpt1p will limit C. albicans virulence through altering phospholipid composition.
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11
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Kim Y, Jung JP, Pack CG, Huh WK. Global analysis of protein homomerization in Saccharomyces cerevisiae. Genome Res 2018; 29:135-145. [PMID: 30567710 PMCID: PMC6314163 DOI: 10.1101/gr.231860.117] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 11/26/2018] [Indexed: 11/24/2022]
Abstract
In vivo analyses of the occurrence, subcellular localization, and dynamics of protein–protein interactions (PPIs) are important issues in functional proteomic studies. The bimolecular fluorescence complementation (BiFC) assay has many advantages in that it provides a reliable way to detect PPIs in living cells with minimal perturbation of the structure and function of the target proteins. Previously, to facilitate the application of the BiFC assay to genome-wide analysis of PPIs, we generated a collection of yeast strains expressing full-length proteins tagged with the N-terminal fragment of Venus (VN), a yellow fluorescent protein variant, from their own native promoters. In the present study, we constructed a VC (the C-terminal fragment of Venus) fusion library consisting of 5671 MATα strains expressing C-terminally VC-tagged proteins (representing ∼91% of the yeast proteome). For genome-wide analysis of protein homomer formation, we mated each strain in the VC fusion library with its cognate strain in the VN fusion library and performed the BiFC assay. From this analysis, we identified 186 homomer candidates. We further investigated the functional relevance of the homomerization of Pln1, a yeast perilipin. Our data set provides a useful resource for understanding the physiological roles of protein homomerization. Furthermore, the VC fusion library together with the VN fusion library will provide a valuable platform to systematically analyze PPIs in the natural cellular context.
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Affiliation(s)
- Yeonsoo Kim
- Department of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Jong Pil Jung
- Department of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Chan-Gi Pack
- ASAN Institute for Life Sciences, ASAN Medical Center, University of Ulsan College of Medicine, Seoul 05505, Republic of Korea
| | - Won-Ki Huh
- Department of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea.,Institute of Microbiology, Seoul National University, Seoul 08826, Republic of Korea
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12
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Ogawa T, Tanaka A, Kawamoto J, Kurihara T. Purification and characterization of 1-acyl-sn-glycerol-3-phosphate acyltransferase with a substrate preference for polyunsaturated fatty acyl donors from the eicosapentaenoic acid-producing bacterium Shewanella livingstonensis Ac10. J Biochem 2018; 164:33-39. [PMID: 29415144 DOI: 10.1093/jb/mvy025] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 01/21/2018] [Indexed: 11/12/2022] Open
Abstract
1-Acyl-sn-glycerol-3-phosphate acyltransferase (designated as PlsC in bacteria) catalyzes the acylation of lysophosphatidic acid and is responsible for the de novo production of phosphatidic acid, a precursor for the synthesis of various membrane glycerophospholipids. Because PlsC is an integral membrane protein, it is generally difficult to solubilize it without causing its inactivation, which has been hampering its biochemical characterization despite its ubiquitous presence and physiological importance. Most biochemical studies of PlsC have been carried out using crude membrane preparations or intact cells. In this study, we succeeded in solubilization and purification of a recombinant PlsC in its active form from the eicosapentaenoic acid-producing bacterium Shewanella livingstonensis Ac10 using 6-cyclohexyl-1-hexyl-β-d-maltoside as the detergent. We characterized the purified enzyme and found that it has a substrate preference for the acyl donors with a polyunsaturated fatty acyl group, such as eicosapentaenoyl group. These results provide a new method for purification of the PlsC family enzyme and demonstrate the occurrence of a new PlsC with unique substrate specificity.
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Affiliation(s)
- Takuya Ogawa
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Asako Tanaka
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Jun Kawamoto
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Tatsuo Kurihara
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
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13
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Lei J, Miao Y, Lan Y, Han X, Liu H, Gan Y, Niu L, Wang Y, Zheng Z. A Novel Complementation Assay for Quick and Specific Screen of Genes Encoding Glycerol-3-Phosphate Acyltransferases. FRONTIERS IN PLANT SCIENCE 2018; 9:353. [PMID: 29616064 PMCID: PMC5867339 DOI: 10.3389/fpls.2018.00353] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Accepted: 03/02/2018] [Indexed: 06/08/2023]
Abstract
The initial step in glycerolipid biosynthesis, especially in diverse allopolyploid crop species, is poorly understood, mainly due to the lack of an effective and convenient method for functional characterization of genes encoding glycerol-3-phosphate acyltransferases (GPATs) catalyzing this reaction. Here we present a novel complementation assay for quick and specific characterization of GPAT-encoding genes. Its key design involves rational construction of yeast conditional lethal gat1Δgat2Δ double mutant bearing the heterologous Arabidopsis AtGPAT1 gene whose leaky expression under repressed conditions does not support any non-specific growth, thereby circumventing the false positive problem encountered with the system based on the gat1Δgat2Δ mutant harboring the native episomal GAT1 gene whose leaky expression appears to be sufficient for generating enough GPAT activities for the non-specific restoration of the mutant growth. A complementation assay developed based on this novel mutant enables quick phenotypic screen of GPAT sequences. A high degree of specificity of our assay was exemplified by its ability to differentiate effectively GPAT-encoding genes from those of other fatty acyltransferases and lipid-related sequences. Using this assay, we show that Arabidopsis AtGPAT1, AtGPAT5, and AtGPAT7 can complement the phosphatidate biosynthetic defect in the double mutants. Collectively, our assay provides a powerful tool for rapid screening, validation and optimization of GPAT sequences, aiding future engineering of the initial step of the triacylglycerol biosynthesis in oilseeds.
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Affiliation(s)
- Jie Lei
- School of Agriculture and Food Science, Zhejiang A & F University, Hangzhou, China
| | - Yingchun Miao
- School of Forestry and Biotechnology, Zhejiang A & F University, Hangzhou, China
| | - Yu Lan
- School of Forestry and Biotechnology, Zhejiang A & F University, Hangzhou, China
| | - Xiuxiu Han
- School of Agriculture and Food Science, Zhejiang A & F University, Hangzhou, China
| | - Hongbo Liu
- School of Agriculture and Food Science, Zhejiang A & F University, Hangzhou, China
| | - Yi Gan
- School of Agriculture and Food Science, Zhejiang A & F University, Hangzhou, China
| | - Leilei Niu
- School of Agriculture and Food Science, Zhejiang A & F University, Hangzhou, China
| | - Yanyan Wang
- School of Agriculture and Food Science, Zhejiang A & F University, Hangzhou, China
| | - Zhifu Zheng
- School of Agriculture and Food Science, Zhejiang A & F University, Hangzhou, China
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14
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Endoplasmic reticulum acyltransferase with prokaryotic substrate preference contributes to triacylglycerol assembly in Chlamydomonas. Proc Natl Acad Sci U S A 2018; 115:1652-1657. [PMID: 29382746 DOI: 10.1073/pnas.1715922115] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Understanding the unique features of triacylglycerol (TAG) metabolism in microalgae may be necessary to realize the full potential of these organisms for biofuel and biomaterial production. In the unicellular green alga Chlamydomonas reinhardtii a chloroplastic (prokaryotic) pathway has been proposed to play a major role in TAG precursor biosynthesis. However, as reported here, C. reinhardtii contains a chlorophyte-specific lysophosphatidic acid acyltransferase, CrLPAAT2, that localizes to endoplasmic reticulum (ER) membranes. Unlike canonical, ER-located LPAATs, CrLPAAT2 prefers palmitoyl-CoA over oleoyl-CoA as the acyl donor substrate. RNA-mediated suppression of CrLPAAT2 indicated that the enzyme is required for TAG accumulation under nitrogen deprivation. Our findings suggest that Chlamydomonas has a distinct glycerolipid assembly pathway that relies on CrLPAAT2 to generate prokaryotic-like TAG precursors in the ER.
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15
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Wei Y, Gossing M, Bergenholm D, Siewers V, Nielsen J. Increasing cocoa butter-like lipid production of Saccharomyces cerevisiae by expression of selected cocoa genes. AMB Express 2017; 7:34. [PMID: 28168573 PMCID: PMC5293708 DOI: 10.1186/s13568-017-0333-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 01/27/2017] [Indexed: 12/29/2022] Open
Abstract
Cocoa butter (CB) extracted from cocoa beans mainly consists of three different kinds of triacylglycerols (TAGs), 1,3-dipalmitoyl-2-oleoyl-glycerol (POP, C16:0–C18:1–C16:0), 1-palmitoyl-3-stearoyl-2-oleoyl-glycerol (POS, C16:0–C18:1–C18:0) and 1,3-distearoyl-2-oleoyl-glycerol (SOS, C18:0–C18:1–C18:0), but CB supply is limited. Therefore, CB-like lipids (CBL, which are composed of POP, POS and SOS) are in great demand. Saccharomyces cerevisiae produces TAGs as storage lipids, which are also mainly composed of C16 and C18 fatty acids. However, POP, POS and SOS are not among the major TAG forms in yeast. TAG synthesis is mainly catalyzed by three enzymes: glycerol-3-phosphate acyltransferase (GPAT), lysophospholipid acyltransferase (LPAT) and diacylglycerol acyltransferase (DGAT). In order to produce CBL in S. cerevisiae, we selected six cocoa genes encoding GPAT, LPAT and DGAT potentially responsible for CB biosynthesis from the cocoa genome using a phylogenetic analysis approach. By expressing the selected cocoa genes in S. cerevisiae, we successfully increased total fatty acid production, TAG production and CBL production in some S. cerevisiae strains. The relative CBL content in three yeast strains harboring cocoa genes increased 190, 230 and 196% over the control strain, respectively; especially, the potential SOS content of the three yeast strains increased 254, 476 and 354% over the control strain. Moreover, one of the three yeast strains had a 2.25-fold increased TAG content and 6.7-fold higher level of CBL compared with the control strain. In summary, CBL production by S. cerevisiae were increased through expressing selected cocoa genes potentially involved in CB biosynthesis.
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16
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Oelkers P, Pokhrel K. Four Acyltransferases Uniquely Contribute to Phospholipid Heterogeneity in Saccharomyces cerevisiae. Lipid Insights 2016; 9:31-41. [PMID: 27920551 PMCID: PMC5127605 DOI: 10.4137/lpi.s40597] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 09/25/2016] [Accepted: 10/25/2016] [Indexed: 11/14/2022] Open
Abstract
Diverse acyl-CoA species and acyltransferase isoenzymes are components of a complex system that synthesizes glycerophospholipids and triacylglycerols. Saccharomyces cerevisiae has four main acyl-CoA species, two main glycerol-3-phosphate 1-O-acyltransferases (Gat1p, Gat2p), and two main 1-acylglycerol-3-phosphate O-acyltransferases (Lpt1p, Slc1p). The in vivo contribution of these isoenzymes to phospholipid heterogeneity was determined using haploids with compound mutations: gat1Δlpt1Δ, gat2Δlpt1Δ, gat1Δslc1Δ, and gat2Δslc1Δ. All mutations mildly reduced [3H]palmitic acid incorporation into phospholipids relative to triacylglycerol. Electrospray ionization tandem mass spectrometry identified few differences from wild type in gat1Δlpt1Δ, dramatic differences in gat2Δslc1Δ, and intermediate changes in gat2Δlpt1Δ and gat1Δslc1Δ. Yeast expressing Gat1p and Lpt1p had phospholipids enriched with acyl chains that were unsaturated, 18 carbons long, and paired for length. These alterations prevented growth at 18.5°C and in 10% ethanol. Therefore, Gat2p and Slc1p dictate phospholipid acyl chain composition in rich media at 30°C. Slc1p selectively pairs acyl chains of different lengths.
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Affiliation(s)
- Peter Oelkers
- Department of Natural Sciences, University of Michigan-Dearborn, Dearborn, MI, USA
| | - Keshav Pokhrel
- Department of Mathematics and Statistics, University of Michigan-Dearborn, Dearborn, MI, USA
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Rovillos MJ, Pauling JK, Hannibal-Bach HK, Vionnet C, Conzelmann A, Ejsing CS. Structural characterization of suppressor lipids by high-resolution mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2016; 30:2215-2227. [PMID: 27484921 DOI: 10.1002/rcm.7704] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 07/15/2016] [Accepted: 07/30/2016] [Indexed: 06/06/2023]
Abstract
RATIONALE Suppressor lipids were originally identified in 1993 and reported to encompass six lipid classes that enable Saccharomyces cerevisiae to live without sphingolipids. Structural characterization, using non-mass spectrometric approaches, revealed that these suppressor lipids are very long chain fatty acid (VLCFA)-containing glycerophospholipids with polar head groups that are typically incorporated into sphingolipids. Here we report, for the first time, the structural characterization of the yeast suppressor lipids using high-resolution mass spectrometry. METHODS Suppressor lipids were isolated by preparative chromatography and subjected to structural characterization using hybrid quadrupole time-of-flight and ion trap-orbitrap mass spectrometry. RESULTS Our investigation recapitulates the overall structural features of the suppressor lipids and provides an in-depth characterization of their fragmentation pathways. Tandem mass analysis identified the positionally defined molecular lipid species phosphatidylinositol (PI) 26:0/16:1, PI mannoside (PIM) 16:0/26:0 and PIM inositol-phosphate (PIMIP) 16:0/26:0 as abundant suppressor lipids. This finding differs from the original study that only inferred the positional isomer PI 16:0/26:0 and prompts new insight into the biosynthesis of suppressor lipids. Moreover, we also report the identification of a novel suppressor lipid featuring an amino sugar residue linked to a VLCFA-containing PI molecule. CONCLUSIONS Fragmentation pathways of yeast suppressor lipids have been delineated. In addition, the fragmentation information has been added to our open source ALEX lipid database to support automated identification and quantitative monitoring of suppressor lipids in yeast and bacteria that produce similar lipid molecules. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Mary Joy Rovillos
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Josch Konstantin Pauling
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Hans Kristian Hannibal-Bach
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Christine Vionnet
- Division of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Andreas Conzelmann
- Division of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Christer S Ejsing
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark.
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18
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Jain S, Dholakia H, Kirtley W, Oelkers P. Energy Storage in Yeast: Regulation and Competition with Ethanol Production. Curr Microbiol 2016; 73:851-858. [PMID: 27620384 DOI: 10.1007/s00284-016-1127-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 08/18/2016] [Indexed: 10/21/2022]
Abstract
Mechanisms that may regulate the storage of energy as triacylglycerol in Saccharomyces cerevisiae were examined. First, the kinetics of Dga1p, which mediates the majority of diacylglycerol esterification, the lone committed step in triacylglycerol synthesis, was measured in vitro. With an apparent K m of 17.0 μM, Dga1p has higher affinity for oleoyl-CoA than the only S. cerevisiae acyltransferase previously kinetically characterized, Lpt1p. Lpt1p is a 1-acylglycerol-3-phosphate O-acyltransferase that produces phosphatidate, a precursor to diacylglycerol. Therefore, limiting triacylglycerol synthesis to situations of elevated acyl-CoA concentration is unlikely. However, Dga1p's apparent V max of 5.8 nmol/min/mg was 20 times lower than Lpt1p's. This supports Dga1p being rate limiting for TAG synthesis. Dga1p activity was not activated or inhibited when seven different molecules (e.g., ATP) which reflect cellular energy status were provided at physiological concentrations. Thus, allosteric regulation was not found. Coordination between triacylglycerol and glycogen synthesis was also tested. Yeast genetically deficient in triacylglycerol synthesis did not store more energy in glycogen and vice versa. Lastly, we tested whether genetically limiting energy storage in triacylglycerol, glycogen, steryl esters, or combinations of these will increase ethanol production efficiency. In nutrient-rich media containing 5 % glucose, solely limiting glycogen synthesis had the greatest affect, increasing ethanol production efficiency by 12 %. Since limiting glycogen synthesis only had a modest effect on growth in media containing 10 % ethanol, such genetic manipulation may improve commercial ethanol production.
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Affiliation(s)
- Shilpa Jain
- Department of Bioscience and Biotechnology, Drexel University, 3245 Chestnut Street, Philadelphia, PA, 19104, USA.,Trac Services Ltd, Trevenson Road, TR153, Truro, Cornwall, UK
| | - Hemal Dholakia
- Department of Natural Sciences, University of Michigan-Dearborn, 4901 Evergreen Rd., Dearborn, MI, 48128, USA
| | - Winston Kirtley
- Department of Natural Sciences, University of Michigan-Dearborn, 4901 Evergreen Rd., Dearborn, MI, 48128, USA
| | - Peter Oelkers
- Department of Natural Sciences, University of Michigan-Dearborn, 4901 Evergreen Rd., Dearborn, MI, 48128, USA.
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Chemogenetic E-MAP in Saccharomyces cerevisiae for Identification of Membrane Transporters Operating Lipid Flip Flop. PLoS Genet 2016; 12:e1006160. [PMID: 27462707 PMCID: PMC4962981 DOI: 10.1371/journal.pgen.1006160] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 06/10/2016] [Indexed: 01/12/2023] Open
Abstract
While most yeast enzymes for the biosynthesis of glycerophospholipids, sphingolipids and ergosterol are known, genes for several postulated transporters allowing the flopping of biosynthetic intermediates and newly made lipids from the cytosolic to the lumenal side of the membrane are still not identified. An E-MAP measuring the growth of 142'108 double mutants generated by systematically crossing 543 hypomorphic or deletion alleles in genes encoding multispan membrane proteins, both on media with or without an inhibitor of fatty acid synthesis, was generated. Flc proteins, represented by 4 homologous genes encoding presumed FAD or calcium transporters of the ER, have a severe depression of sphingolipid biosynthesis and elevated detergent sensitivity of the ER. FLC1, FLC2 and FLC3 are redundant in granting a common function, which remains essential even when the severe cell wall defect of flc mutants is compensated by osmotic support. Biochemical characterization of some other genetic interactions shows that Cst26 is the enzyme mainly responsible for the introduction of saturated very long chain fatty acids into phosphatidylinositol and that the GPI lipid remodelase Cwh43, responsible for introducing ceramides into GPI anchors having a C26:0 fatty acid in sn-2 of the glycerol moiety can also use lyso-GPI protein anchors and various base resistant lipids as substrates. Furthermore, we observe that adjacent deletions in several chromosomal regions show strong negative genetic interactions with a single gene on another chromosome suggesting the presence of undeclared suppressor mutations in certain chromosomal regions that need to be identified in order to yield meaningful E-map data. All living cells define their boundaries by lipid-containing membranes, which are impermeable to ions and water-soluble metabolic intermediates, and thus allow maintaining constant conditions inside the cells and stopping metabolic intermediates from diffusing away. Membranes are formed by amphiphilic lipids that have a hydrophilic and a hydrophobic component. Such lipids form flat double-layered sheets (bilayers) wherein the hydrophilic components of the constituent lipids are directed towards the aqueous surroundings, the hydrophobic ones populate the center of the bilayer. Membranes grow when enzymes resident in the bilayer synthesize new amphiphilic lipids. These enzymes have their active site on one side of the membrane and insert the newly made lipids in only one of the two layers. To ensure symmetric growth of membranes, cells need flippases catalyzing the transfer of lipids from one into the other layer. To identify unknown flippases we performed a chemogenetic interaction screen able to bring to light functions of unknown proteins through their genetic interaction with genes of known function. The data point to Flc proteins as potential lipid flippases of the endoplasmic reticulum, reveal novel lipid modifying activities of Cst26 and Cwh43 and suggest that undeclared suppressor mutations in certain chromosomal regions can generate false genetic interactions.
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20
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Körbes AP, Kulcheski FR, Margis R, Margis-Pinheiro M, Turchetto-Zolet AC. Molecular evolution of the lysophosphatidic acid acyltransferase (LPAAT) gene family. Mol Phylogenet Evol 2016; 96:55-69. [DOI: 10.1016/j.ympev.2015.12.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 10/21/2015] [Accepted: 12/03/2015] [Indexed: 10/22/2022]
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21
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Graziano S, Gullì M, Maestri E, Marmiroli N. The global effect of exposing bakers' yeast to 5-fluoruracil and nystatin; a view to Toxichip. CHEMOSPHERE 2016; 145:470-479. [PMID: 26694798 DOI: 10.1016/j.chemosphere.2015.11.045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 10/07/2015] [Accepted: 11/15/2015] [Indexed: 06/05/2023]
Abstract
A genome-wide screen of a haploid deletion library of bakers' yeast (Saccharomyces cerevisiae) was conducted to document the phenotypic and transcriptional impact of exposure to each of the two pharmaceutical products 5-fluorouracil (an anti-tumor agent) and nystatin (an anti-fungal agent). The combined data set was handled by applying a systems biology perspective. A Gene Ontology analysis identified functional categories previously characterized as likely targets for both compounds. Induced transcription profiles were well correlated in yeast and human HepG2 cells. The identified molecular targets for both compounds were used to suggest a small set of human orthologues as appropriate for testing on human material. The yeast system developed here (denoted "Toxichip") has likely utility for identifying biomarkers relevant for health and environmental risk assessment applications required as part of the development process for novel pharmaceuticals.
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Affiliation(s)
- Sara Graziano
- Department of Life Sciences, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
| | - Mariolina Gullì
- Department of Life Sciences, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
| | - Elena Maestri
- Department of Life Sciences, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
| | - Nelson Marmiroli
- Department of Life Sciences, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy.
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22
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Olson DK, Fröhlich F, Farese RV, Walther TC. Taming the sphinx: Mechanisms of cellular sphingolipid homeostasis. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1861:784-792. [PMID: 26747648 DOI: 10.1016/j.bbalip.2015.12.021] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 12/14/2015] [Accepted: 12/28/2015] [Indexed: 12/11/2022]
Abstract
Sphingolipids are important structural membrane components of eukaryotic cells, and potent signaling molecules. As such, their levels must be maintained to optimize cellular functions in different cellular membranes. Here, we review the current knowledge of homeostatic sphingolipid regulation. We describe recent studies in Saccharomyces cerevisiae that have provided insights into how cells sense changes in sphingolipid levels in the plasma membrane and acutely regulate sphingolipid biosynthesis by altering signaling pathways. We also discuss how cellular trafficking has emerged as an important determinant of sphingolipid homeostasis. Finally, we highlight areas where work is still needed to elucidate the mechanisms of sphingolipid regulation and the physiological functions of such regulatory networks, especially in mammalian cells. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.
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Affiliation(s)
- D K Olson
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, United States; Department of Cell Biology, Yale School of Medicine, United States
| | - F Fröhlich
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, United States
| | - R V Farese
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, United States; Department of Cell Biology, Harvard Medical School, United States; Broad Institute of Harvard and MIT, United States.
| | - T C Walther
- Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, United States; Department of Cell Biology, Harvard Medical School, United States; Broad Institute of Harvard and MIT, United States; Howard Hughes Medical Institute, United States.
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23
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Saccharomyces cerevisiae Is Dependent on Vesicular Traffic between the Golgi Apparatus and the Vacuole When Inositolphosphorylceramide Synthase Aur1 Is Inactivated. EUKARYOTIC CELL 2015; 14:1203-16. [PMID: 26432633 DOI: 10.1128/ec.00117-15] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 09/28/2015] [Indexed: 12/24/2022]
Abstract
Inositolphosphorylceramide (IPC) and its mannosylated derivatives are the only complex sphingolipids of yeast. Their synthesis can be reduced by aureobasidin A (AbA), which specifically inhibits the IPC synthase Aur1. AbA reportedly, by diminishing IPC levels, causes endoplasmic reticulum (ER) stress, an increase in cytosolic calcium, reactive oxygen production, and mitochondrial damage leading to apoptosis. We found that when Aur1 is gradually depleted by transcriptional downregulation, the accumulation of ceramides becomes a major hindrance to cell survival. Overexpression of the alkaline ceramidase YPC1 rescues cells under this condition. We established hydroxylated C26 fatty acids as a reliable hallmark of ceramide hydrolysis. Such hydrolysis occurs only when YPC1 is overexpressed. In contrast, overexpression of YPC1 has no beneficial effect when Aur1 is acutely repressed by AbA. A high-throughput genetic screen revealed that vesicle-mediated transport between Golgi apparatus, endosomes, and vacuole becomes crucial for survival when Aur1 is repressed, irrespective of the mode of repression. In addition, vacuolar acidification becomes essential when cells are acutely stressed by AbA, and quinacrine uptake into vacuoles shows that AbA activates vacuolar acidification. The antioxidant N-acetylcysteine does not improve cell growth on AbA, indicating that reactive oxygen radicals induced by AbA play a minor role in its toxicity. AbA strongly induces the cell wall integrity pathway, but osmotic support does not improve the viability of wild-type cells on AbA. Altogether, the data support and refine current models of AbA-mediated cell death and add vacuolar protein transport and acidification as novel critical elements of stress resistance.
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24
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De Block J, Szopinska A, Guerriat B, Dodzian J, Villers J, Hochstenbach JF, Morsomme P. Yeast Pmp3p has an important role in plasma membrane organization. J Cell Sci 2015; 128:3646-59. [PMID: 26303201 DOI: 10.1242/jcs.173211] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 08/18/2015] [Indexed: 01/24/2023] Open
Abstract
Pmp3p-related proteins are highly conserved proteins that exist in bacteria, yeast, nematodes and plants, and its transcript is regulated in response to abiotic stresses, such as low temperature or high salinity. Pmp3p was originally identified in Saccharomyces cerevisiae, and it belongs to the sensitive to Na(+) (SNA)-protein family, which comprises four members--Pmp3p/Sna1p, Sna2p, Sna3p and Sna4p. Deletion of the PMP3 gene conferred sensitivity to cytotoxic cations, whereas removal of the other SNA genes did not lead to clear phenotypic effects. It has long been believed that Pmp3p-related proteins have a common and important role in the modulation of plasma membrane potential and in the regulation of intracellular ion homeostasis. Here, we show that several growth phenotypes linked to PMP3 deletion can be modulated by the removal of specific genes involved in sphingolipid synthesis. These genetic interactions, together with lipid binding assays and epifluorescence microscopy, as well as other biochemical experiments, suggest that Pmp3p could be part of a phosphoinositide-regulated stress sensor.
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Affiliation(s)
- Julien De Block
- Université Catholique de Louvain, Institut des Sciences de la Vie, Croix du Sud 4-5, Louvain-la-Neuve B-1348, Belgium
| | - Aleksandra Szopinska
- Université Catholique de Louvain, Institut des Sciences de la Vie, Croix du Sud 4-5, Louvain-la-Neuve B-1348, Belgium
| | - Bérengère Guerriat
- Université Catholique de Louvain, Institut des Sciences de la Vie, Croix du Sud 4-5, Louvain-la-Neuve B-1348, Belgium
| | - Joanna Dodzian
- Université Catholique de Louvain, Institut des Sciences de la Vie, Croix du Sud 4-5, Louvain-la-Neuve B-1348, Belgium
| | - Jennifer Villers
- Université Catholique de Louvain, Institut des Sciences de la Vie, Croix du Sud 4-5, Louvain-la-Neuve B-1348, Belgium
| | - Jean-François Hochstenbach
- Université Catholique de Louvain, Institut des Sciences de la Vie, Croix du Sud 4-5, Louvain-la-Neuve B-1348, Belgium
| | - Pierre Morsomme
- Université Catholique de Louvain, Institut des Sciences de la Vie, Croix du Sud 4-5, Louvain-la-Neuve B-1348, Belgium
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25
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Olson DK, Fröhlich F, Christiano R, Hannibal-Bach HK, Ejsing CS, Walther TC. Rom2-dependent phosphorylation of Elo2 controls the abundance of very long-chain fatty acids. J Biol Chem 2014; 290:4238-47. [PMID: 25519905 DOI: 10.1074/jbc.m114.629279] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Sphingolipids are essential components of eukaryotic membranes, where they serve to maintain membrane integrity. They are important components of membrane trafficking and function in signaling as messenger molecules. Sphingolipids are synthesized de novo from very long-chain fatty acids (VLCFA) and sphingoid long-chain bases, which are amide linked to form ceramide and further processed by addition of various headgroups. Little is known concerning the regulation of VLCFA levels and how cells coordinate their synthesis with the availability of long-chain bases for sphingolipid synthesis. Here we show that Elo2, a key enzyme of VLCFA synthesis, is controlled by signaling of the guanine nucleotide exchange factor Rom2, initiating at the plasma membrane. This pathway controls Elo2 phosphorylation state and VLCFA synthesis. Our data identify a regulatory mechanism for coordinating VLCFA synthesis with sphingolipid metabolism and link signal transduction pathways from the plasma membrane to the regulation of lipids for membrane homeostasis.
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Affiliation(s)
- Daniel K Olson
- From the Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115, the Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut 06150
| | - Florian Fröhlich
- From the Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115
| | - Romain Christiano
- From the Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115
| | - Hans K Hannibal-Bach
- the Department of Biochemistry and Molecular Biology, University of Southern Denmark, 0230 Odense, Denmark
| | - Christer S Ejsing
- the Department of Biochemistry and Molecular Biology, University of Southern Denmark, 0230 Odense, Denmark
| | - Tobias C Walther
- From the Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115, the Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, and the Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142
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26
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Selvaraju K, Rajakumar S, Nachiappan V. Identification of a phospholipase B encoded by the LPL1 gene in Saccharomyces cerevisiae. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1842:1383-92. [PMID: 25014274 DOI: 10.1016/j.bbalip.2014.06.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 06/26/2014] [Accepted: 06/28/2014] [Indexed: 10/25/2022]
Abstract
Phospholipids also play a major role in maintaining the lipid droplet (LD) morphology. In our current study, deletion of LPL1 resulted in altered morphology of LDs and was confirmed by microscopic analysis. LPL1/YOR059c contains lipase specific motif GXSXG and acetate labeling in the LPL1 overexpressed strains depicted a decrease in glycerophospholipids and an increase in free fatty acids. The purified Lpl1p showed phospholipase activity with broader substrate specificity, acting on all glycerophospholipids primarily at sn-2 position and later at sn-1 position. Localization studies precisely revealed that Lpl1 is exclusively localized in the LD at the stationary phase. Site directed mutagenesis experiments clearly demonstrated that the lipase motif is vital for the phospholipase activity. In summary, our results demonstrate that yeast Lpl1 exerts phospholipase activity, plays a vital role in LD morphology, and its absence results in altered LD size. Based on the localization and enzyme activity we renamed YOR059c as LPL1 (LD phospholipase 1).
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Affiliation(s)
- Kandasamy Selvaraju
- Department of Biochemistry, School of Life Sciences, Bharathidasan University, Tiruchirappalli, 620024, Tamilnadu, India
| | - Selvaraj Rajakumar
- Department of Biochemistry, School of Life Sciences, Bharathidasan University, Tiruchirappalli, 620024, Tamilnadu, India
| | - Vasanthi Nachiappan
- Department of Biochemistry, School of Life Sciences, Bharathidasan University, Tiruchirappalli, 620024, Tamilnadu, India.
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Koch B, Schmidt C, Daum G. Storage lipids of yeasts: a survey of nonpolar lipid metabolism in Saccharomyces cerevisiae, Pichia pastoris, and Yarrowia lipolytica. FEMS Microbiol Rev 2014; 38:892-915. [PMID: 24597968 DOI: 10.1111/1574-6976.12069] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 02/21/2014] [Accepted: 02/21/2014] [Indexed: 11/29/2022] Open
Abstract
Biosynthesis and storage of nonpolar lipids, such as triacylglycerols (TG) and steryl esters (SE), have gained much interest during the last decades because defects in these processes are related to severe human diseases. The baker's yeast Saccharomyces cerevisiae has become a valuable tool to study eukaryotic lipid metabolism because this single-cell microorganism harbors many enzymes and pathways with counterparts in mammalian cells. In this article, we will review aspects of TG and SE metabolism and turnover in the yeast that have been known for a long time and combine them with new perceptions of nonpolar lipid research. We will provide a detailed insight into the mechanisms of nonpolar lipid synthesis, storage, mobilization, and degradation in the yeast S. cerevisiae. The central role of lipid droplets (LD) in these processes will be addressed with emphasis on the prevailing view that this compartment is more than only a depot for TG and SE. Dynamic and interactive aspects of LD with other organelles will be discussed. Results obtained with S. cerevisiae will be complemented by recent investigations of nonpolar lipid research with Yarrowia lipolytica and Pichia pastoris. Altogether, this review article provides a comprehensive view of nonpolar lipid research in yeast.
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Affiliation(s)
- Barbara Koch
- Institute of Biochemistry, Graz University of Technology, Graz, Austria
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Characterization of a lysophospholipid acyltransferase involved in membrane remodeling in Candida albicans. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1841:505-13. [PMID: 24406902 DOI: 10.1016/j.bbalip.2013.12.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 12/08/2013] [Accepted: 12/30/2013] [Indexed: 11/22/2022]
Abstract
Phospholipid remodeling involves phospholipase activity to remove acyl chains and acyltransferases to replace acyl chains. We here describe the characterization of a lysophospholipid acyltransferase in the opportunistic fungal pathogen, Candida albicans. Expression of this gene, C.a. LPT1, complemented the lysophospholipid acyltransferase defect in Saccharomyces cerevisiae strains lacking the homologous LPT1 gene. In vitro, lysophospholipid acyltransferase activity in these strains showed acyl-CoA substrate specificity, as measured by apparent Vmax/Km ratios, to be linolenoyl-CoA>oleoyl-CoA>linoleoyl-CoA>stearoyl-CoA. To address the physiological importance of C.a. LPT1, homozygous deletion strains were generated. Lysophospholipid acyltransferase activity with amine containing lysophospholipids was dramatically reduced while lysophosphatidylinositol and lysophosphatidic acid esterification was not significantly lowered. However, C.a. LPT1 over-expression yielded an increased amount of lysophosphatidic acyltransferase activity, suggesting a role in de novo phospholipid synthesis. LPT1 deletion strains showed slightly slowed growth in standard liquid media but no phenotype in media containing three antifungals that target sterols. To assess the role of C.a. Lpt1 in phospholipid remodeling, an in vivo, pulse-chase assay utilizing polysorbitan palmitate and mass spectrometry was developed. Cellular phospholipid composition became atypical with the provision of palmitate and gradually returned to the typical distribution when palmitate was removed. Deletion of C.a. LPT1 showed a modest yet significant effect on remodeling under these conditions.
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Acyltransferases and transacylases that determine the fatty acid composition of glycerolipids and the metabolism of bioactive lipid mediators in mammalian cells and model organisms. Prog Lipid Res 2014; 53:18-81. [DOI: 10.1016/j.plipres.2013.10.001] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 07/20/2013] [Accepted: 10/01/2013] [Indexed: 12/21/2022]
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Merscher S, Fornoni A. Podocyte pathology and nephropathy - sphingolipids in glomerular diseases. Front Endocrinol (Lausanne) 2014; 5:127. [PMID: 25126087 PMCID: PMC4115628 DOI: 10.3389/fendo.2014.00127] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 07/14/2014] [Indexed: 01/10/2023] Open
Abstract
Sphingolipids are components of the lipid rafts in plasma membranes, which are important for proper function of podocytes, a key element of the glomerular filtration barrier. Research revealed an essential role of sphingolipids and sphingolipid metabolites in glomerular disorders of genetic and non-genetic origin. The discovery that glucocerebrosides accumulate in Gaucher disease in glomerular cells and are associated with clinical proteinuria initiated intensive research into the function of other sphingolipids in glomerular disorders. The accumulation of sphingolipids in other genetic diseases including Tay-Sachs, Sandhoff, Fabry, hereditary inclusion body myopathy 2, Niemann-Pick, and nephrotic syndrome of the Finnish type and its implications with respect to glomerular pathology will be discussed. Similarly, sphingolipid accumulation occurs in glomerular diseases of non-genetic origin including diabetic kidney disease (DKD), HIV-associated nephropathy, focal segmental glomerulosclerosis (FSGS), and lupus nephritis. Sphingomyelin metabolites, such as ceramide, sphingosine, and sphingosine-1-phosphate have also gained tremendous interest. We recently described that sphingomyelin phosphodiesterase acid-like 3b (SMPDL3b) is expressed in podocytes where it modulates acid sphingomyelinase activity and acts as a master modulator of danger signaling. Decreased SMPDL3b expression in post-reperfusion kidney biopsies from transplant recipients with idiopathic FSGS correlates with the recurrence of proteinuria in patients and in experimental models of xenotransplantation. Increased SMPDL3b expression is associated with DKD. The consequences of differential SMPDL3b expression in podocytes in these diseases with respect to their pathogenesis will be discussed. Finally, the role of sphingolipids in the formation of lipid rafts in podocytes and their contribution to the maintenance of a functional slit diaphragm in the glomerulus will be discussed.
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Affiliation(s)
- Sandra Merscher
- Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, Miami, FL, USA
- *Correspondence: Sandra Merscher, Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, 1580 NW 10th Avenue, Batchelor Building, Room 628, Miami, FL 33136, USA e-mail: ; Alessia Fornoni, Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, 1580 NW 10th Avenue, Batchelor Building, Room 633, Miami, FL 33136, USA e-mail:
| | - Alessia Fornoni
- Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, Miami, FL, USA
- *Correspondence: Sandra Merscher, Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, 1580 NW 10th Avenue, Batchelor Building, Room 628, Miami, FL 33136, USA e-mail: ; Alessia Fornoni, Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, 1580 NW 10th Avenue, Batchelor Building, Room 633, Miami, FL 33136, USA e-mail:
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Liang MH, Jiang JG. Advancing oleaginous microorganisms to produce lipid via metabolic engineering technology. Prog Lipid Res 2013; 52:395-408. [DOI: 10.1016/j.plipres.2013.05.002] [Citation(s) in RCA: 231] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 05/03/2013] [Accepted: 05/06/2013] [Indexed: 02/04/2023]
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Michaillat L, Mayer A. Identification of genes affecting vacuole membrane fragmentation in Saccharomyces cerevisiae. PLoS One 2013; 8:e54160. [PMID: 23383298 PMCID: PMC3562189 DOI: 10.1371/journal.pone.0054160] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 12/10/2012] [Indexed: 11/19/2022] Open
Abstract
The equilibrium of membrane fusion and fission influences the volume and copy number of organelles. Fusion of yeast vacuoles has been well characterized but their fission and the mechanisms determining vacuole size and abundance remain poorly understood. We therefore attempted to systematically characterize factors necessary for vacuole fission. Here, we present results of an in vivo screening for deficiencies in vacuolar fragmentation activity of an ordered collection deletion mutants, representing 4881 non-essential genes of the yeast Saccharomyces cerevisiae. The screen identified 133 mutants with strong defects in vacuole fragmentation. These comprise numerous known fragmentation factors, such as the Fab1p complex, Tor1p, Sit4p and the V-ATPase, thus validating the approach. The screen identified many novel factors promoting vacuole fragmentation. Among those are 22 open reading frames of unknown function and three conspicuous clusters of proteins with known function. The clusters concern the ESCRT machinery, adaptins, and lipases, which influence the production of diacylglycerol and phosphatidic acid. A common feature of these factors of known function is their capacity to change membrane curvature, suggesting that they might promote vacuole fragmentation via this property.
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Affiliation(s)
- Lydie Michaillat
- Département de Biochimie, Université de Lausanne, Epalinges, Switzerland
| | - Andreas Mayer
- Département de Biochimie, Université de Lausanne, Epalinges, Switzerland
- * E-mail:
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Li-Beisson Y, Shorrosh B, Beisson F, Andersson MX, Arondel V, Bates PD, Baud S, Bird D, DeBono A, Durrett TP, Franke RB, Graham IA, Katayama K, Kelly AA, Larson T, Markham JE, Miquel M, Molina I, Nishida I, Rowland O, Samuels L, Schmid KM, Wada H, Welti R, Xu C, Zallot R, Ohlrogge J. Acyl-lipid metabolism. THE ARABIDOPSIS BOOK 2013; 11:e0161. [PMID: 23505340 PMCID: PMC3563272 DOI: 10.1199/tab.0161] [Citation(s) in RCA: 699] [Impact Index Per Article: 63.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Acyl lipids in Arabidopsis and all other plants have a myriad of diverse functions. These include providing the core diffusion barrier of the membranes that separates cells and subcellular organelles. This function alone involves more than 10 membrane lipid classes, including the phospholipids, galactolipids, and sphingolipids, and within each class the variations in acyl chain composition expand the number of structures to several hundred possible molecular species. Acyl lipids in the form of triacylglycerol account for 35% of the weight of Arabidopsis seeds and represent their major form of carbon and energy storage. A layer of cutin and cuticular waxes that restricts the loss of water and provides protection from invasions by pathogens and other stresses covers the entire aerial surface of Arabidopsis. Similar functions are provided by suberin and its associated waxes that are localized in roots, seed coats, and abscission zones and are produced in response to wounding. This chapter focuses on the metabolic pathways that are associated with the biosynthesis and degradation of the acyl lipids mentioned above. These pathways, enzymes, and genes are also presented in detail in an associated website (ARALIP: http://aralip.plantbiology.msu.edu/). Protocols and methods used for analysis of Arabidopsis lipids are provided. Finally, a detailed summary of the composition of Arabidopsis lipids is provided in three figures and 15 tables.
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Meyer SGE, Wendt AE, Scherer M, Liebisch G, Kerkweg U, Schmitz G, de Groot H. Myriocin, an inhibitor of serine palmitoyl transferase, impairs the uptake of transferrin and low-density lipoprotein in mammalian cells. Arch Biochem Biophys 2012; 526:60-8. [PMID: 22841978 DOI: 10.1016/j.abb.2012.07.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 07/09/2012] [Accepted: 07/10/2012] [Indexed: 11/29/2022]
Abstract
The role of sphingolipids in clathrin-mediated endocytosis is only poorly understood in mammalian cells. Thus the relationship between sphingolipid de novo synthesis and clathrin-mediated endocytosis of transferrin were studied in L929 fibroblasts and two other cell lines. Endocytosis was measured using live cell imaging with fluorescent transferrin or (125)I-transferrin. Lipids were primarily measured using electrospray ionization tandem mass spectrometry. At physiological temperature, transferrin uptake was significantly decreased by the inhibitor of serine palmitoyl transferase myriocin. Myriocin inhibited also the uptake of low-density lipoproteins. The endocytosis inhibition by myriocin could be released by the addition of sphingoid base and by the protein phosphorylation effectors phorbol-12-myristate, 13-acetate (PMA) and okadaic acid. Myriocin influenced not only sphingolipids but also the glycerophospholipid profile. The study of phosphatidylcholine species shows adaptations to more saturated, alkylated and longer fatty acid moieties. The reported results imply that in mammalian cells, at 37°C, sphingolipid de novo synthesis is required for clathrin-mediated endocytosis.
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Affiliation(s)
- Sybille G E Meyer
- Institut für Physiologische Chemie, Universitätsklinikum Essen, Essen, Germany.
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Klose C, Surma MA, Gerl MJ, Meyenhofer F, Shevchenko A, Simons K. Flexibility of a eukaryotic lipidome--insights from yeast lipidomics. PLoS One 2012; 7:e35063. [PMID: 22529973 PMCID: PMC3329542 DOI: 10.1371/journal.pone.0035063] [Citation(s) in RCA: 204] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 03/12/2012] [Indexed: 11/20/2022] Open
Abstract
Mass spectrometry-based shotgun lipidomics has enabled the quantitative and comprehensive assessment of cellular lipid compositions. The yeast Saccharomyces cerevisiae has proven to be a particularly valuable experimental system for studying lipid-related cellular processes. Here, by applying our shotgun lipidomics platform, we investigated the influence of a variety of commonly used growth conditions on the yeast lipidome, including glycerophospholipids, triglycerides, ergosterol as well as complex sphingolipids. This extensive dataset allowed for a quantitative description of the intrinsic flexibility of a eukaryotic lipidome, thereby providing new insights into the adjustments of lipid biosynthetic pathways. In addition, we established a baseline for future lipidomic experiments in yeast. Finally, flexibility of lipidomic features is proposed as a new parameter for the description of the physiological state of an organism.
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Affiliation(s)
- Christian Klose
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Michal A. Surma
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Mathias J. Gerl
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Felix Meyenhofer
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Andrej Shevchenko
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Kai Simons
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- * E-mail:
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Ayciriex S, Le Guédard M, Camougrand N, Velours G, Schoene M, Leone S, Wattelet-Boyer V, Dupuy JW, Shevchenko A, Schmitter JM, Lessire R, Bessoule JJ, Testet E. YPR139c/LOA1 encodes a novel lysophosphatidic acid acyltransferase associated with lipid droplets and involved in TAG homeostasis. Mol Biol Cell 2011; 23:233-46. [PMID: 22090344 PMCID: PMC3258169 DOI: 10.1091/mbc.e11-07-0650] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
LOA1, a yeast member of the glycerolipid acyltransferase family, encodes a novel lysophosphatidic acid acyltransferase associated with lipid droplets (LDs) and involved in triacylglycerol (TAG) accumulation. Loa1p, recruited during LD formation, preferentially directs oleic acid–containing phosphatidic acid species into the TAG biosynthetic pathway. For many years, lipid droplets (LDs) were considered to be an inert store of lipids. However, recent data showed that LDs are dynamic organelles playing an important role in storage and mobilization of neutral lipids. In this paper, we report the characterization of LOA1 (alias VPS66, alias YPR139c), a yeast member of the glycerolipid acyltransferase family. LOA1 mutants show abnormalities in LD morphology. As previously reported, cells lacking LOA1 contain more LDs. Conversely, we showed that overexpression results in fewer LDs. We then compared the lipidome of loa1Δ mutant and wild-type strains. Steady-state metabolic labeling of loa1Δ revealed a significant reduction in triacylglycerol content, while phospholipid (PL) composition remained unchanged. Interestingly, lipidomic analysis indicates that both PLs and glycerolipids are qualitatively affected by the mutation, suggesting that Loa1p is a lysophosphatidic acid acyltransferase (LPA AT) with a preference for oleoyl-CoA. This hypothesis was tested by in vitro assays using both membranes of Escherichia coli cells expressing LOA1 and purified proteins as enzyme sources. Our results from purification of subcellular compartments and proteomic studies show that Loa1p is associated with LD and active in this compartment. Loa1p is therefore a novel LPA AT and plays a role in LD formation.
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Affiliation(s)
- Sophie Ayciriex
- Laboratoire de Biogenèse Membranaire, Université Bordeaux, UMR 5200, F-33000 Bordeaux, France
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Pagac M, de la Mora HV, Duperrex C, Roubaty C, Vionnet C, Conzelmann A. Topology of 1-acyl-sn-glycerol-3-phosphate acyltransferases SLC1 and ALE1 and related membrane-bound O-acyltransferases (MBOATs) of Saccharomyces cerevisiae. J Biol Chem 2011; 286:36438-47. [PMID: 21849510 DOI: 10.1074/jbc.m111.256511] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In yeast, phosphatidic acid, the biosynthetic precursor for all glycerophospholipids and triacylglycerols, is made de novo by the 1-acyl-sn-glycerol-3-phosphate acyltransferases Ale1p and Slc1p. Ale1p belongs to the membrane-bound O-acyltransferase (MBOAT) family, which contains many enzymes acylating lipids but also others that acylate secretory proteins residing in the lumen of the ER. A histidine present in a very short loop between two predicted transmembrane domains is the only residue that is conserved throughout the MBOAT gene family. The yeast MBOAT proteins of known function comprise Ale1p, the ergosterol acyltransferases Are1p and Are2p, and Gup1p, the last of which acylates lysophosphatidylinositol moieties of GPI anchors on ER lumenal GPI proteins. C-terminal topology reporters added to truncated versions of Gup1p yield a topology predicting a lumenal location of its uniquely conserved histidine 447 residue. The same approach shows that Ale1p and Are2p also have the uniquely conserved histidine residing in the ER lumen. Because these data raised the possibility that phosphatidic acid could be made in the lumen of the ER, we further investigated the topology of the second yeast 1-acyl-sn-glycerol-3-phosphate acyltransferase, Slc1p. The location of C-terminal topology reporters, microsomal assays probing the protease sensitivity of inserted tags, and the accessibility of natural or artificially inserted cysteines to membrane-impermeant alkylating agents all indicate that the most conserved motif containing the presumed active site histidine of Slc1p is oriented toward the ER lumen, whereas other conserved motifs are cytosolic. The implications of these findings are discussed.
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Affiliation(s)
- Martin Pagac
- Department of Biology, University of Fribourg, CH-1700 Fribourg, Switzerland
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Vionnet C, Roubaty C, Ejsing CS, Knudsen J, Conzelmann A. Yeast cells lacking all known ceramide synthases continue to make complex sphingolipids and to incorporate ceramides into glycosylphosphatidylinositol (GPI) anchors. J Biol Chem 2010; 286:6769-79. [PMID: 21173150 DOI: 10.1074/jbc.m110.176875] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
In yeast, the inositolphosphorylceramides mostly contain C26:0 fatty acids. Inositolphosphorylceramides were considered to be important for viability because the inositolphosphorylceramide synthase AUR1 is essential. However, lcb1Δ cells, unable to make sphingoid bases and inositolphosphorylceramides, are viable if they harbor SLC1-1, a gain of function mutation in the 1-acyl-glycerol-3-phosphate acyltransferase SLC1. SLC1-1 allows the incorporation of C26:0 fatty acids into phosphatidylinositol (PI), thus generating PI″, an abnormal, C26-containing PI, presumably acting as surrogate for inositolphosphorylceramide. Here we show that the lethality of the simultaneous deletion of the known ceramide synthases LAG1/LAC1/LIP1 and YPC1/YDC1 can be rescued by the expression of SLC1-1 or the overexpression of AUR1. Moreover, lag1Δ lac1Δ ypc1Δ ydc1Δ (4Δ) quadruple mutants have been reported to be viable in certain genetic backgrounds but to still make some abnormal uncharacterized inositol-containing sphingolipids. Indeed, we find that 4Δ quadruple mutants make substantial amounts of unphysiological inositolphosphorylphytosphingosines but that they also still make small amounts of normal inositolphosphorylceramides. Moreover, 4Δ strains incorporate exogenously added sphingoid bases into inositolphosphorylceramides, indicating that these cells still possess an unknown pathway allowing the synthesis of ceramides. 4Δ cells also still add quite normal amounts of ceramides to glycosylphosphatidylinositol anchors. Synthesis of inositolphosphorylceramides and inositolphosphorylphytosphingosines is operated by Aur1p and is essential for growth of all 4Δ cells unless they contain SLC1-1. PI″, however, is made without the help of Aur1p. Furthermore, mannosylation of PI″ is required for the survival of sphingolipid-deficient strains, which depend on SLC1-1. In contrast to lcb1Δ SLC1-1, 4Δ SLC1-1 cells grow at 37 °C but remain thermosensitive at 44 °C.
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Affiliation(s)
- Christine Vionnet
- Department of Medicine, University of Fribourg, Chemin du Musée 5, CH-1700 Fribourg, Switzerland
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40
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Li-Beisson Y, Shorrosh B, Beisson F, Andersson MX, Arondel V, Bates PD, Baud S, Bird D, DeBono A, Durrett TP, Franke RB, Graham IA, Katayama K, Kelly AA, Larson T, Markham JE, Miquel M, Molina I, Nishida I, Rowland O, Samuels L, Schmid KM, Wada H, Welti R, Xu C, Zallot R, Ohlrogge J. Acyl-lipid metabolism. THE ARABIDOPSIS BOOK 2010; 8:e0133. [PMID: 22303259 PMCID: PMC3244904 DOI: 10.1199/tab.0133] [Citation(s) in RCA: 236] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Acyl lipids in Arabidopsis and all other plants have a myriad of diverse functions. These include providing the core diffusion barrier of the membranes that separates cells and subcellular organelles. This function alone involves more than 10 membrane lipid classes, including the phospholipids, galactolipids, and sphingolipids, and within each class the variations in acyl chain composition expand the number of structures to several hundred possible molecular species. Acyl lipids in the form of triacylglycerol account for 35% of the weight of Arabidopsis seeds and represent their major form of carbon and energy storage. A layer of cutin and cuticular waxes that restricts the loss of water and provides protection from invasions by pathogens and other stresses covers the entire aerial surface of Arabidopsis. Similar functions are provided by suberin and its associated waxes that are localized in roots, seed coats, and abscission zones and are produced in response to wounding. This chapter focuses on the metabolic pathways that are associated with the biosynthesis and degradation of the acyl lipids mentioned above. These pathways, enzymes, and genes are also presented in detail in an associated website (ARALIP: http://aralip.plantbiology.msu.edu/). Protocols and methods used for analysis of Arabidopsis lipids are provided. Finally, a detailed summary of the composition of Arabidopsis lipids is provided in three figures and 15 tables.
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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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Le Guédard M, Bessoule JJ, Boyer V, Ayciriex S, Velours G, Kulik W, Ejsing CS, Shevchenko A, Coulon D, Lessire R, Testet E. PSI1 is responsible for the stearic acid enrichment that is characteristic of phosphatidylinositol in yeast. FEBS J 2009; 276:6412-24. [DOI: 10.1111/j.1742-4658.2009.07355.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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44
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Rao SS, Hildebrand D. Changes in oil content of transgenic soybeans expressing the yeast SLC1 gene. Lipids 2009; 44:945-51. [PMID: 19768478 DOI: 10.1007/s11745-009-3337-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Accepted: 07/26/2009] [Indexed: 10/20/2022]
Abstract
The wild type (Wt) and mutant form of yeast (sphingolipid compensation) genes, SLC1 and SLC1-1, have been shown to have lysophosphatidic acid acyltransferase (LPAT) activities (Nageic et al. in J Biol Chem 269:22156-22163, 1993). Expression of these LPAT genes was reported to increase oil content in transgenic Arabidopsis and Brassica napus. It is of interest to determine if the TAG content increase would also be seen in soybeans. Therefore, the wild type SLC1 was expressed in soybean somatic embryos under the control of seed specific phaseolin promoter. Some transgenic somatic embryos and in both T2 and T3 transgenic seeds showed higher oil contents. Compared to controls, the average increase in triglyceride values went up by 1.5% in transgenic somatic embryos. A maximum of 3.2% increase in seed oil content was observed in a T3 line. Expression of the yeast Wt LPAT gene did not alter the fatty acid composition of the seed oil.
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Affiliation(s)
- Suryadevara S Rao
- Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546, USA
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Cerantola V, Guillas I, Roubaty C, Vionnet C, Uldry D, Knudsen J, Conzelmann A. Aureobasidin A arrests growth of yeast cells through both ceramide intoxication and deprivation of essential inositolphosphorylceramides. Mol Microbiol 2009; 71:1523-37. [PMID: 19210614 DOI: 10.1111/j.1365-2958.2009.06628.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
All mature Saccharomyces cerevisiae sphingolipids comprise inositolphosphorylceramides containing C26:0 or C24:0 fatty acids and either phytosphingosine or dihydrosphingosine. Here we analysed the lipid profile of lag1Delta lac1Delta mutants lacking acyl-CoA-dependent ceramide synthesis, which require the reverse ceramidase activity of overexpressed Ydc1p for sphingolipid biosynthesis and viability. These cells, termed 2Delta.YDC1, make sphingolipids containing exclusively dihydrosphingosine and an abnormally wide spectrum of fatty acids with between 18 and 26 carbon atoms. Like wild-type cells, 2Delta.YDC1 cells stop growing when exposed to Aureobasidin A (AbA), an inhibitor of the inositolphosphorylceramide synthase AUR1, yet their ceramide levels remain very low. This finding argues against a current hypothesis saying that yeast cells do not require inositolphosphorylceramides and die in the presence of AbA only because ceramides build up to toxic concentrations. Moreover, W303lag1Delta lac1Delta ypc1Delta ydc1Delta cells, reported to be AbA resistant, stop growing on AbA after a certain number of cell divisions, most likely because AbA blocks the biosynthesis of anomalous inositolphosphorylsphingosides. Thus, data argue that inositolphosphorylceramides of yeast, the equivalent of mammalian sphingomyelins, are essential for growth. Data also clearly confirm that wild-type strains, when exposed to AbA, immediately stop growing because of ceramide intoxication, long before inositolphosphorylceramide levels become subcritical.
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Affiliation(s)
- Vanessa Cerantola
- Department of Medicine, University of Fribourg, Fribourg, Switzerland
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Stålberg K, Neal AC, Ronne H, Ståhl U. Identification of a novel GPCAT activity and a new pathway for phosphatidylcholine biosynthesis in S. cerevisiae. J Lipid Res 2008; 49:1794-806. [DOI: 10.1194/jlr.m800129-jlr200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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47
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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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48
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Dickson RC. Thematic review series: sphingolipids. New insights into sphingolipid metabolism and function in budding yeast. J Lipid Res 2008; 49:909-21. [PMID: 18296751 DOI: 10.1194/jlr.r800003-jlr200] [Citation(s) in RCA: 172] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Our understanding of sphingolipid metabolism and functions in the baker's yeast Saccharomyces cerevisiae has progressed substantially in the past 2 years. Yeast sphingolipids contain a C26-acyl moiety, all of the genes necessary to make these long-chain fatty acids have been identified, and a mechanism for how chain length is determined has been proposed. Advances in understanding how the de novo synthesis of ceramide and complex sphingolipids is regulated have been made, and they demonstrate that the Target Of Rapamycin Complex 2 (TORC2) controls ceramide synthase activity. Other work shows that TORC2 regulates the level of complex sphingolipids in a pathway using the Slm1 and Slm2 proteins to control the protein phosphatase calcineurin, which regulates the breakdown of complex sphingolipids. The activity of Slm1 and Slm2 has also been shown to be regulated during heat stress by phosphoinositides and TORC2, along with sphingoid long-chain bases and the Pkh1 and Pkh2 protein kinases, to control the actin cytoskeleton, the trafficking of nutrient transporters, and cell viability. Together, these results provide the first molecular insights into understanding previous genetic interaction data that indicated a connection between sphingolipids and the TORC2 and phosphoinositide signaling networks. This new knowledge provides a foundation for greatly advancing our understanding of sphingolipid biology in yeast.
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Affiliation(s)
- Robert C Dickson
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536-0509, USA.
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Ghosh AK, Ramakrishnan G, Rajasekharan R. YLR099C (ICT1) encodes a soluble Acyl-CoA-dependent lysophosphatidic acid acyltransferase responsible for enhanced phospholipid synthesis on organic solvent stress in Saccharomyces cerevisiae. J Biol Chem 2008; 283:9768-75. [PMID: 18252723 DOI: 10.1074/jbc.m708418200] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
One of the major determinants of organic solvent tolerance is the increase in membrane phospholipids. Here we report for the first time that an increase in the synthesis of phosphatidic acid is responsible for enhanced phospholipid synthesis that confers tolerance to the organic solvent in Saccharomyces cerevisiae. This increase in phosphatidic acid formation is because of the induction of Ict1p, a soluble oleoyl-CoA:lysophosphatidic acid acyltransferase. YLR099C (ICT1) was reported to be maximally expressed during solvent tolerance (Miura, S., Zou, W., Ueda, M., and Tanaka, A. (2000) Appl. Environ. Microbiol. 66, 4883-4889); however, its physiological significance was not understood. In silico analysis revealed the absence of any transmembrane domain in Ict1p. Domain analysis showed that it has a hydrolase/acyltransferase domain with a distinct lipid-binding motif and a lysophospholipase domain. Analysis of ict1Delta strain showed a drastic reduction in phosphatidic acid suggesting the role of Ict1p in phosphatidic acid biosynthesis. Overexpression of Ict1p in S. cerevisiae showed an increase in phosphatidic acid and other phospholipids on organic solvent exposure. To understand the biochemical function of Ict1p, the gene was cloned and expressed in Escherichia coli. The purified recombinant enzyme was found to specifically acylate lysophosphatidic acid. Specific activity of Ict1p was found to be higher for oleoyl-CoA as compared with palmitoyl- and stearoyl-CoAs. This study provides a mechanism for organic solvent tolerance from the point of membrane dynamics in S. cerevisiae.
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Affiliation(s)
- Ananda K Ghosh
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
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50
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Riekhof WR, Wu J, Gijón MA, Zarini S, Murphy RC, Voelker DR. Lysophosphatidylcholine metabolism in Saccharomyces cerevisiae: the role of P-type ATPases in transport and a broad specificity acyltransferase in acylation. J Biol Chem 2007; 282:36853-61. [PMID: 17951629 DOI: 10.1074/jbc.m706718200] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We recently described a new route for the synthesis of phosphatidylethanolamine (PtdEtn) from exogenous lyso-PtdEtn, which we have termed the exogenous lysolipid metabolism (ELM) pathway. The ELM pathway for lyso-PtdEtn requires the action of plasma membrane P-type ATPases Dnf1p and Dnf2p and their requisite beta-subunit, Lem3p, for the active uptake of lyso-PtdEtn. In addition, the acyl-CoA-dependent acyltransferase, Ale1p, mediates the acylation of the imported lysolipid to form PtdEtn. We now report that these components of the lyso-PtdEtn ELM pathway are also active with lyso-1-acyl-2-hydroxyl-sn-glycero-3-phosphocholine (PtdCho) as a substrate. Lyso-PtdCho supports the growth of a choline auxotrophic pem1Delta pem2Delta strain. Uptake of radiolabeled lyso-PtdCho was impaired by the dnf2Delta and lem3Delta mutations. Introduction of a lem3Delta mutation into a pem1Delta pem2Delta background impaired the ability of the resulting strain to grow with lyso-PtdCho as the sole precursor of PtdCho. After import of lyso-PtdCho, the recently characterized lyso-PtdEtn acyltransferase, Ale1p, functioned as the sole lyso-PtdCho acyltransferase in yeast. A pem1Delta pem2Delta ale1Delta strain grew with lyso-PtdCho as a substrate but showed a profound reduction in PtdCho content when lyso-PtdCho was the only precursor of PtdCho. Ale1p acylates lyso-PtdCho with a preference for monounsaturated acyl-CoA species, and the specific LPCAT activity of Ale1p in yeast membranes is >50-fold higher than the basal rate of de novo aminoglycerophospholipid biosynthesis from phosphatidylserine synthase activity. In addition to lyso-PtdCho, lyso-PtdEtn, and lyso-phosphatidic acid, Ale1p was also active with lysophosphatidylserine, lysophosphatidylglycerol, and lysophosphatidylinositol as substrates. These results establish a new pathway for the net synthesis of PtdCho in yeast and provide new tools for the study of PtdCho synthesis, transport, and remodeling.
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Affiliation(s)
- Wayne R Riekhof
- Department of Medicine, Program in Cell Biology, National Jewish Medical and Research Center, Denver, Colorado 80206, USA
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