Lipid-dependent Subcellular Relocalization of the Acyl Chain Desaturase in Yeast

Tatzer, Verena; Zellnig, Günther; Kohlwein, Sepp D.; Schneiter, Roger

doi:10.1091/mbc.e02-04-0196

Cited by 32 publications

(24 citation statements)

References 54 publications

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“…yeast, Ole1p (52,53,62); accordingly, overexpression of OLE1 under control of the strong GAL1/10 promoter neither stimulated desaturation, nor did it enhance cell death of the quadruple mutant (data not shown), consistent with the notion of multiple levels of control of desaturase activity in yeast (53). Second, saturated FA supplementation to mutants unable to synthesize TAG had no apparent effect on viability, in yeast.…”

Section: Strainsupporting

confidence: 56%

Good Fat, Essential Cellular Requirements for Triacylglycerol Synthesis to Maintain Membrane Homeostasis in Yeast

Petschnigg

Wolinski

Kolb

et al. 2009

Journal of Biological Chemistry

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196

205

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Storage triacylglycerols (TAG) and membrane phospholipids share common precursors, i.e. phosphatidic acid and diacylglycerol, in the endoplasmic reticulum. In addition to providing a biophysically rather inert storage pool for fatty acids, TAG synthesis plays an important role to buffer excess fatty acids (FA). The inability to incorporate exogenous oleic acid into TAG in a yeast mutant lacking the acyltransferases Lro1p, Dga1p, Are1p, and Are2p contributing to TAG synthesis results in dysregulation of lipid synthesis, massive proliferation of intracellular membranes, and ultimately cell death. Carboxypeptidase Y trafficking from the endoplasmic reticulum to the vacuole is severely impaired, but the unfolded protein response is only moderately up-regulated, and dispensable for membrane proliferation, upon exposure to oleic acid. FA-induced toxicity is specific to oleic acid and much less pronounced with palmitoleic acid and is not detectable with the saturated fatty acids, palmitic and stearic acid. Palmitic acid supplementation partially suppresses oleic acid-induced lipotoxicity and restores carboxypeptidase Y trafficking to the vacuole. These data show the following: (i) FA uptake is not regulated by the cellular lipid requirements; (ii) TAG synthesis functions as a crucial intracellular buffer for detoxifying excess unsaturated fatty acids; (iii) membrane lipid synthesis and proliferation are responsive to and controlled by a balanced fatty acid composition.In the aqueous cellular environment, fatty acyl chains esterified in glycerophospholipids constitute the hydrophobic barrier of biological membranes. Thus, fatty acid (FA) 3 composition is a crucial determinant of cellular membrane function. Establishment of the specific FA profiles in lipid species of various organelle membranes (1) relies on an intricate balance between endogenous FA synthesis, recycling of FA from lipid breakdown, and perhaps uptake from the exterior. Glycerophospholipids and triacylglycerols (TAG), which serve as the major storage form of FA, share the similar precursors phosphatidic acid (PA) and diacylglycerol (DAG), both generated in the endoplasmic reticulum (ER) membrane. TAG are packaged into lipid droplets and are thus sequestered away from the ER membrane by a mechanism not yet understood. In addition, membranes and lipid storage pools (2, 3) undergo significant turnover and intracellular flux, e.g. during secretion or endocytosis and cellular growth, which must be accounted for by mechanisms that establish and maintain lipid homeostasis in these dynamic membrane systems (4). We have recently shown that TAG degradation provides metabolites that are critical for efficient cell cycle progression at the G 1

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Section: Strainsupporting

confidence: 56%

Good Fat, Essential Cellular Requirements for Triacylglycerol Synthesis to Maintain Membrane Homeostasis in Yeast

Petschnigg

Wolinski

Kolb

et al. 2009

Journal of Biological Chemistry

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196

205

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“…All these proteins are described as ER-localized enzymes (7,39,40). The reason for a higher proportion of mislocalized sphingolipid enzymes was not due to the expression from an episomal plasmid but may rather reflect particular sensitivity of these enzymes to C-terminal modification and/or interference Endoplasmic reticulum (92) a ALG9, AQY1, ARE1, ARE2, AUR1, AYR1*, BOS1*, CHO1, CHO2, COX10*, CSG2*, CSR1*, CYB5, DGA1*, DPL1, DPP1*, EHT1*, ELO1, EPT1*, ERG1*, ERG2*, ERG24*, ERG25*, ERG26, ERG27*, ERG3*, ERG4, ERG5, ERG6*, ERG7*, ERG9*, EUG1*, FAA1*, FAA4*, FAT1*, FEN1, FEN2, FPS1, GAA1*, GOG5, GPI11, GPI2, GPI8, GSF2, GUP1, HMG1*, INP54*, IRE1, LCB2, LPP1*, MEC1, NCP1, NCR1, OLE1, OPI3*, PAU7*, PHO86, PIK1*, PIS1*, PLB1*, PLB2*, PTC2*, RVS161*, SAC1*, SCS7*, SEC14*, SEC22*, SLA1*, SLC1*, SPC1, STE14, SUR2, SUR4, TIP1, TSC10*, YBR204C*, YDC1*, YDL015C*, YDL193W*, YDR018C*, YIL011W, YIM1*, YJU3*, YKL174C*, YKR003W*, YLR343W, YOL132W*, YOR059C*, LCB1, YJU3*, NVJ1, YDL015C* Lipid droplets (23) AYR1*, DGA1*, EHT1*, ERG1*, ERG27*, ERG6*, ERG7*, FAA4*, FAT1*, PDR16*, SLC1*, TGL1, TGL3, YBR042C, YBR204C*, YDL193W*, YDR018C*, YIM1*, YJU3*, YKR046C, YKR089C, YOR059C*, YOR081C Peroxisomes (17) ACS1, DCI1*, FAA2*, MDH3*, PEX10, PEX11, PEX13, PEX14, PEX17*, PEX19*, PEX2*, PEX3, PEX4, PEX5*, POT1, POX1, SPS19* Plasma membrane (14) ALR1*, ERG13*, FAA1*, FAA3, GIT1*, PDR16*, PDR17*, SNQ2, TSC10*, VHT1*, YJL145W*, YLL012W, YMR210W*, YOR009W* Mitochondria (27) AAD10, ACP1, AGP2, BIO2, CEM1*, COQ1, COX10*, COX4, CPT1, CRC1, CYB2, ECM1, ERG13*, GUT1, HEM1, PGS1, PPT2*, PSD1, RAM1*, RVS167, SCS3, TES1, TGL2, YAP1, YBR159W*, YDR531W, YPR140W Vacuole, membrane (7) ALR1*, AST2*, DPP1*, PIB1, PIB2, VPH1, YBR161W* Vacuole, lumen (5) GIT1*, PKA3*, SUR1*, YIL005W, YOR009W* Nucleus, lumen (56) ACS2, ADA2*, ALD2, ARD1*, BDF1, BET2*, BET4, CDC43*, DCI1*, ERG10, ERG13*, FMS1*, GCN5, GDS1, HAP2, HAP5, HDA1, HHF1, HHT1, HHT2, HTA3*, IML3*, INO4*, MRS6*, MUQ1*, NAT1, NDD1*, PGD1*, PIP2*, PKA3*, QRI2, RAD61, RAM2*, REX3, RFA2*, RFA3*, ROX1, RPD3*, RTT105, SCM3, SEC21, SKN7, SPO12, THI3, TOR2*, TUP1*, YCR072C*, YGL144C*, YGR198W*, YHR046C*, YJR107W*, YKL091C, YLR323C, YMR192W, YNL086W*, YOL054W Nucleus, nucleolus (5) ADA2*, HTA3*, IML3*, RER2*, YCR072C* Nucleus, envelope (6) ADR1, NDD1*, NUP53, OPI1, PCT1, YPC1* Vesicles (55) APG7*, APL2*, AQY2, AST2*, BET1, BOS1*, CDC48*, CSG2*, DPP1*, ERG2*, ERG20, ERG24*, ERG25*, ERG3*, ERG9*, EUG1*, FAA1*, GAA1*, GIT1*, GTS1, HES1*, HFA1*, HMG1*, INP54*, KES1*, LPP1*, OPI3*, PAU7*, PDR5*, PIS1*, PKA3*, PLB1*, PLB2*, PLB3*, PPT2*, PTC2*, RER2*, SCS7*, SEC22*, SUR1*, TSC10*, VHT1*, VPS4*, YBR108W*, YBR161W*, YDC1*, YDL015C*, YGR198W*, YJL072C, YKL174C*, YKR003W*, YKT6, YOL132W*, YOR009W*, YPC1* Golgi (7) BET3*, EPT1*, GDA1, PIK1*, PIS1*, SAC1*, SEC14* Cytoskeleton (7) SAC6*, SLA1*, SRV2*, YGR136W, YSC84*, YDR532C*, ZTA1* Others (8) SEC2*, VPS24, CEM1*, GCD7, HNM1, STT4, TOR1, YDR541C* Cytoplasm (177) AAD6, AAH1, ACB1, ACF2, ACH1, ALD6, APG1, APG12, APG13, APG16, APG7*, APG9, APL2*, ARD1*, AST1, AST2*, AUT7, BET2*, BET3*, B...…”

Section: Overexpression Of Gfp Fusions Results In Stablementioning

confidence: 99%

“…We have previously observed that a conditional variant of the Ole1 protein, Mdm2 ts (54), is reversibly sequestered within minutes into ER domains under restrictive conditions when the enzyme is unable to desaturate fatty acids. This relocalization process is suppressed by unsaturated fatty acid supplementation (55), clearly demonstrating that localization of this lipidmetabolizing enzyme is strongly dependent on its lipid environment, which may become modified by its own enzymatic activity. Such a model would also explain how changes in the lipid profiles by altered growth conditions or mutations result in major rearrangements of membrane lipid compositions.…”

Section: Yeast Large Scale Gfp Localization Studymentioning

confidence: 93%

The Spatial Organization of Lipid Synthesis in the Yeast Saccharomyces cerevisiae Derived from Large Scale Green Fluorescent Protein Tagging and High Resolution Microscopy

Natter

Leitner

Faschinger

et al. 2005

Molecular & Cellular Proteomics

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161

151

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The localization pattern of proteins involved in lipid metabolism in the yeast Saccharomyces cerevisiae was determined using C-terminal green fluorescent protein tagging and high resolution confocal laser scanning microscopy. A list of 493 candidate proteins (ϳ9% of the yeast proteome) was assembled based on proteins of known function in lipid metabolism, their interacting proteins, proteins defined by genetic interactions, and regulatory factors acting on selected genes or proteins. Overall 400 (81%) transformants yielded a positive green fluorescent protein signal, and of these, 248 (62% of the 400) displayed a localization pattern that was not cytosolic. Observations for many proteins with known localization patterns were consistent with published data derived from cell fractionation or large scale localization approaches. However, in many cases, high resolution microscopy provided additional information that indicated that proteins distributed to multiple subcellular locations. The majority of tagged enzymes localized to the endoplasmic reticulum (91), but others localized to mitochondria (27), peroxisomes (17), lipid droplets (23), and vesicles (53). We assembled enzyme localization patterns for phospholipid, sterol, and sphingolipid biosynthetic pathways and propose a model, based on enzyme localization, for concerted regulation of sterol and sphingolipid metabolism that involves shuttling of key enzymes between endoplasmic reticulum, lipid droplets, vesicles, and Golgi. Molecular & Cellular Proteomics 4:662-672, 2005.Biological membranes are characterized by a highly complex mixture of lipids that are key determinants of the biophysical parameters of membranes, such as fluidity, permeability, and signaling functions. Thus, lipids affect structure and function of peripheral and integral membrane proteins, and thus play a pivotal role in organelle (membrane) function. In the yeast Saccharomyces cerevisiae, the lipid composition appears rather simple, consisting mainly of glycerophospholipids, sphingolipids, and ergosterol (1); however, recent advances in analytical techniques such as nanoelectrospray ionization tandem mass spectrometry (2) have unveiled a great degree of heterogeneity within the molecular species of phospholipids. Furthermore subcellular membranes differ not only in their lipid composition in terms of lipid classes, they are also characterized by a distinct distribution of molecular species of phospholipids (3). Because only a few membranes harbor enzymes involved in lipid synthesis, this heterogeneity may be established by localized synthesis, localized degradation, and selective trafficking of membrane lipids. Interestingly apparently "linear" pathways for the synthesis of major membrane lipids involve multiple organelles: the synthesis of phosphatidylserine by a synthase (Cho1p) occurs in the endoplasmic reticulum (ER) 1 and is followed by decarboxylation to phosphatidylethanolamine in the mitochondrial inner membrane (by Psd1p) or Golgi/vacuoles (by Psd2p). Subsequently phosphatidyletha...

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“…To determine the membrane association and topology of the GFP-tagged lipases, detergent and salt extractions and proteinase K protection experiments were performed essentially as previously described (47). Detergent and salt extractions of microsomal membranes (P13) were performed by incubating 50 g of the microsomal fraction with either 1% Triton X-100, 7% SDS, 1 M NaCl, or 0.1 M Na 2 CO 3 in lysis buffer A without protease inhibitors for 30 min on ice.…”

Section: Methodsmentioning

confidence: 99%

The Saccharomyces cerevisiae YLL012/YEH1, YLR020/YEH2, and TGL1 Genes Encode a Novel Family of Membrane-Anchored Lipases That Are Required for Steryl Ester Hydrolysis

Köffel

Tiwari

Falquet

et al. 2005

Molecular and Cellular Biology

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131

115

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Sterol homeostasis in eukaryotic cells relies on the reciprocal interconversion of free sterols and steryl esters. The formation of steryl esters is well characterized, but the mechanisms that control steryl ester mobilization upon cellular demand are less well understood. We have identified a family of three lipases of Saccharomyces cerevisiae that are required for efficient steryl ester mobilization. These lipases, encoded by YLL012/ YEH1, YLR020/YEH2, and TGL1, are paralogues of the mammalian acid lipase family, which is composed of the lysosomal acid lipase, the gastric lipase, and four novel as yet uncharacterized human open reading frames. Sterols are essential lipids of eukaryotic cells. They are present in two major forms: free sterols and steryl esters. Free sterols are synthesized in the endoplasmic reticulum (ER) membrane but are greatly enriched at the plasma membrane, which harbors 90% of the free-sterol pool of a cell (27). Steryl esters, on the other hand, serve as a storage form for fatty acids and sterols that are deposited in intracellular lipid bodies or particles. The conversion of free sterols and acyl coenzymes A to steryl esters is localized to the ER (14). The formation of steryl esters is important to maintain sterol homeostasis, as the steryl ester pool conceptually serves to buffer both excess and a lack of free sterols (12). The genes required for the synthesis of steryl esters in yeast have been identified, and mutants that lack steryl esters are viable, indicating that their synthesis is not essential under standard growth conditions (52, 53). The reverse process, however, how endogenously synthesized steryl esters are mobilized from their stores and hydrolyzed to release free sterols and fatty acids, is less well understood, even though cleavage of this ester bond is generally thought to be catalyzed by a lipase.Lipases constitute a heterogeneous family of proteins with carboxyl esterase activity and are activated by a lipid-water interface (for reviews, see references 34 and 51). Crystallographic analysis revealed that lipases are remarkably similar in structure despite low overall sequence conservation. They belong to the alpha/beta hydrolase fold family of enzymes with diverse hydrolytic functions. Their catalytic domain consist of a predominantly parallel beta-sheet structure of eight beta sheets connected by helical loops of various lengths that contain the catalytic-triad residues serine, aspartic acid, and histidine (10,37,42). The nucleophilic serine of this triad is itself part of the nearly ubiquitous lipase consensus sequence motif GXSXG (17). These three amino acids, assisted by the dipolar oxyanion hole, which stabilizes the charge distribution of the transition state, catalyze the hydrolysis of the ester bond (37).Only a few gene products with lipolytic activity against neutral lipids have been characterized in Saccharomyces cerevisiae. Tgl1 has been proposed to be a triglyceride-specific lipase on the basis of its homology to lipases from humans and rats, but enzymat...

show abstract

Lipid-dependent Subcellular Relocalization of the Acyl Chain Desaturase in Yeast

Cited by 32 publications

References 54 publications

Good Fat, Essential Cellular Requirements for Triacylglycerol Synthesis to Maintain Membrane Homeostasis in Yeast

Good Fat, Essential Cellular Requirements for Triacylglycerol Synthesis to Maintain Membrane Homeostasis in Yeast

The Spatial Organization of Lipid Synthesis in the Yeast Saccharomyces cerevisiae Derived from Large Scale Green Fluorescent Protein Tagging and High Resolution Microscopy

The Saccharomyces cerevisiae YLL012/YEH1, YLR020/YEH2, and TGL1 Genes Encode a Novel Family of Membrane-Anchored Lipases That Are Required for Steryl Ester Hydrolysis

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