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Yasukawa T, Iwama R, Yamasaki Y, Masuo N, Noda Y. Yeast Rim11 kinase responds to glutathione-induced stress by regulating the transcription of phospholipid biosynthetic genes. Mol Biol Cell 2024; 35:ar8. [PMID: 37938929 PMCID: PMC10881166 DOI: 10.1091/mbc.e23-03-0116] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 10/23/2023] [Accepted: 10/30/2023] [Indexed: 11/10/2023] Open
Abstract
Glutathione (GSH), a tripeptide composed of glycine, cysteine, and glutamic acid, is an abundant thiol found in a wide variety of cells, ranging from bacterial to mammalian cells. Adequate levels of GSH are essential for maintaining iron homeostasis. The ratio of oxidized/reduced GSH is strictly regulated in each organelle to maintain the cellular redox potential. Cellular redox imbalances cause defects in physiological activities, which can lead to various diseases. Although there are many reports regarding the cellular response to GSH depletion, studies on stress response to high levels of GSH are limited. Here, we performed genome-scale screening in the yeast Saccharomyces cerevisiae and identified RIM11, BMH1, and WHI2 as multicopy suppressors of the growth defect caused by GSH stress. The deletion strains of each gene were sensitive to GSH. We found that Rim11, a kinase important in the regulation of meiosis, was activated via autophosphorylation upon GSH stress in a glucose-rich medium. Furthermore, RNA-seq revealed that transcription of phospholipid biosynthetic genes was downregulated under GSH stress, and introduction of multiple copies of RIM11 counteracted this effect. These results demonstrate that S. cerevisiae copes with GSH stress via multiple stress-responsive pathways, including a part of the adaptive pathway to glucose limitation.
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Affiliation(s)
- Taishi Yasukawa
- Mitsubishi Corporation Life Sciences Limited, Tokyo Takarazuka Building 14F, 1-1-3 Yurakucho, Chiyoda-ku, Tokyo 100-0006, Japan
| | - Ryo Iwama
- Collaborative Research Institute for Innovative Microbiology, Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Yuriko Yamasaki
- Mitsubishi Corporation Life Sciences Limited, Tokyo Takarazuka Building 14F, 1-1-3 Yurakucho, Chiyoda-ku, Tokyo 100-0006, Japan
| | - Naohisa Masuo
- Mitsubishi Corporation Life Sciences Limited, Tokyo Takarazuka Building 14F, 1-1-3 Yurakucho, Chiyoda-ku, Tokyo 100-0006, Japan
| | - Yoichi Noda
- Collaborative Research Institute for Innovative Microbiology, Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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2
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Thammahong A, Dhingra S, Bultman KM, Kerkaert JD, Cramer RA. An Ssd1 Homolog Impacts Trehalose and Chitin Biosynthesis and Contributes to Virulence in Aspergillus fumigatus. mSphere 2019; 4:e00244-19. [PMID: 31068436 PMCID: PMC6506620 DOI: 10.1128/msphere.00244-19] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 04/24/2019] [Indexed: 12/24/2022] Open
Abstract
Regulation of fungal cell wall biosynthesis is critical to maintain cell wall integrity in dynamic fungal infection microenvironments. Genes involved in this response that impact fungal fitness and host immune responses remain to be fully defined. In this study, we observed that a yeast ssd1 homolog, ssdA, in the filamentous fungus Aspergillus fumigatus is involved in trehalose and cell wall homeostasis. An ssdA null mutant strain exhibited an increase in trehalose levels and a reduction in fungal colony growth rate. In contrast, overexpression of ssdA perturbed trehalose biosynthesis and reduced germination of conidia. The ssdA null mutant strain was more resistant to cell wall-perturbing agents, while overexpression of ssdA increased sensitivity. Overexpression of ssdA significantly increased chitin levels, and both loss and overexpression of ssdA altered subcellular localization of the class V chitin synthase CsmA. Strikingly, overexpression of ssdA abolished adherence to abiotic surfaces and severely attenuated the virulence of A. fumigatus in a murine model of invasive pulmonary aspergillosis. Despite the severe in vitro fitness defects observed upon loss of ssdA, neither surface adherence nor murine survival was impacted. In conclusion, A. fumigatus SsdA plays a critical role in cell wall homeostasis impacting A. fumigatus-host interactions.IMPORTANCE The incidence of life-threatening infections caused by the filamentous fungus Aspergillus fumigatus is increasing along with an increase in the number of fungal strains resistant to contemporary antifungal therapies. The fungal cell wall and the associated carbohydrates required for its synthesis and maintenance are attractive drug targets given that many genes encoding proteins involved in cell wall biosynthesis and integrity are absent in humans. Importantly, genes and associated cell wall biosynthesis and homeostasis regulatory pathways remain to be fully defined in A. fumigatus In this report, we identify SsdA as an important component of trehalose and fungal cell wall biosynthesis in A. fumigatus that consequently impacts the host immune response and fungal virulence in animal models of infection.
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Affiliation(s)
- Arsa Thammahong
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Sourabh Dhingra
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Katherine M Bultman
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Joshua D Kerkaert
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Robert A Cramer
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
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3
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Ganesan S, Sosa Ponce ML, Tavassoli M, Shabits BN, Mahadeo M, Prenner EJ, Terebiznik MR, Zaremberg V. Metabolic control of cytosolic-facing pools of diacylglycerol in budding yeast. Traffic 2019; 20:226-245. [PMID: 30569465 DOI: 10.1111/tra.12632] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 12/18/2018] [Accepted: 12/18/2018] [Indexed: 12/12/2022]
Abstract
Diacylglycerol (DAG) is a key signaling lipid and intermediate in lipid metabolism. Our knowledge of DAG distribution and dynamics in cell membranes is limited. Using live-cell fluorescence microscopy we investigated the localization of yeast cytosolic-facing pools of DAG in response to conditions where lipid homeostasis and DAG levels were known to be altered. Two main pools were monitored over time using DAG sensors. One pool was associated with vacuolar membranes and the other localized to sites of polarized growth. Dynamic changes in DAG distribution were observed during resumption of growth from stationary phase, when DAG is used to support phospholipid synthesis for membrane proliferation. Vacuolar membranes experienced constant morphological changes displaying DAG enriched microdomains coexisting with liquid-disordered areas demarcated by Vph1. Formation of these domains was dependent on triacylglycerol (TAG) lipolysis. DAG domains and puncta were closely connected to lipid droplets. Lack of conversion of DAG to phosphatidate in growth conditions dependent on TAG mobilization, led to the accumulation of DAG in a vacuolar-associated compartment, impacting the polarized distribution of DAG at budding sites. DAG polarization was also regulated by phosphatidylserine synthesis/traffic and sphingolipid synthesis in the Golgi.
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Affiliation(s)
| | - Maria L Sosa Ponce
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Marjan Tavassoli
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Brittney N Shabits
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Mark Mahadeo
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Elmar J Prenner
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Mauricio R Terebiznik
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada.,Department of Cell and System Biology, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Vanina Zaremberg
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
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4
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Jin HH, Jiang JG. Phosphatidic acid phosphatase and diacylglycerol acyltransferase: potential targets for metabolic engineering of microorganism oil. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:3067-77. [PMID: 25672855 DOI: 10.1021/jf505975k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Oleaginous microorganism is becoming one of the most promising oil feedstocks for biodiesel production due to its great advantages in triglyceride (TAG) accumulation. Previous studies have shown that de novo TAG biosynthesis can be divided into two parts: the fatty acid biosynthesis pathway (the upstream part which generates acyl-CoAs) and the glycerol-3-phosphate acylation pathway (the downstream part in which three acyl groups are sequentially added onto a glycerol backbone). This review mainly focuses on two enzymes in the G3P pathway, phosphatidic acid phosphatase (PAP) and diacylglycerol acyltransferase (DGAT). The former catalyzes a dephosphorylation reaction, and the latter catalyzes a subsequent acylation reaction. Genes, functional motifs, transmembrane domains, action mechanism, and new studies of the two enzymes are discussed in detail. Furthermore, this review also covers diacylglycerol kinase, an enzyme that catalyzes the reverse reaction of diacylglycerol formation. In addition, PAP and DGAT are the conjunction points of the G3P pathway, the Kennedy pathway, and the CDP-diacylglycerol pathway (CDP-DAG pathway), and the mutual transformation between TAGs and phospholipids is discussed as well. Given that both the Kennedy and CDP-diacylglycerol pathways are in metabolic interlock (MI) with the G3P pathway, it is suggested that, via metabolic engineering, TAG accumulation can be improved by the two pathways based on the pivotal function of PAP and DGAT.
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Affiliation(s)
- Hong-Hao Jin
- College of Food and Bioengineering, South China University of Technology, Guangzhou, 510640, China
| | - Jian-Guo Jiang
- College of Food and Bioengineering, South China University of Technology, Guangzhou, 510640, China
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5
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Identification of two Legionella pneumophila effectors that manipulate host phospholipids biosynthesis. PLoS Pathog 2012; 8:e1002988. [PMID: 23133385 PMCID: PMC3486869 DOI: 10.1371/journal.ppat.1002988] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Accepted: 08/28/2012] [Indexed: 12/31/2022] Open
Abstract
The intracellular pathogen Legionella pneumophila translocates a large number of effector proteins into host cells via the Icm/Dot type-IVB secretion system. Some of these effectors were shown to cause lethal effect on yeast growth. Here we characterized one such effector (LecE) and identified yeast suppressors that reduced its lethal effect. The LecE lethal effect was found to be suppressed by the over expression of the yeast protein Dgk1 a diacylglycerol (DAG) kinase enzyme and by a deletion of the gene encoding for Pah1 a phosphatidic acid (PA) phosphatase that counteracts the activity of Dgk1. Genetic analysis using yeast deletion mutants, strains expressing relevant yeast genes and point mutations constructed in the Dgk1 and Pah1 conserved domains indicated that LecE functions similarly to the Nem1-Spo7 phosphatase complex that activates Pah1 in yeast. In addition, by using relevant yeast genetic backgrounds we examined several L. pneumophila effectors expected to be involved in phospholipids biosynthesis and identified an effector (LpdA) that contains a phospholipase-D (PLD) domain which caused lethal effect only in a dgk1 deletion mutant of yeast. Additionally, LpdA was found to enhance the lethal effect of LecE in yeast cells, a phenomenon which was found to be dependent on its PLD activity. Furthermore, to determine whether LecE and LpdA affect the levels or distribution of DAG and PA in-vivo in mammalian cells, we utilized fluorescent DAG and PA biosensors and validated the notion that LecE and LpdA affect the in-vivo levels and distribution of DAG and PA, respectively. Finally, we examined the intracellular localization of both LecE and LpdA in human macrophages during L. pneumophila infection and found that both effectors are localized to the bacterial phagosome. Our results suggest that L. pneumophila utilize at least two effectors to manipulate important steps in phospholipids biosynthesis. Legionella pneumophila is an intracellular pathogen that causes a severe pneumonia known as Legionnaires' disease. Following infection, the bacteria use a Type-IVB secretion system to translocate multiple effector proteins into macrophages and generate the Legionella-containing vacuole (LCV). The formation of the LCV involves the recruitment of specific bacterial effectors and host cell factors to the LCV as well as changes in its lipids composition. By screening L. pneumophila effectors for yeast growth inhibition, we have identified an effector, named LecE, that strongly inhibits yeast growth. By using yeast genetic tools, we found that LecE activates the yeast lipin homolog – Pah1, an enzyme that catalyzes the conversion of diacylglycerol to phosphatidic acid, these two molecules function as bioactive lipid signaling molecules in eukaryotic cells. In addition, by using yeast deletion mutants in genes relevant to lipids biosynthesis, we have identified another effector, named LpdA, which function as a phospholipase-D enzyme. Both effectors were found to be localized to the LCV during infection. Our results reveal a possible mechanism by which an intravacuolar pathogen might change the lipid composition of the vacuole in which it resides, a process that might lead to the recruitment of specific bacterial and host cell factors to the vacoule.
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6
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Fakas S, Konstantinou C, Carman GM. DGK1-encoded diacylglycerol kinase activity is required for phospholipid synthesis during growth resumption from stationary phase in Saccharomyces cerevisiae. J Biol Chem 2010; 286:1464-74. [PMID: 21071438 DOI: 10.1074/jbc.m110.194308] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
In the yeast Saccharomyces cerevisiae, triacylglycerol mobilization for phospholipid synthesis occurs during growth resumption from stationary phase, and this metabolism is essential in the absence of de novo fatty acid synthesis. In this work, we provide evidence that DGK1-encoded diacylglycerol kinase activity is required to convert triacylglycerol-derived diacylglycerol to phosphatidate for phospholipid synthesis. Cells lacking diacylglycerol kinase activity (e.g. dgk1Δ mutation) failed to resume growth in the presence of the fatty acid synthesis inhibitor cerulenin. Lipid analysis data showed that dgk1Δ mutant cells did not mobilize triacylglycerol for membrane phospholipid synthesis and accumulated diacylglycerol. The dgk1Δ phenotypes were partially complemented by preventing the formation of diacylglycerol by the PAH1-encoded phosphatidate phosphatase and by channeling diacylglycerol to phosphatidylcholine via the Kennedy pathway. These observations, coupled to an inhibitory effect of dioctanoyl-diacylglycerol on the growth of wild type cells, indicated that diacylglycerol kinase also functions to alleviate diacylglycerol toxicity.
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Affiliation(s)
- Stylianos Fakas
- Department of Food Science and Rutgers Center for Lipid Research, Rutgers University, New Brunswick, New Jersey 08901, USA
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7
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Rodicio R, Heinisch JJ. Together we are strong-cell wall integrity sensors in yeasts. Yeast 2010; 27:531-40. [DOI: 10.1002/yea.1785] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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Li L, Lu Y, Qin LX, Bar-Joseph Z, Werner-Washburne M, Breeden LL. Budding yeast SSD1-V regulates transcript levels of many longevity genes and extends chronological life span in purified quiescent cells. Mol Biol Cell 2009; 20:3851-64. [PMID: 19570907 DOI: 10.1091/mbc.e09-04-0347] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Ssd1 is an RNA-binding protein that affects literally hundreds of different processes and is polymorphic in both wild and lab yeast strains. We have used transcript microarrays to compare mRNA levels in an isogenic pair of mutant (ssd1-d) and wild-type (SSD1-V) cells across the cell cycle. We find that 15% of transcripts are differentially expressed, but there is no correlation with those mRNAs bound by Ssd1. About 20% of cell cycle regulated transcripts are affected, and most show sharper amplitudes of oscillation in SSD1-V cells. Many transcripts whose gene products influence longevity are also affected, the largest class of which is involved in translation. Ribosomal protein mRNAs are globally down-regulated by SSD1-V. SSD1-V has been shown to increase replicative life span currency and we show that SSD1-V also dramatically increases chronological life span (CLS). Using a new assay of CLS in pure populations of quiescent prototrophs, we find that the CLS for SSD1-V cells is twice that of ssd1-d cells.
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Affiliation(s)
- Lihong Li
- Fred Hutchinson Cancer Research Center, Basic Sciences Division, Seattle, WA 98109, USA
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9
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Han GS, O'Hara L, Carman GM, Siniossoglou S. An unconventional diacylglycerol kinase that regulates phospholipid synthesis and nuclear membrane growth. J Biol Chem 2008; 283:20433-42. [PMID: 18458075 PMCID: PMC2459266 DOI: 10.1074/jbc.m802903200] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Changes in nuclear size and shape during the cell cycle or during development require coordinated nuclear membrane remodeling, but the underlying molecular events are largely unknown. We have shown previously that the activity of the conserved phosphatidate phosphatase Pah1p/Smp2p regulates nuclear structure in yeast by controlling phospholipid synthesis and membrane biogenesis at the nuclear envelope. Two screens for novel regulators of phosphatidate led to the identification of DGK1. We show that Dgk1p is a unique diacylglycerol kinase that uses CTP, instead of ATP, to generate phosphatidate. DGK1 counteracts the activity of PAH1 at the nuclear envelope by controlling phosphatidate levels. Overexpression of DGK1 causes the appearance of phosphatidate-enriched membranes around the nucleus and leads to its expansion, without proliferating the cortical endoplasmic reticulum membrane. Mutations that decrease phosphatidate levels decrease nuclear membrane growth in pah1Δ cells. We propose that phosphatidate metabolism is a critical factor determining nuclear structure by regulating nuclear membrane biogenesis.
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Affiliation(s)
- Gil-Soo Han
- Department of Food Science and the Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA
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10
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Han GS, O'Hara L, Siniossoglou S, Carman GM. Characterization of the yeast DGK1-encoded CTP-dependent diacylglycerol kinase. J Biol Chem 2008; 283:20443-53. [PMID: 18458076 DOI: 10.1074/jbc.m802866200] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Saccharomyces cerevisiae DGK1 gene encodes a diacylglycerol kinase enzyme that catalyzes the formation of phosphatidate from diacylglycerol. Unlike the diacylglycerol kinases from bacteria, plants, and animals, the yeast enzyme utilizes CTP, instead of ATP, as the phosphate donor in the reaction. Dgk1p contains a CTP transferase domain that is present in the SEC59-encoded dolichol kinase and CDS1-encoded CDP-diacylglycerol synthase enzymes. Deletion analysis showed that the CTP transferase domain was sufficient for diacylglycerol kinase activity. Point mutations (R76A, K77A, D177A, and G184A) of conserved residues within the CTP transferase domain caused a loss of diacylglycerol kinase activity. Analysis of DGK1 alleles showed that the in vivo functions of Dgk1p were specifically due to its diacylglycerol kinase activity. The DGK1-encoded enzyme had a pH optimum at 7.0-7.5, required Ca(2+) or Mg(2+) ions for activity, was potently inhibited by N-ethylmaleimide, and was labile at temperatures above 40 degrees C. The enzyme exhibited positive cooperative (Hill number = 2.5) kinetics with respect to diacylglycerol (apparent K(m) = 6.5 mol %) and saturation kinetics with respect to CTP (apparent K(m) = 0.3 mm). dCTP was both a substrate (apparent K(m) = 0.4 mm) and competitive inhibitor (apparent K(i) = 0.4 mm) of the enzyme. Diacylglycerol kinase activity was stimulated by major membrane phospholipids and was inhibited by CDP-diacylglycerol and sphingoid bases.
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Affiliation(s)
- Gil-Soo Han
- Department of Food Science and the Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA
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11
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Fernandes H, Roumanie O, Claret S, Gatti X, Thoraval D, Doignon F, Crouzet M. The Rho3 and Rho4 small GTPases interact functionally with Wsc1p, a cell surface sensor of the protein kinase C cell-integrity pathway in Saccharomyces cerevisiae. Microbiology (Reading) 2006; 152:695-708. [PMID: 16514150 DOI: 10.1099/mic.0.28231-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Rgd1, a GTPase-activating protein, is the only known negative regulator of the Rho3 and Rho4 small GTPases in the yeastSaccharomyces cerevisiae. Rho3p and Rho4p are involved in regulating cell polarity by controlling polarized exocytosis. Co-inactivation ofRGD1andWSC1, which is a cell wall sensor-encoding gene, is lethal. Another plasma membrane sensor, Mid2p, is known to rescue thergd1Δwsc1Δ synthetic lethality. It has been proposed that Wsc1p and Mid2p act upstream of the protein kinase C (PKC) pathway to function as mechanosensors of cell wall stress. Analysis of the synthetic lethal phenomenon revealed that production of activated Rho3p and Rho4p leads to lethality inwsc1Δ cells. Inactivation ofRHO3orRHO4was able to rescue thergd1Δwsc1Δ synthetic lethality, supporting the idea that the accumulation of GTP-bound Rho proteins, following loss of Rgd1p, is detrimental if the Wsc1 sensor is absent. In contrast, the genetic interaction betweenRGD1andMID2was not due to an accumulation of GTP-bound Rho proteins. It was proposed that simultaneous inactivation ofRGD1andWSC1constitutively activates the PKC–mitogen-activated protein kinase (MAP kinase) pathway. Moreover, it was shown that the activity of this pathway was not involved in the synthetic lethal interaction, which suggests the existence of another mechanism. Consistent with this idea, it was found that perturbations in Rho3-mediated polarized exocytosis specifically impair the abundance and processing of Wsc1 and Mid2 proteins. Hence, it is proposed that Wsc1p participates in the regulation of a Rho3/4-dependent cellular mechanism, and that this is distinct from the role of Wsc1p in the PKC–MAP kinase pathway.
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Affiliation(s)
- Helder Fernandes
- Laboratoire de Biologie Moléculaire et de Séquençage, Institut de Biochimie et Génétique Cellulaires, UMR Université Victor Segalen Bordeaux 2-CNRS 5095, box 64, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France
| | - Olivier Roumanie
- Laboratoire de Biologie Moléculaire et de Séquençage, Institut de Biochimie et Génétique Cellulaires, UMR Université Victor Segalen Bordeaux 2-CNRS 5095, box 64, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France
| | - Sandra Claret
- Laboratoire de Biologie Moléculaire et de Séquençage, Institut de Biochimie et Génétique Cellulaires, UMR Université Victor Segalen Bordeaux 2-CNRS 5095, box 64, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France
| | - Xavier Gatti
- Laboratoire de Biologie Moléculaire et de Séquençage, Institut de Biochimie et Génétique Cellulaires, UMR Université Victor Segalen Bordeaux 2-CNRS 5095, box 64, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France
| | - Didier Thoraval
- Laboratoire de Biologie Moléculaire et de Séquençage, Institut de Biochimie et Génétique Cellulaires, UMR Université Victor Segalen Bordeaux 2-CNRS 5095, box 64, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France
| | - François Doignon
- Laboratoire de Biologie Moléculaire et de Séquençage, Institut de Biochimie et Génétique Cellulaires, UMR Université Victor Segalen Bordeaux 2-CNRS 5095, box 64, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France
| | - Marc Crouzet
- Laboratoire de Biologie Moléculaire et de Séquençage, Institut de Biochimie et Génétique Cellulaires, UMR Université Victor Segalen Bordeaux 2-CNRS 5095, box 64, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France
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12
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Kurischko C, Weiss G, Ottey M, Luca FC. A role for the Saccharomyces cerevisiae regulation of Ace2 and polarized morphogenesis signaling network in cell integrity. Genetics 2005; 171:443-55. [PMID: 15972461 PMCID: PMC1456762 DOI: 10.1534/genetics.105.042101] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Accepted: 06/14/2005] [Indexed: 01/11/2023] Open
Abstract
Saccharomyces cerevisiae RAM is a conserved signaling network that regulates maintenance of polarized growth and daughter-cell-specific transcription, the latter of which is critical for septum degradation. Consequently, cells defective in RAM function (designated ramDelta) are round in morphology, form feeble mating projections, and fail to separate following cytokinesis. It was recently demonstrated that RAM genes are essential in strains containing functional SSD1 (SSD1-v), which encodes a protein of unknown function that binds the RAM Cbk1p kinase. Here we investigated the essential function of RAM in SSD1-v strains and identified two functional groups of dosage suppressors for ramDelta lethality. We establish that all ramDelta mutants exhibit cell integrity defects and cell lysis. All dosage suppressors rescue the lysis but not the cell polarity or cell separation defects of ramDelta cells. One class of dosage suppressors is composed of genes encoding cell wall proteins, indicating that alterations in cell wall structure can rescue the cell lysis in ramDelta cells. Another class of ramDelta dosage suppressors is composed of ZRG8 and SRL1, which encode two unrelated proteins of unknown function. We establish that ZRG8 and SRL1 share similar genetic interactions and phenotypes. Significantly, Zrg8p coprecipitates with Ssd1p, localizes similarly to RAM proteins, and is dependent on RAM for localization. Collectively, these data indicate that RAM and Ssd1p function cooperatively to control cell integrity and suggest that Zrg8p and Srl1p function as nonessential inhibitors of Ssd1p.
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Affiliation(s)
- Cornelia Kurischko
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, 19104, USA
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13
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Tomishige N, Noda Y, Adachi H, Shimoi H, Yoda K. SKG1, a suppressor gene of synthetic lethality ofkex2?gas1? mutations, encodes a novel membrane protein that affects cell wall composition. Yeast 2005; 22:141-55. [PMID: 15645486 DOI: 10.1002/yea.1206] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The fungal GAS1-related genes encode GPI-anchored beta-1,3-glucanosyltransferase, and their loss causes a defect in the assembly of the cell wall. The KEX2 gene encodes a processing protease in the late Golgi compartment and its loss also results in defects in the cell wall. Simultaneous mutations of these genes are lethal in Saccharomyces cerevisiae. To understand the basis of this synthetic lethality, we screened for multicopy suppressors and identified 13 SKG (suppressor of kex2 gas1 synthetic lethality) genes. SKG1 encodes a transmembrane protein that localizes on the inner surface of the plasma membrane at the bud and in the daughter cell. The multicopy SKG1 increases the sensitivity of cells to zymolyase, and the skg1Delta null mutation increases resistance to it. This zymolyase susceptibility corresponds to an increase of alkali-soluble beta-1,3-glucan and a decrease of chitin in the cell wall. Thus SKG1 encodes a novel protein that affects the cell wall polymer composition in the growing region of the cell.
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Affiliation(s)
- Nario Tomishige
- Department of Biotechnology, University of Tokyo, Bunkyo-Ku, Tokyo 113-8657, Japan
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14
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Kaeberlein M, Andalis AA, Liszt GB, Fink GR, Guarente L. Saccharomyces cerevisiae SSD1-V confers longevity by a Sir2p-independent mechanism. Genetics 2005; 166:1661-72. [PMID: 15126388 PMCID: PMC1470832 DOI: 10.1534/genetics.166.4.1661] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The SSD1 gene of Saccharomyces cerevisiae is a polymorphic locus that affects diverse cellular processes including cell integrity, cell cycle progression, and growth at high temperature. We show here that the SSD1-V allele is necessary for cells to achieve extremely long life span. Furthermore, addition of SSD1-V to cells can increase longevity independently of SIR2, although SIR2 is necessary for SSD1-V cells to attain maximal life span. Past studies of yeast aging have been performed in short-lived ssd1-d strain backgrounds. We propose that SSD1-V defines a previously undescribed pathway affecting cellular longevity and suggest that future studies on longevity-promoting genes should be carried out in long-lived SSD1-V strains.
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Affiliation(s)
- Matt Kaeberlein
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, USA.
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Kaeberlein M, Andalis AA, Liszt GB, Fink GR, Guarente L. Saccharomyces cerevisiae SSD1-V Confers Longevity by a Sir2p-Independent Mechanism. Genetics 2004. [DOI: 10.1093/genetics/166.4.1661] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
The SSD1 gene of Saccharomyces cerevisiae is a polymorphic locus that affects diverse cellular processes including cell integrity, cell cycle progression, and growth at high temperature. We show here that the SSD1-V allele is necessary for cells to achieve extremely long life span. Furthermore, addition of SSD1-V to cells can increase longevity independently of SIR2, although SIR2 is necessary for SSD1-V cells to attain maximal life span. Past studies of yeast aging have been performed in short-lived ssd1-d strain backgrounds. We propose that SSD1-V defines a previously undescribed pathway affecting cellular longevity and suggest that future studies on longevity-promoting genes should be carried out in long-lived SSD1-V strains.
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Affiliation(s)
- Matt Kaeberlein
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195
| | - Alex A Andalis
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142
| | - Gregory B Liszt
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Gerald R Fink
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142
| | - Leonard Guarente
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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Rosenwald AG, Rhodes MA, Van Valkenburgh H, Palanivel V, Chapman G, Boman A, Zhang CJ, Kahn RA. ARL1 and membrane traffic in Saccharomyces cerevisiae. Yeast 2002; 19:1039-56. [PMID: 12210899 DOI: 10.1002/yea.897] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
To examine the functions of the Arf-like protein, Arl1p, in Saccharomyces cerevisiae, a null allele, arl1delta::HIS3, was constructed in two strains. In one background only, loss of ARL1 resulted in temperature-sensitive (ts) growth (suppressed on high-osmolarity media). Allelic variation at the SSD1 locus accounted for differences between strains. Strains lacking ARL1 exhibited several defects in membrane traffic. First, arl1delta strains secreted less protein as measured by TCA-precipitable radioactivity found in the media of [(35)S]-labelled cells. A portion of newly synthesized carboxypeptidase Y (CPY) was secreted rather than correctly targeted to the vacuole. Uptake of the fluid-phase marker, lucifer yellow, was reduced. All these phenotypes were exacerbated in an ssd1 background. The ts phenotype of the arl1deltassd1 strain was suppressed by YPT1, the yeast Rab1a homologue, suggesting that ARL1 and YPT1 have partially overlapping functions. These findings demonstrate that ARL1 encodes a regulator of membrane traffic.
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Affiliation(s)
- Anne G Rosenwald
- Department of Biology, Georgetown University, Washington, DC 20057, USA.
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Current awareness on yeast. Yeast 2001. [PMID: 11746606 DOI: 10.1002/yea.691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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