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Lewis AG, Carmichael L, Wang RY, Gibney PA. Characterizing a panel of amino acid auxotrophs under auxotrophic starvation conditions. Yeast 2024; 41:5-18. [PMID: 37997284 DOI: 10.1002/yea.3910] [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: 08/09/2023] [Revised: 10/20/2023] [Accepted: 11/09/2023] [Indexed: 11/25/2023] Open
Abstract
Auxotrophic strains starving for their cognate nutrient, termed auxotrophic starvation, are characterized by a shorter lifespan, higher glucose wasting phenotype, and inability to accomplish cell cycle arrest when compared to a "natural starvation," where a cell is starving for natural environmental growth-limiting nutrients such as phosphate. Since evidence of this physiological response is limited to only a subset of auxotrophs, we evaluated a panel of auxotrophic mutants to determine whether these responses are characteristic of a broader range of amino acid auxotrophs. Based on the starvation survival kinetics, the panel of strains was grouped into three categories-short-lived strains, strains with survival similar to a prototrophic wild type strain, and long-lived strains. Among the short-lived strains, we observed that the tyrosine, asparagine, threonine, and aspartic acid auxotrophs rapidly decline in viability, with all strains unable to arrest cell cycle progression. The three basic amino acid auxotrophs had a survival similar to a prototrophic strain starving in minimal media. The leucine, tryptophan, methionine, and cysteine auxotrophs displayed the longest lifespan. We also demonstrate how the phenomenon of glucose wasting is limited to only a subset of the tested auxotrophs, namely the asparagine, leucine, and lysine auxotrophs. Furthermore, we observed pleiotropic phenotypes associated with a subgroup of auxotrophs, highlighting the importance of considering unintended phenotypic effects when using auxotrophic strains especially in chronological aging experiments.
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Affiliation(s)
- Alisha G Lewis
- Department of Food Science, Cornell University, Ithaca, New York, USA
| | - Laurin Carmichael
- Department of Food Science, Cornell University, Ithaca, New York, USA
| | - Rebecca Y Wang
- Calico Life Sciences LLC, South San Francisco, California, USA
| | - Patrick A Gibney
- Department of Food Science, Cornell University, Ithaca, New York, USA
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2
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Miles S, Lee C, Breeden L. BY4741 cannot enter quiescence from rich medium. MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.000742. [PMID: 37012989 PMCID: PMC10066452 DOI: 10.17912/micropub.biology.000742] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 03/02/2023] [Accepted: 03/16/2023] [Indexed: 04/05/2023]
Abstract
In rich medium, W303 Saccharomyces cerevisiae begins to accumulate in G1 an hour before it exhausts the available glucose. It undergoes one more asymmetrical cell division, then stops dividing in G1. In contrast, BY4741, stops dividing four hours before glucose exhaustion, at one-fourth the cell density achieved by W303. There is no asymmetrical cell division and only 50% of the cells arrest in G1. We conclude that BY4741 growth is not limited by glucose and they do not go through the stereotypical events carried out by other strains as they enter quiescence from rich medium. In W303, the timing of glucose limitation and the transition to quiescence is correlated with the rate of biomass accumulation and cell doubling time.
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Affiliation(s)
- Shawna Miles
- Basic Science, Fred Hutchinson Cancer Center, Seattle, Washington, United States
| | - Cameron Lee
- Tune Therapeutics, 1930 Boren Ave., Seattle, Washington, United States
| | - Linda Breeden
- Basic Science, Fred Hutchinson Cancer Center, Seattle, Washington, United States
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3
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Abstract
Most cells live in environments that are permissive for proliferation only a small fraction of the time. Entering quiescence enables cells to survive long periods of nondivision and reenter the cell cycle when signaled to do so. Here, we describe what is known about the molecular basis for quiescence in Saccharomyces cerevisiae, with emphasis on the progress made in the last decade. Quiescence is triggered by depletion of an essential nutrient. It begins well before nutrient exhaustion, and there is extensive crosstalk between signaling pathways to ensure that all proliferation-specific activities are stopped when any one essential nutrient is limiting. Every aspect of gene expression is modified to redirect and conserve resources. Chromatin structure and composition change on a global scale, from histone modifications to three-dimensional chromatin structure. Thousands of proteins and RNAs aggregate, forming unique structures with unique fates, and the cytoplasm transitions to a glass-like state.
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Affiliation(s)
- Linda L Breeden
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, Washington, USA; ,
| | - Toshio Tsukiyama
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, Washington, USA; ,
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4
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Huang LJ, Chen RH. Lipid saturation induces degradation of squalene epoxidase for sterol homeostasis and cell survival. Life Sci Alliance 2022; 6:6/1/e202201612. [PMID: 36368908 PMCID: PMC9652772 DOI: 10.26508/lsa.202201612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 10/24/2022] [Accepted: 10/25/2022] [Indexed: 11/13/2022] Open
Abstract
A fluid membrane containing a mix of unsaturated and saturated lipids is essential for life. However, it is unclear how lipid saturation might affect lipid homeostasis, membrane-associated proteins, and membrane organelles. Here, we generate temperature-sensitive mutants of the sole fatty acid desaturase gene OLE1 in the budding yeast Saccharomyces cerevisiae Using these mutants, we show that lipid saturation triggers the endoplasmic reticulum-associated degradation (ERAD) of squalene epoxidase Erg1, a rate-limiting enzyme in sterol biosynthesis, via the E3 ligase Doa10-Ubc7 complex. We identify the P469L mutation that abolishes the lipid saturation-induced ERAD of Erg1. Overexpressed WT or stable Erg1 mutants all mislocalize into foci in the ole1 mutant, whereas the stable Erg1 causes aberrant ER and severely compromises the growth of ole1, which are recapitulated by doa10 deletion. The toxicity of the stable Erg1 and doa10 deletion is due to the accumulation of lanosterol and misfolded proteins in ole1 Our study identifies Erg1 as a novel lipid saturation-regulated ERAD target, manifesting a close link between lipid homeostasis and proteostasis that maintains sterol homeostasis under the lipid saturation condition for cell survival.
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Affiliation(s)
| | - Rey-Huei Chen
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
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5
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Miles S, Bradley GT, Breeden LL. The budding yeast transition to quiescence. Yeast 2021; 38:30-38. [PMID: 33350501 DOI: 10.1002/yea.3546] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 12/18/2020] [Indexed: 11/06/2022] Open
Abstract
A subset of Saccharomyces cerevisiae cells in a stationary phase culture achieve a unique quiescent state characterized by increased cell density, stress tolerance, and longevity. Trehalose accumulation is necessary but not sufficient for conferring this state, and it is not recapitulated by abrupt starvation. The fraction of cells that achieve this state varies widely in haploids and diploids and can approach 100%, indicating that both mother and daughter cells can enter quiescence. The transition begins when about half the glucose has been taken up from the medium. The high affinity glucose transporters are turned on, glycogen storage begins, the Rim15 kinase enters the nucleus and the accumulation of cells in G1 is initiated. After the diauxic shift (DS), when glucose is exhausted from the medium, growth promoting genes are repressed by the recruitment of the histone deacetylase Rpd3 by quiescence-specific repressors. The final division that takes place post-DS is highly asymmetrical and G1 arrest is complete after 48 h. The timing of these events can vary considerably, but they are tightly correlated with total biomass of the culture, suggesting that the transition to quiescence is tightly linked to changes in external glucose levels. After 7 days in culture, there are massive morphological changes at the protein and organelle level. There are global changes in histone modification. An extensive array of condensin-dependent, long-range chromatin interactions lead to genome-wide chromatin compaction that is conserved in yeast and human cells. These interactions are required for the global transcriptional repression that occurs in quiescent yeast.
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Affiliation(s)
- Shawna Miles
- Fred Hutchinson Cancer Research Center, Basic Science Division, Seattle, Washington, USA
| | | | - Linda L Breeden
- Fred Hutchinson Cancer Research Center, Basic Science Division, Seattle, Washington, USA
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6
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Acton E, Lee AHY, Zhao PJ, Flibotte S, Neira M, Sinha S, Chiang J, Flaherty P, Nislow C, Giaever G. Comparative functional genomic screens of three yeast deletion collections reveal unexpected effects of genotype in response to diverse stress. Open Biol 2018; 7:rsob.160330. [PMID: 28592509 PMCID: PMC5493772 DOI: 10.1098/rsob.160330] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 04/24/2017] [Indexed: 12/25/2022] Open
Abstract
The Yeast Knockout (YKO) collection has provided a wealth of functional annotations from genome-wide screens. An unintended consequence is that 76% of gene annotations derive from one genotype. The nutritional auxotrophies in the YKO, in particular, have phenotypic consequences. To address this issue, ‘prototrophic’ versions of the YKO collection have been constructed, either by introducing a plasmid carrying wild-type copies of the auxotrophic markers (Plasmid-Borne, PBprot) or by backcrossing (Backcrossed, BCprot) to a wild-type strain. To systematically assess the impact of the auxotrophies, genome-wide fitness profiles of prototrophic and auxotrophic collections were compared across diverse drug and environmental conditions in 250 experiments. Our quantitative profiles uncovered broad impacts of genotype on phenotype for three deletion collections, and revealed genotypic and strain-construction-specific phenotypes. The PBprot collection exhibited fitness defects associated with plasmid maintenance, while BCprot fitness profiles were compromised due to strain loss from nutrient selection steps during strain construction. The repaired prototrophic versions of the YKO collection did not restore wild-type behaviour nor did they clarify gaps in gene annotation resulting from the auxotrophic background. To remove marker bias and expand the experimental scope of deletion libraries, construction of a bona fide prototrophic collection from a wild-type strain will be required.
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Affiliation(s)
- Erica Acton
- Department of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Genome Science and Technology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Amy Huei-Yi Lee
- Department of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Pei Jun Zhao
- Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Stephane Flibotte
- Department of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Zoology and Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - Mauricio Neira
- Department of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Sunita Sinha
- Department of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jennifer Chiang
- Department of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Patrick Flaherty
- Department of Mathematics and Statistics, University of Massachusetts, Amherst, MA, USA
| | - Corey Nislow
- Department of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Guri Giaever
- Department of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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7
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Triana S, de Cock H, Ohm RA, Danies G, Wösten HAB, Restrepo S, González Barrios AF, Celis A. Lipid Metabolic Versatility in Malassezia spp. Yeasts Studied through Metabolic Modeling. Front Microbiol 2017; 8:1772. [PMID: 28959251 PMCID: PMC5603697 DOI: 10.3389/fmicb.2017.01772] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 08/31/2017] [Indexed: 01/23/2023] Open
Abstract
Malassezia species are lipophilic and lipid-dependent yeasts belonging to the human and animal microbiota. Typically, they are isolated from regions rich in sebaceous glands. They have been associated with dermatological diseases such as seborrheic dermatitis, pityriasis versicolor, atopic dermatitis, and folliculitis. The genomes of Malassezia globosa, Malassezia sympodialis, and Malassezia pachydermatis lack the genes related to fatty acid synthesis. Here, the lipid-synthesis pathways of these species, as well as of Malassezia furfur, and of an atypical M. furfur variant were reconstructed using genome data and Constraints Based Reconstruction and Analysis. To this end, the genomes of M. furfur CBS 1878 and the atypical M. furfur 4DS were sequenced and annotated. The resulting Enzyme Commission numbers and predicted reactions were similar to the other Malassezia strains despite the differences in their genome size. Proteomic profiling was utilized to validate flux distributions. Flux differences were observed in the production of steroids in M. furfur and in the metabolism of butanoate in M. pachydermatis. The predictions obtained via these metabolic reconstructions also suggested defects in the assimilation of palmitic acid in M. globosa, M. sympodialis, M. pachydermatis, and the atypical variant of M. furfur, but not in M. furfur. These predictions were validated via physiological characterization, showing the predictive power of metabolic network reconstructions to provide new clues about the metabolic versatility of Malassezia.
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Affiliation(s)
- Sergio Triana
- Department of Biological Sciences, Universidad de los AndesBogotá, Colombia
- Grupo de Diseño de Productos y Procesos, Department of Chemical Engineering, Universidad de los AndesBogotá, Colombia
- Structural and Computational Biology Unit, European Molecular Biology LaboratoryHeidelberg, Germany
| | - Hans de Cock
- Microbiology, Department of Biology, Faculty of Science, Utrecht UniversityUtrecht, Netherlands
| | - Robin A. Ohm
- Microbiology, Department of Biology, Faculty of Science, Utrecht UniversityUtrecht, Netherlands
| | - Giovanna Danies
- Department of Biological Sciences, Universidad de los AndesBogotá, Colombia
| | - Han A. B. Wösten
- Microbiology, Department of Biology, Faculty of Science, Utrecht UniversityUtrecht, Netherlands
| | - Silvia Restrepo
- Department of Biological Sciences, Universidad de los AndesBogotá, Colombia
| | - Andrés F. González Barrios
- Grupo de Diseño de Productos y Procesos, Department of Chemical Engineering, Universidad de los AndesBogotá, Colombia
| | - Adriana Celis
- Department of Biological Sciences, Universidad de los AndesBogotá, Colombia
- Microbiology, Department of Biology, Faculty of Science, Utrecht UniversityUtrecht, Netherlands
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8
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Blank HM, Perez R, He C, Maitra N, Metz R, Hill J, Lin Y, Johnson CD, Bankaitis VA, Kennedy BK, Aramayo R, Polymenis M. Translational control of lipogenic enzymes in the cell cycle of synchronous, growing yeast cells. EMBO J 2017; 36:487-502. [PMID: 28057705 PMCID: PMC5694946 DOI: 10.15252/embj.201695050] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 11/09/2016] [Accepted: 11/18/2016] [Indexed: 02/04/2023] Open
Abstract
Translational control during cell division determines when cells start a new cell cycle, how fast they complete it, the number of successive divisions, and how cells coordinate proliferation with available nutrients. The translational efficiencies of mRNAs in cells progressing synchronously through the mitotic cell cycle, while preserving the coupling of cell division with cell growth, remain uninvestigated. We now report comprehensive ribosome profiling of a yeast cell size series from the time of cell birth, to identify mRNAs under periodic translational control. The data reveal coordinate translational activation of mRNAs encoding lipogenic enzymes late in the cell cycle including Acc1p, the rate-limiting enzyme acetyl-CoA carboxylase. An upstream open reading frame (uORF) confers the translational control of ACC1 and adjusts Acc1p protein levels in different nutrients. The ACC1 uORF is relevant for cell division because its ablation delays cell cycle progression, reduces cell size, and suppresses the replicative longevity of cells lacking the Sch9p protein kinase regulator of ribosome biogenesis. These findings establish an unexpected relationship between lipogenesis and protein synthesis in mitotic cell divisions.
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Affiliation(s)
- Heidi M Blank
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - Ricardo Perez
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Chong He
- The Buck Institute for Research on Aging, Novato, CA, USA
| | - Nairita Maitra
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - Richard Metz
- Genomics and Bioinformatics Services, Texas A&M Agrilife Research, College Station, TX, USA
| | - Joshua Hill
- Genomics and Bioinformatics Services, Texas A&M Agrilife Research, College Station, TX, USA
| | - Yuhong Lin
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - Charles D Johnson
- Genomics and Bioinformatics Services, Texas A&M Agrilife Research, College Station, TX, USA
| | - Vytas A Bankaitis
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
- Department of Molecular & Cellular Medicine, Texas A&M Health Sciences Center, College Station, TX, USA
- Department of Chemistry, Texas A&M University, College Station, TX, USA
| | | | - Rodolfo Aramayo
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Michael Polymenis
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
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9
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Park Y, Han GS, Mileykovskaya E, Garrett TA, Carman GM. Altered Lipid Synthesis by Lack of Yeast Pah1 Phosphatidate Phosphatase Reduces Chronological Life Span. J Biol Chem 2015; 290:25382-94. [PMID: 26338708 DOI: 10.1074/jbc.m115.680314] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Indexed: 01/20/2023] Open
Abstract
In Saccharomyces cerevisiae, Pah1 phosphatidate phosphatase, which catalyzes the dephosphorylation of phosphatidate to yield diacylglycerol, plays a crucial role in the synthesis of the storage lipid triacylglycerol. This evolutionarily conserved enzyme also plays a negative regulatory role in controlling de novo membrane phospholipid synthesis through its consumption of phosphatidate. We found that the pah1Δ mutant was defective in the utilization of non-fermentable carbon sources but not in oxidative phosphorylation; the mutant did not exhibit major changes in oxygen consumption rate, mitochondrial membrane potential, F1F0-ATP synthase activity, or gross mitochondrial morphology. The pah1Δ mutant contained an almost normal complement of major mitochondrial phospholipids with some alterations in molecular species. Although oxidative phosphorylation was not compromised in the pah1Δ mutant, the cellular levels of ATP in quiescent cells were reduced by 2-fold, inversely correlating with a 4-fold increase in membrane phospholipids. In addition, the quiescent pah1Δ mutant cells had 3-fold higher levels of mitochondrial superoxide and cellular lipid hydroperoxides, had reduced activities of superoxide dismutase 2 and catalase, and were hypersensitive to hydrogen peroxide. Consequently, the pah1Δ mutant had a shortened chronological life span. In addition, the loss of Tsa1 thioredoxin peroxidase caused a synthetic growth defect with the pah1Δ mutation. The shortened chronological life span of the pah1Δ mutant along with its growth defect on non-fermentable carbon sources and hypersensitivity to hydrogen peroxide was suppressed by the loss of Dgk1 diacylglycerol kinase, indicating that the underpinning of pah1Δ mutant defects was the excess synthesis of membrane phospholipids.
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Affiliation(s)
- Yeonhee Park
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Gil-Soo Han
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Eugenia Mileykovskaya
- the Department of Biochemistry and Molecular Biology, University of Texas-Houston Medical School, Houston, Texas 77030, and
| | - Teresa A Garrett
- the Department of Chemistry, Vassar College, Poughkeepsie, New York 12604
| | - George M Carman
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901,
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10
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Shpilka T, Welter E, Borovsky N, Amar N, Mari M, Reggiori F, Elazar Z. Lipid droplets and their component triglycerides and steryl esters regulate autophagosome biogenesis. EMBO J 2015; 34:2117-31. [PMID: 26162625 DOI: 10.15252/embj.201490315] [Citation(s) in RCA: 156] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 06/09/2015] [Indexed: 12/14/2022] Open
Abstract
Autophagy is a major catabolic process responsible for the delivery of proteins and organelles to the lysosome/vacuole for degradation. Malfunction of this pathway has been implicated in numerous pathological conditions. Different organelles have been found to contribute to the formation of autophagosomes, but the exact mechanism mediating this process remains obscure. Here, we show that lipid droplets (LDs) are important for the regulation of starvation-induced autophagy. Deletion of Dga1 and Lro1 enzymes responsible for triacylglycerol (TAG) synthesis, or of Are1 and Are2 enzymes responsible for the synthesis of steryl esters (STE), results in the inhibition of autophagy. Moreover, we identified the STE hydrolase Yeh1 and the TAG lipase Ayr1 as well as the lipase/hydrolase Ldh1 as essential for autophagy. Finally, we provide evidence that the ER-LD contact-site proteins Ice2 and Ldb16 regulate autophagy. Our study thus highlights the importance of lipid droplet dynamics for the autophagic process under nitrogen starvation.
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Affiliation(s)
- Tomer Shpilka
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
| | - Evelyn Welter
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
| | - Noam Borovsky
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
| | - Nira Amar
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
| | - Muriel Mari
- Department of Cell Biology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Fulvio Reggiori
- Department of Cell Biology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Zvulun Elazar
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
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11
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Fatty acid synthase is preferentially degraded by autophagy upon nitrogen starvation in yeast. Proc Natl Acad Sci U S A 2015; 112:1434-9. [PMID: 25605918 DOI: 10.1073/pnas.1409476112] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Autophagy, an evolutionarily conserved intracellular catabolic process, leads to the degradation of cytosolic proteins and organelles in the vacuole/lysosome. Different forms of selective autophagy have recently been described. Starvation-induced protein degradation, however, is considered to be nonselective. Here we describe a novel interaction between autophagy-related protein 8 (Atg8) and fatty acid synthase (FAS), a pivotal enzymatic complex responsible for the entire synthesis of C16- and C18-fatty acids in yeast. We show that although FAS possesses housekeeping functions, under starvation conditions it is delivered to the vacuole for degradation by autophagy in a Vac8- and Atg24-dependent manner. We also provide evidence that FAS degradation is essential for survival under nitrogen deprivation. Our results imply that during nitrogen starvation specific proteins are preferentially recruited into autophagosomes.
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12
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The response to inositol: regulation of glycerolipid metabolism and stress response signaling in yeast. Chem Phys Lipids 2014; 180:23-43. [PMID: 24418527 DOI: 10.1016/j.chemphyslip.2013.12.013] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Accepted: 12/26/2013] [Indexed: 12/13/2022]
Abstract
This article focuses on discoveries of the mechanisms governing the regulation of glycerolipid metabolism and stress response signaling in response to the phospholipid precursor, inositol. The regulation of glycerolipid lipid metabolism in yeast in response to inositol is highly complex, but increasingly well understood, and the roles of individual lipids in stress response are also increasingly well characterized. Discoveries that have emerged over several decades of genetic, molecular and biochemical analyses of metabolic, regulatory and signaling responses of yeast cells, both mutant and wild type, to the availability of the phospholipid precursor, inositol are discussed.
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13
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Li L, Miles S, Melville Z, Prasad A, Bradley G, Breeden LL. Key events during the transition from rapid growth to quiescence in budding yeast require posttranscriptional regulators. Mol Biol Cell 2013; 24:3697-709. [PMID: 24088570 PMCID: PMC3842996 DOI: 10.1091/mbc.e13-05-0241] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The transition to quiescence in budding yeast involves highly asymmetric cell divisions and elaborate cell wall fortifications that can be followed by flow cytometry. Posttranscriptional regulators Ssd1V, Mpt5, and Lsm1 are important for this transition. Yeast that naturally exhaust the glucose from their environment differentiate into three distinct cell types distinguishable by flow cytometry. Among these is a quiescent (Q) population, which is so named because of its uniform but readily reversed G1 arrest, its fortified cell walls, heat tolerance, and longevity. Daughter cells predominate in Q-cell populations and are the longest lived. The events that differentiate Q cells from nonquiescent (nonQ) cells are initiated within hours of the diauxic shift, when cells have scavenged all the glucose from the media. These include highly asymmetric cell divisions, which give rise to very small daughter cells. These daughters modify their cell walls by Sed1- and Ecm33-dependent and dithiothreitol-sensitive mechanisms that enhance Q-cell thermotolerance. Ssd1 speeds Q-cell wall assembly and enables mother cells to enter this state. Ssd1 and the related mRNA-binding protein Mpt5 play critical overlapping roles in Q-cell formation and longevity. These proteins deliver mRNAs to P-bodies, and at least one P-body component, Lsm1, also plays a unique role in Q-cell longevity. Cells lacking Lsm1 and Ssd1 or Mpt5 lose viability under these conditions and fail to enter the quiescent state. We conclude that posttranscriptional regulation of mRNAs plays a crucial role in the transition in and out of quiescence.
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Affiliation(s)
- Lihong Li
- Basic Science Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109
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14
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15
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Nguyen LN, Nosanchuk JD. The inhibitory effect of cerulenin to yeasts is fungicidal. Commun Integr Biol 2011; 4:631-2. [PMID: 22448300 DOI: 10.4161/cib.17446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Fatty acid biosynthesis plays a significant role in the growth and survival of diverse organisms. In yeasts, the de novo fatty acid synthesis (FAS) pathway produces and regulates essential fatty acid species such as saturated (SFA) and unsaturated (UFA) fatty acids that are required for generation and maintenance of cell membranes. Inhibition of enzymes in this pathway, such as fatty acid synthase and fatty acid desaturase, impede yeast cell growth unless appropriate exogenous fatty acids are provided.(1,2 )Although, the fatty acid biosynthesis pathway is essential to yeast cells, exploration of this pathway for combating fungal infections has been largely neglected. We and others have shown that deletion of a fatty acid synthase dramatically attenuates the virulence of the yeast Candida parapsilosis 2 and Candida albicans.(1) Significantly, our data has revealed that inhibition of FAS enzymes results in the hypersensitivity of the yeast to serum, indicating that targeting this pathway is potentially an ideal way to combat systemic yeast infections.(2) We demonstrated that using the minimal inhibitory concentration of cerulenin, a fatty acid synthase inhibitor, we could kill the wild type yeast cells in serum.(2) Thus, the inhibitory effect of cerulenin (ie. blockade of the FAS pathway) on the yeast cells is fungicidal.
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16
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Khare G, Kar R, Tyagi AK. Identification of inhibitors against Mycobacterium tuberculosis thiamin phosphate synthase, an important target for the development of anti-TB drugs. PLoS One 2011; 6:e22441. [PMID: 21818324 PMCID: PMC3144219 DOI: 10.1371/journal.pone.0022441] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Accepted: 06/28/2011] [Indexed: 11/18/2022] Open
Abstract
Tuberculosis (TB) continues to pose a serious challenge to human health afflicting a large number of people throughout the world. In spite of the availability of drugs for the treatment of TB, the non-compliance to 6–9 months long chemotherapeutic regimens often results in the emergence of multidrug resistant strains of Mycobacterium tuberculosis adding to the precariousness of the situation. This has necessitated the development of more effective drugs. Thiamin biosynthesis, an important metabolic pathway of M.tuberculosis, is shown to be essential for the intracellular growth of this pathogen and hence, it is believed that inhibition of this pathway would severely affect the growth of M.tuberculosis. In this study, a comparative homology model of M.tuberculosis thiamin phosphate synthase (MtTPS) was generated and employed for virtual screening of NCI diversity set II to select potential inhibitors. The best 39 compounds based on the docking results were evaluated for their potential to inhibit the MtTPS activity. Seven compounds inhibited MtTPS activity with IC50 values ranging from 20 – 100 µg/ml and two of these exhibited weak inhibition of M.tuberculosis growth with MIC99 values being 125 µg/ml and 162.5 µg/ml while one compound was identified as a very potent inhibitor of M.tuberculosis growth with an MIC99 value of 6 µg/ml. This study establishes MtTPS as a novel drug target against M.tuberculosis leading to the identification of new lead molecules for the development of antitubercular drugs. Further optimization of these lead compounds could result in more potent therapeutic molecules against Tuberculosis.
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Affiliation(s)
- Garima Khare
- Department of Biochemistry, University of Delhi, New Delhi, India
| | - Ritika Kar
- Department of Biochemistry, University of Delhi, New Delhi, India
| | - Anil K. Tyagi
- Department of Biochemistry, University of Delhi, New Delhi, India
- * E-mail:
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17
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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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18
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Influence of genotype and nutrition on survival and metabolism of starving yeast. Proc Natl Acad Sci U S A 2008; 105:6930-5. [PMID: 18456835 DOI: 10.1073/pnas.0802601105] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Starvation of yeast cultures limited by auxotrophic requirements results in glucose wasting and failure to achieve prompt cell-cycle arrest when compared with starvation for basic natural nutrients like phosphate or sulfate. We measured the survival of yeast auxotrophs upon starvation for different nutrients and found substantial differences: When deprived of leucine or uracil, viability declined exponentially with a half-life of <2 days, whereas when the same strains were deprived of phosphate or sulfate, the half-life was approximately 10 days. The survival rates of nongrowing auxotrophs deprived of uracil or leucine depended on the carbon source available during starvation, but were independent of the carbon source during prior growth. We performed an enrichment procedure for mutants that suppress lethality during auxotrophy starvation. We repeatedly found loss-of-function mutations in a number of functionally related genes. Mutations in PPM1, which methylates protein phosphatase 2A, and target of rapamycin (TOR1) were characterized further. Deletion of PPM1 almost completely suppressed the rapid lethality and substantially suppressed glucose wasting during starvation for leucine or uracil. Suppression by a deletion of TOR1 was less complete. We suggest that, similar to the Warburg effect observed in tumor cells, starving yeast auxotrophs wastes glucose as a consequence of the failure of conserved growth control pathways. Furthermore, we suggest that our results on condition-dependent chronological lifespan have important implications for the interpretation and design of studies on chronological aging.
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19
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Bailey A, Keon J, Owen J, Hargreaves J. The ACC1 gene, encoding acetyl-CoA carboxylase, is essential for growth in Ustilago maydis. MOLECULAR & GENERAL GENETICS : MGG 1995; 249:191-201. [PMID: 7500941 DOI: 10.1007/bf00290366] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Acetyl-CoA carboxylase [ACCase; acetyl-CoA:carbon dioxide ligase (ADP forming), EC 6.4.1.2] catalyses the ATP-dependent carboxylation of acetyl-CoA to form malonyl-CoA. We have amplified a fragment of the biotin carboxylase (BC) domain of the Ustilago maydis acetyl-CoA carboxylase (ACC1) gene from genomic DNA and used this amplified DNA fragment as a probe to recover the complete gene from a lambda EMBL3 genomic library. The ACC1 gene has a reading frame of 6555 nucleotides, which is interrupted by a single intron of 80 bp in length. The gene encodes a protein containing 2185 amino acids, with a calculated M(r) of 242,530; this is in good agreement with the size of ACCases from other sources. Further identification was based on the position of putative binding sites for acetyl-CoA, ATP, biotin and carboxybiotin found in other ACCases. A single ACC1 allele was disrupted in a diploid wild-type strain. After sporulation of diploid disruptants, no haploid progeny containing a disrupted acc1 allele were recovered, even though an exogenous source of fatty acids was provided. The data indicate that, in U. maydis, ACCase is required for essential cellular processes other than de novo fatty acid biosynthesis.
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Affiliation(s)
- A Bailey
- Department of Agricultural Sciences, University of Bristol, UK
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20
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Pinto WJ, Srinivasan B, Shepherd S, Schmidt A, Dickson RC, Lester RL. Sphingolipid long-chain-base auxotrophs of Saccharomyces cerevisiae: genetics, physiology, and a method for their selection. J Bacteriol 1992; 174:2565-74. [PMID: 1556075 PMCID: PMC205895 DOI: 10.1128/jb.174.8.2565-2574.1992] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
A selection method for sphingolipid long-chain-base auxotrophs of Saccharomyces cerevisiae was devised after observing that strains that require a long-chain base for growth become denser when starved for this substance. Genetic analysis of over 60 such strains indicated only two complementation classes, lcb1 and lcb2. Mutant strains from each class grew equally well with 3-ketodihydrosphingosine, erythrodihydrosphingosine or threodihydrosphingosine, or phytosphingosine. Since these metabolites represent the first, second, and last components, respectively, of the long-chain-base biosynthetic pathway, it is likely that the LCB1 and LCB2 genes are involved in the first step of long-chain-base synthesis. The results of long-chain-base starvation in the Lcb- strains suggest that one or more sphingolipids have a vital role in S. cerevisiae. Immediate sequelae of long-chain-base starvation were loss of viability, exacerbated in the presence of alpha-cyclodextrin, and loss of phosphoinositol sphingolipid synthesis but not phosphatidylinositol synthesis. Loss of viability with long-chain-base starvation could be prevented by also blocking either protein or nucleic acid synthesis. Without a long-chain-base, cell division, dry mass accumulation, and protein synthesis continued at a diminished rate and were further inhibited by the detergent Tergitol. The cell density increase induced by long-chain-base starvation is thus explained as a differential loss of cell division and mass accumulation. Long-chain-base starvation in Lcb- S. cerevisiae and inositol starvation of Inos- S. cerevisiae share common features: an increase in cell density and a loss of cell viability overcome by blocking macromolecular synthesis.
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Affiliation(s)
- W J Pinto
- Department of Biochemistry, University of Kentucky College of Medicine, Lexington 40536
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21
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Isolation and characterization of OLE1, a gene affecting fatty acid desaturation from Saccharomyces cerevisiae. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)84740-3] [Citation(s) in RCA: 232] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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22
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Kawasaki S, Ramgopal M, Chin J, Bloch K. Sterol control of the phosphatidylethanolamine-phosphatidylcholine conversion in the yeast mutant GL7. Proc Natl Acad Sci U S A 1985; 82:5715-9. [PMID: 3898069 PMCID: PMC390622 DOI: 10.1073/pnas.82.17.5715] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The relatively slow growth rate of the yeast mutant GL7, a sterol auxotroph, on medium containing cholesterol is markedly accelerated by supplementation with small amounts of ergosterol. Under these conditions (sterol synergism) cellular phospholipid synthesis is enhanced. We now find that one of the ergosterol-stimulated processes is the methylation of phosphatidylethanolamine to phosphatidylcholine. This is shown by comparing methyltransferase activities of membrane preparations derived from cells grown on either ergosterol, cholesterol, or the synergistic sterol pair. Incorporation of 32P from [gamma-32P]ATP into the yeast membranes is rapid and greater when ergosterol-grown cells rather than cholesterol-grown cells are the source of membranes.
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23
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Atkinson KD, Ramirez RM. Secretion can proceed uncoupled from net plasma membrane expansion in inositol-starved Saccharomyces cerevisiae. J Bacteriol 1984; 160:80-6. [PMID: 6384202 PMCID: PMC214684 DOI: 10.1128/jb.160.1.80-86.1984] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Secretion of acid phosphatase and invertase was examined in an inositol-requiring ino1 mutant of the yeast Saccharomyces cerevisiae. Inositol starvation is known to block plasma membrane expansion, presumably due to restricted membrane phospholipid synthesis. If membrane expansion and extracellular protein secretion are accomplished by the same intracellular transport process, one would expect secretion to fail coordinately with cessation of plasma membrane growth in inositol-starved cells. In glucose-grown, inositol-starved cells, plasma membrane expansion and acid phosphatase secretion stopped coordinately, and intracellular acid phosphatase accumulated. In sucrose-grown, inositol-starved cells, plasma membrane growth halted, but secretion of both acid phosphatase and invertase continued until the onset of inositol-less death. Although glucose-grown and sucrose-grown cells differ in their ability to secrete when deprived of inositol, they exhibited the same disturbances in phospholipid synthesis. Phosphatidylinositol synthesis failed, and its precursors phosphatidic acid and CDP-diglyceride accumulated equally in both cultures. Sucrose-grown yeast cells appear to accomplish normal levels of extracellular protein secretion by an inositol-independent mechanism. In glucose-grown yeasts, both plasma membrane expansion and secretion are inositol dependent.
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24
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Schweizer E. Chapter 3 Genetics of fatty acid biosynthesis in yeast. ACTA ACUST UNITED AC 1984. [DOI: 10.1016/s0167-7306(08)60121-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2023]
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25
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Wright C, Kafkewitz D, Somberg EW. Eucaryote thermophily: role of lipids in the growth of Talaromyces thermophilus. J Bacteriol 1983; 156:493-7. [PMID: 6630144 PMCID: PMC217859 DOI: 10.1128/jb.156.2.493-497.1983] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The effects of growth temperature on the fatty acid composition of the phospholipids of the fungus Talaromyces thermophilus were investigated. This thermophilic organism was unable to increase the degree of unsaturation of its fatty acids when shifted from high to low growth temperatures. Inhibition of fatty acid synthesis by the antibiotic cerulenin was reversed by the addition of a mixture of palmitic, stearic, and oleic acids and ergosterol. The data obtained were consistent with the hypothesis that the thermophilic character of T. thermophilus is due to metabolic limitations that restrict its ability to regulate membrane fluidity.
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26
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Ramirez RM, Ishida-Schick T, Krilowicz BL, Leish BA, Atkinson KD. Plasma membrane expansion terminates in Saccharomyces cerevisiae secretion-defective mutants while phospholipid synthesis continues. J Bacteriol 1983; 154:1276-83. [PMID: 6343347 PMCID: PMC217601 DOI: 10.1128/jb.154.3.1276-1283.1983] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Phospholipid synthesis activity and plasma membrane growth have been studied in the Saccharomyces cerevisiae temperature-sensitive, secretion-defective mutants isolated by Novick and Schekman (Proc. Natl. Acad. Sci. U.S.A. 76:1858-1862, 1979; Novick et al., Cell 21:205-215, 1980). The mutants, sec1 through sec23, do not grow at 37 degrees C and exhibit lower rates of phospholipid synthesis than does the wild-type strain X2180. None of the mutants exhibits a decline in lipid synthesis rapid enough to explain secretion failure. Plasma membrane growth was assessed indirectly by examining the osmotic sensitivity of spheroplasts derived from cultures transferred from 24 to 37 degrees C. Spheroplasts from the normal-growing strain X2180 exhibited a small rapid increase in osmotic sensitivity and stabilized at a more sensitive state. Spheroplasts from the sec mutants exposed to the same temperature shift exhibited progressively increasing osmotic sensitivity. Cycloheximide treatment prevented progressive increases in osmotic fragility. These data are compatible with the hypothesis that plasma membrane expansion is restricted in the sec mutants. During incubation at 37 degrees C, the accumulation of intracellular materials within the no-longer expanding plasma membrane exerts osmotic stress on the membrane, increasing with time. The gene products defective in Novick and Schekman's sec mutants appear to be required for both extracellular protein secretion and plasma membrane growth in yeast cells.
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27
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Manian S, Ward F. The effect of growth rate on the viability ofBacillus stearothermophilus. FEMS Microbiol Lett 1983. [DOI: 10.1111/j.1574-6968.1983.tb00471.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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28
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Buttke TM, Pyle AL. Effects of unsaturated fatty acid deprivation on neutral lipid synthesis in Saccharomyces cerevisiae. J Bacteriol 1982; 152:747-56. [PMID: 6752117 PMCID: PMC221524 DOI: 10.1128/jb.152.2.747-756.1982] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The effects of unsaturated fatty acid deprivation on lipid synthesis in Saccharomyces cerevisiae strain GL7 were determined by following the incorporation of [14C]acetate. Compared to yeast cells grown with oleic acid, unsaturated fatty acid-deprived cells contained 200 times as much 14C label in squalene, with correspondingly less label in 2,3-oxidosqualene and 2,3;22,23-dioxidosqualene. Cells deprived of either methionine or cholesterol did not accumulate squalene, demonstrating that the effect of unsaturated fatty acid starvation on squalene oxidation was not due to an inhibition of cell growth. Cells deprived of olefinic supplements displayed additional changes in lipid metabolism: (i) an increase in 14C-labeled diacylglycerides, (ii) a decrease in 14C-labeled triacylglycerides, and (iii) increased levels of 14C-labeled decanoic and dodecanoic fatty acids. The changes in squalene oxidation and acylglyceride metabolism in unsaturated fatty acid-deprived cells were readily reversed by adding oleic acid. Pulse-chase studies demonstrated that the [14C]squalene and 14C-labeled diacylglycerides which accumulated during starvation were further metabolized when cells were resupplemented with oleic acid. These results demonstrate that unsaturated fatty acids are essential for normal lipid metabolism in yeasts.
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29
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Esfahani M, Cavanaugh JR, Pfeffer PE, Luken DW, Devlin TM. 19F-NMR and fluorescence polarization of yeast plasma membrane and isolated lipids. Biochem Biophys Res Commun 1981; 101:306-11. [PMID: 7025840 DOI: 10.1016/s0006-291x(81)80045-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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30
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Esfahani M, Kucirka EM, Timmons FX, Tyagi S, Lord AE, Henry SA. Effect of exogenous fatty acids on growth, membrane fluidity, and phospholipid fatty acid composition in yeast. JOURNAL OF SUPRAMOLECULAR STRUCTURE AND CELLULAR BIOCHEMISTRY 1981; 15:119-28. [PMID: 6100953 DOI: 10.1002/jsscb.1981.380150203] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The growth response of a double-mutant fatty acid auxotroph of yeast Saccharomyces cerevisiae to exogenous saturated fatty acids of a homologous series from 12:0 to 16:0, each supplied with oleate, linoleate, linolenate, or cis-delta 11-eicosenoate, cannot be explained in terms of the efficiency of incorporation of the fatty acids into phospholipids or alteration of membrane fluidity. There is, however, a negative correlation between growth and levels of 12:0 plus 13:0 in phospholipids, as well as a positive correlation between growth and levels of 14:0, 15:0, and 16:0. We, therefore, conclude that the predominant factor in these phospholipid fatty acyl chain modifications is maintenance of an optimal concentration of C14:0 through C16:0 in phospholipids of this organism.
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Affiliation(s)
- M Esfahani
- Department of Biological Chemistry, Hahnemann Medical College, Philadelphia, Pennsylvania 19102
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31
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Contreras I, Bender RA, Mansour J, Henry S, Shapiro L. Caulobacter cresentus mutant defective in membrane phospholipid synthesis. J Bacteriol 1979; 140:612-9. [PMID: 500564 PMCID: PMC216689 DOI: 10.1128/jb.140.2.612-619.1979] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
To study the relationship between phospholipid synthesis and organelle biogenesis in the dimorphic bacterium Caulobacter crescentus, auxotrophs have been isolated which require exogenous glycerol or glycerol 3-phosphate for growth when glucose is used as the carbon source. Upon glycerol deprivation, net phospholipid synthesis ceased immediately in a glycerol 3-phosphate auxotroph which was shown to have levels of biosynthetic sn-glycerol 3-phosphate dehydrogenase (E.C. 1.1.1.8) activity 10 times lower than that of the wild type. In the absence of glycerol, the optical density of the culture continued to increase for the equivalent of one generation, although the cells did not divide. After the equivalent of one generation time, rapid cell death occurred. Cell death also occurred when phospholipid synthesis was inhibited by cerulenin. Although ribonucleic acid and protein syntheses continued at a reduced rate for the equivalent of one generation in mutant strains, a substantial decrease in the rate of deoxyribonucleic acid synthesis occurred immediately upon glycerol deprivation. Revertant strains had wild-type levels of glycerol 3-phosphate dehydrogenase activity and normal rates of phospholipid and macromolecular synthesis.
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32
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Sumrada R, Cooper TG. Control of vacuole permeability and protein degradation by the cell cycle arrest signal in Saccharomyces cerevisiae. J Bacteriol 1978; 136:234-46. [PMID: 361691 PMCID: PMC218654 DOI: 10.1128/jb.136.1.234-246.1978] [Citation(s) in RCA: 41] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Saccharomyces cerevisiae responds to deperivation of nutrients by arresting cell division at the unbudded G1 stage. Cells situated outside of G1 at the time of deperivation complete the cell cycle before arresting. This prompted an investigation of the source of nutrients used by these cells to complete division and the mechanisms controlling their availability. We found a close correlation between accumulation of unbudded cells and loss of previously formed allophanate hydrolase activity after nutrient starvation. These losses were not specific to the allantoin, system since they have been observed for a number of other enzymes and also when cellular protein levels were monitored with [3H]leucine. Loss of hydrolase activity was also observed when protein synthesis was inhibited either by addition of inhibitors or loss of the prtl gene product. We found that onset of nutrient starvation brought about release of large quantities of arginine and allantoin normally sequestered in the cell vacuole. Treatment of a cells with alpha-factor resulted in both the release of allantoin and arginine from the cell vacuole and the onset of intracellular protein degradation. These effects were not observed when either alpha cells or a/alpha diploid strains were treated with alpha-factor. These data suggest that release of vacuolar constitutents and protein turnover may be regulated by the G1 arrest signal.
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33
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Rana RS, Munkres KD. Ageing of Neurospora crassa. V. Lipid peroxidation and decay of respiratory enzymes in an inositol auxotroph. Mech Ageing Dev 1978; 7:241-72. [PMID: 204836 DOI: 10.1016/0047-6374(78)90070-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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34
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Stevenson KE, Graumlich TR. Injury and recovery of yeasts and molds. ADVANCES IN APPLIED MICROBIOLOGY 1978; 23:203-17. [PMID: 356540 DOI: 10.1016/s0065-2164(08)70070-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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35
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Atkinson KD, Kolat AI, Henry SA. Osmotic imbalance in inositol-starved spheroplasts of Saccharomyces cerevisiae. J Bacteriol 1977; 132:806-17. [PMID: 336608 PMCID: PMC235582 DOI: 10.1128/jb.132.3.806-817.1977] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Physiological states associated with inositol starvation of spheroplasts of Saccharomyces cerevisiae were investigated and compared with conditions preceding death of starved whole cells. In the absence of synthesis of inositol-containing lipids, cell surface expansion terminated after one doubling of whole cells. In spheroplasts, cessation of membrane expansion was apparently followed by rapid development of an osmotic imbalance, causing lysis. Continued synthesis and accumulation of cytoplasmic constituents within the limited cell volume were implicated as a cause of the osmotic imbalance. In whole cells, an increase in internal osmotic pressure also follows termination of membrane and cell wall expansion. The cell wall prevents lysis, allowing a state of increasing cytoplasmic osmotic pressure to persist in the period preceding onset of inositol-less death.
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36
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Becker G, Lester R. Changes in phospholipids of Saccharomyces cerevisiae associated with inositol-less death. J Biol Chem 1977. [DOI: 10.1016/s0021-9258(19)75275-2] [Citation(s) in RCA: 81] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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37
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Henry SA, Atkinson KD, Kolat AI, Culbertson MR. Growth and metabolism of inositol-starved Saccharomyces cerevisiae. J Bacteriol 1977; 130:472-84. [PMID: 323239 PMCID: PMC235226 DOI: 10.1128/jb.130.1.472-484.1977] [Citation(s) in RCA: 114] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Upon starvation for inositol, a phospholipid precursor, an inositol-requiring mutant of Saccharomyces cerevisiae has been shown to die if all other conditions are growth supporting. The growth and metabolism of inositol-starved cells has been investigated in order to determine the physiological state leading to "inositolless death". The synthesis of the major inositol-containing phospholipid ceases within 30 min after the removal of inositol from the growth medium. The cells, however, continue in an apparently normal fashion for one generation (2 h under the growth conditions used in this study). The cessation of cell division is not preceded or accompanied by any detectable change in the rate of macromolecular synthesis. When cell division ceases, the cells remain constant in volume, whereas macromolecular synthesis continues at first at an unchanged rate and eventually at a decreasing rate. Macromolecular synthesis terminates after about 4 h of inositol starvation, at approximately the time when the cells begin to die. Cell death is also accompanied by a decline in cellular potassium and adenosine triphosphate levels. The cells can be protected from inositolless death by several treatments that block cellular metabolism. It is concluded that inositol starvation results in a imbalance between the expansion of cell volume and the accumulation of cytoplasmic constituents. This imbalance is very likely the cause of inositolless death.
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38
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Keith AD, Pollard EC, Snipes W. Inositol-less death in yeast results in a simultaneous increase in intracellular viscosity. Biophys J 1977; 17:205-12. [PMID: 191118 PMCID: PMC1473239 DOI: 10.1016/s0006-3495(77)85650-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Inositol auxotrophs of yeast developing on isositol-deficient medium continue protein synthesis for 4-6 h, lose viability rapidly after 6 h, and show an increase in cytoplasmic viscosity as measured by spin label rotational motion. Cycloheximide prevents the rapid loss of cell viability, stops protein synthesis, and simultaneously prevents an increase in cytoplasmic viscosity. From these observations, we infer that intracellular translational diffusion is upset as a consequence of inositol starvation. Cell death may be caused by a modified intracellular diffusion environment.
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39
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Hardie ID, Dawes IW. Optimal conditions for selecting specific auxotrophs of Saccharomyces cerevisiae using temperature-sensitive suicide mutants. Mutat Res 1977; 42:215-22. [PMID: 320464 DOI: 10.1016/s0027-5107(77)80025-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Of 48 temperature-sensitive mutants of Saccharomyces cerevisiae examined, five belonging to the same complementation group were found to undergo extensive loss of viability at the restrictive temperature. These mutants were protected from the lethal effects of exposure to a non-permissive temperature by starving for an auxotrophic requirement. By analogy with the method described by Littlewood [6] for selecting antibiotic-sensitive mutants, these temperature-sensitive mutants were found suitable in enriching for specific auxotrophs. Optimal conditions have been determined for selecting specific auxotrophs after mutagenesis by N-methyl-N'-nitro-N-nitrosoguanidine. These enable 20-fold enrichment and at least in the case of mutation to adenine dependence the method does not appear to favour mutations at any particular locus.
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Henry SA, Keith AD, Snipes W. Changes in the restriction of molecular rotational diffusion of water-soluble spin labels during fatty acid starvation of yeast. Biophys J 1976; 16:641-53. [PMID: 179632 PMCID: PMC1334887 DOI: 10.1016/s0006-3495(76)85718-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Yeast mutants lacking fatty acid synthetase activity (fas-) die when deprived of saturated fatty acid under conditions which are otherwise growth-supporting. The spin label technique is used to show that restriction of molecular rotational diffusion of spin label molecules dissolved in aqueous zones increases several fold under conditions of fatty acid starvation while the apparent physical state of cellular hydrocarbon zones remains essentially unchanged. We focus attention on the cellular aqueous interior as the potential site of alteration under selective starvation conditions. Correspondences exist between restriction of molecular motion of water soluble spin labels dissolved in the cell and loss of cell viability. The correspondences to changes in the molecular motion of hydrocarbon soluble spin labels are much less or are not detectable.
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Culbertson MR, Donahue TF, Henry SA. Control of inositol biosynthesis in Saccharomyces cerevisiae: properties of a repressible enzyme system in extracts of wild-type (Ino+) cells. J Bacteriol 1976; 126:232-42. [PMID: 4423 PMCID: PMC233280 DOI: 10.1128/jb.126.1.232-242.1976] [Citation(s) in RCA: 81] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Inositol biosynthesis was studied in soluble, cell extracts of a wild-type (Ino) strain of Saccharomyces cerevisiae. Two reactions were detected: (i) conversion of D-glucose-6-phosphate to a phosphorylated form of inositol, presumably inositol-1-phosphate (IP synthethase, EC5.5.1.4), and (ii) conversion of phosphorylated inositol to inositol (IP phosphatase, EC3.1.3.25). The in vitro rate of conversion of glucose-6-phosphate to inositol was proportional to incubaion time and enzyme concentration. The pH optimum was 7.0. The synthesis of inositol required oxidized nicotinamide adenine dinucleotide (NAD) and was stimulated byNH4C1 and MgC12. NADP substituted poorly for NAD, and NADH inhibitedthe reaction. Phosphorylated inositol accumulated in the absence of MgC12, suggesting that inositol-phosphate is an intermediate in the pathway and that Mg ions stimulate the dephosphorylation of inositol-phosphate. IP synthetase was inhibited approximately 20% in the presence of inositol in the reaction mixture at concentrations exceeding 1 mM. The enzyme was repressed approximately 50-fold when inositol was present in the growth medium at concentrations exceeding 50 muM. IP synthetase reached the fully repressed level approximately 10 h after the addition of inositol to logarithmic cultures grown in the absence of inositol. The specific activity of the enzyme increased with time in logarithmically growing cultures lacking inositol andapproached the fully depressed level as the cells entered stationary phase.
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Inoue H, Ishikawa T. Death resulting from unbalanced growth in a temperature-sensitive mutant of Neurospora crassa. Arch Microbiol 1975; 104:1-6. [PMID: 125567 DOI: 10.1007/bf00447292] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A temperature-sensitive mutant of Neurospora crassa was found to undergo rapid death on minimal medium at 35 degrees C. The loss of viability in this mutant was prevented by various factors which retard growth, including deprivation of carbon sources or interruption of protein synthesis. Synthesis of nucleic acids and protein in this mutant was normal at the early stages of germination and then depressed at 35 degrees C. The active transport of glucose and the respiration rate in this mutant were depressed at 35 degrees C. Phopholipid synthesis was significantly repressed at 35 degrees C. The possible significance of the characteristics of this mutant is discussed in terms of membrane biosynthesis.
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Abstract
A new method for the selection of auxotrophic, antibiotic- and temperature=sensitivemutants in Saccharomyces cerevisiae is reported. The technique is based upon the observation that certain fatty acid auxotrophs of yeast die when deprived of fatty acid only under conditions supporting growth. When macromolecular synthesis is blocked, the fattyacid-starved cells survive. By appropriate manipulation of a fatty acid-requiring strain enrichment as great as 75-fold was achieved for certain classes of auxotrophic mutants. An enrichment of approximately 100-fold is possible for some antibiotic-sensitive mutants. Selection for temperature-sensitive mutants, however, resulted in less than a 2-fold increase in the frequency of such mutants, probably because of the heterogeneity ofthis mutant category. It is likely that only that fraction of temperature-sensitivemutations which rapidly and reversibly blocks macromolecular synthesis is selected by this technique.
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Chapter 11 Mutagenesis in Yeast. Methods Cell Biol 1975. [DOI: 10.1016/s0091-679x(08)60958-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Littlewood BS. Methods for selecting auxotrophic and temperature-sensitive mutants in yeasts. Methods Cell Biol 1975; 11:273-85. [PMID: 1102852 DOI: 10.1016/s0091-679x(08)60328-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Pringle JR. Induction, selection, and experimental uses of temperature-sensitive and other conditional mutants of yeast. Methods Cell Biol 1975; 12:233-72. [PMID: 591 DOI: 10.1016/s0091-679x(08)60959-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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