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Liu C, Shi K, Lyu K, Liu D, Wang X. The toxicity of neodymium and genome-scale genetic screen of neodymium-sensitive gene deletion mutations in the yeast Saccharomyces cerevisiae. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:41439-41454. [PMID: 35088271 DOI: 10.1007/s11356-021-18100-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 12/09/2021] [Indexed: 06/14/2023]
Abstract
The wide usage of neodymium (Nd) in industry, agriculture, and medicine has made it become an emerging pollutant in the environment. Increasing Nd pollution has potential hazards to plants, animals, and microorganisms. Thus, it is necessary to study the toxicity of Nd and the mechanism of Nd transportation and detoxification in microorganisms. Through genome-scale screening, we identified 70 yeast monogene deletion mutations sensitive to Nd ions. These genes are mainly involved in metabolism, transcription, protein synthesis, cell cycle, DNA processing, protein folding, modification, and cell transport processes. Furthermore, the regulatory networks of Nd toxicity were identified by using the protein interaction group analysis. These networks are associated with various signal pathways, including calcium ion transport, phosphate pathways, vesicular transport, and cell autophagy. In addition, the content of Nd ions in yeast was detected by an inductively coupled plasma mass spectrometry, and most of these Nd-sensitive mutants showed an increased intracellular Nd content. In all, our results provide the basis for understanding the molecular mechanisms of detoxifying Nd ions in yeast cells, which will be useful for future studies on Nd-related issues in the environment, agriculture, and human health.
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Affiliation(s)
- Chengkun Liu
- School of Life Sciences, Shandong University of Technology, Zibo, 255049, Shandong, China
| | - Kailun Shi
- School of Life Sciences, Shandong University of Technology, Zibo, 255049, Shandong, China
| | - Keliang Lyu
- School of Life Sciences, Shandong University of Technology, Zibo, 255049, Shandong, China
| | - Dongwu Liu
- School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo, 255049, China
| | - Xue Wang
- School of Life Sciences, Shandong University of Technology, Zibo, 255049, Shandong, China
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2
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Barney JB, Chandrashekarappa DG, Soncini SR, Schmidt MC. Drug resistance in diploid yeast is acquired through dominant alleles, haploinsufficiency, gene duplication and aneuploidy. PLoS Genet 2021; 17:e1009800. [PMID: 34555030 PMCID: PMC8460028 DOI: 10.1371/journal.pgen.1009800] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 08/31/2021] [Indexed: 02/04/2023] Open
Abstract
Previous studies of adaptation to the glucose analog, 2-deoxyglucose, by Saccharomyces cerevisiae have utilized haploid cells. In this study, diploid cells were used in the hope of identifying the distinct genetic mechanisms used by diploid cells to acquire drug resistance. While haploid cells acquire resistance to 2-deoxyglucose primarily through recessive alleles in specific genes, diploid cells acquire resistance through dominant alleles, haploinsufficiency, gene duplication and aneuploidy. Dominant-acting, missense alleles in all three subunits of yeast AMP-activated protein kinase confer resistance to 2-deoxyglucose. Dominant-acting, nonsense alleles in the REG1 gene, which encodes a negative regulator of AMP-activated protein kinase, confer 2-deoxyglucose resistance through haploinsufficiency. Most of the resistant strains isolated in this study achieved resistance through aneuploidy. Cells with a monosomy of chromosome 4 are resistant to 2-deoxyglucose. While this genetic strategy comes with a severe fitness cost, it has the advantage of being readily reversible when 2-deoxyglucose selection is lifted. Increased expression of the two DOG phosphatase genes on chromosome 8 confers resistance and was achieved through trisomies and tetrasomies of that chromosome. Finally, resistance was also mediated by increased expression of hexose transporters, achieved by duplication of a 117 kb region of chromosome 4 that included the HXT3, HXT6 and HXT7 genes. The frequent use of aneuploidy as a genetic strategy for drug resistance in diploid yeast and human tumors may be in part due to its potential for reversibility when selection pressure shifts.
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Affiliation(s)
- Jordan B. Barney
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Dakshayini G. Chandrashekarappa
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Samantha R. Soncini
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Martin C. Schmidt
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
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3
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Yang X, Meng L, Lin X, Jiang HY, Hu XP, Li CF. Role of Elm1, Tos3, and Sak1 Protein Kinases in the Maltose Metabolism of Baker's Yeast. Front Microbiol 2021; 12:665261. [PMID: 34140941 PMCID: PMC8204090 DOI: 10.3389/fmicb.2021.665261] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 04/23/2021] [Indexed: 11/25/2022] Open
Abstract
Glucose repression is a key regulatory system controlling the metabolism of non-glucose carbon source in yeast. Glucose represses the utilization of maltose, the most abundant fermentable sugar in lean dough and wort, thereby negatively affecting the fermentation efficiency and product quality of pasta products and beer. In this study, the focus was on the role of three kinases, Elm1, Tos3, and Sak1, in the maltose metabolism of baker’s yeast in lean dough. The results suggested that the three kinases played different roles in the regulation of the maltose metabolism of baker’s yeast with differential regulations on MAL genes. Elm1 was necessary for the maltose metabolism of baker’s yeast in maltose and maltose-glucose, and the overexpression of ELM1 could enhance the maltose metabolism and lean dough fermentation ability by upregulating the transcription of MALx1 (x is the locus) in maltose and maltose-glucose and MALx2 in maltose. The native level of TOS3 and SAK1 was essential for yeast cells to adapt glucose repression, but the overexpression of TOS3 and SAK1 alone repressed the expression of MALx1 in maltose-glucose and MALx2 in maltose. Moreover, the three kinases might regulate the maltose metabolism via the Snf1-parallel pathways with a carbon source-dependent manner. These results, for the first time, suggested that Elm1, rather than Tos3 and Sak1, might be the dominant regulator in the maltose metabolism of baker’s yeast. These findings provided knowledge about the glucose repression of maltose and gave a new perspective for breeding industrial yeasts with rapid maltose metabolism.
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Affiliation(s)
- Xu Yang
- College of Food Science and Engineering, Hainan University, Haikou, China
| | - Lu Meng
- College of Food Science and Engineering, Hainan University, Haikou, China
| | - Xue Lin
- College of Food Science and Engineering, Hainan University, Haikou, China.,Engineering Research Center of Utilization of Tropical Polysaccharide Resources, Ministry of Education, Haikou, China.,Hainan Key Laboratory of Food Nutrition and Functional Food, Haikou, China
| | - Huan-Yuan Jiang
- College of Food Science and Engineering, Hainan University, Haikou, China
| | - Xiao-Ping Hu
- College of Food Science and Engineering, Hainan University, Haikou, China.,Engineering Research Center of Utilization of Tropical Polysaccharide Resources, Ministry of Education, Haikou, China.,Hainan Key Laboratory of Food Nutrition and Functional Food, Haikou, China
| | - Cong-Fa Li
- College of Food Science and Engineering, Hainan University, Haikou, China.,Engineering Research Center of Utilization of Tropical Polysaccharide Resources, Ministry of Education, Haikou, China.,Hainan Key Laboratory of Food Nutrition and Functional Food, Haikou, China
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4
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Spontaneous mutations that confer resistance to 2-deoxyglucose act through Hxk2 and Snf1 pathways to regulate gene expression and HXT endocytosis. PLoS Genet 2020; 16:e1008484. [PMID: 32673313 PMCID: PMC7386655 DOI: 10.1371/journal.pgen.1008484] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 07/28/2020] [Accepted: 06/01/2020] [Indexed: 12/31/2022] Open
Abstract
Yeast and fast-growing human tumor cells share metabolic similarities in that both cells use fermentation of glucose for energy and both are highly sensitive to the glucose analog 2-deoxyglucose. Spontaneous mutations in S. cerevisiae that conferred resistance to 2-deoxyglucose were identified by whole genome sequencing. Missense alleles of the HXK2, REG1, GLC7 and SNF1 genes were shown to confer significant resistance to 2-deoxyglucose and all had the potential to alter the activity and or target selection of the Snf1 kinase signaling pathway. All three missense alleles in HXK2 resulted in significantly reduced catalytic activity. Addition of 2DG promotes endocytosis of the glucose transporter Hxt3. All but one of the 2DG-resistant strains reduced the 2DG-mediated hexose transporter endocytosis by increasing plasma membrane occupancy of the Hxt3 protein. Increased expression of the DOG (deoxyglucose) phosphatases has been associated with resistance to 2-deoxyglucose. Expression of both the DOG1 and DOG2 mRNA was elevated after treatment with 2-deoxyglucose but induction of these genes is not associated with 2DG-resistance. RNAseq analysis of the transcriptional response to 2DG showed large scale, genome-wide changes in mRNA abundance that were greatly reduced in the 2DG resistant strains. These findings suggest the common adaptive response to 2DG is to limit the magnitude of the response. Genetic studies of 2DG resistance using the dominant SNF1-G53R allele in cells that are genetically compromised in both the endocytosis and DOG pathways suggest that at least one more mechanism for conferring resistance to this glucose analog remains to be discovered. Yeast and fast-growing human tumor cells share metabolic similarities in that both cells use fermentation of glucose for energy and both are highly sensitive to the glucose analog 2-deoxyglucose. Another similarity between yeast cells and human tumor cells is that both cells can acquire resistance to 2-deoxyglucose, an outcome that can limit the usefulness of some cancer therapeutics. In this study, we used bakers’ yeast as a model organism to better understand the mechanism of toxicity and acquisition of resistance to 2-deoxyglucose. Spontaneous mutations in S. cerevisiae that conferred resistance to 2-deoxyglucose were isolated and identified by whole genome sequencing, a technology that was not available until recently. Our studies indicate that 2-deoxyglucose becomes toxic after it is phosphorylated by an enzyme called hexokinase. One important route to resistance is to reduce hexokinase activity. Other parallel pathways to resistance include increased expression of a hydrolase that degrades the toxic metabolite, altered localization of glucose transporters and altered glucose signal transduction pathways.
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5
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Lin X, Zhang CY, Meng L, Bai XW, Xiao DG. Overexpression of SNF4 and deletions of REG1- and REG2-enhanced maltose metabolism and leavening ability of baker's yeast in lean dough. J Ind Microbiol Biotechnol 2018; 45:827-838. [PMID: 29936578 DOI: 10.1007/s10295-018-2058-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 06/18/2018] [Indexed: 01/07/2023]
Abstract
Maltose metabolism of baker's yeast (Saccharomyces cerevisiae) in lean dough is suppressed by the glucose effect, which negatively affects dough fermentation. In this study, differences and interactions among SNF4 (encoding for the regulatory subunit of Snf1 kinase) overexpression and REG1 and REG2 (which encodes for the regulatory subunits of the type I protein phosphatase) deletions in maltose metabolism of baker's yeast were investigated using various mutants. Results revealed that SNF4 overexpression and REG1 and REG2 deletions effectively alleviated glucose repression at different levels, thereby enhancing maltose metabolism and leavening ability to varying degrees. SNF4 overexpression combined with REG1/REG2 deletions further enhanced the increases in glucose derepression and maltose metabolism. The overexpressed SNF4 with deleted REG1 and REG2 mutant ΔREG1ΔREG2 + SNF4 displayed the highest maltose metabolism and strongest leavening ability under the test conditions. Such baker's yeast strains had excellent potential applications.
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Affiliation(s)
- Xue Lin
- College of Food Science and Technology, Hainan University, Haikou, 570228, People's Republic of China.,Tianjin Industrial Microbiology Key Laboratory, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China
| | - Cui-Ying Zhang
- Tianjin Industrial Microbiology Key Laboratory, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China.
| | - Lu Meng
- College of Food Science and Technology, Hainan University, Haikou, 570228, People's Republic of China
| | - Xiao-Wen Bai
- Tianjin Industrial Microbiology Key Laboratory, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China
| | - Dong-Guang Xiao
- Tianjin Industrial Microbiology Key Laboratory, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China.
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6
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Adnan M, Zheng W, Islam W, Arif M, Abubakar YS, Wang Z, Lu G. Carbon Catabolite Repression in Filamentous Fungi. Int J Mol Sci 2017; 19:ijms19010048. [PMID: 29295552 PMCID: PMC5795998 DOI: 10.3390/ijms19010048] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Revised: 12/13/2017] [Accepted: 12/20/2017] [Indexed: 12/18/2022] Open
Abstract
Carbon Catabolite Repression (CCR) has fascinated scientists and researchers around the globe for the past few decades. This important mechanism allows preferential utilization of an energy-efficient and readily available carbon source over relatively less easily accessible carbon sources. This mechanism helps microorganisms to obtain maximum amount of glucose in order to keep pace with their metabolism. Microorganisms assimilate glucose and highly favorable sugars before switching to less-favored sources of carbon such as organic acids and alcohols. In CCR of filamentous fungi, CreA acts as a transcription factor, which is regulated to some extent by ubiquitination. CreD-HulA ubiquitination ligase complex helps in CreA ubiquitination, while CreB-CreC deubiquitination (DUB) complex removes ubiquitin from CreA, which causes its activation. CCR of fungi also involves some very crucial elements such as Hexokinases, cAMP, Protein Kinase (PKA), Ras proteins, G protein-coupled receptor (GPCR), Adenylate cyclase, RcoA and SnfA. Thorough study of molecular mechanism of CCR is important for understanding growth, conidiation, virulence and survival of filamentous fungi. This review is a comprehensive revision of the regulation of CCR in filamentous fungi as well as an updated summary of key regulators, regulation of different CCR-dependent mechanisms and its impact on various physical characteristics of filamentous fungi.
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Affiliation(s)
- Muhammad Adnan
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
- Key Laboratory of Bio-Pesticides and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Wenhui Zheng
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
- Key Laboratory of Bio-Pesticides and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Waqar Islam
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Muhammad Arif
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Yakubu Saddeeq Abubakar
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
- Key Laboratory of Bio-Pesticides and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Zonghua Wang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
- Key Laboratory of Bio-Pesticides and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Guodong Lu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
- Key Laboratory of Bio-Pesticides and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
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7
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Shellhammer JP, Morin-Kensicki E, Matson JP, Yin G, Isom DG, Campbell SL, Mohney RP, Dohlman HG. Amino acid metabolites that regulate G protein signaling during osmotic stress. PLoS Genet 2017; 13:e1006829. [PMID: 28558063 PMCID: PMC5469498 DOI: 10.1371/journal.pgen.1006829] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 06/13/2017] [Accepted: 05/17/2017] [Indexed: 12/29/2022] Open
Abstract
All cells respond to osmotic stress by implementing molecular signaling events to protect the organism. Failure to properly adapt can lead to pathologies such as hypertension and ischemia-reperfusion injury. Mitogen-activated protein kinases (MAPKs) are activated in response to osmotic stress, as well as by signals acting through G protein-coupled receptors (GPCRs). For proper adaptation, the action of these kinases must be coordinated. To identify second messengers of stress adaptation, we conducted a mass spectrometry-based global metabolomics profiling analysis, quantifying nearly 300 metabolites in the yeast S. cerevisiae. We show that three branched-chain amino acid (BCAA) metabolites increase in response to osmotic stress and require the MAPK Hog1. Ectopic addition of these BCAA derivatives promotes phosphorylation of the G protein α subunit and dampens G protein-dependent transcription, similar to that seen in response to osmotic stress. Conversely, genetic ablation of Hog1 activity or the BCAA-regulatory enzymes leads to diminished phosphorylation of Gα and increased transcription. Taken together, our results define a new class of candidate second messengers that mediate cross talk between osmotic stress and GPCR signaling pathways.
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Affiliation(s)
- James P. Shellhammer
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | | | - Jacob P. Matson
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Guowei Yin
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Daniel G. Isom
- The University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Sharon L. Campbell
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Robert P. Mohney
- Metabolon, Inc., Research Triangle Park, North Carolina, United States of America
| | - Henrik G. Dohlman
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail:
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8
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Springing into Action: Reg2 Negatively Regulates Snf1 Protein Kinase and Facilitates Recovery from Prolonged Glucose Starvation in Saccharomyces cerevisiae. Appl Environ Microbiol 2016; 82:3875-3885. [PMID: 27107116 DOI: 10.1128/aem.00154-16] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Accepted: 04/14/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Glucose is the preferred carbon source for the yeast Saccharomyces cerevisiae Glucose limitation activates Snf1 protein kinase, a key regulator of energy homeostasis that promotes utilization of alternative carbon sources and enforces energy conservation. Snf1 activation requires phosphorylation of its T-loop threonine (Thr210) by upstream kinases. When glucose is abundant, Snf1 is inhibited by Thr210 dephosphorylation. This involves the function of the type 1 protein phosphatase Glc7, which is targeted to Snf1 by a regulatory subunit, Reg1. The reg1 mutation causes increased Snf1 activity and mimics various aspects of glucose limitation, including slower growth. Reg2 is another Glc7 regulatory subunit encoded by a paralogous gene, REG2 Previous evidence indicated that the reg2 mutation exacerbates the Snf1-dependent slow-growth phenotype caused by reg1, suggesting a link between Reg2 and Snf1. Here, we explore this link in more detail and present evidence that Reg2 contributes to Snf1 Thr210 dephosphorylation. Consistent with this role, Reg2 interacts with wild-type Snf1 but not with nonphosphorylatable Snf1-T210A. Reg2 accumulation increases in a Snf1-dependent manner during prolonged glucose deprivation, and glucose-starved cells lacking Reg2 exhibit delayed Snf1 Thr210 dephosphorylation and slower growth recovery upon glucose replenishment. Accordingly, cells lacking Reg2 are outcompeted by wild-type cells in the course of several glucose starvation/replenishment cycles. Collectively, our results support a model in which Reg2-Glc7 contributes to the negative control of Snf1 in response to glucose refeeding after prolonged starvation. The competitive growth advantage provided by Reg2 underscores the evolutionary significance of this paralog for S. cerevisiae IMPORTANCE The ability of microorganisms to respond to stress is essential for their survival. However, rapid recovery from stress could be equally crucial in competitive environments. Therefore, a wise stress response program should prepare cells for quick recovery upon reexposure to favorable conditions. Glucose is the preferred carbon source for the yeast S. cerevisiae Glucose depletion activates the stress response protein kinase Snf1, which functions to limit energy-consuming processes, such as growth. We show that prolonged glucose deprivation also leads to Snf1-dependent accumulation of Reg2 and that this protein helps to inhibit Snf1 and to accelerate growth recovery upon glucose replenishment. Cells lacking Reg2 are readily outcompeted by wild-type cells during glucose depletion/replenishment cycles. Thus, while prolonged glucose deprivation might seem to put yeast cells "on their knees," concomitant accumulation of Reg2 helps configure the cells into a "sprinter's crouch start position" to spring into action once glucose becomes available.
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Hübscher V, Mudholkar K, Chiabudini M, Fitzke E, Wölfle T, Pfeifer D, Drepper F, Warscheid B, Rospert S. The Hsp70 homolog Ssb and the 14-3-3 protein Bmh1 jointly regulate transcription of glucose repressed genes in Saccharomyces cerevisiae. Nucleic Acids Res 2016; 44:5629-45. [PMID: 27001512 PMCID: PMC4937304 DOI: 10.1093/nar/gkw168] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 03/03/2016] [Indexed: 11/26/2022] Open
Abstract
Chaperones of the Hsp70 family interact with a multitude of newly synthesized polypeptides and prevent their aggregation. Saccharomyces cerevisiae cells lacking the Hsp70 homolog Ssb suffer from pleiotropic defects, among others a defect in glucose-repression. The highly conserved heterotrimeric kinase SNF1/AMPK (AMP-activated protein kinase) is required for the release from glucose-repression in yeast and is a key regulator of energy balance also in mammalian cells. When glucose is available the phosphatase Glc7 keeps SNF1 in its inactive, dephosphorylated state. Dephosphorylation depends on Reg1, which mediates targeting of Glc7 to its substrate SNF1. Here we show that the defect in glucose-repression in the absence of Ssb is due to the ability of the chaperone to bridge between the SNF1 and Glc7 complexes. Ssb performs this post-translational function in concert with the 14-3-3 protein Bmh, to which Ssb binds via its very C-terminus. Raising the intracellular concentration of Ssb or Bmh enabled Glc7 to dephosphorylate SNF1 even in the absence of Reg1. By that Ssb and Bmh efficiently suppressed transcriptional deregulation of Δreg1 cells. The findings reveal that Ssb and Bmh comprise a new chaperone module, which is involved in the fine tuning of a phosphorylation-dependent switch between respiration and fermentation.
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Affiliation(s)
- Volker Hübscher
- Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, D-79104 Freiburg, Germany
| | - Kaivalya Mudholkar
- Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, D-79104 Freiburg, Germany
| | - Marco Chiabudini
- Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, D-79104 Freiburg, Germany BIOSS Centre for Biological Signaling Studies, University of Freiburg, D-79104 Freiburg, Germany
| | - Edith Fitzke
- Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, D-79104 Freiburg, Germany
| | - Tina Wölfle
- Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, D-79104 Freiburg, Germany
| | - Dietmar Pfeifer
- Genomics Lab, Department of Hematology, Oncology and Stem Cell Transplantation, University Medical Center, University of Freiburg, D-79106 Freiburg, Germany
| | - Friedel Drepper
- BIOSS Centre for Biological Signaling Studies, University of Freiburg, D-79104 Freiburg, Germany Department of Biochemistry and Functional Proteomics, Faculty of Biology, University of Freiburg, D-79104 Freiburg, Germany
| | - Bettina Warscheid
- BIOSS Centre for Biological Signaling Studies, University of Freiburg, D-79104 Freiburg, Germany Department of Biochemistry and Functional Proteomics, Faculty of Biology, University of Freiburg, D-79104 Freiburg, Germany
| | - Sabine Rospert
- Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, D-79104 Freiburg, Germany BIOSS Centre for Biological Signaling Studies, University of Freiburg, D-79104 Freiburg, Germany
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10
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Vega M, Riera A, Fernández-Cid A, Herrero P, Moreno F. Hexokinase 2 Is an Intracellular Glucose Sensor of Yeast Cells That Maintains the Structure and Activity of Mig1 Protein Repressor Complex. J Biol Chem 2016; 291:7267-85. [PMID: 26865637 DOI: 10.1074/jbc.m115.711408] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Indexed: 11/06/2022] Open
Abstract
Hexokinase 2 (Hxk2) fromSaccharomyces cerevisiaeis a bi-functional enzyme, being both a catalyst in the cytosol and an important regulator of the glucose repression signal in the nucleus. Despite considerable recent progress, little is known about the regulatory mechanism that controls nuclear Hxk2 association with theSUC2promoter chromatin and how this association is necessary forSUC2gene repression. Our data indicate that in theSUC2promoter context, Hxk2 functions through a variety of structurally unrelated factors, mainly the DNA-binding Mig1 and Mig2 repressors and the regulatory Snf1 and Reg1 factors. Hxk2 sustains the repressor complex architecture maintaining transcriptional repression at theSUC2gene. Using chromatin immunoprecipitation assays, we discovered that the Hxk2 in its open configuration, at low glucose conditions, leaves the repressor complex that induces its dissociation and promotesSUC2gene expression. In high glucose conditions, Hxk2 adopts a close conformation that promotes Hxk2 binding to the Mig1 protein and the reassembly of theSUC2repressor complex. Additional findings highlight the possibility that Hxk2 constitutes an intracellular glucose sensor that operates by changing its conformation in response to cytoplasmic glucose levels that regulate its interaction with Mig1 and thus its recruitment to the repressor complex of theSUC2promoter. Thus, our data indicate that Hxk2 is more intimately involved in gene regulation than previously thought.
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Affiliation(s)
- Montserrat Vega
- From the Department of Biochemistry and Molecular Biology, University of Oviedo, 33006-Oviedo, Spain
| | - Alberto Riera
- From the Department of Biochemistry and Molecular Biology, University of Oviedo, 33006-Oviedo, Spain
| | - Alejandra Fernández-Cid
- From the Department of Biochemistry and Molecular Biology, University of Oviedo, 33006-Oviedo, Spain
| | - Pilar Herrero
- From the Department of Biochemistry and Molecular Biology, University of Oviedo, 33006-Oviedo, Spain
| | - Fernando Moreno
- From the Department of Biochemistry and Molecular Biology, University of Oviedo, 33006-Oviedo, Spain
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11
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Lubitz T, Welkenhuysen N, Shashkova S, Bendrioua L, Hohmann S, Klipp E, Krantz M. Network reconstruction and validation of the Snf1/AMPK pathway in baker's yeast based on a comprehensive literature review. NPJ Syst Biol Appl 2015; 1:15007. [PMID: 28725459 PMCID: PMC5516868 DOI: 10.1038/npjsba.2015.7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Revised: 06/19/2015] [Accepted: 07/14/2015] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND/OBJECTIVES The SNF1/AMPK protein kinase has a central role in energy homeostasis in eukaryotic cells. It is activated by energy depletion and stimulates processes leading to the production of ATP while it downregulates ATP-consuming processes. The yeast SNF1 complex is best known for its role in glucose derepression. METHODS We performed a network reconstruction of the Snf1 pathway based on a comprehensive literature review. The network was formalised in the rxncon language, and we used the rxncon toolbox for model validation and gap filling. RESULTS We present a machine-readable network definition that summarises the mechanistic knowledge of the Snf1 pathway. Furthermore, we used the known input/output relationships in the network to identify and fill gaps in the information transfer through the pathway, to produce a functional network model. Finally, we convert the functional network model into a rule-based model as a proof-of-principle. CONCLUSIONS The workflow presented here enables large scale reconstruction, validation and gap filling of signal transduction networks. It is analogous to but distinct from that established for metabolic networks. We demonstrate the workflow capabilities, and the direct link between the reconstruction and dynamic modelling, with the Snf1 network. This network is a distillation of the knowledge from all previous publications on the Snf1/AMPK pathway. The network is a knowledge resource for modellers and experimentalists alike, and a template for similar efforts in higher eukaryotes. Finally, we envisage the workflow as an instrumental tool for reconstruction of large signalling networks across Eukaryota.
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Affiliation(s)
- Timo Lubitz
- Theoretical Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Niek Welkenhuysen
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
| | - Sviatlana Shashkova
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
| | - Loubna Bendrioua
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
| | - Stefan Hohmann
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
| | - Edda Klipp
- Theoretical Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Marcus Krantz
- Theoretical Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
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Effects of GLC7 and REG1 deletion on maltose metabolism and leavening ability of baker's yeast in lean dough. J Biotechnol 2015; 209:1-6. [PMID: 26073997 DOI: 10.1016/j.jbiotec.2015.06.386] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2014] [Revised: 05/19/2015] [Accepted: 06/08/2015] [Indexed: 01/25/2023]
Abstract
Maltose metabolism and leavening ability of baker's yeast (Saccharomyces cerevisiae) in lean dough is negatively influenced by glucose repression. To improve maltose metabolism and leavening ability, it is necessary to alleviate glucose repression. In this study, we focus on the effects of regulators (GLC7 encoding the catalytic and REG1 encoding the regulatory subunits of protein phosphatase type 1) of glucose repression on maltose metabolism and leavening ability of baker's yeast in lean dough. To this end, GLC7 and/or REG1 deletions were constructed and characterized in terms of the growth characteristics, maltose metabolism, leavening ability, and enzyme activities. The results suggest that GLC7 and/or REG1 deletions increased maltose metabolism and leavening ability at different level with glucose derepression and increased enzymes (maltase and maltose permease) activities. In a medium containing glucose and maltose, at the point of glucose exhaustion the maltose metabolized and the leavening ability were increased 59.3% and 23.1%, respectively, in the case of a REG1 single gene deletion.
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Abstract
Aerobic glycolysis is a metabolic pathway utilized by human cancer cells and also by yeast cells when they ferment glucose to ethanol. Both cancer cells and yeast cells are inhibited by the presence of low concentrations of 2-deoxyglucose (2DG). Genetic screens in yeast used resistance to 2-deoxyglucose to identify a small set of genes that function in regulating glucose metabolism. A recent high throughput screen for 2-deoxyglucose resistance identified a much larger set of seemingly unrelated genes. Here, we demonstrate that these newly identified genes do not in fact confer significant resistance to 2-deoxyglucose. Further, we show that the relative toxicity of 2-deoxyglucose is carbon source dependent, as is the resistance conferred by gene deletions. Snf1 kinase, the AMP-activated protein kinase of yeast, is required for 2-deoxyglucose resistance in cells growing on glucose. Mutations in the SNF1 gene that reduce kinase activity render cells hypersensitive to 2-deoxyglucose, while an activating mutation in SNF1 confers 2-deoxyglucose resistance. Snf1 kinase activated by 2-deoxyglucose does not phosphorylate the Mig1 protein, a known Snf1 substrate during glucose limitation. Thus, different stimuli elicit distinct responses from the Snf1 kinase.
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Rødkaer SV, Faergeman NJ. Glucose- and nitrogen sensing and regulatory mechanisms inSaccharomyces cerevisiae. FEMS Yeast Res 2014; 14:683-96. [DOI: 10.1111/1567-1364.12157] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 04/11/2014] [Accepted: 04/13/2014] [Indexed: 11/29/2022] Open
Affiliation(s)
- Steven V. Rødkaer
- Villum Center for Bioanalytical Sciences; Department of Biochemistry and Molecular Biology; University of Southern Denmark; Odense M Denmark
| | - Nils J. Faergeman
- Villum Center for Bioanalytical Sciences; Department of Biochemistry and Molecular Biology; University of Southern Denmark; Odense M Denmark
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15
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Protein phosphatase PP1/GLC7 interaction domain in yeast eIF2γ bypasses targeting subunit requirement for eIF2α dephosphorylation. Proc Natl Acad Sci U S A 2014; 111:E1344-53. [PMID: 24706853 DOI: 10.1073/pnas.1400129111] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Whereas the protein kinases GCN2, HRI, PKR, and PERK specifically phosphorylate eukaryotic translation initiation factor 2 (eIF2α) on Ser51 to regulate global and gene-specific mRNA translation, eIF2α is dephosphorylated by the broadly acting serine/threonine protein phosphatase 1 (PP1). In mammalian cells, the regulatory subunits GADD34 and CReP target PP1 to dephosphorylate eIF2α; however, as there are no homologs of these targeting subunits in yeast, it is unclear how GLC7, the functional homolog of PP1 in yeast, is recruited to dephosphorylate eIF2α. Here, we show that a novel N-terminal extension on yeast eIF2γ contains a PP1-binding motif (KKVAF) that enables eIF2γ to pull down GLC7 and target it to dephosphorylate eIF2α. Truncation or point mutations designed to eliminate the KKVAF motif in eIF2γ impair eIF2α dephosphorylation in vivo and in vitro and enhance expression of GCN4. Replacement of the N terminus of eIF2γ with the GLC7-binding domain from GAC1 or fusion of heterologous dimerization domains to eIF2γ and GLC7, respectively, maintained eIF2α phosphorylation at basal levels. Taken together, these results indicate that, in contrast to the paradigm of distinct PP1-targeting or regulatory subunits, the unique N terminus of yeast eIF2γ functions in cis to target GLC7 to dephosphorylate eIF2α.
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Castermans D, Somers I, Kriel J, Louwet W, Wera S, Versele M, Janssens V, Thevelein JM. Glucose-induced posttranslational activation of protein phosphatases PP2A and PP1 in yeast. Cell Res 2012; 22:1058-77. [PMID: 22290422 PMCID: PMC3367521 DOI: 10.1038/cr.2012.20] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The protein phosphatases PP2A and PP1 are major regulators of a variety of cellular processes in yeast and other eukaryotes. Here, we reveal that both enzymes are direct targets of glucose sensing. Addition of glucose to glucose-deprived yeast cells triggered rapid posttranslational activation of both PP2A and PP1. Glucose activation of PP2A is controlled by regulatory subunits Rts1, Cdc55, Rrd1 and Rrd2. It is associated with rapid carboxymethylation of the catalytic subunits, which is necessary but not sufficient for activation. Glucose activation of PP1 was fully dependent on regulatory subunits Reg1 and Shp1. Absence of Gac1, Glc8, Reg2 or Red1 partially reduced activation while Pig1 and Pig2 inhibited activation. Full activation of PP2A and PP1 was also dependent on subunits classically considered to belong to the other phosphatase. PP2A activation was dependent on PP1 subunits Reg1 and Shp1 while PP1 activation was dependent on PP2A subunit Rts1. Rts1 interacted with both Pph21 and Glc7 under different conditions and these interactions were Reg1 dependent. Reg1-Glc7 interaction is responsible for PP1 involvement in the main glucose repression pathway and we show that deletion of Shp1 also causes strong derepression of the invertase gene SUC2. Deletion of the PP2A subunits Pph21 and Pph22, Rrd1 and Rrd2, specifically enhanced the derepression level of SUC2, indicating that PP2A counteracts SUC2 derepression. Interestingly, the effect of the regulatory subunit Rts1 was consistent with its role as a subunit of both PP2A and PP1, affecting derepression and repression of SUC2, respectively. We also show that abolished phosphatase activation, except by reg1Δ, does not completely block Snf1 dephosphorylation after addition of glucose. Finally, we show that glucose activation of the cAMP-PKA (protein kinase A) pathway is required for glucose activation of both PP2A and PP1. Our results provide novel insight into the complex regulatory role of these two major protein phosphatases in glucose regulation.
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Affiliation(s)
- Dries Castermans
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KULeuven, Belgium
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Reg1 protein regulates phosphorylation of all three Snf1 isoforms but preferentially associates with the Gal83 isoform. EUKARYOTIC CELL 2011; 10:1628-36. [PMID: 22002657 DOI: 10.1128/ec.05176-11] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The phosphorylation status of the Snf1 activation loop threonine is determined by changes in the rate of its dephosphorylation, catalyzed by the yeast PP1 phosphatase Glc7 in complex with the Reg1 protein. Previous studies have shown that Reg1 can associate with both Snf1 and Glc7, suggesting substrate binding as a mechanism for Reg1-mediated targeting of Glc7. In this study, the association of Reg1 with the three Snf1 isoforms was measured by two-hybrid analysis and coimmunoprecipitation. We found that Reg1 association with Snf1 occurred almost exclusively with the Gal83 isoform of the Snf1 complex. Nonetheless, Reg1 plays an important role in determining the phosphorylation status of all three Snf1 isoforms. We found that the rate of dephosphorylation for isoforms of Snf1 did not correlate with the amount of associated Reg1 protein. Functional chimeric β subunits containing residues from Gal83 and Sip2 were used to map the residues needed to promote Reg1 association with the N-terminal 150 residues of Gal83. The Gal83 isoform of Snf1 is the only isoform capable of nuclear localization. A Gal83-Sip2 chimera containing the first 150 residues of Gal83 was able to associate with the Reg1 protein but did not localize to the nucleus. Therefore, nuclear localization is not required for Reg1 association. Taken together, these data indicate that the ability of Reg1 to promote the dephosphorylation of Snf1 is not directly related to the strength of its association with the Snf1 complex.
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Current awareness on yeast. Yeast 2010. [DOI: 10.1002/yea.1723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Cannon JF. Function of protein phosphatase-1, Glc7, in Saccharomyces cerevisiae. ADVANCES IN APPLIED MICROBIOLOGY 2010; 73:27-59. [PMID: 20800758 DOI: 10.1016/s0065-2164(10)73002-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Budding yeast, Saccharomyces cerevisiae, and its close relatives are unique among eukaryotes in having a single gene, GLC7, encoding protein phosphatase-1 (PP1). This enzyme with a highly conserved amino acid sequence controls many processes in all eukaryotic cells. Therefore, the study of Glc7 function offers a unique opportunity to gain a comprehensive understanding of this critical regulatory enzyme. This review summarizes our current knowledge of how Glc7 function modulates processes in the cytoplasm and nucleus. Additionally, global Glc7 regulation is described.
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Affiliation(s)
- John F Cannon
- Department of Molecular Microbiology and Immunology, University of Missouri, Columbia, Missouri, USA.
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