1
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Schlarmann P, Sakuragi K, Ikeda A, Yang Y, Sasaki S, Hanaoka K, Araki M, Shibata T, Kanai M, Funato K. The tricalbin family of membrane contact site tethers is involved in the transcriptional responses of Saccharomyces cerevisiae to glucose. J Biol Chem 2024; 300:107665. [PMID: 39128724 PMCID: PMC11408865 DOI: 10.1016/j.jbc.2024.107665] [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: 03/05/2024] [Revised: 07/24/2024] [Accepted: 08/05/2024] [Indexed: 08/13/2024] Open
Abstract
Cellular organelles maintain areas of close apposition with other organelles at which the cytosolic gap in between them is reduced to a minimum. These membrane contact sites (MCS) are vital for organelle communication and are formed by molecular tethers that physically connect opposing membranes. Although many regulatory pathways are known to converge at MCS, a link between MCS and transcriptional regulation-the primary mechanism through which cells adapt their metabolism to environmental cues-remains largely elusive. In this study, we performed RNA-sequencing on Saccharomyces cerevisiae cells lacking tricalbin proteins (Tcb1, Tcb2, and Tcb3), a family of tethering proteins that connect the endoplasmic reticulum with the plasma membrane and Golgi, to investigate if gene expression is altered when MCS are disrupted. Our results indicate that in the tcb1Δ2Δ3Δ strain, pathways responsive to a high-glucose environment, including glycolysis, fermentation, amino acid synthesis, and low-affinity glucose uptake, are upregulated. Conversely, pathways crucial during glucose depletion, such as the tricarboxylic acid cycle, respiration, high-affinity glucose uptake, and amino acid uptake are downregulated. In addition, we demonstrate that the altered gene expression of tcb1Δ2Δ3Δ in glucose metabolism correlates with increased growth, glucose consumption, CO2 production, and ethanol generation. In conclusion, our findings reveal that tricalbin protein deletion induces a shift in gene expression patterns mimicking cellular responses to a high-glucose environment. This suggests that MCS play a role in sensing and signaling pathways that modulate gene transcription in response to glucose availability.
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Affiliation(s)
- Philipp Schlarmann
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Keiko Sakuragi
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Atsuko Ikeda
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Yujia Yang
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Saku Sasaki
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Kazuki Hanaoka
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Misako Araki
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Tomoko Shibata
- National Research Institute of Brewing, Higashi-Hiroshima, Japan
| | - Muneyoshi Kanai
- National Research Institute of Brewing, Higashi-Hiroshima, Japan
| | - Kouichi Funato
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan.
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de Holanda Paranhos L, Magalhães RSS, de Araújo Brasil A, Neto JRM, Ribeiro GD, Queiroz DD, Dos Santos VM, Eleutherio ECA. The familial amyotrophic lateral sclerosis-associated A4V SOD1 mutant is not able to regulate aerobic glycolysis. Biochim Biophys Acta Gen Subj 2024; 1868:130634. [PMID: 38788983 DOI: 10.1016/j.bbagen.2024.130634] [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: 02/08/2024] [Revised: 04/23/2024] [Accepted: 05/20/2024] [Indexed: 05/26/2024]
Abstract
Under certain stress conditions, astrocytes operate in aerobic glycolysis, a process controlled by pyruvate dehydrogenase (PDH) inhibition through its E1 α subunit (Pda1) phosphorylation. This supplies lactate to neurons, which save glucose to obtain NADPH to, among other roles, counteract reactive oxygen species. A failure in this metabolic cooperation causes severe damage to neurons. In this work, using humanized Saccharomyces cerevisiae cells in which its endogenous Cu/Zn Superoxide Dismutase (SOD1) was replaced by human ortholog, we investigated the role of human SOD1 (hSOD1) in aerobic glycolysis regulation and its implications to amyotrophic lateral sclerosis (ALS), a neurodegenerative disease. Yeast cells ferment glucose even in the presence of oxygen and switch to respiratory metabolism after glucose exhaustion. However, like cells of SOD1-knockout strain, cells expressing A4V mutant of hSOD1 growing on glucose showed a respiratory phenotype, i.e., low glucose and high oxygen consumptions and low intracellular oxidation levels in response to peroxide stress, contrary to cells expressing wild-type (WT) SOD1 (yeast or human). The A4V mutation in hSOD1 is linked to ALS. In contrast to WT SOD1 strains, PDH activity of both sod1Δ and A4V hSOD1 cells did not change in response to a metabolic shift toward oxidative metabolism, which was associated to lower Pda1 phosphorylation levels under growth on glucose. Taken together, our results suggest that A4V mutant cannot regulate aerobic glycolysis via Pda1 phosphorylation the same way WT hSOD1, which might be linked to problems observed in the motor neurons of ALS patients with the SOD1 A4V mutation.
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Affiliation(s)
- Luan de Holanda Paranhos
- Department of Biochemistry, Institute of Chemistry, Federal University of Rio de Janeiro (UFRJ), Brazil
| | | | - Aline de Araújo Brasil
- Department of Biochemistry, Institute of Chemistry, Federal University of Rio de Janeiro (UFRJ), Brazil
| | | | - Gabriela Delaqua Ribeiro
- Department of Biochemistry, Institute of Chemistry, Federal University of Rio de Janeiro (UFRJ), Brazil
| | - Daniela Dias Queiroz
- Department of Biochemistry, Institute of Chemistry, Federal University of Rio de Janeiro (UFRJ), Brazil
| | - Vanessa Mattos Dos Santos
- Department of Biochemistry, Institute of Chemistry, Federal University of Rio de Janeiro (UFRJ), Brazil
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Yan W, Li Y, Louis EJ, Kyriacou CP, Hu Y, Cordell RL, Xie X. Quantitative genetic analysis of attractiveness of yeast products to Drosophila. Genetics 2024; 227:iyae048. [PMID: 38560786 PMCID: PMC11151935 DOI: 10.1093/genetics/iyae048] [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: 10/25/2023] [Revised: 02/19/2024] [Accepted: 02/20/2024] [Indexed: 04/04/2024] Open
Abstract
An attractive perfume is a complex mixture of compounds, some of which may be unpleasant on their own. This is also true for the volatile combinations from yeast fermentation products in vineyards and orchards when assessed by Drosophila. Here, we used crosses between a yeast strain with an attractive fermentation profile and another strain with a repulsive one and tested fly responses using a T-maze. QTL analysis reveals allelic variation in four yeast genes, namely PTC6, SAT4, YFL040W, and ARI1, that modulated expression levels of volatile compounds [assessed by gas chromatography-mass spectrometry (GC-MS)] and in different combinations, generated various levels of attractiveness. The parent strain that is more attractive to Drosophila has repulsive alleles at two of the loci, while the least attractive parent has attractive alleles. Behavioral assays using artificial mixtures mimicking the composition of odors from fermentation validated the results of GC-MS and QTL mapping, thereby directly connecting genetic variation in yeast to attractiveness in flies. This study can be used as a basis for dissecting the combination of olfactory receptors that mediate the attractiveness/repulsion of flies to yeast volatiles and may also serve as a model for testing the attractiveness of pest species such as Drosophila suzukii to their host fruit.
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Affiliation(s)
- Weiru Yan
- Institute of Genetics, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China
- Department of Genetics & Genome Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Yishen Li
- Department of Genetics & Genome Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Edward J Louis
- Department of Genetics & Genome Biology, University of Leicester, Leicester LE1 7RH, UK
| | | | - Yue Hu
- Department of Genetics & Genome Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Rebecca L Cordell
- School of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - Xiaodong Xie
- Institute of Genetics, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China
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4
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Rahmat E, Yu JS, Lee BS, Lee J, Ban Y, Yim NH, Park JH, Kang CH, Kim KH, Kang Y. Secondary metabolites and transcriptomic analysis of novel pulcherrimin producer Metschnikowia persimmonesis KIOM G15050: A potent and safe food biocontrol agent. Heliyon 2024; 10:e28464. [PMID: 38571591 PMCID: PMC10988027 DOI: 10.1016/j.heliyon.2024.e28464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 03/18/2024] [Accepted: 03/19/2024] [Indexed: 04/05/2024] Open
Abstract
Metschnikowia persimmonesis, a novel endophytic yeast strain isolated from Diospyros kaki calyx, possesses strong antimicrobial activity. We investigated its potential use as an environmentally safe food biocontrol agent through genomics, transcriptomics, and metabolomics. Secondary metabolites were isolated from M. persimmonesis, followed by chemical structure elucidation, PUL gene cluster identification, and RNA sequencing. Pulcherrimin was isolated using 2 M NaOH, its structure was confirmed, and the yield was quantified. Biocontrol efficacy of M. persimmonesis on persimmon fruits and calyx was evaluated by assessing lesion diameter and disease incidence. Following compounds were isolated from M. persimmonesis co-culture with Botrytis cinerea and Fusarium oxysporum: fusaric acid, benzoic acid, benzeneacetic acid, 4-hydroxybenzeneacetic acid, 4-(-2-hydoxyethyl)-benzoic acid, cyclo (Leu-Leu), benzenemethanol, 4-hydroxy-benzaldehide, 2-hydroxy-4-methoxy-benzoic acid, 4-hydroxy-benzoic acid, lumichrome, heptadecanoic acid, and nonadecanoic acid. Exposing M. persimmonesis to different growth media conditions (with or without sugar) resulted in the isolation of five compounds: Tyrosol, Cyclo (Pro-Val), cyclo(L-Pro-L-Tyr), cyclo(Leu-Leu), and cyclo(l-tyrosilylicine). Differentially expressed gene analysis revealed 3264 genes that were significantly expressed (fold change ≥2 and p-value ≤0.05) during M. persimmonesis growth in different media, of which only 270 (8.27%) showed altered expression in all sample combinations with Luria-Bertani Agar as control. Minimal media with ferric ions and tween-80 triggered the most gene expression changes, with the highest levels of PUL gene expression and pulcherrimin yield (262.166 mg/L) among all media treatments. M. persimmonesis also produced a higher amount of pulcherrimin (209.733 mg/L) than Metschnikowia pulcherrima (152.8 mg/L). M. persimmonesis inhibited the growth of Fusarium oxysporum in persimmon fruit and calyx. Toxicity evaluation of M. persimmonesis extracts showed no harmful effects on the liver and mitochondria of zebrafish, and no potential risk of cardiotoxicity in hERG-HEK293 cell lines. Thus, M. persimmonesis can be commercialized as a potent and safe biocontrol agent for preserving food products.
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Affiliation(s)
- Endang Rahmat
- Biotechnology Department, Faculty of Engineering, Bina Nusantara University, Jakarta, 11480, Indonesia
| | - Jae Sik Yu
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
- Department of Integrative Biological Sciences and Industry, Sejong University, Seoul, 05006, Republic of Korea
| | - Bum Soo Lee
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Jiyoung Lee
- University of Science & Technology (UST), KIOM Campus, Korean Convergence Medicine Major, Daejeon, 34054, Republic of Korea
- Biological Resource Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup, 56212, Republic of Korea
| | - Yeongjun Ban
- Herbal Medicine Resources Research Center, Korea Institute of Oriental Medicine, 111 Geonjae-ro, Naju-si, Jeollanam-do, 58245, Republic of Korea
| | - Nam-Hui Yim
- Korean Medicine Application Center, Korea Institute of Oriental Medicine 70 Cheomdan-ro, Dong-gu, Daegu, 41062, Republic of Korea
| | - Jeong Hwan Park
- KM Data Division, Korea Institute of Oriental Medicine (KIOM), 1672 Yuseongdae-ro, Yuseong-gu, Daejeon, 34054, Republic of Korea
| | - Chang Ho Kang
- Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, Gyeongnam, 52828, Republic of Korea
| | - Ki Hyun Kim
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Youngmin Kang
- University of Science & Technology (UST), KIOM Campus, Korean Convergence Medicine Major, Daejeon, 34054, Republic of Korea
- Herbal Medicine Resources Research Center, Korea Institute of Oriental Medicine, 111 Geonjae-ro, Naju-si, Jeollanam-do, 58245, Republic of Korea
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5
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Ibisoglu MS, Tan M, Yilmazer M, Yilmaz S, Uzuner SK, Topal-Sarikaya A, Palabiyik B. Effects of ScRgt1-Like DNA-binding transcription factor SpRgt1 (SPCC320.03) on Hexose transporters gene expression in Schizosaccharomyces pombe. Arch Microbiol 2024; 206:155. [PMID: 38480568 DOI: 10.1007/s00203-024-03901-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 02/16/2024] [Accepted: 02/17/2024] [Indexed: 03/17/2024]
Abstract
Glucose, which plays an essential role in carbon and energy metabolism in eukaryotes, is vital in directing various energy-consuming cellular processes. In S. cerevisiae, transcription factors involved in regulating hexose transporters and their mechanisms of action under different carbon sources were revealed in detail. However, there is limited information on these processes in S. pombe. In this study, the effect of SPCC320.03 (named SpRgt1), the ortholog of ScRgt1 whose molecular mechanism is known in detail in S. cerevisiae, on the transcriptional regulation of hexose transporters (ght1-8) dependent on different carbon sources was investigated. We measured the transcript levels of ght1-8 using the qPCR technique and performed relative evaluation in S. pombe strains (parental, rgt1 deleted mutant, rgt1 overexpressed, and vectoral rgt1 carrying mutant). We aimed to investigate the transcriptional changes caused by the protein product of the rgt1 (SPCC320.03) gene in terms of ght1-8 genes in strains that are grown in different carbon sources (2% glucose, 2% glycerol + 0.1% glucose, and 2% gluconate). Here, we show that SpRgt1 is involved in the regulation of the ght3, ght4, ght6, and ght7 genes but that the ght1, ght2, ght5, and ght8 gene expression vary depending on carbon sources, independently of SpRgt1.
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Affiliation(s)
- Merve Seda Ibisoglu
- Institute of Graduate Studies in Sciences, Department of Molecular Biology and Genetics, Istanbul University, Istanbul, Turkey
- Faculty of Science and Literature, Department of Molecular Biology and Genetics, Istanbul Yeni Yuzyil University, Istanbul, Turkey
| | - Medet Tan
- Institute of Graduate Studies in Sciences, Department of Molecular Biology and Genetics, Istanbul University, Istanbul, Turkey
| | - Merve Yilmazer
- Faculty of Science, Department of Molecular Biology and Genetics, Istanbul University, Istanbul, Turkey
| | - Sibel Yilmaz
- Faculty of Science and Literature, Department of Molecular Biology and Genetics, Istanbul Yeni Yuzyil University, Istanbul, Turkey
| | - Semian Karaer Uzuner
- Faculty of Science, Department of Molecular Biology and Genetics, Istanbul University, Istanbul, Turkey
| | - Ayşegül Topal-Sarikaya
- Faculty of Science and Literature, Department of Molecular Biology and Genetics, Istanbul Yeni Yuzyil University, Istanbul, Turkey
- Department of Medical Biology and Genetics, Istanbul Yeni Yuzyil University, Istanbul, Turkey
| | - Bedia Palabiyik
- Faculty of Science, Department of Molecular Biology and Genetics, Istanbul University, Istanbul, Turkey.
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6
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Kim JH, Mailloux L, Bloor D, Tae H, Nguyen H, McDowell M, Padilla J, DeWaard A. Multiple roles for the cytoplasmic C-terminal domains of the yeast cell surface receptors Rgt2 and Snf3 in glucose sensing and signaling. Sci Rep 2024; 14:4055. [PMID: 38374219 PMCID: PMC10876965 DOI: 10.1038/s41598-024-54628-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 02/14/2024] [Indexed: 02/21/2024] Open
Abstract
The plasma membrane proteins Rgt2 and Snf3 are glucose sensing receptors (GSRs) that generate an intracellular signal for the induction of gene expression in response to high and low extracellular glucose concentrations, respectively. The GSRs consist of a 12-transmembrane glucose recognition domain and a cytoplasmic C-terminal signaling tail. The GSR tails are dissimilar in length and sequence, but their distinct roles in glucose signal transduction are poorly understood. Here, we show that swapping the tails between Rgt2 and Snf3 does not alter the signaling activity of the GSRs, so long as their tails are phosphorylated in a Yck-dependent manner. Attachment of the GSR tails to Hxt1 converts the transporter into a glucose receptor; however, the tails attached to Hxt1 are not phosphorylated by the Ycks, resulting in only partial signaling. Moreover, in response to non-fermentable carbon substrates, Rgt2 and Hxt1-RT (RT, Rgt2-tail) are efficiently endocytosed, whereas Snf3 and Hxt1-ST (ST, Snf3-tail) are endocytosis-impaired. Thus, the tails are important regulatory domains required for the endocytosis of the Rgt2 and Snf3 glucose sensing receptors triggered by different cellular stimuli. Taken together, these results suggest multiple roles for the tail domains in GSR-mediated glucose sensing and signaling.
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Affiliation(s)
- Jeong-Ho Kim
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA.
| | - Levi Mailloux
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
| | - Daniel Bloor
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
| | - Haeun Tae
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
| | - Han Nguyen
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
| | - Morgan McDowell
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
| | - Jaqueline Padilla
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
| | - Anna DeWaard
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
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7
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Milanes JE, Kwain S, Drawdy A, Dodson L, Monaghan MT, Rice CA, Dominy BN, Whitehead DC, Morris JC. Glucose metabolism in the pathogenic free-living amoebae: Tempting targets for treatment development. Chem Biol Drug Des 2024; 103:e14377. [PMID: 37864277 PMCID: PMC10843269 DOI: 10.1111/cbdd.14377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 09/18/2023] [Accepted: 10/04/2023] [Indexed: 10/22/2023]
Abstract
Pathogenic free-living amoebae (pFLA) are single-celled eukaryotes responsible for causing intractable infections with high morbidity and mortality in humans and animals. Current therapeutic approaches include cocktails of antibiotic, antifungal, and antimicrobial compounds. Unfortunately, the efficacy of these can be limited, driving the need for the discovery of new treatments. Pan anti-amebic agents would be ideal; however, identifying these agents has been a challenge, likely due to the limited evolutionary relatedness of the different pFLA. Here, we discuss the potential of targeting amoebae glucose metabolic pathways as the differences between pFLA and humans suggest specific inhibitors could be developed as leads for new therapeutics.
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Affiliation(s)
- Jillian E. Milanes
- Eukaryotic Pathogens Innovation Center, Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634
| | - Samuel Kwain
- Eukaryotic Pathogens Innovation Center, Department of Chemistry, Clemson University, Clemson SC 29634
| | - Allyson Drawdy
- Eukaryotic Pathogens Innovation Center, Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634
| | - Laura Dodson
- Eukaryotic Pathogens Innovation Center, Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634
| | - Matthew T. Monaghan
- Eukaryotic Pathogens Innovation Center, Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634
| | - Christopher A. Rice
- Department of Comparative Pathobiology, College of Veterinary Medicine, Purdue University, West Lafayette, IN 47907
- Purdue Institute for Drug Discovery (PIDD), Purdue University, West Lafayette, IN 47907
- Purdue Institute of Inflammation, Immunology and Infectious Disease (PI4D), Purdue University, West Lafayette, IN 47907
| | - Brian N. Dominy
- Department of Chemistry, Clemson University, Clemson SC 29634
| | - Daniel C. Whitehead
- Eukaryotic Pathogens Innovation Center, Department of Chemistry, Clemson University, Clemson SC 29634
| | - James C. Morris
- Eukaryotic Pathogens Innovation Center, Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634
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Lu H, Fan Y, Yuan Y, Niu X, Zhao B, Liu Y, Xiao F. Tomato SlSTK is involved in glucose response and regulated by the ubiquitin ligase SlSINA4. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2023; 331:111672. [PMID: 36921631 DOI: 10.1016/j.plantsci.2023.111672] [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: 12/15/2022] [Revised: 03/05/2023] [Accepted: 03/10/2023] [Indexed: 06/18/2023]
Abstract
Glucose signaling plays an essential role in plant growth, development and stress response. Previous studies have shown that STOREKEEPER (STK) is a new class of DNA binding protein that regulates patatin expression in potato tubers and confers elevated sensitivity to glucose response in Arabidopsis thaliana. However, the biological functions of STK gene in tomato (Solanum lycopersicum) have not been studied. Here, we characterized the tomato SlSTK and determined its role in glucose signaling. The SlSTK protein was localized in the nucleus and the expression of the SlSTK gene was induced by the glucose treatment. Overexpression of SlSTK in tomato enhanced glucose sensitivity, as manifested by reduced seed germination rate and arrested growth at the early seedling stage. In contrast, the SlSTK-knockout plants generated via the clustered regularly interspaced short palindromic repeats (CRISPR) - CRISPR-associated protein 9 (CRISPR-Cas9) technique attenuated the sensitivity to glucose. In addition, SlSTK was ubiquitinated in plant cells and interacted with the tomato ubiquitin ligase SEVEN IN ABSENTIA4 (SlSINA4) that degrades SlSTK in a ligase-dependent manner. Taken together, these results suggest that SlSTK is involved in glucose signaling and its stability is regulated by the ubiquitin ligase SlSINA4.
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Affiliation(s)
- Han Lu
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, Anhui 230009, China; Department of Plant Sciences, University of Idaho, Moscow, ID 83844-2339, USA
| | - Youhong Fan
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, Anhui 230009, China; Department of Plant Sciences, University of Idaho, Moscow, ID 83844-2339, USA
| | - Yulin Yuan
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Xiangli Niu
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, Anhui 230009, China; Department of Plant Sciences, University of Idaho, Moscow, ID 83844-2339, USA
| | - Bingyu Zhao
- School of Plant and Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Yongsheng Liu
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, Anhui 230009, China; School of Horticulture, State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei 230036, China; Ministry of Education Key Laboratory for Bio-resource and Eco-environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, Sichuan 610064, China.
| | - Fangming Xiao
- Department of Plant Sciences, University of Idaho, Moscow, ID 83844-2339, USA.
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9
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Analysing and meta-analysing time-series data of microbial growth and gene expression from plate readers. PLoS Comput Biol 2022; 18:e1010138. [PMID: 35617352 PMCID: PMC9176753 DOI: 10.1371/journal.pcbi.1010138] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 06/08/2022] [Accepted: 04/26/2022] [Indexed: 11/29/2022] Open
Abstract
Responding to change is a fundamental property of life, making time-series data invaluable in biology. For microbes, plate readers are a popular, convenient means to measure growth and also gene expression using fluorescent reporters. Nevertheless, the difficulties of analysing the resulting data can be a bottleneck, particularly when combining measurements from different wells and plates. Here we present omniplate, a Python module that corrects and normalises plate-reader data, estimates growth rates and fluorescence per cell as functions of time, calculates errors, exports in different formats, and enables meta-analysis of multiple plates. The software corrects for autofluorescence, the optical density’s non-linear dependence on the number of cells, and the effects of the media. We use omniplate to measure the Monod relationship for the growth of budding yeast in raffinose, showing that raffinose is a convenient carbon source for controlling growth rates. Using fluorescent tagging, we study yeast’s glucose transport. Our results are consistent with the regulation of the hexose transporter (HXT) genes being approximately bipartite: the medium and high affinity transporters are predominately regulated by both the high affinity glucose sensor Snf3 and the kinase complex SNF1 via the repressors Mth1, Mig1, and Mig2; the low affinity transporters are predominately regulated by the low affinity sensor Rgt2 via the co-repressor Std1. We thus demonstrate that omniplate is a powerful tool for exploiting the advantages offered by time-series data in revealing biological regulation. Time series of growth and of gene expression via fluorescent reporters are rich ways to characterise the behaviours of cells. With plate readers, it is straightforward to measure 96 independent time series in a single experiment, with readings taken every 10 minutes and each time series lasting tens of hours. Analysing such data can become challenging, particularly if multiple plate-reader experiments are required to characterise a phenomenon, which then should be analysed simultaneously. Taking advantage of existing packages in Python, we have written code that automates this analysis but yet still allows users to develop custom routines. Our omniplate software corrects both measurements of optical density to become linear in the number of cells and measurements of fluorescence for autofluorescence. It estimates growth rates and fluorescence per cell as continuous functions of time and enables tens of plate-reader experiments to be analysed together. Data can be exported in text files in a format immediately suitable for public repositories. Plate readers are a convenient way to study cells; omniplate provides an equally convenient yet powerful way to analyse the resulting data.
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10
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Snf1p/Hxk2p/Mig1p pathway regulates hexose transporters transcript levels, affecting the exponential growth and mitochondrial respiration of Saccharomyces cerevisiae. Fungal Genet Biol 2022; 161:103701. [DOI: 10.1016/j.fgb.2022.103701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 04/12/2022] [Accepted: 04/30/2022] [Indexed: 11/19/2022]
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11
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Kim JH, Bloor D, Rodriguez R, Mohler E, Mailloux L, Melton S, Jung D. Casein kinases are required for the stability of the glucose-sensing receptor Rgt2 in yeast. Sci Rep 2022; 12:1598. [PMID: 35102180 PMCID: PMC8803954 DOI: 10.1038/s41598-022-05569-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 01/12/2022] [Indexed: 11/30/2022] Open
Abstract
In yeast, glucose induction of HXT (glucose transporter gene) expression is achieved via the Rgt2 and Snf3 glucose sensing receptor (GSR)-mediated signal transduction pathway. The membrane-associated casein kinases Yck1 and Yck2 (Ycks) are involved in this pathway, but their exact role remains unclear. Previous work suggests that the Ycks are activated by the glucose-bound GSRs and transmit the glucose signal from the plasma membrane to the nucleus. However, here we provide evidence that the YCks are constitutively active and required for the stability of the Rgt2 receptor. Cell surface levels of Rgt2 are significantly decreased in a yck1Δyck2ts mutant, but this is not due to endocytosis-mediated vacuolar degradation of the receptor. Similar observations are made in an akr1Δ mutant, where the Ycks are no longer associated with the membrane, and in a sod1Δ mutant in which the kinases are unstable. Of note, in an akr1Δ mutant, both the Ycks and Rgt2 are mislocalized to the cytoplasm, where Rgt2 is stable and functions as an effective receptor for glucose signaling. We also demonstrate that Rgt2 is phosphorylated on the putative Yck consensus phosphorylation sites in its C-terminal domain (CTD) in a Yck-dependent manner and that this glucose-induced modification is critical for its stability and function. Thus, these results indicate a role for the Ycks in stabilizing Rgt2 and suggest that Rgt2 may use glucose binding as a molecular switch not to activate the Ycks but to promote Yck-dependent interaction and phosphorylation of the CTD that increases its stability.
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Affiliation(s)
- Jeong-Ho Kim
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA.
| | - Daniel Bloor
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
| | - Rebeca Rodriguez
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
| | - Emma Mohler
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
| | - Levi Mailloux
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
| | - Sarah Melton
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
| | - Dajeong Jung
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
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12
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Brink DP, Borgström C, Persson VC, Ofuji Osiro K, Gorwa-Grauslund MF. D-Xylose Sensing in Saccharomyces cerevisiae: Insights from D-Glucose Signaling and Native D-Xylose Utilizers. Int J Mol Sci 2021; 22:12410. [PMID: 34830296 PMCID: PMC8625115 DOI: 10.3390/ijms222212410] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/11/2021] [Accepted: 11/12/2021] [Indexed: 11/17/2022] Open
Abstract
Extension of the substrate range is among one of the metabolic engineering goals for microorganisms used in biotechnological processes because it enables the use of a wide range of raw materials as substrates. One of the most prominent examples is the engineering of baker's yeast Saccharomyces cerevisiae for the utilization of d-xylose, a five-carbon sugar found in high abundance in lignocellulosic biomass and a key substrate to achieve good process economy in chemical production from renewable and non-edible plant feedstocks. Despite many excellent engineering strategies that have allowed recombinant S. cerevisiae to ferment d-xylose to ethanol at high yields, the consumption rate of d-xylose is still significantly lower than that of its preferred sugar d-glucose. In mixed d-glucose/d-xylose cultivations, d-xylose is only utilized after d-glucose depletion, which leads to prolonged process times and added costs. Due to this limitation, the response on d-xylose in the native sugar signaling pathways has emerged as a promising next-level engineering target. Here we review the current status of the knowledge of the response of S. cerevisiae signaling pathways to d-xylose. To do this, we first summarize the response of the native sensing and signaling pathways in S. cerevisiae to d-glucose (the preferred sugar of the yeast). Using the d-glucose case as a point of reference, we then proceed to discuss the known signaling response to d-xylose in S. cerevisiae and current attempts of improving the response by signaling engineering using native targets and synthetic (non-native) regulatory circuits.
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Affiliation(s)
- Daniel P. Brink
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden; (C.B.); (V.C.P.); (K.O.O.)
| | - Celina Borgström
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden; (C.B.); (V.C.P.); (K.O.O.)
- BioZone Centre for Applied Bioscience and Bioengineering, Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College St., Toronto, ON M5S 3E5, Canada
| | - Viktor C. Persson
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden; (C.B.); (V.C.P.); (K.O.O.)
| | - Karen Ofuji Osiro
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden; (C.B.); (V.C.P.); (K.O.O.)
- Genetics and Biotechnology Laboratory, Embrapa Agroenergy, Brasília 70770-901, DF, Brazil
| | - Marie F. Gorwa-Grauslund
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden; (C.B.); (V.C.P.); (K.O.O.)
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13
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Zhou X, Li J, Tang N, Xie H, Fan X, Chen H, Tang M, Xie X. Genome-Wide Analysis of Nutrient Signaling Pathways Conserved in Arbuscular Mycorrhizal Fungi. Microorganisms 2021; 9:1557. [PMID: 34442636 PMCID: PMC8401276 DOI: 10.3390/microorganisms9081557] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/13/2021] [Accepted: 07/16/2021] [Indexed: 01/03/2023] Open
Abstract
Arbuscular mycorrhizal (AM) fungi form a mutualistic symbiosis with a majority of terrestrial vascular plants. To achieve an efficient nutrient trade with their hosts, AM fungi sense external and internal nutrients, and integrate different hierarchic regulations to optimize nutrient acquisition and homeostasis during mycorrhization. However, the underlying molecular networks in AM fungi orchestrating the nutrient sensing and signaling remain elusive. Based on homology search, we here found that at least 72 gene components involved in four nutrient sensing and signaling pathways, including cAMP-dependent protein kinase A (cAMP-PKA), sucrose non-fermenting 1 (SNF1) protein kinase, target of rapamycin kinase (TOR) and phosphate (PHO) signaling cascades, are well conserved in AM fungi. Based on the knowledge known in model yeast and filamentous fungi, we outlined the possible gene networks functioning in AM fungi. These pathways may regulate the expression of downstream genes involved in nutrient transport, lipid metabolism, trehalase activity, stress resistance and autophagy. The RNA-seq analysis and qRT-PCR results of some core genes further indicate that these pathways may play important roles in spore germination, appressorium formation, arbuscule longevity and sporulation of AM fungi. We hope to inspire further studies on the roles of these candidate genes involved in these nutrient sensing and signaling pathways in AM fungi and AM symbiosis.
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Affiliation(s)
- Xiaoqin Zhou
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
| | - Jiangyong Li
- Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China;
| | - Nianwu Tang
- UMR Interactions Arbres/Microorganismes, Centre INRA-Grand Est-Nancy, 54280 Champenoux, France;
| | - Hongyun Xie
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
| | - Xiaoning Fan
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
| | - Hui Chen
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
| | - Ming Tang
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
| | - Xianan Xie
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
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14
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Glucose regulation of the paralogous glucose sensing receptors Rgt2 and Snf3 of the yeast Saccharomyces cerevisiae. Biochim Biophys Acta Gen Subj 2021; 1865:129881. [PMID: 33617932 DOI: 10.1016/j.bbagen.2021.129881] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/08/2021] [Accepted: 02/16/2021] [Indexed: 11/22/2022]
Abstract
BACKGROUND The yeast Saccharomyces cerevisiae senses extracellular glucose levels through the two paralogous glucose sensing receptors Rgt2 and Snf3, which appear to sense high and low levels of glucose, respectively. METHODS Western blotting and qRT-PCR were used to determine expression levels of the glucose sensing receptors. RESULTS Rgt2 and Snf3 are expressed at different levels in response to different glucose concentrations. SNF3 expression is repressed by high glucose, whereas Rgt2 is turned over in response to glucose starvation. As a result, Rgt2 is predominant in cells grown on high glucose, whereas Snf3 is more abundant of the two paralogs in cells grown on low glucose. When expressed from a constitutive promoter, however, Snf3 behaves like Rgt2, being able to transduce the high glucose signal that induces HXT1 expression. Of note, constitutively active Rgt2 does not undergo glucose starvation-induced endocytic downregulation, whereas signaling defective Rgt2 is constitutively targeted for vacuolar degradation. These results suggest that glucose protects Rgt2 from endocytic degradation and reveal a previously unknown function of glucose as a signaling molecule that regulates the stability of its receptor. CONCLUSION Expression of Rgt2 and Snf3 is regulated by different mechanisms: Rgt2 expression is highly regulated at the level of protein stability; Snf3 expression is mainly regulated at the level of transcription. GENERAL SIGNIFICANCE The difference in the roles of Rgt2 and Snf3 in glucose sensing is a consequence of their cell surface abundance rather than a result of the two paralogous proteins having different functions.
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15
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Transcriptional regulatory proteins in central carbon metabolism of Pichia pastoris and Saccharomyces cerevisiae. Appl Microbiol Biotechnol 2020; 104:7273-7311. [PMID: 32651601 DOI: 10.1007/s00253-020-10680-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 05/04/2020] [Accepted: 05/10/2020] [Indexed: 01/21/2023]
Abstract
System-wide interactions in living cells and discovery of the diverse roles of transcriptional regulatory proteins that are mediator proteins with catalytic domains and regulatory subunits and transcription factors in the cellular pathways have become crucial for understanding the cellular response to environmental conditions. This review provides information for future metabolic engineering strategies through analyses on the highly interconnected regulatory networks in Saccharomyces cerevisiae and Pichia pastoris and identifying their components. We discuss the current knowledge on the carbon catabolite repression (CCR) mechanism, interconnecting regulatory system of the central metabolic pathways that regulate cell metabolism based on nutrient availability in the industrial yeasts. The regulatory proteins and their functions in the CCR signalling pathways in both yeasts are presented and discussed. We highlight the importance of metabolic signalling networks by signifying ways on how effective engineering strategies can be designed for generating novel regulatory circuits, furthermore to activate pathways that reconfigure the network architecture. We summarize the evidence that engineering of multilayer regulation is needed for directed evolution of the cellular network by putting the transcriptional control into a new perspective for the regulation of central carbon metabolism of the industrial yeasts; furthermore, we suggest research directions that may help to enhance production of recombinant products in the widely used, creatively engineered, but relatively less studied P. pastoris through de novo metabolic engineering strategies based on the discovery of components of signalling pathways in CCR metabolism. KEY POINTS: • Transcriptional regulation and control is the key phenomenon in the cellular processes. • Designing de novo metabolic engineering strategies depends on the discovery of signalling pathways in CCR metabolism. • Crosstalk between pathways occurs through essential parts of transcriptional machinery connected to specific catalytic domains. • In S. cerevisiae, a major part of CCR metabolism is controlled through Snf1 kinase, Glc7 phosphatase, and Srb10 kinase. • In P. pastoris, signalling pathways in CCR metabolism have not yet been clearly known yet. • Cellular regulations on the transcription of promoters are controlled with carbon sources.
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16
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Lagree K, Woolford CA, Huang MY, May G, McManus CJ, Solis NV, Filler SG, Mitchell AP. Roles of Candida albicans Mig1 and Mig2 in glucose repression, pathogenicity traits, and SNF1 essentiality. PLoS Genet 2020; 16:e1008582. [PMID: 31961865 PMCID: PMC6994163 DOI: 10.1371/journal.pgen.1008582] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 01/31/2020] [Accepted: 12/20/2019] [Indexed: 12/16/2022] Open
Abstract
Metabolic adaptation is linked to the ability of the opportunistic pathogen Candida albicans to colonize and cause infection in diverse host tissues. One way that C. albicans controls its metabolism is through the glucose repression pathway, where expression of alternative carbon source utilization genes is repressed in the presence of its preferred carbon source, glucose. Here we carry out genetic and gene expression studies that identify transcription factors Mig1 and Mig2 as mediators of glucose repression in C. albicans. The well-studied Mig1/2 orthologs ScMig1/2 mediate glucose repression in the yeast Saccharomyces cerevisiae; our data argue that C. albicans Mig1/2 function similarly as repressors of alternative carbon source utilization genes. However, Mig1/2 functions have several distinctive features in C. albicans. First, Mig1 and Mig2 have more co-equal roles in gene regulation than their S. cerevisiae orthologs. Second, Mig1 is regulated at the level of protein accumulation, more akin to ScMig2 than ScMig1. Third, Mig1 and Mig2 are together required for a unique aspect of C. albicans biology, the expression of several pathogenicity traits. Such Mig1/2-dependent traits include the abilities to form hyphae and biofilm, tolerance of cell wall inhibitors, and ability to damage macrophage-like cells and human endothelial cells. Finally, Mig1 is required for a puzzling feature of C. albicans biology that is not shared with S. cerevisiae: the essentiality of the Snf1 protein kinase, a central eukaryotic carbon metabolism regulator. Our results integrate Mig1 and Mig2 into the C. albicans glucose repression pathway and illuminate connections among carbon control, pathogenicity, and Snf1 essentiality. All organisms tailor genetic programs to the available nutrients, such as sources of carbon. Here we define two key regulators of the genetic programs for carbon source utilization in the fungal pathogen Candida albicans. The two regulators have many shared roles, yet are partially specialized to control carbon acquisition and metabolism, respectively. In addition, the regulators together control traits associated with pathogenicity, an indication that carbon regulation is integrated into the pathogenicity program. Finally, the regulators help to explain a long-standing riddle—that the central carbon regulator Snf1 is essential for C. albicans viability.
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Affiliation(s)
- Katherine Lagree
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Carol A. Woolford
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Manning Y. Huang
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Gemma May
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - C. Joel McManus
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Norma V. Solis
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, United States of America
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Scott G. Filler
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, United States of America
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Aaron P. Mitchell
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- Department of Microbiology, University of Georgia, Athens, Georgia, United States of America
- * E-mail:
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17
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Tiukova IA, Brandenburg J, Blomqvist J, Sampels S, Mikkelsen N, Skaugen M, Arntzen MØ, Nielsen J, Sandgren M, Kerkhoven EJ. Proteome analysis of xylose metabolism in Rhodotorula toruloides during lipid production. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:137. [PMID: 31171938 PMCID: PMC6547517 DOI: 10.1186/s13068-019-1478-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 05/25/2019] [Indexed: 05/28/2023]
Abstract
BACKGROUND Rhodotorula toruloides is a promising platform organism for production of lipids from lignocellulosic substrates. Little is known about the metabolic aspects of lipid production from the lignocellolosic sugar xylose by oleaginous yeasts in general and R. toruloides in particular. This study presents the first proteome analysis of the metabolism of R. toruloides during conversion of xylose to lipids. RESULTS Rhodotorula toruloides cultivated on either glucose or xylose was subjected to comparative analysis of its growth dynamics, lipid composition, fatty acid profiles and proteome. The maximum growth and sugar uptake rate of glucose-grown R. toruloides cells were almost twice that of xylose-grown cells. Cultivation on xylose medium resulted in a lower final biomass yield although final cellular lipid content was similar between glucose- and xylose-grown cells. Analysis of lipid classes revealed the presence of monoacylglycerol in the early exponential growth phase as well as a high proportion of free fatty acids. Carbon source-specific changes in lipid profiles were only observed at early exponential growth phase, where C18 fatty acids were more saturated in xylose-grown cells. Proteins involved in sugar transport, initial steps of xylose assimilation and NADPH regeneration were among the proteins whose levels increased the most in xylose-grown cells across all time points. The levels of enzymes involved in the mevalonate pathway, phospholipid biosynthesis and amino acids biosynthesis differed in response to carbon source. In addition, xylose-grown cells contained higher levels of enzymes involved in peroxisomal beta-oxidation and oxidative stress response compared to cells cultivated on glucose. CONCLUSIONS The results obtained in the present study suggest that sugar import is the limiting step during xylose conversion by R. toruloides into lipids. NADPH appeared to be regenerated primarily through pentose phosphate pathway although it may also involve malic enzyme as well as alcohol and aldehyde dehydrogenases. Increases in enzyme levels of both fatty acid biosynthesis and beta-oxidation in xylose-grown cells was predicted to result in a futile cycle. The results presented here are valuable for the development of lipid production processes employing R. toruloides on xylose-containing substrates.
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Affiliation(s)
- Ievgeniia A. Tiukova
- Systems and Synthetic Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, Göteborg, Sweden
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Jule Brandenburg
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Johanna Blomqvist
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
- Faculty of Science and Technology, Norwegian University of Life Sciences, Ås, Norway
| | - Sabine Sampels
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Nils Mikkelsen
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Morten Skaugen
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Magnus Ø. Arntzen
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Jens Nielsen
- Systems and Synthetic Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, Göteborg, Sweden
| | - Mats Sandgren
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Eduard J. Kerkhoven
- Systems and Synthetic Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, Göteborg, Sweden
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18
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Van Ende M, Wijnants S, Van Dijck P. Sugar Sensing and Signaling in Candida albicans and Candida glabrata. Front Microbiol 2019; 10:99. [PMID: 30761119 PMCID: PMC6363656 DOI: 10.3389/fmicb.2019.00099] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 01/16/2019] [Indexed: 12/30/2022] Open
Abstract
Candida species, such as Candida albicans and Candida glabrata, cause infections at different host sites because they adapt their metabolism depending on the available nutrients. They are able to proliferate under both nutrient-rich and nutrient-poor conditions. This adaptation is what makes these fungi successful pathogens. For both species, sugars are very important nutrients and as the sugar level differs depending on the host niche, different sugar sensing systems must be present. Saccharomyces cerevisiae has been used as a model for the identification of these sugar sensing systems. One of the main carbon sources for yeast is glucose, for which three different pathways have been described. First, two transporter-like proteins, ScSnf3 and ScRgt2, sense glucose levels resulting in the induction of different hexose transporter genes. This situation is comparable in C. albicans and C. glabrata, where sensing of glucose by CaHgt4 and CgSnf3, respectively, also results in hexose transporter gene induction. The second glucose sensing mechanism in S. cerevisiae is via the G-protein coupled receptor ScGpr1, which causes the activation of the cAMP/PKA pathway, resulting in rapid adaptation to the presence of glucose. The main components of this glucose sensing system are also conserved in C. albicans and C. glabrata. However, it seems that the ligand(s) for CaGpr1 are not sugars but lactate and methionine. In C. glabrata, this pathway has not yet been investigated. Finally, the glucose repression pathway ensures repression of respiration and repression of the use of alternative carbon sources. This pathway is not well characterized in Candida species. It is important to note that, apart from glucose, other sugars and sugar-analogs, such as N-acetylglucosamine in the case of C. albicans, are also important carbon sources. In these fungal pathogens, sensing sugars is important for a number of virulence attributes, including adhesion, oxidative stress resistance, biofilm formation, morphogenesis, invasion, and antifungal drug tolerance. In this review, the sugar sensing and signaling mechanisms in these Candida species are compared to S. cerevisiae.
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Affiliation(s)
- Mieke Van Ende
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, Department of Biology, KU Leuven, Leuven, Belgium
- VIB-KU Leuven Center for Microbiology, Leuven, Belgium
| | - Stefanie Wijnants
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, Department of Biology, KU Leuven, Leuven, Belgium
- VIB-KU Leuven Center for Microbiology, Leuven, Belgium
| | - Patrick Van Dijck
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, Department of Biology, KU Leuven, Leuven, Belgium
- VIB-KU Leuven Center for Microbiology, Leuven, Belgium
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19
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Lane S, Xu H, Oh EJ, Kim H, Lesmana A, Jeong D, Zhang G, Tsai CS, Jin YS, Kim SR. Glucose repression can be alleviated by reducing glucose phosphorylation rate in Saccharomyces cerevisiae. Sci Rep 2018; 8:2613. [PMID: 29422502 PMCID: PMC5805702 DOI: 10.1038/s41598-018-20804-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 01/19/2018] [Indexed: 01/06/2023] Open
Abstract
Microorganisms commonly exhibit preferential glucose consumption and diauxic growth when cultured in mixtures of glucose and other sugars. Although various genetic perturbations have alleviated the effects of glucose repression on consumption of specific sugars, a broadly applicable mechanism remains unknown. Here, we report that a reduction in the rate of glucose phosphorylation alleviates the effects of glucose repression in Saccharomyces cerevisiae. Through adaptive evolution under a mixture of xylose and the glucose analog 2-deoxyglucose, we isolated a mutant strain capable of simultaneously consuming glucose and xylose. Genome sequencing of the evolved mutant followed by CRISPR/Cas9-based reverse engineering revealed that mutations in the glucose phosphorylating enzymes (Hxk1, Hxk2, Glk1) were sufficient to confer simultaneous glucose and xylose utilization. We then found that varying hexokinase expression with an inducible promoter led to the simultaneous utilization of glucose and xylose. Interestingly, no mutations in sugar transporters occurred during the evolution, and no specific transporter played an indispensable role in simultaneous sugar utilization. Additionally, we demonstrated that slowing glucose consumption also enabled simultaneous utilization of glucose and galactose. These results suggest that the rate of intracellular glucose phosphorylation is a decisive factor for metabolic regulations of mixed sugars.
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Affiliation(s)
- Stephan Lane
- Carl Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.,Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Haiqing Xu
- Carl Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.,Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Eun Joong Oh
- Carl Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.,Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Heejin Kim
- Carl Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.,Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Anastashia Lesmana
- Carl Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.,Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Deokyeol Jeong
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, Republic of Korea
| | - Guochang Zhang
- Carl Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.,Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Ching-Sung Tsai
- Carl Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.,Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Yong-Su Jin
- Carl Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA. .,Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
| | - Soo Rin Kim
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, Republic of Korea. .,Institute of Agricultural Science & Technology, Kyungpook National University, Daegu, Republic of Korea.
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Osiro KO, Brink DP, Borgström C, Wasserstrom L, Carlquist M, Gorwa-Grauslund MF. Assessing the effect of d-xylose on the sugar signaling pathways of Saccharomyces cerevisiae in strains engineered for xylose transport and assimilation. FEMS Yeast Res 2018; 18:4791530. [DOI: 10.1093/femsyr/fox096] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 12/27/2017] [Indexed: 01/18/2023] Open
Affiliation(s)
- Karen O Osiro
- Applied Microbiology, Department of Chemistry, Lund University, Kemicentrum, Naturvetarvägen 14, Lund 223 62, Sweden
| | - Daniel P Brink
- Applied Microbiology, Department of Chemistry, Lund University, Kemicentrum, Naturvetarvägen 14, Lund 223 62, Sweden
| | - Celina Borgström
- Applied Microbiology, Department of Chemistry, Lund University, Kemicentrum, Naturvetarvägen 14, Lund 223 62, Sweden
| | - Lisa Wasserstrom
- Applied Microbiology, Department of Chemistry, Lund University, Kemicentrum, Naturvetarvägen 14, Lund 223 62, Sweden
| | - Magnus Carlquist
- Applied Microbiology, Department of Chemistry, Lund University, Kemicentrum, Naturvetarvägen 14, Lund 223 62, Sweden
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Broxton CN, He B, Bruno VM, Culotta VC. A role for Candida albicans superoxide dismutase enzymes in glucose signaling. Biochem Biophys Res Commun 2017; 495:814-820. [PMID: 29154829 DOI: 10.1016/j.bbrc.2017.11.084] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 11/12/2017] [Indexed: 01/18/2023]
Abstract
The Saccharomyces cerevisiae and Candida albicans yeasts have evolved to differentially use glucose for fermentation versus respiration. S. cerevisiae is Crabtree positive, where glucose represses respiration and promotes fermentation, while the opportunistic fungal pathogen C. albicans is Crabtree negative and does not repress respiration with glucose. We have previously shown that glucose control in S. cerevisiae involves the antioxidant enzyme Cu/Zn superoxide dismutase (SOD1), where H2O2 generated by SOD1 stabilizes the casein kinase YCK1 for glucose sensing. We now demonstrate that C. albicans SODs also participate in glucose regulation. C. albicans expresses two cytosolic SODs, Cu/Zn SOD1 and Mn containing SOD3, and both complemented a S. cerevisiae sod1Δ mutant in stabilizing YCK1. Moreover, in C. albicans cells, both SODs functioned to repress glucose transporter genes in response to glucose. However, the action of SODs in glucose control has diverged in the two yeasts. In S. cerevisiae, SOD1 specifically functions in the glucose sensing pathway involving YCK1 and the RGT1 repressor, but the analogous YCK/RGT1 pathway in C. albicans shows no control by SOD enzymes. Instead C. albicans SODs work in the glucose repression pathway involving the MIG1 transcriptional repressor. In C. albicans, the SODs repress glucose uptake, while in S. cerevisiae, SOD1 activates glucose uptake, in accordance with the divergent modes for glucose utilization in these two distantly related yeasts.
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Affiliation(s)
- Chynna N Broxton
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD 21205, USA
| | - Bixi He
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD 21205, USA
| | - Vincent M Bruno
- Department Microbiology and Immunology, Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD 21201, USA
| | - Valeria C Culotta
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD 21205, USA.
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Adamczyk M, Szatkowska R. Low RNA Polymerase III activity results in up regulation of HXT2 glucose transporter independently of glucose signaling and despite changing environment. PLoS One 2017; 12:e0185516. [PMID: 28961268 PMCID: PMC5621690 DOI: 10.1371/journal.pone.0185516] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 09/14/2017] [Indexed: 01/13/2023] Open
Abstract
Background Saccharomyces cerevisiae responds to glucose availability in the environment, inducing the expression of the low-affinity transporters and high-affinity transporters in a concentration dependent manner. This cellular decision making is controlled through finely tuned communication between multiple glucose sensing pathways including the Snf1-Mig1, Snf3/Rgt2-Rgt1 (SRR) and cAMP-PKA pathways. Results We demonstrate the first evidence that RNA Polymerase III (RNAP III) activity affects the expression of the glucose transporter HXT2 (RNA Polymerase II dependent—RNAP II) at the level of transcription. Down-regulation of RNAP III activity in an rpc128-1007 mutant results in a significant increase in HXT2 mRNA, which is considered to respond only to low extracellular glucose concentrations. HXT2 expression is induced in the mutant regardless of the growth conditions either at high glucose concentration or in the presence of a non-fermentable carbon source such as glycerol. Using chromatin immunoprecipitation (ChIP), we found an increased association of Rgt1 and Tup1 transcription factors with the highly activated HXT2 promoter in the rpc128-1007 strain. Furthermore, by measuring cellular abundance of Mth1 corepressor, we found that in rpc128-1007, HXT2 gene expression was independent from Snf3/Rgt2-Rgt1 (SRR) signaling. The Snf1 protein kinase complex, which needs to be active for the release from glucose repression, also did not appear perturbed in the mutated strain. Conclusions/Significance These findings suggest that the general activity of RNAP III can indirectly affect the RNAP II transcriptional machinery on the HXT2 promoter when cellular perception transduced via the major signaling pathways, broadly recognized as on/off switch essential to either positive or negative HXT gene regulation, remain entirely intact. Further, Rgt1/Ssn6-Tup1 complex, which has a dual function in gene transcription as a repressor-activator complex, contributes to HXT2 transcriptional activation.
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Affiliation(s)
- Malgorzata Adamczyk
- Institute of Biotechnology, Faculty of Chemistry, Warsaw University of Technology, Warsaw, Poland
- * E-mail:
| | - Roza Szatkowska
- Institute of Biotechnology, Faculty of Chemistry, Warsaw University of Technology, Warsaw, Poland
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Galello F, Pautasso C, Reca S, Cañonero L, Portela P, Moreno S, Rossi S. Transcriptional regulation of the protein kinase a subunits inSaccharomyces cerevisiaeduring fermentative growth. Yeast 2017; 34:495-508. [DOI: 10.1002/yea.3252] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 07/26/2017] [Accepted: 08/09/2017] [Indexed: 11/08/2022] Open
Affiliation(s)
- Fiorella Galello
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento Química Biológica and CONICET - Universidad de Buenos Aires; Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Buenos Aires Argentina
| | - Constanza Pautasso
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento Química Biológica and CONICET - Universidad de Buenos Aires; Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Buenos Aires Argentina
| | - Sol Reca
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento Química Biológica and CONICET - Universidad de Buenos Aires; Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Buenos Aires Argentina
| | - Luciana Cañonero
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento Química Biológica and CONICET - Universidad de Buenos Aires; Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Buenos Aires Argentina
| | - Paula Portela
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento Química Biológica and CONICET - Universidad de Buenos Aires; Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Buenos Aires Argentina
| | - Silvia Moreno
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento Química Biológica and CONICET - Universidad de Buenos Aires; Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Buenos Aires Argentina
| | - Silvia Rossi
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento Química Biológica and CONICET - Universidad de Buenos Aires; Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Buenos Aires Argentina
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24
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Abstract
To respond to the changing environment, cells must be able to sense external conditions. This is important for many processes including growth, mating, the expression of virulence factors, and several other regulatory effects. Nutrient sensing at the plasma membrane is mediated by different classes of membrane proteins that activate downstream signaling pathways: nontransporting receptors, transceptors, classical and nonclassical G-protein-coupled receptors, and the newly defined extracellular mucin receptors. Nontransporting receptors have the same structure as transport proteins, but have lost the capacity to transport while gaining a receptor function. Transceptors are transporters that also function as a receptor, because they can rapidly activate downstream signaling pathways. In this review, we focus on these four types of fungal membrane proteins. We mainly discuss the sensing mechanisms relating to sugars, ammonium, and amino acids. Mechanisms for other nutrients, such as phosphate and sulfate, are discussed briefly. Because the model yeast Saccharomyces cerevisiae has been the most studied, especially regarding these nutrient-sensing systems, each subsection will commence with what is known in this species.
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Laera L, Guaragnella N, Ždralević M, Marzulli D, Liu Z, Giannattasio S. The transcription factors ADR1 or CAT8 are required for RTG pathway activation and evasion from yeast acetic acid-induced programmed cell death in raffinose. ACTA ACUST UNITED AC 2016; 3:621-631. [PMID: 28357334 PMCID: PMC5348981 DOI: 10.15698/mic2016.12.549] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Yeast Saccharomyces cerevisiae grown on glucose undergoes programmed cell death (PCD) induced by acetic acid (AA-PCD), but evades PCD when grown in raffinose. This is due to concomitant relief of carbon catabolite repression (CCR) and activation of mitochondrial retrograde signaling, a mitochondria-to-nucleus communication pathway causing up-regulation of various nuclear target genes, such as CIT2, encoding peroxisomal citrate synthase, dependent on the positive regulator RTG2 in response to mitochondrial dysfunction. CCR down-regulates genes mainly involved in mitochondrial respiratory metabolism. In this work, we investigated the relationships between the RTG and CCR pathways in the modulation of AA-PCD sensitivity under glucose repression or de-repression conditions. Yeast single and double mutants lacking RTG2 and/or certain factors regulating carbon source utilization, including MIG1, HXK2, ADR1, CAT8, and HAP4, have been analyzed for their survival and CIT2 expression after acetic acid treatment. ADR1 and CAT8 were identified as positive regulators of RTG-dependent gene transcription. ADR1 and CAT8 interact with RTG2 and with each other in inducing cell resistance to AA-PCD in raffinose and controlling the nature of cell death. In the absence of ADR1 and CAT8, AA-PCD evasion is acquired through activation of an alternative factor/pathway repressed by RTG2, suggesting that RTG2 may play a function in promoting necrotic cell death in repressing conditions when RTG pathway is inactive. Moreover, our data show that simultaneous mitochondrial retrograde pathway activation and SNF1-dependent relief of CCR have a key role in central carbon metabolism reprogramming which modulates the yeast acetic acid-stress response.
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Affiliation(s)
- Luna Laera
- National Research Council of Italy, Institute of Biomembranes and Bioenergetics, Bari, Italy
| | - Nicoletta Guaragnella
- National Research Council of Italy, Institute of Biomembranes and Bioenergetics, Bari, Italy
| | - Maša Ždralević
- National Research Council of Italy, Institute of Biomembranes and Bioenergetics, Bari, Italy
| | - Domenico Marzulli
- National Research Council of Italy, Institute of Biomembranes and Bioenergetics, Bari, Italy
| | - Zhengchang Liu
- Department of Biological Sciences, University of New Orleans, New Orleans, LA, USA
| | - Sergio Giannattasio
- National Research Council of Italy, Institute of Biomembranes and Bioenergetics, Bari, Italy
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26
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Alcaíno J, Bravo N, Córdova P, Marcoleta AE, Contreras G, Barahona S, Sepúlveda D, Fernández-Lobato M, Baeza M, Cifuentes V. The Involvement of Mig1 from Xanthophyllomyces dendrorhous in Catabolic Repression: An Active Mechanism Contributing to the Regulation of Carotenoid Production. PLoS One 2016; 11:e0162838. [PMID: 27622474 PMCID: PMC5021340 DOI: 10.1371/journal.pone.0162838] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 08/29/2016] [Indexed: 11/18/2022] Open
Abstract
The red yeast X. dendrorhous is one of the few natural sources of astaxanthin, a carotenoid used in aquaculture for salmonid fish pigmentation and in the cosmetic and pharmaceutical industries for its antioxidant properties. Genetic control of carotenogenesis is well characterized in this yeast; however, little is known about the regulation of the carotenogenesis process. Several lines of evidence have suggested that carotenogenesis is regulated by catabolic repression, and the aim of this work was to identify and functionally characterize the X. dendrorhous MIG1 gene encoding the catabolic repressor Mig1, which mediates transcriptional glucose-dependent repression in other yeasts and fungi. The identified gene encodes a protein of 863 amino acids that demonstrates the characteristic conserved features of Mig1 proteins, and binds in vitro to DNA fragments containing Mig1 boxes. Gene functionality was demonstrated by heterologous complementation in a S. cerevisiae mig1- strain; several aspects of catabolic repression were restored by the X. dendrorhous MIG1 gene. Additionally, a X. dendrorhous mig1- mutant was constructed and demonstrated a higher carotenoid content than the wild-type strain. Most important, the mig1- mutation alleviated the glucose-mediated repression of carotenogenesis in X. dendrorhous: the addition of glucose to mig1- and wild-type cultures promoted the growth of both strains, but carotenoid synthesis was observed only in the mutant strain. Transcriptomic and RT-qPCR analyses revealed that several genes were differentially expressed between X. dendrorhous mig1- and the wild-type strain when cultured with glucose as the sole carbon source. The results obtained in this study demonstrate that catabolic repression in X. dendrorhous is an active process in which the identified MIG1 gene product plays a central role in the regulation of several biological processes, including carotenogenesis.
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Affiliation(s)
- Jennifer Alcaíno
- Laboratorio de Genética, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Natalia Bravo
- Laboratorio de Genética, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Pamela Córdova
- Laboratorio de Genética, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Andrés E. Marcoleta
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Gabriela Contreras
- Laboratorio de Genética, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Salvador Barahona
- Laboratorio de Genética, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Dionisia Sepúlveda
- Laboratorio de Genética, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - María Fernández-Lobato
- Centro de Biología Molecular Severo Ochoa, Departamento de Biología Molecular (UAM-CSIC), Universidad Autónoma, Madrid, Cantoblanco, España
| | - Marcelo Baeza
- Laboratorio de Genética, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Víctor Cifuentes
- Laboratorio de Genética, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
- * E-mail:
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27
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Hinkle KL, Anderson CC, Forkey B, Griffin J, Cone K, Vitzthum C, Olsen D. Exposure to the lampricide 3-trifluoromethyl-4-nitrophenol results in increased expression of carbohydrate transporters in Saccharomyces cerevisiae. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2016; 35:1727-1732. [PMID: 26606276 PMCID: PMC5076018 DOI: 10.1002/etc.3314] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 09/10/2015] [Accepted: 11/24/2015] [Indexed: 06/05/2023]
Abstract
The lampricide 3-trifluoromethyl-4-nitrophenol (TFM) is used to control sea lamprey (Petromyzon marinus) populations in freshwater lakes. Although TFM can have sublethal and lethal effects, little is known about gene expression changes with TFM exposure. Microarray analysis was used to determine differential gene expression over 4 h of exposure in Saccharomyces cerevisiae. Among the most significantly up-regulated genes were regulators of carbohydrate transport, including HXT1, HXT3, HXT4, IMA5, MIG2, and YKR075C. Environ Toxicol Chem 2016;35:1727-1732. © 2015 SETAC.
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Affiliation(s)
- Karen L. Hinkle
- Department of Biology and Physical Education, Norwich University, Northfield, VT USA
| | - Chad C. Anderson
- Department of Biology and Physical Education, Norwich University, Northfield, VT USA
| | - Blake Forkey
- Department of Biology and Physical Education, Norwich University, Northfield, VT USA
| | - Jacob Griffin
- Department of Biology and Physical Education, Norwich University, Northfield, VT USA
- Department of Mathematics, Norwich University, Northfield, VT USA
| | - Kelsey Cone
- Department of Biology and Physical Education, Norwich University, Northfield, VT USA
| | - Carl Vitzthum
- Department of Biology and Physical Education, Norwich University, Northfield, VT USA
| | - Darlene Olsen
- Department of Mathematics, Norwich University, Northfield, VT USA
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28
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Heterozygote Advantage Is a Common Outcome of Adaptation in Saccharomyces cerevisiae. Genetics 2016; 203:1401-13. [PMID: 27194750 DOI: 10.1534/genetics.115.185165] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 05/15/2016] [Indexed: 12/31/2022] Open
Abstract
Adaptation in diploids is predicted to proceed via mutations that are at least partially dominant in fitness. Recently, we argued that many adaptive mutations might also be commonly overdominant in fitness. Natural (directional) selection acting on overdominant mutations should drive them into the population but then, instead of bringing them to fixation, should maintain them as balanced polymorphisms via heterozygote advantage. If true, this would make adaptive evolution in sexual diploids differ drastically from that of haploids. The validity of this prediction has not yet been tested experimentally. Here, we performed four replicate evolutionary experiments with diploid yeast populations (Saccharomyces cerevisiae) growing in glucose-limited continuous cultures. We sequenced 24 evolved clones and identified initial adaptive mutations in all four chemostats. The first adaptive mutations in all four chemostats were three copy number variations, all of which proved to be overdominant in fitness. The fact that fitness overdominant mutations were always the first step in independent adaptive walks supports the prediction that heterozygote advantage can arise as a common outcome of directional selection in diploids and demonstrates that overdominance of de novo adaptive mutations in diploids is not rare.
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29
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Roy A, Hashmi S, Li Z, Dement AD, Cho KH, Kim JH. The glucose metabolite methylglyoxal inhibits expression of the glucose transporter genes by inactivating the cell surface glucose sensors Rgt2 and Snf3 in yeast. Mol Biol Cell 2016; 27:862-71. [PMID: 26764094 PMCID: PMC4803311 DOI: 10.1091/mbc.e15-11-0789] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 01/05/2016] [Indexed: 01/04/2023] Open
Abstract
Methylglyoxal (MG) is a cytotoxic by-product of glycolysis. MG inhibits the growth of glucose-fermenting yeast cells by inhibiting glycolysis. MG does so by inducing endocytosis and degradation of the cell-surface glucose sensors Rgt2 and Snf3, which are required for glucose induction of HXT (glucose transporter) gene expression. Methylglyoxal (MG) is a cytotoxic by-product of glycolysis. MG has inhibitory effect on the growth of cells ranging from microorganisms to higher eukaryotes, but its molecular targets are largely unknown. The yeast cell-surface glucose sensors Rgt2 and Snf3 function as glucose receptors that sense extracellular glucose and generate a signal for induction of expression of genes encoding glucose transporters (HXTs). Here we provide evidence that these glucose sensors are primary targets of MG in yeast. MG inhibits the growth of glucose-fermenting yeast cells by inducing endocytosis and degradation of the glucose sensors. However, the glucose sensors with mutations at their putative ubiquitin-acceptor lysine residues are resistant to MG-induced degradation. These results suggest that the glucose sensors are inactivated through ubiquitin-mediated endocytosis and degraded in the presence of MG. In addition, the inhibitory effect of MG on the glucose sensors is greatly enhanced in cells lacking Glo1, a key component of the MG detoxification system. Thus the stability of these glucose sensors seems to be critically regulated by intracellular MG levels. Taken together, these findings suggest that MG attenuates glycolysis by promoting degradation of the cell-surface glucose sensors and thus identify MG as a potential glycolytic inhibitor.
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Affiliation(s)
- Adhiraj Roy
- Department of Biochemistry and Molecular Medicine, George Washington University School of Medicine and Health Science, Washington, DC 20037
| | - Salman Hashmi
- Department of Biochemistry and Molecular Medicine, George Washington University School of Medicine and Health Science, Washington, DC 20037
| | - Zerui Li
- Department of Biochemistry and Molecular Medicine, George Washington University School of Medicine and Health Science, Washington, DC 20037
| | - Angela D Dement
- Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
| | - Kyu Hong Cho
- Department of Biology, Indiana State University, Terre Haute, IN 47809
| | - Jeong-Ho Kim
- Department of Biochemistry and Molecular Medicine, George Washington University School of Medicine and Health Science, Washington, DC 20037
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30
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Sugar and Glycerol Transport in Saccharomyces cerevisiae. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 892:125-168. [PMID: 26721273 DOI: 10.1007/978-3-319-25304-6_6] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In Saccharomyces cerevisiae the process of transport of sugar substrates into the cell comprises a complex network of transporters and interacting regulatory mechanisms. Members of the large family of hexose (HXT) transporters display uptake efficiencies consistent with their environmental expression and play physiological roles in addition to feeding the glycolytic pathway. Multiple glucose-inducing and glucose-independent mechanisms serve to regulate expression of the sugar transporters in yeast assuring that expression levels and transporter activity are coordinated with cellular metabolism and energy needs. The expression of sugar transport activity is modulated by other nutritional and environmental factors that may override glucose-generated signals. Transporter expression and activity is regulated transcriptionally, post-transcriptionally and post-translationally. Recent studies have expanded upon this suite of regulatory mechanisms to include transcriptional expression fine tuning mediated by antisense RNA and prion-based regulation of transcription. Much remains to be learned about cell biology from the continued analysis of this dynamic process of substrate acquisition.
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31
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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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32
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Yeast prions: Paramutation at the protein level? Semin Cell Dev Biol 2015; 44:51-61. [DOI: 10.1016/j.semcdb.2015.08.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 08/18/2015] [Indexed: 11/20/2022]
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33
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Abstract
Glucose is the primary source of energy for the budding yeast Saccharomyces cerevisiae. Although yeast cells can utilize a wide range of carbon sources, presence of glucose suppresses molecular activities involved in the use of alternate carbon sources as well as it represses respiration and gluconeogenesis. This dominant effect of glucose on yeast carbon metabolism is coordinated by several signaling and metabolic interactions that mainly regulate transcriptional activity but are also effective at post-transcriptional and post-translational levels. This review describes effects of glucose repression on yeast carbon metabolism with a focus on roles of the Snf3/Rgt2 glucose-sensing pathway and Snf1 signal transduction in establishment and relief of glucose repression. The role of Snf1 signaling in glucose repression and carbon metabolism in Saccharomyces cerevisae.
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Affiliation(s)
- Ömur Kayikci
- Department of Biology and Biological Engineering, Kemivägen 10, Chalmers University of Technology, SE41296 Gothenburg, Sweden Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, SE41296 Gothenburg, Sweden
| | - Jens Nielsen
- Department of Biology and Biological Engineering, Kemivägen 10, Chalmers University of Technology, SE41296 Gothenburg, Sweden Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, SE41296 Gothenburg, Sweden Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, DK2970 Hørsholm, Denmark
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The repressor Rgt1 and the cAMP-dependent protein kinases control the expression of the SUC2 gene in Saccharomyces cerevisiae. Biochim Biophys Acta Gen Subj 2015; 1850:1362-7. [DOI: 10.1016/j.bbagen.2015.03.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 03/10/2015] [Accepted: 03/15/2015] [Indexed: 10/23/2022]
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Shashkova S, Welkenhuysen N, Hohmann S. Molecular communication: crosstalk between the Snf1 and other signaling pathways. FEMS Yeast Res 2015; 15:fov026. [DOI: 10.1093/femsyr/fov026] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/15/2015] [Indexed: 02/02/2023] Open
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Schuler D, Wahl R, Wippel K, Vranes M, Münsterkötter M, Sauer N, Kämper J. Hxt1, a monosaccharide transporter and sensor required for virulence of the maize pathogen Ustilago maydis. THE NEW PHYTOLOGIST 2015; 206:1086-1100. [PMID: 25678342 DOI: 10.1111/nph.13314] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 12/23/2014] [Indexed: 05/23/2023]
Abstract
The smut Ustilago maydis, a ubiquitous pest of corn, is highly adapted to its host to parasitize on its organic carbon sources. We have identified a hexose transporter, Hxt1, as important for fungal development during both the saprophytic and the pathogenic stage of the fungus. Hxt1 was characterized as a high-affinity transporter for glucose, fructose, and mannose; ∆hxt1 strains show significantly reduced growth on these substrates, setting Hxt1 as the main hexose transporter during saprophytic growth. After plant infection, ∆hxt1 strains show decreased symptom development. However, expression of a Hxt1 protein with a mutation leading to constitutively active signaling in the yeast glucose sensors Snf3p and Rgt2p results in completely apathogenic strains. Fungal development is stalled immediately after plant penetration, implying a dual function of Hxt1 as transporter and sensor. As glucose sensors are only known for yeasts, 'transceptor' as Hxt1 may constitute a general mechanism for sensing of glucose in fungi. In U. maydis, Hxt1 links a nutrient-dependent environmental signal to the developmental program during pathogenic development.
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Affiliation(s)
- David Schuler
- Department of Genetics, Institute of Applied Biosciences, Karlsruhe Institute of Technology, Hertzstrasse 16, Karlsruhe, 76187, Germany
| | - Ramon Wahl
- Department of Genetics, Institute of Applied Biosciences, Karlsruhe Institute of Technology, Hertzstrasse 16, Karlsruhe, 76187, Germany
| | - Kathrin Wippel
- Molecular Plant Physiology, Friedrich Alexander University Erlangen-Nuremberg, Staudtstrasse 5, Erlangen, 91058, Germany
| | - Miroslav Vranes
- Department of Genetics, Institute of Applied Biosciences, Karlsruhe Institute of Technology, Hertzstrasse 16, Karlsruhe, 76187, Germany
| | - Martin Münsterkötter
- Institute of Bioinformatics and Systems Biology, Helmholtz Center Munich, Ingolstädter Landstraße 1, Neuherberg, 85764, Germany
| | - Norbert Sauer
- Molecular Plant Physiology, Friedrich Alexander University Erlangen-Nuremberg, Staudtstrasse 5, Erlangen, 91058, Germany
| | - Jörg Kämper
- Department of Genetics, Institute of Applied Biosciences, Karlsruhe Institute of Technology, Hertzstrasse 16, Karlsruhe, 76187, Germany
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Coregulated expression of the Na+/phosphate Pho89 transporter and Ena1 Na+-ATPase allows their functional coupling under high-pH stress. Mol Cell Biol 2014; 34:4420-35. [PMID: 25266663 DOI: 10.1128/mcb.01089-14] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The yeast Saccharomyces cerevisiae has two main high-affinity inorganic phosphate (Pi) transporters, Pho84 and Pho89, that are functionally relevant at acidic/neutral pH and alkaline pH, respectively. Upon Pi starvation, PHO84 and PHO89 are induced by the activation of the PHO regulon by the binding of the Pho4 transcription factor to specific promoter sequences. We show that PHO89 and PHO84 are induced by alkalinization of the medium with different kinetics and that the network controlling Pho89 expression in response to alkaline pH differs from that of other members of the PHO regulon. In addition to Pho4, the PHO89 promoter is regulated by the transcriptional activator Crz1 through the calcium-activated phosphatase calcineurin, and it is under the control of several repressors (Mig2, Nrg1, and Nrg2) coordinately regulated by the Snf1 protein kinase and the Rim101 transcription factor. This network mimics the one regulating expression of the Na(+)-ATPase gene ENA1, encoding a major determinant for Na(+) detoxification. Our data highlight a scenario in which the activities of Pho89 and Ena1 are functionally coordinated to sustain growth in an alkaline environment.
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38
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Roy A, Kim YB, Cho KH, Kim JH. Glucose starvation-induced turnover of the yeast glucose transporter Hxt1. Biochim Biophys Acta Gen Subj 2014; 1840:2878-85. [PMID: 24821015 DOI: 10.1016/j.bbagen.2014.05.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 05/02/2014] [Accepted: 05/05/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND The budding yeast Saccharomyces cerevisiae possesses multiple glucose transporters with different affinities for glucose that enable it to respond to a wide range of glucose concentrations. The steady-state levels of glucose transporters are regulated in response to changes in the availability of glucose. This study investigates the glucose regulation of the low affinity, high capacity glucose transporter Hxt1. METHODS AND RESULTS Western blotting and confocal microscopy were performed to evaluate glucose regulation of the stability of Hxt1. Our results show that glucose starvation induces endocytosis and degradation of Hxt1 and that this event requires End3, a protein required for endocytosis, and the Doa4 deubiquitination enzyme. Mutational analysis of the lysine residues in the Hxt1 N-terminal domain demonstrates that the two lysine residues, K12 and K39, serve as the putative ubiquitin-acceptor sites by the Rsp5 ubiquitin ligase. We also demonstrate that inactivation of PKA (cAMP-dependent protein kinase A) is needed for Hxt1 turnover, implicating the role of the Ras/cAMP-PKA glucose signaling pathway in the stability of Hxt1. CONCLUSION AND GENERAL SIGNIFICANCE Hxt1, most useful when glucose is abundant, is internalized and degraded when glucose becomes depleted. Of note, the stability of Hxt1 is regulated by PKA, known as a positive regulator for glucose induction of HXT1 gene expression, demonstrating a dual role of PKA in regulation of Hxt1.
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Affiliation(s)
- Adhiraj Roy
- Department of Biochemistry and Molecular Medicine, The George Washington University Medical Center, 2300 Eye Street, Washington, DC 20037, USA
| | - Yong-Bae Kim
- Department of Biochemistry and Molecular Medicine, The George Washington University Medical Center, 2300 Eye Street, Washington, DC 20037, USA
| | - Kyu Hong Cho
- Department of Microbiology, Southern Illinois University Carbondale, 1125 Lincoln Drive, Carbondale, IL 62901, USA
| | - Jeong-Ho Kim
- Department of Biochemistry and Molecular Medicine, The George Washington University Medical Center, 2300 Eye Street, Washington, DC 20037, USA.
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39
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Conrad M, Schothorst J, Kankipati HN, Van Zeebroeck G, Rubio-Texeira M, Thevelein JM. Nutrient sensing and signaling in the yeast Saccharomyces cerevisiae. FEMS Microbiol Rev 2014; 38:254-99. [PMID: 24483210 PMCID: PMC4238866 DOI: 10.1111/1574-6976.12065] [Citation(s) in RCA: 419] [Impact Index Per Article: 41.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 12/23/2013] [Accepted: 01/22/2014] [Indexed: 02/04/2023] Open
Abstract
The yeast Saccharomyces cerevisiae has been a favorite organism for pioneering studies on nutrient-sensing and signaling mechanisms. Many specific nutrient responses have been elucidated in great detail. This has led to important new concepts and insight into nutrient-controlled cellular regulation. Major highlights include the central role of the Snf1 protein kinase in the glucose repression pathway, galactose induction, the discovery of a G-protein-coupled receptor system, and role of Ras in glucose-induced cAMP signaling, the role of the protein synthesis initiation machinery in general control of nitrogen metabolism, the cyclin-controlled protein kinase Pho85 in phosphate regulation, nitrogen catabolite repression and the nitrogen-sensing target of rapamycin pathway, and the discovery of transporter-like proteins acting as nutrient sensors. In addition, a number of cellular targets, like carbohydrate stores, stress tolerance, and ribosomal gene expression, are controlled by the presence of multiple nutrients. The protein kinase A signaling pathway plays a major role in this general nutrient response. It has led to the discovery of nutrient transceptors (transporter receptors) as nutrient sensors. Major shortcomings in our knowledge are the relationship between rapid and steady-state nutrient signaling, the role of metabolic intermediates in intracellular nutrient sensing, and the identity of the nutrient sensors controlling cellular growth.
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Affiliation(s)
- Michaela Conrad
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU LeuvenLeuven-Heverlee, Flanders, Belgium
- Department of Molecular Microbiology, VIBLeuven-Heverlee, Flanders, Belgium
| | - Joep Schothorst
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU LeuvenLeuven-Heverlee, Flanders, Belgium
- Department of Molecular Microbiology, VIBLeuven-Heverlee, Flanders, Belgium
| | - Harish Nag Kankipati
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU LeuvenLeuven-Heverlee, Flanders, Belgium
- Department of Molecular Microbiology, VIBLeuven-Heverlee, Flanders, Belgium
| | - Griet Van Zeebroeck
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU LeuvenLeuven-Heverlee, Flanders, Belgium
- Department of Molecular Microbiology, VIBLeuven-Heverlee, Flanders, Belgium
| | - Marta Rubio-Texeira
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU LeuvenLeuven-Heverlee, Flanders, Belgium
- Department of Molecular Microbiology, VIBLeuven-Heverlee, Flanders, Belgium
| | - Johan M Thevelein
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU LeuvenLeuven-Heverlee, Flanders, Belgium
- Department of Molecular Microbiology, VIBLeuven-Heverlee, Flanders, Belgium
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40
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Roy A, Kim JH. Endocytosis and vacuolar degradation of the yeast cell surface glucose sensors Rgt2 and Snf3. J Biol Chem 2014; 289:7247-7256. [PMID: 24451370 DOI: 10.1074/jbc.m113.539411] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sensing and signaling the presence of extracellular glucose is crucial for the yeast Saccharomyces cerevisiae because of its fermentative metabolism, characterized by high glucose flux through glycolysis. The yeast senses glucose through the cell surface glucose sensors Rgt2 and Snf3, which serve as glucose receptors that generate the signal for induction of genes involved in glucose uptake and metabolism. Rgt2 and Snf3 detect high and low glucose concentrations, respectively, perhaps because of their different affinities for glucose. Here, we provide evidence that cell surface levels of glucose sensors are regulated by ubiquitination and degradation. The glucose sensors are removed from the plasma membrane through endocytosis and targeted to the vacuole for degradation upon glucose depletion. The turnover of the glucose sensors is inhibited in endocytosis defective mutants, and the sensor proteins with a mutation at their putative ubiquitin-acceptor lysine residues are resistant to degradation. Of note, the low affinity glucose sensor Rgt2 remains stable only in high glucose grown cells, and the high affinity glucose sensor Snf3 is stable only in cells grown in low glucose. In addition, constitutively active, signaling forms of glucose sensors do not undergo endocytosis, whereas signaling defective sensors are constitutively targeted for degradation, suggesting that the stability of the glucose sensors may be associated with their ability to sense glucose. Therefore, our findings demonstrate that the amount of glucose available dictates the cell surface levels of the glucose sensors and that the regulation of glucose sensors by glucose concentration may enable yeast cells to maintain glucose sensing activity at the cell surface over a wide range of glucose concentrations.
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Affiliation(s)
- Adhiraj Roy
- Department of Biochemistry and Molecular Medicine, George Washington University Medical Center, Washington, D.C. 20037
| | - Jeong-Ho Kim
- Department of Biochemistry and Molecular Medicine, George Washington University Medical Center, Washington, D.C. 20037.
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41
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Weinhandl K, Winkler M, Glieder A, Camattari A. Carbon source dependent promoters in yeasts. Microb Cell Fact 2014; 13:5. [PMID: 24401081 PMCID: PMC3897899 DOI: 10.1186/1475-2859-13-5] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 12/16/2013] [Indexed: 11/22/2022] Open
Abstract
Budding yeasts are important expression hosts for the production of recombinant proteins. The choice of the right promoter is a crucial point for efficient gene expression, as most regulations take place at the transcriptional level. A wide and constantly increasing range of inducible, derepressed and constitutive promoters have been applied for gene expression in yeasts in the past; their different behaviours were a reflection of the different needs of individual processes. Within this review we summarize the majority of the large available set of carbon source dependent promoters for protein expression in yeasts, either induced or derepressed by the particular carbon source provided. We examined the most common derepressed promoters for Saccharomyces cerevisiae and other yeasts, and described carbon source inducible promoters and promoters induced by non-sugar carbon sources. A special focus is given to promoters that are activated as soon as glucose is depleted, since such promoters can be very effective and offer an uncomplicated and scalable cultivation procedure.
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Affiliation(s)
| | | | | | - Andrea Camattari
- Institute of Molecular Biotechnology, Technical University Graz, Graz, Austria.
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42
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Roy A, Jouandot D, Cho KH, Kim JH. Understanding the mechanism of glucose-induced relief of Rgt1-mediated repression in yeast. FEBS Open Bio 2014; 4:105-11. [PMID: 24490134 PMCID: PMC3907687 DOI: 10.1016/j.fob.2013.12.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 12/05/2013] [Accepted: 12/24/2013] [Indexed: 11/24/2022] Open
Abstract
The yeast Rgt1 repressor inhibits transcription of the glucose transporter (HXT) genes in the absence of glucose. It does so by recruiting the general corepressor complex Ssn6-Tup1 and the HXT corepressor Mth1. In the presence of glucose, Rgt1 is phosphorylated by the cAMP-activated protein kinase A (PKA) and dissociates from the HXT promoters, resulting in expression of HXT genes. In this study, using Rgt1 chimeras that bind DNA constitutively, we investigate how glucose regulates Rgt1 function. Our results show that the DNA-bound Rgt1 constructs repress expression of the HXT1 gene in conjunction with Ssn6-Tup1 and Mth1, and that this repression is lifted when they dissociate from Ssn6-Tup1 in high glucose conditions. Mth1 mediates the interaction between the Rgt1 constructs and Ssn6-Tup1, and glucose-induced downregulation of Mth1 enables PKA to phosphorylate the Rgt1 constructs. This phosphorylation induces dissociation of Ssn6-Tup1 from the DNA-bound Rgt1 constructs, resulting in derepression of HXT gene expression. Therefore, Rgt1 removal from DNA occurs in response to glucose but is not necessary for glucose induction of HXT gene expression, suggesting that glucose regulates Rgt1 function by primarily modulating the Rgt1 interaction with Ssn6-Tup1. Rgt1 represses gene expression by recruiting Ssn6-Tup1 to its target promoters. Dissociation of Rgt1 from DNA is not required to lift Rgt1-mediated repression. Rgt1 dissociation from Ssn6-Tup1 is sufficient for derepression of its target genes.
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Affiliation(s)
- Adhiraj Roy
- Department of Biochemistry and Molecular Medicine, The George Washington University Medical Center, 2300 Eye Street, Washington, DC 20037, USA
| | - David Jouandot
- Department of Biological Sciences, The University of Southern Mississippi, 118 College Dr., Hattiesburg, MS 39406, USA
| | - Kyu Hong Cho
- Department of Microbiology, Southern Illinois University Carbondale, 1125 Lincoln Drive, Carbondale, IL 62901, USA
| | - Jeong-Ho Kim
- Department of Biochemistry and Molecular Medicine, The George Washington University Medical Center, 2300 Eye Street, Washington, DC 20037, USA
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Lin Y, Chomvong K, Acosta-Sampson L, Estrela R, Galazka JM, Kim SR, Jin YS, Cate JHD. Leveraging transcription factors to speed cellobiose fermentation by Saccharomyces cerevisiae. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:126. [PMID: 25435910 PMCID: PMC4243952 DOI: 10.1186/s13068-014-0126-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 08/06/2014] [Indexed: 05/02/2023]
Abstract
BACKGROUND Saccharomyces cerevisiae, a key organism used for the manufacture of renewable fuels and chemicals, has been engineered to utilize non-native sugars derived from plant cell walls, such as cellobiose and xylose. However, the rates and efficiencies of these non-native sugar fermentations pale in comparison with those of glucose. Systems biology methods, used to understand biological networks, hold promise for rational microbial strain development in metabolic engineering. Here, we present a systematic strategy for optimizing non-native sugar fermentation by recombinant S. cerevisiae, using cellobiose as a model. RESULTS Differences in gene expression between cellobiose and glucose metabolism revealed by RNA deep sequencing indicated that cellobiose metabolism induces mitochondrial activation and reduces amino acid biosynthesis under fermentation conditions. Furthermore, glucose-sensing and signaling pathways and their target genes, including the cAMP-dependent protein kinase A pathway controlling the majority of glucose-induced changes, the Snf3-Rgt2-Rgt1 pathway regulating hexose transport, and the Snf1-Mig1 glucose repression pathway, were at most only partially activated under cellobiose conditions. To separate correlations from causative effects, the expression levels of 19 transcription factors perturbed under cellobiose conditions were modulated, and the three strongest promoters under cellobiose conditions were applied to fine-tune expression of the heterologous cellobiose-utilizing pathway. Of the changes in these 19 transcription factors, only overexpression of SUT1 or deletion of HAP4 consistently improved cellobiose fermentation. SUT1 overexpression and HAP4 deletion were not synergistic, suggesting that SUT1 and HAP4 may regulate overlapping genes important for improved cellobiose fermentation. Transcription factor modulation coupled with rational tuning of the cellobiose consumption pathway significantly improved cellobiose fermentation. CONCLUSIONS We used systems-level input to reveal the regulatory mechanisms underlying suboptimal metabolism of the non-glucose sugar cellobiose. By identifying key transcription factors that cause suboptimal cellobiose fermentation in engineered S. cerevisiae, and by fine-tuning the expression of a heterologous cellobiose consumption pathway, we were able to greatly improve cellobiose fermentation by engineered S. cerevisiae. Our results demonstrate a powerful strategy for applying systems biology methods to rapidly identify metabolic engineering targets and overcome bottlenecks in performance of engineered strains.
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Affiliation(s)
- Yuping Lin
- />Departments of Molecular and Cell Biology, University of California, Berkeley, CA 94720 USA
| | - Kulika Chomvong
- />Plant and Microbial Biology, University of California, Berkeley, CA 94720 USA
| | - Ligia Acosta-Sampson
- />Departments of Molecular and Cell Biology, University of California, Berkeley, CA 94720 USA
| | - Raíssa Estrela
- />Departments of Molecular and Cell Biology, University of California, Berkeley, CA 94720 USA
| | - Jonathan M Galazka
- />Departments of Molecular and Cell Biology, University of California, Berkeley, CA 94720 USA
| | - Soo Rin Kim
- />Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 USA
- />Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 USA
| | - Yong-Su Jin
- />Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 USA
- />Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 USA
| | - Jamie HD Cate
- />Departments of Molecular and Cell Biology, University of California, Berkeley, CA 94720 USA
- />Chemistry, University of California, Berkeley, CA 94720 USA
- />Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
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Abstract
The AMP-activated protein kinase (AMPK) is a major stress sensor of mammalian cells. AMPK's homolog in the yeast Saccharomyces cerevisiae, the SNF1 protein kinase, is a central regulator of carbon metabolism that inhibits the Snf3/Rgt2-Rgt1 glucose sensing pathway and activates genes involved in respiration. We present evidence that glucose induces modification of the Snf1 catalytic subunt of SNF1 with the small ubiquitin-like modifier protein SUMO, catalyzed by the SUMO (E3) ligase Mms21. Our results suggest that SUMOylation of Snf1 inhibits its function in two ways: by interaction of SUMO attached to lysine 549 with a SUMO-interacting sequence motif located near the active site of Snf1, and by targeting Snf1 for destruction via the Slx5-Slx8 (SUMO-directed) ubiquitin ligase. These findings reveal another way SNF1 function is regulated in response to carbon source.
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45
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Ziv N, Siegal ML, Gresham D. Genetic and nongenetic determinants of cell growth variation assessed by high-throughput microscopy. Mol Biol Evol 2013; 30:2568-78. [PMID: 23938868 PMCID: PMC3840306 DOI: 10.1093/molbev/mst138] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In microbial populations, growth initiation and proliferation rates are major components of fitness and therefore likely targets of selection. We used a high-throughput microscopy assay, which enables simultaneous analysis of tens of thousands of microcolonies, to determine the sources and extent of growth rate variation in the budding yeast (Saccharomyces cerevisiae) in different glucose environments. We find that cell growth rates are regulated by the extracellular concentration of glucose as proposed by Monod (1949), but that significant heterogeneity in growth rates is observed among genetically identical individuals within an environment. Yeast strains isolated from different geographic locations and habitats differ in their growth rate responses to different glucose concentrations. Inheritance patterns suggest that the genetic determinants of growth rates in different glucose concentrations are distinct. In addition, we identified genotypes that differ in the extent of variation in growth rate within an environment despite nearly identical mean growth rates, providing evidence that alleles controlling phenotypic variability segregate in yeast populations. We find that the time to reinitiation of growth (lag) is negatively correlated with growth rate, yet this relationship is strain-dependent. Between environments, the respirative activity of individual cells negatively correlates with glucose abundance and growth rate, but within an environment respirative activity and growth rate show a positive correlation, which we propose reflects differences in protein expression capacity. Our study quantifies the sources of genetic and nongenetic variation in cell growth rates in different glucose environments with unprecedented precision, facilitating their molecular genetic dissection.
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Affiliation(s)
- Naomi Ziv
- Center for Genomics and Systems Biology, Department of Biology, New York University
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46
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Kim JH, Roy A, Jouandot D, Cho KH. The glucose signaling network in yeast. Biochim Biophys Acta Gen Subj 2013; 1830:5204-10. [PMID: 23911748 DOI: 10.1016/j.bbagen.2013.07.025] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 07/24/2013] [Accepted: 07/26/2013] [Indexed: 01/26/2023]
Abstract
BACKGROUND Most cells possess a sophisticated mechanism for sensing glucose and responding to it appropriately. Glucose sensing and signaling in the budding yeast Saccharomyces cerevisiae represent an important paradigm for understanding how extracellular signals lead to changes in the gene expression program in eukaryotes. SCOPE OF REVIEW This review focuses on the yeast glucose sensing and signaling pathways that operate in a highly regulated and cooperative manner to bring about glucose-induction of HXT gene expression. MAJOR CONCLUSIONS The yeast cells possess a family of glucose transporters (HXTs), with different kinetic properties. They employ three major glucose signaling pathways-Rgt2/Snf3, AMPK, and cAMP-PKA-to express only those transporters best suited for the amounts of glucose available. We discuss the current understanding of how these pathways are integrated into a regulatory network to ensure efficient uptake and utilization of glucose. GENERAL SIGNIFICANCE Elucidating the role of multiple glucose signals and pathways involved in glucose uptake and metabolism in yeast may reveal the molecular basis of glucose homeostasis in humans, especially under pathological conditions, such as hyperglycemia in diabetics and the elevated rate of glycolysis observed in many solid tumors.
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Affiliation(s)
- Jeong-Ho Kim
- Department of Biochemistry and Molecular Medicine, The George Washington University Medical Center, 2300 Eye Street, Washington, DC 20037, USA.
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47
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Liu TB, Wang Y, Baker GM, Fahmy H, Jiang L, Xue C. The glucose sensor-like protein Hxs1 is a high-affinity glucose transporter and required for virulence in Cryptococcus neoformans. PLoS One 2013; 8:e64239. [PMID: 23691177 PMCID: PMC3653957 DOI: 10.1371/journal.pone.0064239] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 04/08/2013] [Indexed: 01/14/2023] Open
Abstract
Cryptococcus is a major fungal pathogen that frequently causes systemic infection in patients with compromised immunity. Glucose, an important signal molecule and the preferred carbon source for Cryptococcus, plays a critical role in fungal development and virulence. Cryptococcus contains more than 50 genes sharing high sequence homology with hexose transporters in Saccharomyces cerevisiae. However, there is no report on their function in glucose sensing or transport. In this study, we investigated two hexose transporter-like proteins (Hxs1 and Hxs2) in Cryptococcus that share the highest sequence identity with the glucose sensors Snf3 and Rgt2 in S. cerevisiae. The expression of HXS1 is repressed by high glucose, while the HXS2 expression is not regulated by glucose. Functional studies showed that Hxs1 is required for fungal resistance to oxidative stress and fungal virulence. The hxs1Δ mutant exhibited a significant reduction in glucose uptake activity, indicating that Hxs1 is required for glucose uptake. Heterologous expression of Cryptococcus HXS1 rendered the S. cerevisiae mutant lacking all 20 hexose transporters a high glucose uptake activity, demonstrating that Hxs1 functions as a glucose transporter. Heterologous expression of HXS1 in the snf3Δ rgt2Δ double mutant did not complement its growth in YPD medium containing the respiration inhibitor antimycin A, suggesting that Hxs1 may not function as a glucose sensor. Taken together, our results demonstrate that Hxs1 is a high-affinity glucose transporter and required for fungal virulence.
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Affiliation(s)
- Tong-Bao Liu
- Public Health Research Institute Center, University of Medicine and Dentistry of New Jersey, Newark, New Jersey, USA
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48
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Roy A, Shin YJ, Cho KH, Kim JH. Mth1 regulates the interaction between the Rgt1 repressor and the Ssn6-Tup1 corepressor complex by modulating PKA-dependent phosphorylation of Rgt1. Mol Biol Cell 2013; 24:1493-503. [PMID: 23468525 PMCID: PMC3639059 DOI: 10.1091/mbc.e13-01-0047] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The yeast glucose transporter gene (HXT) repressor Rgt1 recruits the general corepressor complex Ssn6-Tup1 to bring about repression. The glucose-responsive transcription factor Mth1 is a transcriptional corepressor that mediates the interaction of Rgt1 with Ssn6-Tup1 by blocking the PKA-dependent phosphorylation of Rgt1. Glucose uptake, the first, rate-limiting step of its utilization, is facilitated by glucose transporters. Expression of several glucose transporter (HXT) genes in yeast is repressed by the Rgt1 repressor, which recruits the glucose-responsive transcription factor Mth1 and the general corepressor complex Ssn6-Tup1 in the absence of glucose; however, it is derepressed when Mth1 is inactivated by glucose. Here we show that Ssn6-Tup1 interferes with the DNA-binding ability of Rgt1 in the absence of Mth1 and that the Rgt1 function abrogated by Ssn6 overexpression is restored by co-overexpression of Mth1. Thus Mth1 likely regulates Rgt1 function not by modulating its DNA-binding activity directly but by functionally antagonizing Ssn6-Tup1. Mth1 does so by acting as a scaffold-like protein to recruit Ssn6-Tup1 to Rgt1. Supporting evidence shows that Mth1 blocks the protein kinase A–dependent phosphorylation of Rgt1 that impairs the ability of Rgt1 to interact with Ssn6-Tup1. Of note, Rgt1 can bind DNA in the absence of Ssn6-Tup1 but does not inhibit transcription, suggesting that dissociation of Rgt1 from Ssn6-Tup1, but not from DNA, is necessary and sufficient for the expression of its target genes. Taken together, these findings show that Mth1 is a transcriptional corepressor that facilitates the recruitment of Ssn6-Tup1 by Rgt1.
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Affiliation(s)
- Adhiraj Roy
- Department of Biochemistry and Molecular Biology, George Washington University Medical Center, Washington, DC 20037, USA
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Regulations of sugar transporters: insights from yeast. Curr Genet 2013; 59:1-31. [PMID: 23455612 DOI: 10.1007/s00294-013-0388-8] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 01/28/2013] [Accepted: 02/02/2013] [Indexed: 12/24/2022]
Abstract
Transport across the plasma membrane is the first step at which nutrient supply is tightly regulated in response to intracellular needs and often also rapidly changing external environment. In this review, I describe primarily our current understanding of multiple interconnected glucose-sensing systems and signal-transduction pathways that ensure fast and optimum expression of genes encoding hexose transporters in three yeast species, Saccharomyces cerevisiae, Kluyveromyces lactis and Candida albicans. In addition, an overview of GAL- and MAL-specific regulatory networks, controlling galactose and maltose utilization, is provided. Finally, pathways generating signals inducing posttranslational degradation of sugar transporters will be highlighted.
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Dietzel KL, Ramakrishnan V, Murphy EE, Bisson LF. MTH1 and RGT1 demonstrate combined haploinsufficiency in regulation of the hexose transporter genes in Saccharomyces cerevisiae. BMC Genet 2012; 13:107. [PMID: 23234240 PMCID: PMC3564936 DOI: 10.1186/1471-2156-13-107] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 12/04/2012] [Indexed: 02/04/2023] Open
Abstract
Background The SNF3 gene in the yeast Saccharomyces cerevisiae encodes a low glucose sensor that regulates expression of an important subset of the hexose transporter (HXT) superfamily. Null mutations of snf3 result in a defect in growth on low glucose concentrations due to the inability to relieve repression of a subset of the HXT genes. The snf3 null mutation phenotype is suppressed by the loss of either one of the downstream co-repressor proteins Rgt1p or Mth1p. The relief of repression allows expression of HXT transporter proteins, the resumption of glucose uptake and therefore of growth in the absence of a functional Snf3 sensor. Results Strains heterozygous for both the RGT1 and MTH1 genes (RGT1/rgt1Δ MTH1/mth1Δ snf3Δ/snf3Δ) but homozygous for the snf3∆ were found to grow on low glucose. Since null alleles in the heterozygous state lead to suppression, MTH1 and RGT1 display the phenomenon of combined haploinsufficiency. This observed haploinsufficiency is consistent with the finding of repressor titration as a mechanism of suppression of snf3. Mutants of the STD1 homolog of MTH1 did not display haploinsufficiency singly or in combination with mutations in RGT1. HXT gene reporter fusion assays indicated that the presence of heterozygosity at the MTH1 and RGT1 alleles leads to increased expression of the HXT2 gene. Deletion of the HXT2 gene in a heterozygous diploid, RGT1/rgt1Δ MTH1/mth1Δ snf3Δ/snf3Δ hxt2Δ/hxt2Δ, prevented the suppression of snf3Δ. Conclusions These findings support the model of relief of repression as the mechanism of restoration of growth on low glucose concentrations in the absence of functional Snf3p. Further, the observation that HXT2 is the gene responsible for restoration of growth under these conditions suggests that the numbers of repressor binding domains found in the regulatory regions of members of the HXT family may have biological relevance and enable differential regulation.
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Affiliation(s)
- Kevin L Dietzel
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, 95616, USA
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