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Váchová L, Plocek V, Maršíková J, Rešetárová S, Hatáková L, Palková Z. Differential stability of Gcn4p controls its cell-specific activity in differentiated yeast colonies. mBio 2024; 15:e0068924. [PMID: 38624209 PMCID: PMC11077963 DOI: 10.1128/mbio.00689-24] [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: 03/07/2024] [Accepted: 03/22/2024] [Indexed: 04/17/2024] Open
Abstract
Gcn4p belongs to conserved AP-1 transcription factors involved in many cellular processes, including cell proliferation, stress response, and nutrient availability in yeast and mammals. AP-1 activities are regulated at different levels, such as translational activation or protein degradation, which increases the variability of regulation under different conditions. Gcn4p activity in unstructured yeast liquid cultures increases upon amino acid deficiency and is rapidly eliminated upon amino acid excess. Gcn2p kinase is the major described regulator of Gcn4p that enables GCN4 mRNA translation via the uORFs mechanism. Here, we show that Gcn4p is specifically active in U cells in the upper regions and inactive in L cells in the lower regions of differentiated colonies. Using in situ microscopy in combination with analysis of mutants and strains with GFP at different positions in the translational regulatory region of Gcn4p, we show that cell-specific Gcn4p activity is independent of Gcn2p or other translational or transcriptional regulation. Genetically, biochemically, and microscopically, we identified cell-specific proteasomal degradation as a key mechanism that diversifies Gcn4p function between U and L cells. The identified regulation leading to active Gcn4p in U cells with amino acids and efficient degradation in starved L cells differs from known regulations of Gcn4p in yeast but shows similarities to the activity of AP-1 ATF4 in mammals during insulin signaling. These findings may open new avenues for understanding the parallel activities of Gcn4p/ATF4 and reveal a novel biological role for cell type-specific regulation of proteasome-dependent degradation.IMPORTANCEIn nature, microbes usually live in spatially structured communities and differentiate into precisely localized, functionally specialized cells. The coordinated interplay of cells and their response to environmental changes, such as starvation, followed by metabolic adaptation, is critical for the survival of the entire community. Transcription factor Gcn4p is responsible for yeast adaptation under amino acid starvation in liquid cultures, and its activity is regulated mainly at the level of translation involving Gcn2p kinase. Whether Gcn4p functions in structured communities was unknown. We show that translational regulation of Gcn4p plays no role in the development of colony subpopulations; the main regulation occurs at the level of stabilization of the Gcn4p molecule in the cells of one subpopulation and its proteasomal degradation in the other. This regulation ensures specific spatiotemporal activity of Gcn4p in the colony. Our work highlights differences in regulatory networks in unorganized populations and organized structures of yeast, which in many respects resemble multicellular organisms.
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Affiliation(s)
- Libuše Váchová
- Institute of Microbiology of the Czech Academy of Sciences, BIOCEV, Prague, Czech Republic
| | - Vítězslav Plocek
- Faculty of Science, Charles University, BIOCEV, Prague, Czech Republic
| | - Jana Maršíková
- Faculty of Science, Charles University, BIOCEV, Prague, Czech Republic
| | - Stanislava Rešetárová
- Institute of Microbiology of the Czech Academy of Sciences, BIOCEV, Prague, Czech Republic
| | | | - Zdena Palková
- Faculty of Science, Charles University, BIOCEV, Prague, Czech Republic
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2
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Brückner S, Schubert R, Kraushaar T, Hartmann R, Hoffmann D, Jelli E, Drescher K, Müller DJ, Oliver Essen L, Mösch HU. Kin discrimination in social yeast is mediated by cell surface receptors of the Flo11 adhesin family. eLife 2020; 9:55587. [PMID: 32286952 PMCID: PMC7156268 DOI: 10.7554/elife.55587] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 04/03/2020] [Indexed: 02/06/2023] Open
Abstract
Microorganisms have evolved specific cell surface molecules that enable discrimination between cells from the same and from a different kind. Here, we investigate the role of Flo11-type cell surface adhesins from social yeasts in kin discrimination. We measure the adhesion forces mediated by Flo11A-type domains using single-cell force spectroscopy, quantify Flo11A-based cell aggregation in populations and determine the Flo11A-dependent segregation of competing yeast strains in biofilms. We find that Flo11A domains from diverse yeast species confer remarkably strong adhesion forces by establishing homotypic interactions between single cells, leading to efficient cell aggregation and biofilm formation in homogenous populations. Heterotypic interactions between Flo11A domains from different yeast species or Saccharomyces cerevisiae strains confer weak adhesive forces and lead to efficient strain segregation in heterogenous populations, indicating that in social yeasts Flo11A-mediated cell adhesion is a major mechanism for kin discrimination at species and sub-species levels. These findings, together with our structure and mutation analysis of selected Flo11A domains, provide a rationale of how cell surface receptors have evolved in microorganisms to mediate kin discrimination.
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Affiliation(s)
- Stefan Brückner
- Department of Genetics, Philipps-Universität Marburg, Marburg, Germany
| | - Rajib Schubert
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | - Timo Kraushaar
- Department of Biochemistry, Philipps-Universität Marburg, Marburg, Germany
| | - Raimo Hartmann
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Daniel Hoffmann
- Department of Genetics, Philipps-Universität Marburg, Marburg, Germany
| | - Eric Jelli
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Knut Drescher
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Daniel J Müller
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | - Lars Oliver Essen
- Department of Biochemistry, Philipps-Universität Marburg, Marburg, Germany.,LOEWE Center for Synthetic Microbiology, Philipps-Universität Marburg, Marburg, Germany
| | - Hans-Ulrich Mösch
- Department of Genetics, Philipps-Universität Marburg, Marburg, Germany.,LOEWE Center for Synthetic Microbiology, Philipps-Universität Marburg, Marburg, Germany
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3
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Kock M, Brückner S, Wozniak N, Maestre-Reyna M, Veelders M, Schlereth J, Mösch HU, Essen LO. Structural and Functional Characterization of PA14/Flo5-Like Adhesins From Komagataella pastoris. Front Microbiol 2018; 9:2581. [PMID: 30425696 PMCID: PMC6218569 DOI: 10.3389/fmicb.2018.02581] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Accepted: 10/10/2018] [Indexed: 12/19/2022] Open
Abstract
Cell–cell and cell-substrate based adhesion of yeasts are major determinants of their adoption of different life styles. Genome-mining of ascomycetous GPI-anchored cell wall proteins with lectin-like PA14 domains identified a unique class of putative adhesins in the clade of methylotrophic Komagataella yeasts, many of which are known to colonize plants and insects involving yet unknown adhesion mechanisms. Here, we report the functional and structural analysis of two of its members: KpFlo1 (=Cea1), that is highly specific for terminal N-acetylglucosamine moieties, and KpFlo2, which represents an orphan lectin with intact binding site but unknown specificity. Crystal structures of the Cea1 adhesion domain complexed to N-acetylglucosamine and N,N′-diacetylchitobiose reveal a Ca2+-dependent binding mode that differs from other members of the PA14/Flo5 adhesin family. Heterologous expression of Cea1A in Saccharomyces cerevisiae promotes cellular adhesion to non-reducing ends of non-crystalline chitin. Overall, our data suggest that high-affinity recognition of β-GlcNAc-capped glycans by Cea1 enable Komagataella species to interact with surface cues present in fungi and insects.
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Affiliation(s)
- Michael Kock
- Department of Biochemistry, Faculty of Chemistry, Philipps University of Marburg, Marburg, Germany
| | - Stefan Brückner
- Department of Genetics, Faculty of Biology, Philipps University of Marburg, Marburg, Germany
| | - Nina Wozniak
- Department of Genetics, Faculty of Biology, Philipps University of Marburg, Marburg, Germany
| | | | - Maik Veelders
- Department of Biochemistry, Faculty of Chemistry, Philipps University of Marburg, Marburg, Germany
| | - Julia Schlereth
- Department of Biochemistry, Faculty of Chemistry, Philipps University of Marburg, Marburg, Germany
| | - Hans-Ulrich Mösch
- Department of Genetics, Faculty of Biology, Philipps University of Marburg, Marburg, Germany.,LOEWE Center for Synthetic Microbiology, Philipps University of Marburg, Marburg, Germany
| | - Lars-Oliver Essen
- Department of Biochemistry, Faculty of Chemistry, Philipps University of Marburg, Marburg, Germany.,LOEWE Center for Synthetic Microbiology, Philipps University of Marburg, Marburg, Germany
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4
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Conrad M, Kankipati HN, Kimpe M, Van Zeebroeck G, Zhang Z, Thevelein JM. The nutrient transceptor/PKA pathway functions independently of TOR and responds to leucine and Gcn2 in a TOR-independent manner. FEMS Yeast Res 2018; 17:3950251. [PMID: 28810702 PMCID: PMC5812495 DOI: 10.1093/femsyr/fox048] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 07/06/2017] [Indexed: 12/25/2022] Open
Abstract
Two nutrient-controlled signalling pathways, the PKA and TOR pathway, play a major role in nutrient regulation of growth as well as growth-correlated properties in yeast. The relationship between the two pathways is not well understood. We have used Gap1 and Pho84 transceptor-mediated activation of trehalase and phosphorylation of fragmented Sch9 as a read-out for rapid nutrient activation of PKA or TORC1, respectively. We have identified conditions in which L-citrulline-induced activation of Sch9 phosphorylation is compromised, but not activation of trehalase: addition of the TORC1 inhibitor, rapamycin and low levels of L-citrulline. The same disconnection was observed for phosphate activation in phosphate-starved cells. The leu2 auxotrophic mutation reduces amino acid activation of trehalase, which is counteracted by deletion of GCN2. Both effects were also independent of TORC1. Our results show that rapid activation of the TOR pathway by amino acids is not involved in rapid activation of the PKA pathway and that effects of Gcn2 inactivation as well as leu2 auxotrophy all act independently of the TOR pathway. Hence, rapid nutrient signalling to PKA and TOR in cells arrested by nutrient starvation acts through parallel pathways.
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Affiliation(s)
- Michaela Conrad
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, B-3001 KU Leuven, Belgium.,Center for Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium
| | - Harish Nag Kankipati
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, B-3001 KU Leuven, Belgium.,Center for Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium
| | - Marlies Kimpe
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, B-3001 KU Leuven, Belgium.,Center for Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium
| | - Griet Van Zeebroeck
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, B-3001 KU Leuven, Belgium.,Center for Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium
| | - Zhiqiang Zhang
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, B-3001 KU Leuven, Belgium.,Center for Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium
| | - Johan M Thevelein
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, B-3001 KU Leuven, Belgium.,Center for Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium
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5
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Dal81 Regulates Expression of Arginine Metabolism Genes in Candida parapsilosis. mSphere 2018; 3:3/2/e00028-18. [PMID: 29564399 PMCID: PMC5853489 DOI: 10.1128/msphere.00028-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 02/08/2018] [Indexed: 01/26/2023] Open
Abstract
Fungi can use a wide variety of nitrogen sources. In the absence of preferred sources such as ammonium, glutamate, and glutamine, secondary sources, including most other amino acids, are used. Expression of the nitrogen utilization pathways is very strongly controlled at the transcriptional level. Here, we investigated the regulation of nitrogen utilization in the pathogenic yeast Candida parapsilosis. We found that the functions of many regulators are conserved with respect to Saccharomyces cerevisiae and other fungi. For example, the core GATA activators GAT1 and GLN3 have a conserved role in nitrogen catabolite repression (NCR). There is one ortholog of GZF3 and DAL80, which represses expression of genes in preferred nitrogen sources. The regulators PUT3 and UGA3 are required for metabolism of proline and γ-aminobutyric acid (GABA), respectively. However, the role of the Dal81 transcription factor is distinctly different. In S. cerevisiae, Dal81 is a positive regulator of acquisition of nitrogen from GABA, allantoin, urea, and leucine, and it is required for maximal induction of expression of the relevant pathway genes. In C. parapsilosis, induction of GABA genes is independent of Dal81, and deleting DAL81 has no effect on acquisition of nitrogen from GABA or allantoin. Instead, Dal81 represses arginine synthesis during growth under preferred nitrogen conditions. IMPORTANCE Utilization of nitrogen by fungi is controlled by nitrogen catabolite repression (NCR). Expression of many genes is switched off during growth on nonpreferred nitrogen sources. Gene expression is regulated through a combination of activation and repression. Nitrogen regulation has been studied best in the model yeast Saccharomyces cerevisiae. We found that although many nitrogen regulators have a conserved function in Saccharomyces species, some do not. The Dal81 transcriptional regulator has distinctly different functions in S. cerevisiae and C. parapsilosis. In the former, it regulates utilization of nitrogen from GABA and allantoin, whereas in the latter, it regulates expression of arginine synthesis genes. Our findings make an important contribution to our understanding of nitrogen regulation in a human-pathogenic fungus.
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6
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Mohler K, Mann R, Kyle A, Reynolds N, Ibba M. Aminoacyl-tRNA quality control is required for efficient activation of the TOR pathway regulator Gln3p. RNA Biol 2017; 15:594-603. [PMID: 28910581 DOI: 10.1080/15476286.2017.1379635] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The aminoacylation status of the cellular tRNA pool regulates both general amino acid control (GAAC) and target of rapamycin (TOR) stress response pathways in yeast. Consequently, fidelity of translation at the level of aminoacyl-tRNA synthesis plays a central role in determining accuracy and sensitivity of stress responses. To investigate effects of translational quality control (QC) on cell physiology under stress conditions, phenotypic microarray analyses were used to identify changes in QC deficient cells. Nitrogen source growth assays showed QC deficient yeast grew differently compared to WT. The QC deficient strain was more tolerant to caffeine treatment than wild type through altered interactions with the TOR and GAAC pathways. Increased caffeine tolerance of the QC deficient strain was consistent with the observation that the activity of Gln3p, a transcription factor controlled by the TOR pathway, is decreased in the QC deficient strain compared to WT. GCN4 translation, which is typically repressed in the absence of nutritional stress, was enhanced in the QC deficient strain through TOR inhibition. QC did not impact cell cycle regulation; however, the chronological lifespan of QC deficient yeast strains decreased compared to wild type, likely due to translational errors and alteration of the TOR-associated regulon. These findings support the idea that changes in translational fidelity provide a mechanism of cellular adaptation by modulating TOR activity. This, in turn, supports a central role for aminoacyl-tRNA synthesis QC in the integrated stress response by maintaining the proper aa-tRNA pools necessary to coordinate the GAAC and TOR.
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Affiliation(s)
- Kyle Mohler
- a Department of Microbiology , The Ohio State University , Columbus , Ohio , USA.,b Center for RNA Biology , The Ohio State University , Columbus , Ohio , USA
| | - Rebecca Mann
- a Department of Microbiology , The Ohio State University , Columbus , Ohio , USA
| | - Amanda Kyle
- a Department of Microbiology , The Ohio State University , Columbus , Ohio , USA
| | - Noah Reynolds
- a Department of Microbiology , The Ohio State University , Columbus , Ohio , USA
| | - Michael Ibba
- a Department of Microbiology , The Ohio State University , Columbus , Ohio , USA.,b Center for RNA Biology , The Ohio State University , Columbus , Ohio , USA
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7
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Responses of Saccharomyces cerevisiae to nitrogen starvation in wine alcoholic fermentation. Appl Microbiol Biotechnol 2015. [DOI: 10.1007/s00253-015-6810-z] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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8
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Auxotrophic Mutations Reduce Tolerance of Saccharomyces cerevisiae to Very High Levels of Ethanol Stress. EUKARYOTIC CELL 2015; 14:884-97. [PMID: 26116212 DOI: 10.1128/ec.00053-15] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 06/22/2015] [Indexed: 12/26/2022]
Abstract
Very high ethanol tolerance is a distinctive trait of the yeast Saccharomyces cerevisiae with notable ecological and industrial importance. Although many genes have been shown to be required for moderate ethanol tolerance (i.e., 6 to 12%) in laboratory strains, little is known of the much higher ethanol tolerance (i.e., 16 to 20%) in natural and industrial strains. We have analyzed the genetic basis of very high ethanol tolerance in a Brazilian bioethanol production strain by genetic mapping with laboratory strains containing artificially inserted oligonucleotide markers. The first locus contained the ura3Δ0 mutation of the laboratory strain as the causative mutation. Analysis of other auxotrophies also revealed significant linkage for LYS2, LEU2, HIS3, and MET15. Tolerance to only very high ethanol concentrations was reduced by auxotrophies, while the effect was reversed at lower concentrations. Evaluation of other stress conditions showed that the link with auxotrophy is dependent on the type of stress and the type of auxotrophy. When the concentration of the auxotrophic nutrient is close to that limiting growth, more stress factors can inhibit growth of an auxotrophic strain. We show that very high ethanol concentrations inhibit the uptake of leucine more than that of uracil, but the 500-fold-lower uracil uptake activity may explain the strong linkage between uracil auxotrophy and ethanol sensitivity compared to leucine auxotrophy. Since very high concentrations of ethanol inhibit the uptake of auxotrophic nutrients, the active uptake of scarce nutrients may be a major limiting factor for growth under conditions of ethanol stress.
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9
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Brice C, Sanchez I, Bigey F, Legras JL, Blondin B. A genetic approach of wine yeast fermentation capacity in nitrogen-starvation reveals the key role of nitrogen signaling. BMC Genomics 2014; 15:495. [PMID: 24947828 PMCID: PMC4073503 DOI: 10.1186/1471-2164-15-495] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 06/10/2014] [Indexed: 11/16/2022] Open
Abstract
Background In conditions of nitrogen limitation, Saccharomyces cerevisiae strains differ in their fermentation capacities, due to differences in their nitrogen requirements. The mechanisms ensuring the maintenance of glycolytic flux in these conditions are unknown. We investigated the genetic basis of these differences, by studying quantitative trait loci (QTL) in a population of 133 individuals from the F2 segregant population generated from a cross between two strains with different nitrogen requirements for efficient fermentation. Results By comparing two bulks of segregants with low and high nitrogen requirements, we detected four regions making a quantitative contribution to these traits. We identified four polymorphic genes, in three of these four regions, for which involvement in the phenotype was validated by hemizygote comparison. The functions of the four validated genes, GCN1, MDS3, ARG81 and BIO3, relate to key roles in nitrogen metabolism and signaling, helping to maintain fermentation performance. Conclusions This study reveals that differences in nitrogen requirement between yeast strains results from a complex allelic combination. The identification of three genes involved in sensing and signaling nitrogen and specially one from the TOR pathway as affecting nitrogen requirements suggests a role for this pathway in regulating the fermentation rate in starvation through unknown mechanisms linking nitrogen signaling to glycolytic flux. Electronic supplementary material The online version of this article (doi: 10.1186/1471-2164-15-495) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | - Bruno Blondin
- INRA, UMR1083 Science pour l'Œnologie, 2 Place Viala, F-34060 Montpellier, France.
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10
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Ramachandra S, Linde J, Brock M, Guthke R, Hube B, Brunke S. Regulatory networks controlling nitrogen sensing and uptake in Candida albicans. PLoS One 2014; 9:e92734. [PMID: 24651113 PMCID: PMC3961412 DOI: 10.1371/journal.pone.0092734] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 02/24/2014] [Indexed: 12/22/2022] Open
Abstract
Nitrogen is one of the key nutrients for microbial growth. During infection, pathogenic fungi like C. albicans need to acquire nitrogen from a broad range of different and changing sources inside the host. Detecting the available nitrogen sources and adjusting the expression of genes for their uptake and degradation is therefore crucial for survival and growth as well as for establishing an infection. Here, we analyzed the transcriptional response of C. albicans to nitrogen starvation and feeding with the infection-relevant nitrogen sources arginine and bovine serum albumin (BSA), representing amino acids and proteins, respectively. The response to nitrogen starvation was marked by an immediate repression of protein synthesis and an up-regulation of general amino acid permeases, as well as an up-regulation of autophagal processes in its later stages. Feeding with arginine led to a fast reduction in expression of general permeases for amino acids and to resumption of protein synthesis. The response to BSA feeding was generally slower, and was additionally characterized by an up-regulation of oligopeptide transporter genes. From time-series data, we inferred network interaction models for genes relevant in nitrogen detection and uptake. Each individual network was found to be largely specific for the experimental condition (starvation or feeding with arginine or BSA). In addition, we detected several novel connections between regulator and effector genes, with putative roles in nitrogen uptake. We conclude that C. albicans adopts a particular nitrogen response network, defined by sets of specific gene-gene connections for each environmental condition. All together, they form a grid of possible gene regulatory networks, increasing the transcriptional flexibility of C. albicans.
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Affiliation(s)
- Shruthi Ramachandra
- Department of Microbial Biochemistry and Physiology, Leibniz Institute for Natural Product Research and Infection Biology – Hans Knoell Institute, Jena, Germany
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology – Hans Knoell Institute, Jena, Germany
| | - Jörg Linde
- Department of Systems Biology & Bioinformatics, Leibniz Institute for Natural Product Research and Infection Biology – Hans Knoell Institute, Jena, Germany
| | - Matthias Brock
- Department of Microbial Biochemistry and Physiology, Leibniz Institute for Natural Product Research and Infection Biology – Hans Knoell Institute, Jena, Germany
- Friedrich Schiller University, Jena, Germany
| | - Reinhard Guthke
- Department of Systems Biology & Bioinformatics, Leibniz Institute for Natural Product Research and Infection Biology – Hans Knoell Institute, Jena, Germany
| | - Bernhard Hube
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology – Hans Knoell Institute, Jena, Germany
- Center for Sepsis Control and Care (CSCC), Jena University Hospital, Jena, Germany
- Friedrich Schiller University, Jena, Germany
| | - Sascha Brunke
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology – Hans Knoell Institute, Jena, Germany
- Center for Sepsis Control and Care (CSCC), Jena University Hospital, Jena, Germany
- * E-mail:
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11
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Chen YL, Gao Y, Zhang KQ, Zou CG. Autophagy is required for trap formation in the nematode-trapping fungus Arthrobotrys oligospora. ENVIRONMENTAL MICROBIOLOGY REPORTS 2013; 5:511-7. [PMID: 23864564 DOI: 10.1111/1758-2229.12054] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 03/20/2013] [Indexed: 05/05/2023]
Abstract
Nematode-trapping fungi live mainly as saprobes in soil environments. When encountering nematodes, these fungi become 'carnivorous' and develop specialized trapping devices to attack their hosts for extracting nutrients, especially nitrogen source. Thus, nematode-trapping fungi are model organisms for understanding the molecular mechanism of the switch between saprobic and parasitic phases of pathogen life cycles. Arthrobotrys oligospora, one of the best-studied nematode-trapping fungi, mainly lives as a saprobe. In the presence of nematodes, A.oligospora enters the parasitic stage by forming adhesive reticulate traps to capture nematodes. In filamentous fungi, autophagy has been shown to be involved in morphogenesis and morphology. In this study, we demonstrate that autophagy is induced by nematodes during the early stage of trap formation in A.oligospora. Disruption of atg8 gene not only abolishes the nematode-induced autophagy, but also suppresses trap formation and reduces pathogenicity for nematodes. During the early stage of trap formation, the expression of genes involved in amino acid biosynthesis is upregulated and the transcriptional activity of GCN4 is induced in A.oligospora, suggesting that nematodes induce autophagy probably by triggering intracellular amino acid starvation. Autophagy is thus crucial for trap formation in A.oligospora during infection of nematodes.
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Affiliation(s)
- Yuan-Li Chen
- Laboratory for Conservation and Utilization of Bio-Resources, Yunnan University, Kunming, Yunnan, 650091, China
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12
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Mutual cross talk between the regulators Hac1 of the unfolded protein response and Gcn4 of the general amino acid control of Saccharomyces cerevisiae. EUKARYOTIC CELL 2013; 12:1142-54. [PMID: 23794510 DOI: 10.1128/ec.00123-13] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Hac1 is the activator of the cellular response to the accumulation of unfolded proteins in the endoplasmic reticulum. Hac1 function requires the activity of Gcn4, which mainly acts as a regulator of the general amino acid control network providing Saccharomyces cerevisiae cells with amino acids. Here, we demonstrate novel functions of Hac1 and describe a mutual connection between Hac1 and Gcn4. Hac1 is required for induction of Gcn4-responsive promoter elements in haploid as well as diploid cells and therefore participates in the cellular amino acid supply. Furthermore, Hac1 and Gcn4 mutually influence their mRNA expression levels. Hac1 is also involved in FLO11 expression and adhesion upon amino acid starvation. Hac1 and Gcn4 act through the same promoter regions of the FLO11 flocculin. The results indicate an indirect effect of both transcription factors on FLO11 expression. Our data suggest a complex mutual cross talk between the Hac1- and Gcn4-controlled networks.
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13
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Abstract
The Kes1 OSBP (oxysterol-binding protein) is a key regulator of membrane trafficking through the TGN (trans-Golgi network) and endosomal membranes. We demonstrated recently that Kes1 acts as a sterol-regulated rheostat for TGN/endosomal phosphatidylinositol 4-phosphate signalling. Kes1 utilizes its dual lipid-binding activities to integrate endosomal lipid metabolism with TORC1 (target of rapamycin complex 1)-dependent proliferative pathways and transcriptional control of nutrient signalling.
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14
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Mousley CJ, Yuan P, Gaur NA, Trettin KD, Nile AH, Deminoff SJ, Dewar BJ, Wolpert M, Macdonald JM, Herman PK, Hinnebusch AG, Bankaitis VA. A sterol-binding protein integrates endosomal lipid metabolism with TOR signaling and nitrogen sensing. Cell 2012; 148:702-15. [PMID: 22341443 DOI: 10.1016/j.cell.2011.12.026] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 10/13/2011] [Accepted: 12/05/2011] [Indexed: 11/18/2022]
Abstract
Kes1, and other oxysterol-binding protein superfamily members, are involved in membrane and lipid trafficking through trans-Golgi network (TGN) and endosomal systems. We demonstrate that Kes1 represents a sterol-regulated antagonist of TGN/endosomal phosphatidylinositol-4-phosphate signaling. This regulation modulates TOR activation by amino acids and dampens gene expression driven by Gcn4, the primary transcriptional activator of the general amino acid control regulon. Kes1-mediated repression of Gcn4 transcription factor activity is characterized by nonproductive Gcn4 binding to its target sequences, involves TGN/endosome-derived sphingolipid signaling, and requires activity of the cyclin-dependent kinase 8 (CDK8) module of the enigmatic "large Mediator" complex. These data describe a pathway by which Kes1 integrates lipid metabolism with TORC1 signaling and nitrogen sensing.
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Affiliation(s)
- Carl J Mousley
- Department of Cell and Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7090, USA.
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15
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Hernández H, Aranda C, Riego L, González A. Gln3-Gcn4 hybrid transcriptional activator determines catabolic and biosynthetic gene expression in the yeast Saccharomyces cerevisiae. Biochem Biophys Res Commun 2010; 404:859-64. [PMID: 21184740 DOI: 10.1016/j.bbrc.2010.12.075] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 12/15/2010] [Indexed: 10/18/2022]
Abstract
The yeast Saccharomyces cerevisiae is able to sense the availability and quality of nitrogen sources and the intrinsic variation of amino acid disponibility for protein synthesis. When this yeast is provided with secondary nitrogen sources, transcription of genes encoding enzymes involved in their catabolism is elicited through the action of Gln3, which constitutes the main activator of the Nitrogen Catabolite Repression network (NCR). Activation of genes encoding enzymes involved in the amino acid biosynthetic pathways is achieved through the action of the GCN4-encoded transcriptional modulator whose transcriptional activation is induced at the translational level by limitation for any amino acid. Thus the role of each one of these activators had been secluded to either catabolic or biosynthetic pathways. However, some observations have suggested that under peculiar physiological conditions, Gln3 and Gcn4 could act simultaneously in order to contemporaneously increase expression of both sets of genes. This paper addresses the question of whether Gln3 and Gcn4 cooperatively determine expression of their target genes. Results presented herein show that induced expression of catabolic and biosynthetic genes when cells are grown under nitrogen derepressive conditions and amino acid deprivation is dependent on the concurrent action of Gln3 and Gcn4, which form part of a unique transcriptional complex. We propose that the combination of Gln3 and Gcn4 results in the constitution of a hybrid modulator which elicits a novel transcriptional response, not evoked when these modulators act in a non-combinatorial fashion.
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Affiliation(s)
- Hugo Hernández
- Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, 04510 Mexico City, Mexico
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16
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A feedback circuit between transcriptional activation and self-destruction of Gcn4 separates its metabolic and morphogenic response in diploid yeasts. J Mol Biol 2010; 405:909-25. [PMID: 21111745 DOI: 10.1016/j.jmb.2010.11.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2010] [Revised: 11/06/2010] [Accepted: 11/16/2010] [Indexed: 11/20/2022]
Abstract
The basic zipper Gcn4 protein activates transcription in the yeast Saccharomyces cerevisiae in response to amino acid starvation. This includes numerous metabolic genes of amino acid or purine biosynthesis and the developmental cell-surface flocculin gene FLO11, which is required for diploid pseudohyphae formation and for adhesion upon nutrient starvation. We separated the metabolic from the developmental response by screening for GCN4 alleles that allow growth during amino acid starvation but are impaired in adhesion and are unable to form pseudohyphae. The identified Gcn4(L267S) variant carries an amino acid substitution in the third of the four conserved leucines of the zipper dimerization domain. This mutation abolished FLO11 expression and results in reduced but sufficient transcriptional activity for amino acid biosynthetic genes. The Leu267Ser substitution impairs Gcn4 homodimer formation and is a significantly more stable protein than the wild-type protein. A helix-breaker substitution in Leu253 results in a transcriptionally inactive but highly stable protein variant. This is due to a feedback circuit between transcriptional activity of Gcn4 and its own stability, which depends on the Gcn4-controlled cyclin PCL5. Gcn4(L253G) reduces the expression of Pcl5 and therefore reduces its own degradation. This self-controlled buffer system to restrict transcriptional activity results in a reciprocal correlation between Gcn4 transcriptional activity and protein stability.
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17
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Wu WS, Chen BS. Identifying Stress Transcription Factors Using Gene Expression and TF-Gene Association Data. Bioinform Biol Insights 2009; 1:137-45. [PMID: 20066130 PMCID: PMC2789697 DOI: 10.4137/bbi.s292] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Unicellular organisms such as yeasts have evolved to survive environmental stresses by rapidly reorganizing the genomic expression program to meet the challenges of harsh environments. The complex adaptation mechanisms to stress remain to be elucidated. In this study, we developed Stress Transcription Factor Identification Algorithm (STFIA), which integrates gene expression and TF-gene association data to identify the stress transcription factors (TFs) of six kinds of stresses. We identified some general stress TFs that are in response to various stresses, and some specific stress TFs that are in response to one specific stress. The biological significance of our findings is validated by the literature. We found that a small number of TFs may be sufficient to control a wide variety of expression patterns in yeast under different stresses. Two implications can be inferred from this observation. First, the adaptation mechanisms to different stresses may have a bow-tie structure. Second, there may exist extensive regulatory cross-talk among different stress responses. In conclusion, this study proposes a network of the regulators of stress responses and their mechanism of action.
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Affiliation(s)
- Wei-Sheng Wu
- Lab of Control and Systems Biology, Department of Electrical Engineering, National Tsing Hua University, Hsinchu, 300, Taiwan
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18
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Hood HM, Neafsey DE, Galagan J, Sachs MS. Evolutionary roles of upstream open reading frames in mediating gene regulation in fungi. Annu Rev Microbiol 2009; 63:385-409. [PMID: 19514854 DOI: 10.1146/annurev.micro.62.081307.162835] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Upstream open reading frames (uORFs) are frequently present in the 5'-leader regions of fungal mRNAs. They can affect translation by controlling the ability of ribosomes that scan from the mRNA 5' end to reach the downstream genic reading frame. The translation of uORFs can also affect mRNA stability. For several genes, including Saccharomyces cerevisiae GCN4, S. cerevisiae CPA1, and Neurospora crassa arg-2, regulation by uORFs controls expression in response to specific physiological signals. The roles of many uORFs that are identified by genome-level approaches, as have been initiated for Saccharomyces, Aspergillus, and Cryptococcus species, remain to be determined. Some uORFs may have regulatory roles, while others may exist to insulate the genic reading frame from the negative impacts of upstream translation start sites in the mRNA 5' leader.
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Affiliation(s)
- Heather M Hood
- Department of Science and Engineering, Oregon Health & Science University, Beaverton, Oregon 97006, USA
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19
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Schönig B, Vogel S, Tudzynski B. Cpc1 mediates cross-pathway control independently of Mbf1 in Fusarium fujikuroi. Fungal Genet Biol 2009; 46:898-908. [PMID: 19679194 DOI: 10.1016/j.fgb.2009.08.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Revised: 08/05/2009] [Accepted: 08/05/2009] [Indexed: 10/20/2022]
Abstract
The deletion of glnA, encoding the glutamine synthetase (GS), had led to the down-regulation of genes involved in secondary metabolism and up-regulation of cpc1, the cross-pathway control transcription factor. In the present study, a Deltacpc1 mutant was created and used for transcriptional profiling by macroarray analysis. Most of the Cpc1 target genes were amino acid biosynthesis genes besides a homologue of the multi-protein bridging factor MBF1 that binds to the yeast Cpc1 homologue GCN4. We show that Deltambf1 mutants exhibit no Cpc1-related phenotype and that both proteins do not interact with each other in Fusarium fujikuroi. Moreover, results presented here suggest that Cpc1 is not responsible for the GS-dependent down-regulation of secondary metabolism and that its role is focused on the activation of amino acid biosynthesis in response to the amino acid status of the cell. Surprisingly, cross-pathway control is repressed by nitrogen limitation in an AreA-dependent manner.
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Affiliation(s)
- Birgit Schönig
- Institut für Botanik der Westfälischen Wilhelms-Universität Münster, Schlossgarten 3, 48149 Münster, Germany
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20
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Disrupting vesicular trafficking at the endosome attenuates transcriptional activation by Gcn4. Mol Cell Biol 2008; 28:6796-818. [PMID: 18794364 DOI: 10.1128/mcb.00800-08] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The late endosome (MVB) plays a key role in coordinating vesicular transport of proteins between the Golgi complex, vacuole/lysosome, and plasma membrane. We found that deleting multiple genes involved in vesicle fusion at the MVB (class C/D vps mutations) impairs transcriptional activation by Gcn4, a global regulator of amino acid biosynthetic genes, by decreasing the ability of chromatin-bound Gcn4 to stimulate preinitiation complex assembly at the promoter. The functions of hybrid activators with Gal4 or VP16 activation domains are diminished in class D mutants as well, suggesting a broader defect in activation. Class E vps mutations, which impair protein sorting at the MVB, also decrease activation by Gcn4, provided they elicit rapid proteolysis of MVB cargo proteins in the aberrant late endosome. By contrast, specifically impairing endocytic trafficking from the plasma membrane, or vesicular transport to the vacuole, has a smaller effect on Gcn4 function. Thus, it appears that decreasing cargo proteins in the MVB through impaired delivery or enhanced degradation, and not merely the failure to transport cargo properly to the vacuole or downregulate plasma membrane proteins by endocytosis, is required to attenuate substantially transcriptional activation by Gcn4.
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21
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Cross-species hybridization with Fusarium verticillioides microarrays reveals new insights into Fusarium fujikuroi nitrogen regulation and the role of AreA and NMR. EUKARYOTIC CELL 2008; 7:1831-46. [PMID: 18689524 DOI: 10.1128/ec.00130-08] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In filamentous fungi, the GATA-type transcription factor AreA plays a major role in the transcriptional activation of genes needed to utilize poor nitrogen sources. In Fusarium fujikuroi, AreA also controls genes involved in the biosynthesis of gibberellins, a family of diterpenoid plant hormones. To identify more genes responding to nitrogen limitation or sufficiency in an AreA-dependent or -independent manner, we examined changes in gene expression of F. fujikuroi wild-type and DeltaareA strains by use of a Fusarium verticillioides microarray representing approximately 9,300 genes. Analysis of the array data revealed sets of genes significantly down- and upregulated in the areA mutant under both N starvation and N-sufficient conditions. Among the downregulated genes are those involved in nitrogen metabolism, e.g., those encoding glutamine synthetase and nitrogen permeases, but also those involved in secondary metabolism. Besides AreA-dependent genes, we found an even larger set of genes responding to N starvation and N-sufficient conditions in an AreA-independent manner. To study the impact of NMR on AreA activity, we examined the expression of several AreA target genes in the wild type and in areA and nmr deletion and overexpression mutants. We show that NMR interacts with AreA as expected but affects gene expression only in early growth stages. This is the first report on genome-wide expression studies examining the influence of AreA on nitrogen-responsive gene expression in a genome-wide manner in filamentous fungi.
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22
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Herrera-Camacho I, Rosas-Murrieta NH, Rojo-Domínguez A, Millán L, Reyes-Leyva J, Santos-López G, Suárez-Rendueles P. Biochemical characterization and structural prediction of a novel cytosolic leucyl aminopeptidase of the M17 family from Schizosaccharomyces pombe. FEBS J 2008; 274:6228-40. [PMID: 18028193 DOI: 10.1111/j.1742-4658.2007.06142.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A new leucyl aminopeptidase activity has been identified in the fission yeast Schizosaccharomyces pombe. The enzyme, which has been purified and named leucyl aminopeptidase yspII (LAP yspII), had a molecular mass of 320 and 54 kDa by gel filtration and SDS/PAGE, respectively, suggesting a homohexameric structure. The enzyme cleaved synthetic aminoacyl-4-nitroanilides at an optimum of pH 8.5, and preferred leucine and methionine as N-terminal amino acids. A clear dependence on Mn2+ concentration for activity was found, and an apparent association constant of 0.33 mM was calculated for the metal ion. Bestatin behaved as a competitive inhibitor of LAP yspII (K(i) = 0.14 microM), while chelating agents such as chloroquine, EDTA and 1,10-phenanthroline also reduced enzyme activity. A MALDI-MS analysis, followed by sequencing of two of the resulting peptides, showed that LAP yspII undoubtedly corresponds to the putative aminopeptidase C13A11.05 identified in the S. pombe genome project. The protein exhibited nearly 40% sequence identity to fungal and mammalian aminopeptidases belonging to the M17 family of metallopeptidases. Catalytic residues (Lys292 and Arg366), as well as those involved in coordination with the cocatalytic metal ions (Lys280, Asp285, Asp303, Asp362 and Glu364) and those forming the hydrophobic pocket for substrate binding (Met300, Asn360, Ala363, Thr390, Leu391, Ala483 and Met486), were perfectly conserved among all known aminopeptidases. The S. pombe enzyme is predicted to be formed two clearly distinguished domains with a well conserved C-terminal catalytic domain showing a characteristic topology of eight beta-sheets surrounded by alpha-helical segments in the form of a saddle.
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Affiliation(s)
- Irma Herrera-Camacho
- Laboratorio de Bioquímica y Biología Molecular, Centro de Química del Instituto de Ciencias, Universidad Autónoma de Puebla, Puebla, Mexico.
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23
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Sasse C, Bignell EM, Hasenberg M, Haynes K, Gunzer M, Braus GH, Krappmann S. Basal expression of the Aspergillus fumigatus transcriptional activator CpcA is sufficient to support pulmonary aspergillosis. Fungal Genet Biol 2008; 45:693-704. [PMID: 18249572 DOI: 10.1016/j.fgb.2007.12.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2007] [Revised: 12/13/2007] [Accepted: 12/18/2007] [Indexed: 10/22/2022]
Abstract
Aspergillosis is a disease determined by various factors that influence fungal growth and fitness. A conserved signal transduction cascade linking environmental stress to amino acid homeostasis is the Cross-Pathway Control (CPC) system that acts via phosphorylation of the translation initiation factor eIF2 by a sensor kinase to elevate expression of a transcription factor. Ingestion of Aspergillus fumigatus conidia by macrophages does not trigger this stress response, suggesting that their phagosomal microenvironment is not deficient in amino acids. The cpcC gene encodes the CPC eIF2alpha kinase, and deletion mutants show increased sensitivity towards amino acid starvation. CpcC is specifically required for the CPC response but has limited influence on the amount of phosphorylated eIF2alpha. Strains deleted for the cpcC locus are not impaired in virulence in a murine model of pulmonary aspergillosis. Accordingly, basal expression of the Cross-Pathway Control transcriptional activator appears sufficient to support aspergillosis in this disease model.
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Affiliation(s)
- Christoph Sasse
- Department of Molecular Microbiology and Genetics, Institute for Microbiology & Genetics, Georg-August-University Göttingen, Germany
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24
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Steffensen L, Pedersen PA. Heterologous expression of membrane and soluble proteins derepresses GCN4 mRNA translation in the yeast Saccharomyces cerevisiae. EUKARYOTIC CELL 2006; 5:248-61. [PMID: 16467466 PMCID: PMC1405899 DOI: 10.1128/ec.5.2.248-261.2006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2005] [Accepted: 11/22/2005] [Indexed: 02/02/2023]
Abstract
This paper describes the first physiological response at the translational level towards heterologous protein production in Saccharomyces cerevisiae. In yeast, the phosphorylation of eukaryotic initiation factor 2alpha (eIF-2alpha) by Gcn2p protein kinase mediates derepression of GCN4 mRNA translation. Gcn4p is a transcription factor initially found to be required for transcriptional induction of genes responsible for amino acid or purine biosynthesis. Using various GCN4-lacZ fusions, knockout yeast strains, and anti-eIF-2alpha-P/anti-eIF-2alpha antibodies, we observed that heterologous expression of the membrane-bound alpha1beta1 Na,K-ATPase from pig kidney, the rat pituitary adenylate cyclase seven-transmembrane-domain receptor, or a 401-residue soluble part of the Na,K-ATPase alpha1 subunit derepressed GCN4 mRNA translation up to 70-fold. GCN4 translation was very sensitive to the presence of heterologous protein, as a density of 1 per thousand of heterologous membrane protein derepressed translation maximally. Translational derepression of GCN4 was not triggered by misfolding in the endoplasmic reticulum, as expression of the wild type or temperature-sensitive folding mutants of the Na,K-ATPase increased GCN4 translation to the same extent. In situ activity of the heterologously expressed protein was not required for derepression of GCN4 mRNA translation, as illustrated by the expression of an enzymatically inactive Na,K-ATPase. Two- to threefold overexpression of the highly abundant and plasma membrane-located endogenous H-ATPase also induced GCN4 translation. Derepression of GCN4 translation required phosphorylation of eIF-2alpha, the tRNA binding domain of Gcn2p, and the ribosome-associated proteins Gcn1p and Gcn20p. The increase in Gcn4p density in response to heterologous expression did not induce transcription from the HIS4 promoter, a traditional Gcn4p target.
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Affiliation(s)
- Lotte Steffensen
- Institute of Molecular Biology and Physiology, August Krogh Building, University of Copenhagen, Universitetsparken 13, 2100 Copenhagen OE, Denmark
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25
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Abstract
Cells reprogram gene expression in response to environmental changes by mobilizing transcriptional activators. The activator protein Gcn4 of the yeast Saccharomyces cerevisiae is regulated by an intricate translational control mechanism, which is the primary focus of this review, and also by the modulation of its stability in response to nutrient availability. Translation of GCN4 mRNA is derepressed in amino acid-deprived cells, leading to transcriptional induction of nearly all genes encoding amino acid biosynthetic enzymes. The trans-acting proteins that control GCN4 translation have general functions in the initiation of protein synthesis, or regulate the activities of initiation factors, so that the molecular events that induce GCN4 translation also reduce the rate of general protein synthesis. This dual regulatory response enables cells to limit their consumption of amino acids while diverting resources into amino acid biosynthesis in nutrient-poor environments. Remarkably, mammalian cells use the same strategy to downregulate protein synthesis while inducing transcriptional activators of stress-response genes under various stressful conditions, including amino acid starvation.
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Affiliation(s)
- Alan G Hinnebusch
- Laboratory of Gene Regulation and Development, National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA.
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26
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Calderón-Torres M, Peña A, Thomé PE. DhARO4, an amino acid biosynthetic gene, is stimulated by high salinity inDebaryomyces hansenii. Yeast 2006; 23:725-34. [PMID: 16862599 DOI: 10.1002/yea.1384] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The highly halotolerant yeast Debaryomyces hansenii when grown in the presence of 2M NaCl, increased the expression of ARO4 which is involved in the biosynthesis of aromatic amino acids. The function of the isolated gene was verified by complementation of a Saccharomyces cerevisiae null mutant, aro4Delta, restoring the specific activity of the enzyme (a 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase) to wild-type levels. DhARO4 transcript expression under high salinity was stimulated at the beginning of the exponential growth phase. As the DhARO4 promoter region presents putative GCRE and CRE sequences, its expression was evaluated under conditions of NaCl stress and amino acid starvation, showing similar expression levels for either condition. The combined effect of both stressors resulted in a further increase in transcript levels over the singly added stressors, indicating independent stimulatory events. Our results support the hypothesis that high salinity and amino acid availability are physiologically interconnected.
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Affiliation(s)
- Marissa Calderón-Torres
- Unidad Académica Puerto Morelos, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Apartado Postal 1152, Cancún, Quintana Roo 77500, México.
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27
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Matsuo R, Kubota H, Obata T, Kito K, Ota K, Kitazono T, Ibayashi S, Sasaki T, Iida M, Ito T. The yeast eIF4E-associated protein Eap1p attenuates GCN4 translation upon TOR-inactivation. FEBS Lett 2005; 579:2433-8. [PMID: 15848184 DOI: 10.1016/j.febslet.2005.03.043] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2005] [Revised: 03/14/2005] [Accepted: 03/17/2005] [Indexed: 11/28/2022]
Abstract
Amino acid-starved yeast activates the eIF2alpha kinase Gcn2p to suppress general translation and to selectively derepress the transcription factor Gcn4p, which induces various biosynthetic genes to elicit general amino acid control (GAAC). Well-fed yeast activates the target of rapamycin (TOR) to stimulate translation via the eIF4F complex. A crosstalk was demonstrated between the pathways for GAAC and TOR signaling: the TOR-specific inhibitor rapamycin activates Gcn2p. Here we demonstrate that, upon TOR-inactivation, the putative TOR-regulated eIF4E-associated protein Eap1p likely functions downstream of Gcn2p to attenuate GCN4 translation via a mechanism independent of eIF4E-binding, thereby constituting another interface between the two pathways.
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Affiliation(s)
- Ryu Matsuo
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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28
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Kleinschmidt M, Grundmann O, Blüthgen N, Mösch HU, Braus GH. Transcriptional profiling of Saccharomyces cerevisiae cells under adhesion-inducing conditions. Mol Genet Genomics 2005; 273:382-93. [PMID: 15843968 DOI: 10.1007/s00438-005-1139-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2004] [Accepted: 03/02/2005] [Indexed: 01/09/2023]
Abstract
The ability to adhere to other cells is one of the most prominent determinants of fungal pathogenicity. Thus, adherence of fungi to human tissues or plastics triggers hospital-acquired fungal infections, which are an increasing clinical problem, especially in immunocompromised persons. In the model fungus Saccharomyces cerevisiae adhesion can be induced by starvation for amino acids, and depends on the transcriptional activator of the general amino acid control system, Gcn4p. However, not much is known about the transcriptional program that mediates adhesive growth under such conditions. In this study, we present a genome-wide transcriptional analysis of Sigma1278b yeast cells that were subjected to adhesion-inducing conditions imposed by amino acid starvation. Twenty-two novel genes were identified as inducible by amino acid starvation; 72 genes belonging to different functional groups, which were not previously known to be regulated by Gcn4p, require Gcn4p for full transcriptional induction under adhesion-inducing conditions. In addition, several genes were identified in Sigma1278b cells that were inducible by amino acid starvation in a Gcn4p-independent manner. Our data suggest that adhesion of yeast cells induced by amino acid starvation is regulated by a complex, Sigma1278b-specific transcriptional response.
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Affiliation(s)
- Malte Kleinschmidt
- Institute of Microbiology and Genetics, Georg-August-University, Grisebachstrasse 8, 37077, Göttingen, Germany
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29
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Merrick WC. Cap-dependent and cap-independent translation in eukaryotic systems. Gene 2004; 332:1-11. [PMID: 15145049 DOI: 10.1016/j.gene.2004.02.051] [Citation(s) in RCA: 194] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2003] [Revised: 02/04/2004] [Accepted: 02/27/2004] [Indexed: 12/21/2022]
Abstract
Unlike bacterial protein synthesis, eukaryotic protein synthesis has several mechanisms to initiate translation including cap-dependent initiation, re-initiation and internal initiation. While there is extensive biochemical characterization of the multiple steps in cap-dependent initiation, most of the information on the other two mechanisms is derived from studies on the nucleic acid sequences that influence their efficiency. However, even in the best of circumstances, both re-initiation and internal initiation are only 25% as efficient as cap-dependent initiation and more commonly, are only 1-10% as efficient. This general lack of efficiency leaves open possibilities for mis-interpretation/artifacts in vivo (cryptic promoters, alternate splicing) or in vitro (nuclease degradation). Two examples are cited from the author's laboratory as background for the development of a general set of guidelines to minimize errors and validate authenticity for internal initiation.
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Affiliation(s)
- William C Merrick
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4935, USA.
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30
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Takaku H, Mutoh E, Sagehashi Y, Fukuda R, Horiuchi H, Ochi K, Takagi M, Ohta A. A Gcn4p homolog is essential for the induction of a ribosomal protein L41 variant responsible for cycloheximide resistance in the yeast Candida maltosa. J Biol Chem 2004; 279:23030-7. [PMID: 15039451 DOI: 10.1074/jbc.m400888200] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cycloheximide (CYH) resistance in the yeast Candida maltosa is based on the inducible expression of genes encoding a variant of ribosomal protein L41-Q, with glutamine at position 56 instead of the proline found in normal L41. The promoter of L41-Q2a, one of the L41-Q gene alleles encoding L41-Q, has an element similar to the Gcn4p-responsive element of Saccharomyces cerevisiae. In a previous study, this element was shown to be essential for the induction of L41-Q by CYH. In the present study, a C. maltosa GCN4 homolog, C-GCN4, was cloned. It had a long 5'-leader region with three upstream open reading frames. Enhanced expression of the C-GCN4 reporter fusion gene upon the addition of 3-aminotriazole or by mutations in start codons of all three upstream open reading frames indicates that C-GCN4 expression is under translation repression as was seen with GCN4. The C-GCN4-depleted mutant was unable to grow in a nutrient medium containing CYH and did not express L41-Q genes. Recombinant C-Gcn4p bound to the consensus DNA element for Gcn4p, 5'-(G/A)TGACTCAT-3', located upstream of L41-Q2a. Thus, C-Gcn4p, which likely functions in the general control of amino acid biosynthesis, is essential for the expression of L41-Q genes.
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Affiliation(s)
- Hiroaki Takaku
- Department of Biotechnology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
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31
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Braus GH, Grundmann O, Brückner S, Mösch HU. Amino acid starvation and Gcn4p regulate adhesive growth and FLO11 gene expression in Saccharomyces cerevisiae. Mol Biol Cell 2003; 14:4272-84. [PMID: 14517335 PMCID: PMC207018 DOI: 10.1091/mbc.e03-01-0042] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2003] [Revised: 05/22/2003] [Accepted: 05/27/2003] [Indexed: 11/11/2022] Open
Abstract
In baker's yeast Saccharomyces cerevisiae, cell-cell and cell-surface adhesion are required for haploid invasive growth and diploid pseudohyphal development. These morphogenetic events are induced by starvation for glucose or nitrogen and require the cell surface protein Flo11p. We show that amino acid starvation is a nutritional signal that activates adhesive growth and expression of FLO11 in both haploid and diploid strains in the presence of glucose and ammonium, known suppressors of adhesion. Starvation-induced adhesive growth requires Flo11p and is under control of Gcn2p and Gcn4p, elements of the general amino acid control system. Tpk2p and Flo8p, elements of the cAMP pathway, are also required for activation but not Ste12p and Tec1p, known targets of the mitogen-activated protein kinase cascade. Promoter analysis of FLO11 identifies one upstream activation sequence (UASR) and one repression site (URS) that confer regulation by amino acid starvation. Gcn4p is not required for regulation of the UASR by amino acid starvation, but seems to be indirectly required to overcome the negative effects of the URS on FLO11 transcription. In addition, Gcn4p controls expression of FLO11 by affecting two basal upstream activation sequences (UASB). In summary, our study suggests that amino acid starvation is a nutritional signal that triggers a Gcn4p-controlled signaling pathway, which relieves repression of FLO11 gene expression and induces adhesive growth.
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Affiliation(s)
- Gerhard H Braus
- Institute for Microbiology and Genetics, Georg-August-University, D-37077 Göttingen, Germany.
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Winderickx J, Holsbeeks I, Lagatie O, Giots F, Thevelein J, de Winde H. From feast to famine; adaptation to nutrient availability in yeast. ACTA ACUST UNITED AC 2002. [DOI: 10.1007/3-540-45611-2_7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
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Pries R, Bömeke K, Irniger S, Grundmann O, Braus GH. Amino acid-dependent Gcn4p stability regulation occurs exclusively in the yeast nucleus. EUKARYOTIC CELL 2002; 1:663-72. [PMID: 12455686 PMCID: PMC126753 DOI: 10.1128/ec.1.5.663-672.2002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The c-Jun-like transcriptional activator Gcn4p controls biosynthesis of translational precursors in the yeast Saccharomyces cerevisiae. Protein stability is dependent on amino acid limitation and cis signals within Gcn4p which are recognized by cyclin-dependent protein kinases, including Pho85p. The Gcn4p population within unstarved yeast consists of a small relatively stable cytoplasmic fraction and a larger less stable nuclear fraction. Gcn4p contains two nuclear localization signals (NLS) which function independently of the presence or absence of amino acids. Expression of NLS-truncated Gcn4p results in an increased cytoplasmic fraction and an overall stabilization of the protein. The same effect is achieved for the entire Gcn4p in a yrb1 yeast mutant strain impaired in the nuclear import machinery. In the presence of amino acids, controlled destabilization of Gcn4p is triggered by the phosphorylation activity of Pho85p. A pho85delta mutation stabilizes Gcn4p without affecting nuclear import. Pho85p is localized within the nucleus in the presence or absence of amino acids. Therefore, there is a strict spatial separation of protein synthesis and degradation of Gcn4p in yeast. Control of protein stabilization which antagonizes Gcn4p function is restricted to the nucleus.
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Affiliation(s)
- Ralph Pries
- Institute of Microbiology and Genetics, Georg-August-University, D-37077 Göttingen, Germany
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Takaku H, Horiuchi H, Takagi M, Ohta A. Pseudohyphal growth in a dimorphic yeast, Candida maltosa, after disruption of the C-GCN4 gene, a homolog of Saccharomyces cerevisiae GCN4. Biosci Biotechnol Biochem 2002; 66:1936-9. [PMID: 12400694 DOI: 10.1271/bbb.66.1936] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The transcriptional activator protein Gcn4p increases the transcription of many genes that code for amino acid synthesis genes during amino acid starvation in Saccharomyces cerevisiae. Here we showed that after the disruption of C-GCN4, a homolog in Candida maltosa of GCN4 in S. cerevisiae, formed pseudohyphae in minimal medium. This is the first report that a GCN4 homolog is involved in the control of morphological transition.
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Hinnebusch AG, Natarajan K. Gcn4p, a master regulator of gene expression, is controlled at multiple levels by diverse signals of starvation and stress. EUKARYOTIC CELL 2002; 1:22-32. [PMID: 12455968 PMCID: PMC118051 DOI: 10.1128/ec.01.1.22-32.2002] [Citation(s) in RCA: 259] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Alan G Hinnebusch
- Laboratory of Gene Regulation and Development, National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA.
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Current awareness on yeast. Yeast 2001. [PMID: 11746606 DOI: 10.1002/yea.691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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