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Nowrouzi B, Torres-Montero P, Kerkhoven EJ, Martínez JL, Rios-Solis L. Rewiring Saccharomyces cerevisiae metabolism for optimised Taxol® precursors production. Metab Eng Commun 2024; 18:e00229. [PMID: 38098801 PMCID: PMC10716015 DOI: 10.1016/j.mec.2023.e00229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 10/09/2023] [Accepted: 11/04/2023] [Indexed: 12/17/2023] Open
Abstract
Saccharomyces cerevisiae has been conveniently used to produce Taxol® anticancer drug early precursors. However, the harmful impact of oxidative stress by the first cytochrome P450-reductase enzymes (CYP725A4-POR) of Taxol® pathway has hampered sufficient progress in yeast. Here, we evolved an oxidative stress-resistant yeast strain with three-fold higher titre of their substrate, taxadiene. The performance of the evolved and parent strains were then evaluated in galactose-limited chemostats before and under the oxidative stress by an oxidising agent. The interaction of evolution and oxidative stress was comprehensively evaluated through transcriptomics and metabolite profiles integration in yeast enzyme-constrained genome scale model. Overall, the evolved strain showed improved respiration, reduced overflow metabolites production and oxidative stress re-induction tolerance. The cross-protection mechanism also potentially contributed to better heme, flavin and NADPH availability, essential for CYP725A4 and POR optimal activity in yeast. The results imply that the evolved strain is a robust cell factory for future efforts towards Taxol© production.
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Affiliation(s)
- Behnaz Nowrouzi
- Institute for Bioengineering, School of Engineering, The University of Edinburgh, Edinburgh, EH9 3BF, United Kingdom
- Centre for Engineering Biology, The University of Edinburgh, Edinburgh, EH9 3BD, United Kingdom
- Department of Life Sciences, Chalmers University of Technology, Kemivägen 10, SE-412 96, Gothenburg, Sweden
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads Building 223, Kgs. Lyngby, 2800, Denmark
| | - Pablo Torres-Montero
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads Building 223, Kgs. Lyngby, 2800, Denmark
| | - Eduard J. Kerkhoven
- Department of Life Sciences, Chalmers University of Technology, Kemivägen 10, SE-412 96, Gothenburg, Sweden
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
- SciLifeLab, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden
| | - José L. Martínez
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads Building 223, Kgs. Lyngby, 2800, Denmark
| | - Leonardo Rios-Solis
- Institute for Bioengineering, School of Engineering, The University of Edinburgh, Edinburgh, EH9 3BF, United Kingdom
- Centre for Engineering Biology, The University of Edinburgh, Edinburgh, EH9 3BD, United Kingdom
- School of Natural and Environmental Sciences, Molecular Biology and Biotechnology Division, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
- Department of Biochemical Engineering, The Advanced Centre for Biochemical Engineering, University College London, Gower Street, London, WC1E 6BT, United Kingdom
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2
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Metur SP, Klionsky DJ. Nutrient-dependent signaling pathways that control autophagy in yeast. FEBS Lett 2024; 598:32-47. [PMID: 37758520 PMCID: PMC10841420 DOI: 10.1002/1873-3468.14741] [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: 07/26/2023] [Revised: 09/04/2023] [Accepted: 09/05/2023] [Indexed: 09/29/2023]
Abstract
Macroautophagy/autophagy is a highly conserved catabolic process vital for cellular stress responses and maintaining equilibrium within the cell. Malfunctioning autophagy has been implicated in the pathogenesis of various diseases, including certain neurodegenerative disorders, diabetes, metabolic diseases, and cancer. Cells face diverse metabolic challenges, such as limitations in nitrogen, carbon, and minerals such as phosphate and iron, necessitating the integration of complex metabolic information. Cells utilize a signal transduction network of sensors, transducers, and effectors to coordinate the execution of the autophagic response, concomitant with the severity of the nutrient-starvation condition. This review presents the current mechanistic understanding of how cells regulate the initiation of autophagy through various nutrient-dependent signaling pathways. Emphasizing findings from studies in yeast, we explore the emerging principles that underlie the nutrient-dependent regulation of autophagy, significantly shaping stress-induced autophagy responses under various metabolic stress conditions.
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Affiliation(s)
- Shree Padma Metur
- Department of Molecular, Cellular and Developmental Biology, Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Daniel J Klionsky
- Department of Molecular, Cellular and Developmental Biology, Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
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3
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Lindahl PA. Iron Homeostatic Regulation in Saccharomyces cerevisiae: Introduction to a Computational Modeling Method. Methods Mol Biol 2024; 2839:3-29. [PMID: 39008245 DOI: 10.1007/978-1-0716-4043-2_1] [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] [Indexed: 07/16/2024]
Abstract
Over the past 30 years, much has been learned regarding iron homeostatic regulation in budding yeast, S. cerevisiae, including the identity of many of the proteins and molecular-level regulatory mechanisms involved. Most advances have involved inferring such mechanisms based on the analysis of iron-dysregulation phenotypes arising in various genetic mutant strains. Still lacking is a cellular- or system-level understanding of iron homeostasis. These experimental advances are summarized in this review, and a method for developing cellular-level regulatory mechanisms in yeast is presented. The method employs the results of Mössbauer spectroscopy of whole cells and organelles, iron quantification of the same, and ordinary differential equation-based mathematical models. Current models are simplistic when compared to the complexity of iron homeostasis in real cells, yet they hold promise as a useful, perhaps even required, complement to the popular genetics-based approach. The fundamental problem in comprehending cellular regulatory mechanisms is that, given the complexities involved, different molecular-level mechanisms can often give rise to virtually indistinguishable cellular phenotypes. Mathematical models cannot eliminate this problem, but they can minimize it.
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Affiliation(s)
- Paul A Lindahl
- Departments of Chemistry and of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA.
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4
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Wagner ER, Gasch AP. Advances in S. cerevisiae Engineering for Xylose Fermentation and Biofuel Production: Balancing Growth, Metabolism, and Defense. J Fungi (Basel) 2023; 9:786. [PMID: 37623557 PMCID: PMC10455348 DOI: 10.3390/jof9080786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/19/2023] [Accepted: 07/24/2023] [Indexed: 08/26/2023] Open
Abstract
Genetically engineering microorganisms to produce chemicals has changed the industrialized world. The budding yeast Saccharomyces cerevisiae is frequently used in industry due to its genetic tractability and unique metabolic capabilities. S. cerevisiae has been engineered to produce novel compounds from diverse sugars found in lignocellulosic biomass, including pentose sugars, like xylose, not recognized by the organism. Engineering high flux toward novel compounds has proved to be more challenging than anticipated since simply introducing pathway components is often not enough. Several studies show that the rewiring of upstream signaling is required to direct products toward pathways of interest, but doing so can diminish stress tolerance, which is important in industrial conditions. As an example of these challenges, we reviewed S. cerevisiae engineering efforts, enabling anaerobic xylose fermentation as a model system and showcasing the regulatory interplay's controlling growth, metabolism, and stress defense. Enabling xylose fermentation in S. cerevisiae requires the introduction of several key metabolic enzymes but also regulatory rewiring of three signaling pathways at the intersection of the growth and stress defense responses: the RAS/PKA, Snf1, and high osmolarity glycerol (HOG) pathways. The current studies reviewed here suggest the modulation of global signaling pathways should be adopted into biorefinery microbial engineering pipelines to increase efficient product yields.
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Affiliation(s)
- Ellen R. Wagner
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI 53706, USA
- Center for Genomic Science Innovation, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Audrey P. Gasch
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI 53706, USA
- Center for Genomic Science Innovation, University of Wisconsin-Madison, Madison, WI 53706, USA
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5
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Elias D, Tóth Hervay N, Bujdos M, Gbelska Y. Essential Role of CgErg6p in Maintaining Oxidative Stress Tolerance and Iron Homeostasis in Candida glabrata. J Fungi (Basel) 2023; 9:jof9050579. [PMID: 37233290 DOI: 10.3390/jof9050579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 05/12/2023] [Accepted: 05/16/2023] [Indexed: 05/27/2023] Open
Abstract
The human pathogenic fungus Candida glabrata is the second leading cause of candidemia, a life-threatening invasive mycosis. Clinical outcomes are complicated by reduced susceptibility of C. glabrata to azoles together with its ability to evolve stable resistance to both azoles and echinocandins following drug exposure. Compared to other Candida spp., C. glabrata displays robust oxidative stress resistance. In this study, we investigated the impact of CgERG6 gene deletion on the oxidative stress response in C. glabrata. CgERG6 gene encodes sterol-24-C-methyltransferase, which is involved in the final steps of ergosterol biosynthesis. Our previous results showed that the Cgerg6Δ mutant has a lower ergosterol content in its membranes. Here, we show that the Cgerg6Δ mutant displays increased susceptibility to oxidative stress inducing agents, such as menadione, hydrogen peroxide and diamide, accompanied with increased intracellular ROS production. The Cgerg6Δ mutant is not able to tolerate higher concentrations of iron in the growth media. We observed increased expression of transcription factors, CgYap1p, CgMsn4p and CgYap5p, together with increased expression of catalase encoding the CgCTA1 gene and vacuolar iron transporter CgCCC1 in the Cgerg6Δ mutant cells. However, it seems that the CgERG6 gene deletion does not influence the function of mitochondria.
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Affiliation(s)
- Daniel Elias
- Department of Microbiology and Virology, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovicova 6, 842 15 Bratislava, Slovakia
| | - Nora Tóth Hervay
- Department of Microbiology and Virology, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovicova 6, 842 15 Bratislava, Slovakia
| | - Marek Bujdos
- Faculty of Natural Sciences, Institute of Laboratory Research on Geomaterials, Comenius University in Bratislava, Ilkovicova 6, 842 15 Bratislava, Slovakia
| | - Yvetta Gbelska
- Department of Microbiology and Virology, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovicova 6, 842 15 Bratislava, Slovakia
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The polyHIS Tract of Yeast AMPK Coordinates Carbon Metabolism with Iron Availability. Int J Mol Sci 2023; 24:ijms24021368. [PMID: 36674878 PMCID: PMC9863760 DOI: 10.3390/ijms24021368] [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: 12/13/2022] [Revised: 01/06/2023] [Accepted: 01/07/2023] [Indexed: 01/13/2023] Open
Abstract
Energy status in all eukaryotic cells is sensed by AMP-kinases. We have previously found that the poly-histidine tract at the N-terminus of S. cerevisiae AMPK (Snf1) inhibits its function in the presence of glucose via a pH-regulated mechanism. We show here that in the absence of glucose, the poly-histidine tract has a second function, linking together carbon and iron metabolism. Under conditions of iron deprivation, when different iron-intense cellular systems compete for this scarce resource, Snf1 is inhibited. The inhibition is via an interaction of the poly-histidine tract with the low-iron transcription factor Aft1. Aft1 inhibition of Snf1 occurs in the nucleus at the nuclear membrane, and only inhibits nuclear Snf1, without affecting cytosolic Snf1 activities. Thus, the temporal and spatial regulation of Snf1 activity enables a differential response to iron depending upon the type of carbon source. The linkage of nuclear Snf1 activity to iron sufficiency ensures that sufficient clusters are available to support respiratory enzymatic activity and tests mitochondrial competency prior to activation of nuclear Snf1.
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7
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Nishimura A, Yoshikawa Y, Ichikawa K, Takemoto T, Tanahashi R, Takagi H. Longevity Regulation by Proline Oxidation in Yeast. Microorganisms 2021; 9:microorganisms9081650. [PMID: 34442729 PMCID: PMC8400801 DOI: 10.3390/microorganisms9081650] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 07/28/2021] [Accepted: 07/30/2021] [Indexed: 12/30/2022] Open
Abstract
Proline is a pivotal and multifunctional amino acid that is used not only as a nitrogen source but also as a stress protectant and energy source. Therefore, proline metabolism is known to be important in maintaining cellular homeostasis. Here, we discovered that proline oxidation, catalyzed by the proline oxidase Put1, a mitochondrial flavin-dependent enzyme converting proline into ∆1-pyrroline-5-carboxylate, controls the chronological lifespan of the yeast Saccharomyces cerevisiae. Intriguingly, the yeast strain with PUT1 deletion showed a reduced chronological lifespan compared with the wild-type strain. The addition of proline to the culture medium significantly increased the longevity of wild-type cells but not that of PUT1-deleted cells. We next found that induction of the transcriptional factor Put3-dependent PUT1 and degradation of proline occur during the aging of yeast cells. Additionally, the lifespan of the PUT3-deleted strain, which is deficient in PUT1 induction, was shorter than that of the wild-type strain. More importantly, the oxidation of proline by Put1 helped maintain the mitochondrial membrane potential and ATP production through the aging period. These results indicate that mitochondrial energy metabolism is maintained through oxidative degradation of proline and that this process is important in regulating the longevity of yeast cells.
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8
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Sorribes-Dauden R, Martínez-Pastor MT, Puig S. Expression of a Truncated Yeast Ccc1 Vacuolar Transporter Increases the Accumulation of Endogenous Iron. Genes (Basel) 2021; 12:genes12081120. [PMID: 34440294 PMCID: PMC8391176 DOI: 10.3390/genes12081120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/12/2021] [Accepted: 07/15/2021] [Indexed: 01/13/2023] Open
Abstract
Iron is an essential micronutrient for all eukaryotic organisms because it participates as a redox cofactor in multiple metabolic processes. Iron bioavailability is highly restricted due to the low solubility of its oxidized form, frequently leading to iron deficiency anemia. The baker’s yeast Saccharomyces cerevisiae is used as a model organism for iron homeostasis studies, but also as a food supplement and fermentative microorganism in the food industry. Yeast cells use the vacuolar Ccc1 transporter to detoxify and store excess iron in the vacuoles. Here, we modulate CCC1 expression and properties to increase iron extraction from the environment. We show that constitutive expression of full-length CCC1 is toxic, whereas deletion of its cytosolic amino-terminal (Nt) domain (NtΔCCC1) rescues this phenotype. Toxicity is exacerbated in cells lacking AFT1 transcription factor. Further characterization of NtΔCcc1 protein suggests that it is a partially functional protein. Western blot analyses indicate that deletion of Ccc1 Nt domain does not significantly alter GFP-Ccc1 protein stability. A functional full-length GFP-Ccc1 protein localized to particular regions of the vacuolar membrane, whereas GFP-NtΔCcc1 protein was evenly distributed throughout this endogenous membrane. Interestingly, expression of NtΔCCC1 increased the accumulation of endogenous iron in cells cultivated under iron-sufficient conditions, a strategy that could be used to extract iron from media that are not rich in iron.
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Affiliation(s)
- Raquel Sorribes-Dauden
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Doctor Moliner 50, 46100 Burjassot, Valencia, Spain;
| | - María Teresa Martínez-Pastor
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Doctor Moliner 50, 46100 Burjassot, Valencia, Spain;
- Correspondence: (M.T.M.-P.); (S.P.)
| | - Sergi Puig
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Agustín Escardino 7, 46980 Paterna, Valencia, Spain
- Correspondence: (M.T.M.-P.); (S.P.)
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9
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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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10
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An Internal Promoter Drives the Expression of a Truncated Form of CCC1 Capable of Protecting Yeast from Iron Toxicity. Microorganisms 2021; 9:microorganisms9061337. [PMID: 34203091 PMCID: PMC8235630 DOI: 10.3390/microorganisms9061337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 06/11/2021] [Accepted: 06/15/2021] [Indexed: 11/17/2022] Open
Abstract
In yeast, iron storage and detoxification depend on the Ccc1 transporter that mediates iron accumulation in vacuoles. While deletion of the CCC1 gene renders cells unable to survive under iron overload conditions, the deletion of its previously identified regulators only partially affects survival, indicating that the mechanisms controlling iron storage and detoxification in yeast are still far from well understood. This work reveals that CCC1 is equipped with a complex transcriptional structure comprising several regulatory regions. One of these is located inside the coding sequence of the gene and drives the expression of a short transcript encoding an N-terminally truncated protein, designated as s-Ccc1. s-Ccc1, though less efficiently than Ccc1, is able to promote metal accumulation in the vacuole, protecting cells against iron toxicity. While the expression of the s-Ccc1 appears to be repressed in the normal genomic context, our current data clearly demonstrates that it is functional and has the capacity to play a role under iron overload conditions.
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11
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Bulk autophagy induction and life extension is achieved when iron is the only limited nutrient in Saccharomyces cerevisiae. Biochem J 2021; 478:811-837. [DOI: 10.1042/bcj20200849] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 01/26/2021] [Accepted: 01/27/2021] [Indexed: 01/21/2023]
Abstract
We have investigated the effects that iron limitation provokes in Saccharomyces cerevisiae exponential cultures. We have demonstrated that one primary response is the induction of bulk autophagy mediated by TORC1. Coherently, Atg13 became dephosphorylated whereas Atg1 appeared phosphorylated. The signal of iron deprivation requires Tor2/Ypk1 activity and the inactivation of Tor1 leading to Atg13 dephosphorylation, thus triggering the autophagy process. Iron replenishment in its turn, reduces autophagy flux through the AMPK Snf1 and the subsequent activity of the iron-responsive transcription factor, Aft1. This signalling converges in Atg13 phosphorylation mediated by Tor1. Iron limitation promotes accumulation of trehalose and the increase in stress resistance leading to a quiescent state in cells. All these effects contribute to the extension of the chronological life, in a manner totally dependent on autophagy activation.
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12
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Pujol-Carrion N, Pavón-Vergés M, Arroyo J, de la Torre-Ruiz MA. The MAPK Slt2/Mpk1 plays a role in iron homeostasis through direct regulation of the transcription factor Aft1. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1868:118974. [PMID: 33549702 DOI: 10.1016/j.bbamcr.2021.118974] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 01/14/2021] [Accepted: 01/28/2021] [Indexed: 01/18/2023]
Abstract
Iron is an essential element for life. Cells develop mechanisms to tightly regulate its homeostasis, in order to avoid abnormal accumulation and the consequent cell toxicity. In budding yeast, the high affinity iron regulon is under the control of the transcription factor Aft1. We present evidence demonstrating that the MAPK Slt2 of the cell wall integrity pathway (CWI), phosphorylates and negatively regulates Aft1 activity upon the iron depletion signal, both in fermentative or respiratory conditions. The lack of Slt2 provokes Aft1 dysfunction leading to a shorter chronological life span. The signal of iron scarcity is not transmitted to Slt2 through other signalling pathways such as TOR1, PKA, SNF1 or TOR2/YPK1. The observation that Slt2 physically binds Aft1 rather suggests a direct regulation.
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Affiliation(s)
- Nuria Pujol-Carrion
- Cell Signalling in Yeast Unit, Department of Basic Medical Sciences, Institut de Recerca Biomèdica de Lleida (IRBLleida), University of Lleida, 25198 Lleida, Spain
| | - Mónica Pavón-Vergés
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University Complutense de Madrid, IRYCIS, 28040 Madrid, Spain
| | - Javier Arroyo
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University Complutense de Madrid, IRYCIS, 28040 Madrid, Spain
| | - Maria Angeles de la Torre-Ruiz
- Cell Signalling in Yeast Unit, Department of Basic Medical Sciences, Institut de Recerca Biomèdica de Lleida (IRBLleida), University of Lleida, 25198 Lleida, Spain.
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13
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Sorribes-Dauden R, Peris D, Martínez-Pastor MT, Puig S. Structure and function of the vacuolar Ccc1/VIT1 family of iron transporters and its regulation in fungi. Comput Struct Biotechnol J 2020; 18:3712-3722. [PMID: 33304466 PMCID: PMC7714665 DOI: 10.1016/j.csbj.2020.10.044] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/28/2020] [Accepted: 10/31/2020] [Indexed: 02/06/2023] Open
Abstract
Iron is an essential micronutrient for most living beings since it participates as a redox active cofactor in many biological processes including cellular respiration, lipid biosynthesis, DNA replication and repair, and ribosome biogenesis and recycling. However, when present in excess, iron can participate in Fenton reactions and generate reactive oxygen species that damage cells at the level of proteins, lipids and nucleic acids. Organisms have developed different molecular strategies to protect themselves against the harmful effects of high concentrations of iron. In the case of fungi and plants, detoxification mainly occurs by importing cytosolic iron into the vacuole through the Ccc1/VIT1 iron transporter. New sequenced genomes and bioinformatic tools are facilitating the functional characterization, evolution and ecological relevance of metabolic pathways and homeostatic networks across the Tree of Life. Sequence analysis shows that Ccc1/VIT1 homologs are widely distributed among organisms with the exception of animals. The recent elucidation of the crystal structure of a Ccc1/VIT1 plant ortholog has enabled the identification of both conserved and species-specific motifs required for its metal transport mechanism. Moreover, recent studies in the yeast Saccharomyces cerevisiae have also revealed that multiple transcription factors including Yap5 and Msn2/Msn4 contribute to the expression of CCC1 in high-iron conditions. Interestingly, Malaysian S. cerevisiae strains express a partially functional Ccc1 protein that renders them sensitive to iron. Different regulatory mechanisms have been described for non-Saccharomycetaceae Ccc1 homologs. The characterization of Ccc1/VIT1 proteins is of high interest in the development of biofortified crops and the protection against microbial-derived diseases.
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Key Words
- BLOSUM, BLOcks SUbstitution Matrix
- CBC, CCAAT-binding core complex
- CRD, Cysteine-rich domain
- CS, Consistency score
- Ccc1
- Cg, Candida glabrata
- Eg, Eucalyptus grandis
- Fe, Iron
- Fungi
- H, Helix
- Hap, Heme activator protein
- ISC, Iron-sulfur luster
- Iron detoxification
- Iron regulation
- Iron transport
- MAFFT, Multiple Alignment using Fast Fourier Transform
- MBD, Metal-binding domain
- ML, Maximum-likelihood
- NRAMP, Natural Resistance-Associated Macrophage Protein
- Plants
- ROS, Reactive oxygen species
- TMD, Transmembrane domain
- VIT, Vacuolar iron transporter
- VIT1
- VTL, Vacuolar iron transporter-like
- Vacuole
- YRE, Yap response elements
- Yeast
- bZIP, basic leucine-zipper
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Affiliation(s)
- Raquel Sorribes-Dauden
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Burjassot, Valencia, Spain
| | - David Peris
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain
| | | | - Sergi Puig
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain
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14
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Ramos-Alonso L, Romero AM, Martínez-Pastor MT, Puig S. Iron Regulatory Mechanisms in Saccharomyces cerevisiae. Front Microbiol 2020; 11:582830. [PMID: 33013818 PMCID: PMC7509046 DOI: 10.3389/fmicb.2020.582830] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 08/20/2020] [Indexed: 12/21/2022] Open
Abstract
Iron is an essential micronutrient for all eukaryotic organisms because it participates as a redox cofactor in many cellular processes. However, excess iron can damage cells since it promotes the generation of reactive oxygen species. The budding yeast Saccharomyces cerevisiae has been used as a model organism to study the adaptation of eukaryotic cells to changes in iron availability. Upon iron deficiency, yeast utilizes two transcription factors, Aft1 and Aft2, to activate the expression of a set of genes known as the iron regulon, which are implicated in iron uptake, recycling and mobilization. Moreover, Aft1 and Aft2 activate the expression of Cth2, an mRNA-binding protein that limits the expression of genes encoding for iron-containing proteins or that participate in iron-using processes. Cth2 contributes to prioritize iron utilization in particular pathways over other highly iron-consuming and non-essential processes including mitochondrial respiration. Recent studies have revealed that iron deficiency also alters many other metabolic routes including amino acid and lipid synthesis, the mitochondrial retrograde response, transcription, translation and deoxyribonucleotide synthesis; and activates the DNA damage and general stress responses. At high iron levels, the yeast Yap5, Msn2, and Msn4 transcription factors activate the expression of a vacuolar iron importer called Ccc1, which is the most important high-iron protecting factor devoted to detoxify excess cytosolic iron that is stored into the vacuole for its mobilization upon scarcity. The complete sequencing and annotation of many yeast genomes is starting to unveil the diversity and evolution of the iron homeostasis network in this species.
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Affiliation(s)
- Lucía Ramos-Alonso
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Valencia, Spain
| | - Antonia María Romero
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Valencia, Spain
| | | | - Sergi Puig
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Valencia, Spain
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15
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Lindahl PA. A comprehensive mechanistic model of iron metabolism in Saccharomyces cerevisiae. Metallomics 2019; 11:1779-1799. [PMID: 31531508 DOI: 10.1039/c9mt00199a] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The ironome of budding yeast (circa 2019) consists of approximately 139 proteins and 5 nonproteinaceous species. These proteins were grouped according to location in the cell, type of iron center(s), and cellular function. The resulting 27 groups were used, along with an additional 13 nonprotein components, to develop a mesoscale mechanistic model that describes the import, trafficking, metallation, and regulation of iron within growing yeast cells. The model was designed to be simultaneously mutually autocatalytic and mutually autoinhibitory - a property called autocatinhibitory that should be most realistic for simulating cellular biochemical processes. The model was assessed at the systems' level. General conclusions are presented, including a new perspective on understanding regulatory mechanisms in cellular systems. Some unsettled issues are described. This model, once fully developed, has the potential to mimic the phenotype (at a coarse-grain level) of all iron-related genetic mutations in this simple and well-studied eukaryote.
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Affiliation(s)
- Paul A Lindahl
- Departments of Chemistry and of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843-3255, USA.
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16
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Rodrigues-Pousada C, Devaux F, Caetano SM, Pimentel C, da Silva S, Cordeiro AC, Amaral C. Yeast AP-1 like transcription factors (Yap) and stress response: a current overview. MICROBIAL CELL 2019; 6:267-285. [PMID: 31172012 PMCID: PMC6545440 DOI: 10.15698/mic2019.06.679] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Yeast adaptation to stress has been extensively studied. It involves large reprogramming of genome expression operated by many, more or less specific, transcription factors. Here, we review our current knowledge on the function of the eight Yap transcription factors (Yap1 to Yap8) in Saccharomyces cerevisiae, which were shown to be involved in various stress responses. More precisely, Yap1 is activated under oxidative stress, Yap2/Cad1 under cadmium, Yap4/Cin5 and Yap6 under osmotic shock, Yap5 under iron overload and Yap8/Arr1 by arsenic compounds. Yap3 and Yap7 seem to be involved in hydroquinone and nitrosative stresses, respectively. The data presented in this article illustrate how much knowledge on the function of these Yap transcription factors is advanced. The evolution of the Yap family and its roles in various pathogenic and non-pathogenic fungal species is discussed in the last section.
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Affiliation(s)
- Claudina Rodrigues-Pousada
- Instituto de Tecnologia Química e Biológica Anónio Xavier, Universidade Nova de Lisboa, Avenida da República, EAN, Oeiras 2781-901, Oeiras, Portugal
| | - Frédéric Devaux
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, F-75005, Paris, France
| | - Soraia M Caetano
- Instituto de Tecnologia Química e Biológica Anónio Xavier, Universidade Nova de Lisboa, Avenida da República, EAN, Oeiras 2781-901, Oeiras, Portugal
| | - Catarina Pimentel
- Instituto de Tecnologia Química e Biológica Anónio Xavier, Universidade Nova de Lisboa, Avenida da República, EAN, Oeiras 2781-901, Oeiras, Portugal
| | - Sofia da Silva
- Instituto de Tecnologia Química e Biológica Anónio Xavier, Universidade Nova de Lisboa, Avenida da República, EAN, Oeiras 2781-901, Oeiras, Portugal
| | - Ana Carolina Cordeiro
- Instituto de Tecnologia Química e Biológica Anónio Xavier, Universidade Nova de Lisboa, Avenida da República, EAN, Oeiras 2781-901, Oeiras, Portugal
| | - Catarina Amaral
- Instituto de Tecnologia Química e Biológica Anónio Xavier, Universidade Nova de Lisboa, Avenida da República, EAN, Oeiras 2781-901, Oeiras, Portugal
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17
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Devaux F, Thiébaut A. The regulation of iron homeostasis in the fungal human pathogen Candida glabrata. MICROBIOLOGY-SGM 2019; 165:1041-1060. [PMID: 31050635 DOI: 10.1099/mic.0.000807] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Iron is an essential element to most microorganisms, yet an excess of iron is toxic. Hence, living cells have to maintain a tight balance between iron uptake and iron consumption and storage. The control of intracellular iron concentrations is particularly challenging for pathogens because mammalian organisms have evolved sophisticated high-affinity systems to sequester iron from microbes and because iron availability fluctuates among the different host niches. In this review, we present the current understanding of iron homeostasis and its regulation in the fungal pathogen Candida glabrata. This yeast is an emerging pathogen which has become the second leading cause of candidemia, a life-threatening invasive mycosis. C. glabrata is relatively poorly studied compared to the closely related model yeast Saccharomyces cerevisiae or to the pathogenic yeast Candida albicans. Still, several research groups have started to identify the actors of C. glabrata iron homeostasis and its transcriptional and post-transcriptional regulation. These studies have revealed interesting particularities of C. glabrata and have shed new light on the evolution of fungal iron homeostasis.
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Affiliation(s)
- Frédéric Devaux
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, F-75005, Paris, France
| | - Antonin Thiébaut
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, F-75005, Paris, France
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18
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CgHog1-Mediated CgRds2 Phosphorylation Alters Glycerophospholipid Composition To Coordinate Osmotic Stress in Candida glabrata. Appl Environ Microbiol 2019; 85:AEM.02822-18. [PMID: 30635387 DOI: 10.1128/aem.02822-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 01/04/2019] [Indexed: 12/11/2022] Open
Abstract
Under stress conditions, Hog1 is required for cell survival through transiently phosphorylating downstream targets and reprogramming gene expression. Here, we report that Candida glabrata Hog1 (CgHog1) interacts with and phosphorylates CgRds2, a zinc cluster transcription factor, in response to osmotic stress. Additionally, we found that deletion of CgRDS2 led to decreases in cell growth and cell survival by 23.4% and 39.6%, respectively, at 1.5 M NaCl, compared with levels of the wild-type strain. This is attributed to significant downregulation of the expression levels of glycerophospholipid metabolism genes. As a result, the content of total glycerophospholipid decreased by 30.3%. Membrane integrity also decreased 47.6% in the Cgrds2Δ strain at 1.5 M NaCl. In contrast, overexpression of CgRDS2 increased the cell growth and cell survival by 10.2% and 6.3%, respectively, owing to a significant increase in the total glycerophospholipid content and increased membrane integrity by 27.2% and 12.1%, respectively, at 1.5 M NaCl, compared with levels for the wild-type strain. However, a strain in which the CgRDS2 gene encodes the replacement of Ser64 and Thr97 residues with alanines (Cgrds22A ), harboring a CgRds2 protein that was not phosphorylated by CgHog1, failed to promote glycerophospholipid metabolism and membrane integrity at 1.5 M NaCl. Thus, the above results demonstrate that CgHog1-mediated CgRds2 phosphorylation enhanced glycerophospholipid composition and membrane integrity to resist osmotic stress in C. glabrata IMPORTANCE This study explored the role of CgHog1-mediated CgRds2 phosphorylation in response to osmotic stress in Candida glabrata CgHog1 interacts with and phosphorylates CgRds2, a zinc cluster transcription factor, under osmotic stress. Phosphorylated CgRds2 plays an important role in increasing glycerophospholipid composition and membrane integrity, thereby enhancing cell growth and survival.
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19
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Song Z, Yang J, Xin C, Xing X, Yuan Q, Yin Y, Wang Z. A transcription factor, MrMsn2, in the dimorphic fungus Metarhizium rileyi is essential for dimorphism transition, aggravated pigmentation, conidiation and microsclerotia formation. Microb Biotechnol 2018; 11:1157-1169. [PMID: 30160031 PMCID: PMC6196401 DOI: 10.1111/1751-7915.13302] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 07/07/2018] [Indexed: 11/17/2022] Open
Abstract
Microsclerotia (MS) are pseudoparenchymatous aggregations of hyphae of fungi that can be induced in liquid culture for biocontrol applications. Previously, we determined that the high-osmolarity glycerol (HOG) signalling pathway was involved in regulating MS development in the dimorphic insect pathogen Metarhizium rileyi. To further investigate the mechanisms by which the signalling pathway is regulated, we characterized the transcriptional factor MrMsn2, a homologue of the yeast C2 H2 transcriptional factor Msn2, which is predicted to function downstream of the HOG pathway in M. rileyi. Compared with wild-type and complemented strains, disruption of MrMsn2 increased the yeast-to-hypha transition rate, enhanced conidiation capacity and aggravated pigmentation in M. rileyi. The ▵MrMsn2 mutants were sensitive to stress, produced morphologically abnormal clones and had significantly reduced MS formation and decreased virulence levels. Digital expression profiling revealed that genes involved in antioxidation, pigment biosynthesis and ion transport and storage were regulated by MrMsn2 during conidia and MS development. Taken together, our findings confirm that MrMsn2 controlled the yeast-to-hypha transition, conidia and MS formation, and virulence.
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Affiliation(s)
- Zhangyong Song
- School of Basic Medical SciencesSouthwest Medical UniversityLuzhou646000China
| | - Jie Yang
- School of Basic Medical SciencesSouthwest Medical UniversityLuzhou646000China
| | - Caiyan Xin
- School of Basic Medical SciencesSouthwest Medical UniversityLuzhou646000China
| | - Xiaorui Xing
- School of Basic Medical SciencesSouthwest Medical UniversityLuzhou646000China
| | - Qing Yuan
- School of Basic Medical SciencesSouthwest Medical UniversityLuzhou646000China
| | - Youping Yin
- Chongqing Engineering Research Center for Fungal InsecticideSchool of Life ScienceChongqing UniversityChongqing400030China
| | - Zhongkang Wang
- Chongqing Engineering Research Center for Fungal InsecticideSchool of Life ScienceChongqing UniversityChongqing400030China
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20
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Coccetti P, Nicastro R, Tripodi F. Conventional and emerging roles of the energy sensor Snf1/AMPK in Saccharomyces cerevisiae. MICROBIAL CELL 2018; 5:482-494. [PMID: 30483520 PMCID: PMC6244292 DOI: 10.15698/mic2018.11.655] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
All proliferating cells need to match metabolism, growth and cell cycle progression with nutrient availability to guarantee cell viability in spite of a changing environment. In yeast, a signaling pathway centered on the effector kinase Snf1 is required to adapt to nutrient limitation and to utilize alternative carbon sources, such as sucrose and ethanol. Snf1 shares evolutionary conserved functions with the AMP-activated Kinase (AMPK) in higher eukaryotes which, activated by energy depletion, stimulates catabolic processes and, at the same time, inhibits anabolism. Although the yeast Snf1 is best known for its role in responding to a number of stress factors, in addition to glucose limitation, new unconventional roles of Snf1 have recently emerged, even in glucose repressing and unstressed conditions. Here, we review and integrate available data on conventional and non-conventional functions of Snf1 to better understand the complexity of cellular physiology which controls energy homeostasis.
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Affiliation(s)
- Paola Coccetti
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy.,SYSBIO, Centre of Systems Biology, Milan, Italy
| | - Raffaele Nicastro
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy.,Present address: Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Farida Tripodi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy.,SYSBIO, Centre of Systems Biology, Milan, Italy
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21
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Martins TS, Costa V, Pereira C. Signaling pathways governing iron homeostasis in budding yeast. Mol Microbiol 2018; 109:422-432. [DOI: 10.1111/mmi.14009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Telma S. Martins
- I3S-Instituto de Investigação e Inovação em Saúde; Universidade do Porto; Porto Portugal
- IBMC-Instituto de Biologia Molecular e Celular; Universidade do Porto; Porto Portugal
| | - Vítor Costa
- I3S-Instituto de Investigação e Inovação em Saúde; Universidade do Porto; Porto Portugal
- IBMC-Instituto de Biologia Molecular e Celular; Universidade do Porto; Porto Portugal
- Departamento de Biologia Molecular; Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto; Porto Portugal
| | - Clara Pereira
- I3S-Instituto de Investigação e Inovação em Saúde; Universidade do Porto; Porto Portugal
- IBMC-Instituto de Biologia Molecular e Celular; Universidade do Porto; Porto Portugal
- Departamento de Biologia Molecular; Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto; Porto Portugal
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22
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Li L, Ward DM. Iron toxicity in yeast: transcriptional regulation of the vacuolar iron importer Ccc1. Curr Genet 2017; 64:413-416. [PMID: 29043483 DOI: 10.1007/s00294-017-0767-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 10/11/2017] [Accepted: 10/13/2017] [Indexed: 11/27/2022]
Abstract
All eukaryotes require the transition metal, iron, a redox active element that is an essential cofactor in many metabolic pathways, as well as an oxygen carrier. Iron can also react to generate oxygen radicals such as hydroxyl radicals and superoxide anions, which are highly toxic to cells. Therefore, organisms have developed intricate mechanisms to acquire iron as well as to protect themselves from the toxic effects of excess iron. In fungi and plants, iron is stored in the vacuole as a protective mechanism against iron toxicity. Iron storage in the vacuole is mediated predominantly by the vacuolar metal importer Ccc1 in yeast and the homologous transporter VIT1 in plants. Transcription of yeast CCC1 expression is tightly controlled primarily by the transcription factor Yap5, which sits on the CCC1 promoter and activates transcription through the binding of Fe-S clusters. A second mechanism that regulates CCC1 transcription is through the Snf1 signaling pathway involved in low-glucose sensing. Snf1 activates stress transcription factors Msn2 and Msn4 to mediate CCC1 transcription. Transcriptional regulation by Yap5 and Snf1 are completely independent and provide for a graded response in Ccc1 expression. The identification of multiple independent transcriptional pathways that regulate the levels of Ccc1 under high iron conditions accentuates the importance of protecting cells from the toxic effects of high iron.
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Affiliation(s)
- Liangtao Li
- Division of Microbiology and Immunology, Department of Pathology, School of Medicine, University of Utah, Salt Lake City, UT, 84132-2501, USA
| | - Diane M Ward
- Division of Microbiology and Immunology, Department of Pathology, School of Medicine, University of Utah, Salt Lake City, UT, 84132-2501, USA.
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