1
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Antunes M, Kale D, Sychrová H, Sá-Correia I. The Hrk1 kinase is a determinant of acetic acid tolerance in yeast by modulating H + and K + homeostasis. MICROBIAL CELL (GRAZ, AUSTRIA) 2023; 10:261-276. [PMID: 38053573 PMCID: PMC10695635 DOI: 10.15698/mic2023.12.809] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 10/15/2023] [Accepted: 10/26/2023] [Indexed: 12/07/2023]
Abstract
Acetic acid-induced stress is a common challenge in natural environments and industrial bioprocesses, significantly affecting the growth and metabolic performance of Saccharomyces cerevisiae. The adaptive response and tolerance to this stress involves the activation of a complex network of molecular pathways. This study aims to delve deeper into these mechanisms in S. cerevisiae, particularly focusing on the role of the Hrk1 kinase. Hrk1 is a key determinant of acetic acid tolerance, belonging to the NPR/Hal family, whose members are implicated in the modulation of the activity of plasma membrane transporters that orchestrate nutrient uptake and ion homeostasis. The influence of Hrk1 on S. cerevisiae adaptation to acetic acid-induced stress was explored by employing a physiological approach based on previous phosphoproteomics analyses. The results from this study reflect the multifunctional roles of Hrk1 in maintaining proton and potassium homeostasis during different phases of acetic acid-stressed cultivation. Hrk1 is shown to play a role in the activation of plasma membrane H+-ATPase, maintaining pH homeostasis, and in the modulation of plasma membrane potential under acetic acid stressed cultivation. Potassium (K+) supplementation of the growth medium, particularly when provided at limiting concentrations, led to a notable improvement in acetic acid stress tolerance of the hrk1Δ strain. Moreover, abrogation of this kinase expression is shown to confer a physiological advantage to growth under K+ limitation also in the absence of acetic acid stress. The involvement of the alkali metal cation/H+ exchanger Nha1, another proposed molecular target of Hrk1, in improving yeast growth under K+ limitation or acetic acid stress, is proposed.
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Affiliation(s)
- Miguel Antunes
- iBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
| | - Deepika Kale
- Laboratory of Membrane Transport, Institute of Physiology, Czech Academy of Sciences, Videnska 1083, 142 00 Prague 4, Czech Republic
| | - Hana Sychrová
- Laboratory of Membrane Transport, Institute of Physiology, Czech Academy of Sciences, Videnska 1083, 142 00 Prague 4, Czech Republic
| | - Isabel Sá-Correia
- iBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
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2
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Pirkkanen J, Lalonde C, Lapointe M, Laframboise T, Mendonca MS, Boreham DR, Tharmalingam S, Thome C. The REPAIR Project, a Deep-Underground Radiobiology Experiment Investigating the Biological Effects of Natural Background Radiation: The First 6 Years. Radiat Res 2023; 199:290-293. [PMID: 36745561 DOI: 10.1667/rade-22-00193.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 01/17/2023] [Indexed: 02/07/2023]
Abstract
In 2017, a special edition of Radiation Research was published [Oct; Vol. 188 4.2 (https://bioone.org/journals/radiation-research/volume-188/issue-4.2)] which focused on a recently established radiobiology project within SNOLAB, a unique deep-underground research facility. This special edition included original articles, reviews and commentaries relevant to the research goals of this new project which was titled Researching the Effects of the Presence and Absence of Ionizing Radiation (REPAIR). These research goals were founded in understanding the biological effects of terrestrial and cosmic natural background radiation (NBR). Since 2017, REPAIR has evolved into a sub-NBR radiobiology research program which investigates these effects using multiple model systems and various biological endpoints. This paper summarizes the evolution of the REPAIR project over the first 6-years including its experimental scope and capabilities as well as research accomplishments.
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Affiliation(s)
- Jake Pirkkanen
- School of Natural Sciences, Laurentian University, Sudbury, Ontario, P3E 2C6, Canada
| | - Christine Lalonde
- School of Natural Sciences, Laurentian University, Sudbury, Ontario, P3E 2C6, Canada
| | - Michel Lapointe
- School of Natural Sciences, Laurentian University, Sudbury, Ontario, P3E 2C6, Canada
| | - Taylor Laframboise
- School of Natural Sciences, Laurentian University, Sudbury, Ontario, P3E 2C6, Canada
| | - Marc S Mendonca
- Department of Radiation Oncology, Radiation and Cancer Biology Laboratories, and Department of Medical & Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Douglas R Boreham
- School of Natural Sciences, Laurentian University, Sudbury, Ontario, P3E 2C6, Canada.,Medical Sciences Division, Northern Ontario School of Medicine (NOSM University), Sudbury, Ontario, P3E 2C6, Canada.,Nuclear Innovation Institute, Port Elgin, Ontario, N0H 2C0, Canada
| | - Sujeenthar Tharmalingam
- School of Natural Sciences, Laurentian University, Sudbury, Ontario, P3E 2C6, Canada.,Medical Sciences Division, Northern Ontario School of Medicine (NOSM University), Sudbury, Ontario, P3E 2C6, Canada.,Nuclear Innovation Institute, Port Elgin, Ontario, N0H 2C0, Canada
| | - Christopher Thome
- School of Natural Sciences, Laurentian University, Sudbury, Ontario, P3E 2C6, Canada.,Medical Sciences Division, Northern Ontario School of Medicine (NOSM University), Sudbury, Ontario, P3E 2C6, Canada.,Nuclear Innovation Institute, Port Elgin, Ontario, N0H 2C0, Canada
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3
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Lagunas-Gomez D, Yañez-Dominguez C, Zavala-Padilla G, Barlowe C, Pantoja O. The C-terminus of the cargo receptor Erv14 affects COPII vesicle formation and cargo delivery. J Cell Sci 2023; 136:286926. [PMID: 36651113 PMCID: PMC10022740 DOI: 10.1242/jcs.260527] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 12/22/2022] [Indexed: 01/19/2023] Open
Abstract
The endoplasmic reticulum (ER) is the start site of the secretory pathway, where newly synthesized secreted and membrane proteins are packaged into COPII vesicles through direct interaction with the COPII coat or aided by specific cargo receptors. Little is known about how post-translational modification events regulate packaging of cargo into COPII vesicles. The Saccharomyces cerevisiae protein Erv14, also known as cornichon, belongs to a conserved family of cargo receptors required for the selection and ER export of transmembrane proteins. In this work, we show the importance of a phosphorylation consensus site (S134) at the C-terminus of Erv14. Mimicking phosphorylation of S134 (S134D) prevents the incorporation of Erv14 into COPII vesicles, delays cell growth, exacerbates growth of sec mutants, modifies ER structure and affects localization of several plasma membrane transporters. In contrast, the dephosphorylated mimic (S134A) had less deleterious effects, but still modifies ER structure and slows cell growth. Our results suggest that a possible cycle of phosphorylation and dephosphorylation is important for the correct functioning of Erv14.
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Affiliation(s)
- Daniel Lagunas-Gomez
- Centro de Investigación en Dinámica Celular, Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, Cuernavaca, Morelos 62210, Mexico.,Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca, Morelos 62210, México
| | - Carolina Yañez-Dominguez
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca, Morelos 62210, México
| | - Guadalupe Zavala-Padilla
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca, Morelos 62210, México
| | - Charles Barlowe
- Department of Biochemistry, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755-3844, USA
| | - Omar Pantoja
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca, Morelos 62210, México
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4
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Ruiz-Castilla FJ, Ruiz Pérez FS, Ramos-Moreno L, Ramos J. Candida albicans Potassium Transporters. Int J Mol Sci 2022; 23:ijms23094884. [PMID: 35563275 PMCID: PMC9105532 DOI: 10.3390/ijms23094884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 04/26/2022] [Accepted: 04/26/2022] [Indexed: 12/10/2022] Open
Abstract
Potassium is basic for life. All living organisms require high amounts of intracellular potassium, which fulfils multiple functions. To reach efficient potassium homeostasis, eukaryotic cells have developed a complex and tightly regulated system of transporters present both in the plasma membrane and in the membranes of internal organelles that allow correct intracellular potassium content and distribution. We review the information available on the pathogenic yeast Candida albicans. While some of the plasma membrane potassium transporters are relatively well known and experimental data about their nature, function or regulation have been published, in the case of most of the transporters present in intracellular membranes, their existence and even function have just been deduced because of their homology with those present in other yeasts, such as Saccharomyces cerevisiae. Finally, we analyse the possible links between pathogenicity and potassium homeostasis. We comment on the possibility of using some of these transporters as tentative targets in the search for new antifungal drugs.
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5
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Yeast Trk1 Potassium Transporter Gradually Changes Its Affinity in Response to Both External and Internal Signals. J Fungi (Basel) 2022; 8:jof8050432. [PMID: 35628688 PMCID: PMC9144525 DOI: 10.3390/jof8050432] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 04/14/2022] [Accepted: 04/20/2022] [Indexed: 01/04/2023] Open
Abstract
Yeasts need a high intracellular concentration of potassium to grow. The main K+ uptake system in Saccharomyces cerevisiae is the Trk1 transporter, a complex protein with four MPM helical membrane motifs. Trk1 has been shown to exist in low- or high-affinity modes, which reflect the availability of potassium in the environment. However, when and how the affinity changes, and whether the potassium availability is the only signal for the affinity switch, remains unknown. Here, we characterize the Trk1 kinetic parameters under various conditions and find that Trk1’s KT and Vmax change gradually. This gliding adjustment is rapid and precisely reflects the changes in the intracellular potassium content and membrane potential. A detailed characterization of the specific mutations in the P-helices of the MPM segments reveals that the presence of proline in the P-helix of the second and third MPM domain (F820P and L949P) does not affect the function of Trk1 in general, but rather specifically prevents the transporter’s transition to a high-affinity state. The analogous mutations in the two remaining MPM domains (L81P and L1115P) result in a mislocalized and inactive protein, highlighting the importance of the first and fourth P-helices in proper Trk1 folding and activity at the plasma membrane.
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6
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The Toxic Effects of Ppz1 Overexpression Involve Nha1-Mediated Deregulation of K + and H + Homeostasis. J Fungi (Basel) 2021; 7:jof7121010. [PMID: 34946993 PMCID: PMC8704375 DOI: 10.3390/jof7121010] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/18/2021] [Accepted: 11/23/2021] [Indexed: 11/17/2022] Open
Abstract
The alteration of the fine-tuned balance of phospho/dephosphorylation reactions in the cell often results in functional disturbance. In the yeast Saccharomyces cerevisiae, the overexpression of Ser/Thr phosphatase Ppz1 drastically blocks cell proliferation, with a profound change in the transcriptomic and phosphoproteomic profiles. While the deleterious effect on growth likely derives from the alteration of multiple targets, the precise mechanisms are still obscure. Ppz1 is a negative effector of potassium influx. However, we show that the toxic effect of Ppz1 overexpression is unrelated to the Trk1/2 high-affinity potassium importers. Cells overexpressing Ppz1 exhibit decreased K+ content, increased cytosolic acidification, and fail to properly acidify the medium. These effects, as well as the growth defect, are counteracted by the deletion of NHA1 gene, which encodes a plasma membrane Na+, K+/H+ antiporter. The beneficial effect of a lack of Nha1 on the growth vanishes as the pH of the medium approaches neutrality, is not eliminated by the expression of two non-functional Nha1 variants (D145N or D177N), and is exacerbated by a hyperactive Nha1 version (S481A). All our results show that high levels of Ppz1 overactivate Nha1, leading to an excessive entry of H+ and efflux of K+, which is detrimental for growth.
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7
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Dušková M, Cmunt D, Papoušková K, Masaryk J, Sychrová H. Minority potassium-uptake system Trk2 has a crucial role in yeast survival of glucose-induced cell death. MICROBIOLOGY-SGM 2021; 167. [PMID: 34170815 DOI: 10.1099/mic.0.001065] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The existence of programmed cell death in Saccharomyces cerevisiae has been reported for many years. Glucose induces the death of S. cerevisiae in the absence of additional nutrients within a few hours, and the absence of active potassium uptake makes cells highly sensitive to this process. S. cerevisiae cells possess two transporters, Trk1 and Trk2, which ensure a high intracellular concentration of potassium, necessary for many physiological processes. Trk1 is the major system responsible for potassium acquisition in growing and dividing cells. The contribution of Trk2 to potassium uptake in growing cells is almost negligible, but Trk2 becomes crucial for stationary cells for their survival of some stresses, e.g. anhydrobiosis. As a new finding, we show that both Trk systems contribute to the relative thermotolerance of S. cerevisiae BY4741. Our results also demonstrate that Trk2 is much more important for the cell survival of glucose-induced cell death than Trk1, and that stationary cells deficient in active potassium uptake lose their ATP stocks more rapidly than cells with functional Trk systems. This is probably due to the upregulated activity of plasma-membrane Pma1 H+-ATPase, and consequently, it is the reason why these cells die earlier than cells with functional active potassium uptake.
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Affiliation(s)
- Michala Dušková
- Laboratory of Membrane Transport, Institute of Physiology, Czech Academy of Sciences, Prague 4, Czech Republic
| | - Denis Cmunt
- Laboratory of Membrane Transport, Institute of Physiology, Czech Academy of Sciences, Prague 4, Czech Republic.,Present address: Dept. Oncology, Ludwig Institute for Cancer Research, University of Lausanne, Lausanne, Switzerland
| | - Klára Papoušková
- Laboratory of Membrane Transport, Institute of Physiology, Czech Academy of Sciences, Prague 4, Czech Republic
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8
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The Potassium Transporter Hak1 in Candida Albicans, Regulation and Physiological Effects at Limiting Potassium and under Acidic Conditions. J Fungi (Basel) 2021; 7:jof7050362. [PMID: 34066565 PMCID: PMC8148600 DOI: 10.3390/jof7050362] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/03/2021] [Accepted: 05/04/2021] [Indexed: 11/16/2022] Open
Abstract
The three families of yeast plasma membrane potassium influx transporters are represented in Candida albicans: Trk, Acu, and Hak proteins. Hak transporters work as K+-H+ symporters, and the genes coding for Hak proteins are transcriptionally activated under potassium limitation. This work shows that C. albicans mutant cells lacking CaHAK1 display a severe growth impairment at limiting potassium concentrations under acidic conditions. This is the consequence of a defective capacity to transport K+, as indicated by potassium absorption experiments and by the kinetics parameters of Rb+ (K+) transport. Moreover, hak1- cells are more sensitive to the toxic cation lithium. All these phenotypes became much less robust or even disappeared at alkaline growth conditions. Finally, transcriptional studies demonstrate that the hak1- mutant, in comparison with HAK1+ cells, activates the expression of the K+/Na+ ATPase coded by CaACU1 in the presence of Na+ or in the absence of K+.
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9
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Papouskova K, Moravcova M, Masrati G, Ben-Tal N, Sychrova H, Zimmermannova O. C5 conserved region of hydrophilic C-terminal part of Saccharomyces cerevisiae Nha1 antiporter determines its requirement of Erv14 COPII cargo receptor for plasma-membrane targeting. Mol Microbiol 2020; 115:41-57. [PMID: 32864748 DOI: 10.1111/mmi.14595] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/23/2020] [Accepted: 08/22/2020] [Indexed: 01/03/2023]
Abstract
Erv14, a conserved cargo receptor of COPII vesicles, helps the proper trafficking of many but not all transporters to the yeast plasma membrane, for example, three out of five alkali-metal-cation transporters in Saccharomyces cerevisiae. Among them, the Nha1 cation/proton antiporter, which participates in cell cation and pH homeostasis, is a large membrane protein (985 aa) possessing a long hydrophilic C-terminus (552 aa) containing six conserved regions (C1-C6) with unknown function. A short Nha1 version, lacking almost the entire C-terminus, still binds to Erv14 but does not need it to be targeted to the plasma membrane. Comparing the localization and function of ScNha1 variants shortened at its C-terminus in cells with or without Erv14 reveals that only ScNha1 versions possessing the complete C5 region are dependent on Erv14. In addition, our broad evolutionary conservation analysis of fungal Na+ /H+ antiporters identified new conserved regions in their C-termini, and our experiments newly show C5 and other, so far unknown, regions of the C-terminus, to be involved in the functionality and substrate specificity of ScNha1. Taken together, our results reveal that also relatively small hydrophilic parts of some yeast membrane proteins underlie their need to interact with the Erv14 cargo receptor.
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Affiliation(s)
- Klara Papouskova
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague 4, Czech Republic
| | - Michaela Moravcova
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague 4, Czech Republic
| | - Gal Masrati
- Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Nir Ben-Tal
- Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Hana Sychrova
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague 4, Czech Republic
| | - Olga Zimmermannova
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague 4, Czech Republic
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10
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Hou J, Daniels PN, Burke MD. Small Molecule Channels Harness Membrane Potential to Concentrate Potassium in trk1Δtrk2Δ Yeast. ACS Chem Biol 2020; 15:1575-1580. [PMID: 32427463 DOI: 10.1021/acschembio.0c00180] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Many protein ion channels harness membrane potential to move ions in opposition to their chemical gradient. Deficiencies of such proteins cause several human diseases, including cystic fibrosis, Bartter Syndrome, and proximal renal tubular acidosis. Using yeast as a eukaryotic model system, we asked whether, in the context of a protein ion channel deficiency in vivo, small molecule channels could similarly harness membrane potential to concentrate ions. Trk potassium transporters use membrane potential to move potassium from a relatively low concentration outside cells (∼15 mM) to one of >10× higher inside (150-500 mM); trk1Δtrk2Δ are unable to concentrate potassium or grow in standard media. Here we show that potassium-permeable, but not potassium-selective, small-molecule ion channels formed by amphotericin B can harness membrane potential to concentrate potassium and thereby restore trk1Δtrk2Δ growth. This finding expands the list of potential human channelopathies that might be addressed by a molecular prosthetics approach.
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Affiliation(s)
- Jennifer Hou
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Ave., Urbana, Illinois 61801, United States
| | - Page N Daniels
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Ave., Urbana, Illinois 61801, United States
| | - Martin D Burke
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Ave., Urbana, Illinois 61801, United States
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Ave., Urbana, Illinois 61801, United States
- Carle Illinois College of Medicine, 807 South Wright Street, Champaign, Illinois 61820, United States
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 West Gregory Dr., Urbana, Illinois 61801, United States
- Arnold and Mabel Beckman Institute, University of Illinois at Urbana-Champaign, 405 North Mathews Ave., Urbana, Illinois 61801, United States
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11
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Johnston NR, Strobel SA. Nitrate and Phosphate Transporters Rescue Fluoride Toxicity in Yeast. Chem Res Toxicol 2019; 32:2305-2319. [PMID: 31576749 DOI: 10.1021/acs.chemrestox.9b00315] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Organisms are exposed to fluoride in the air, water, and soil. Yeast and other microbes utilize fluoride channels as a method to prevent intracellular fluoride accumulation and mediate fluoride toxicity. Consequently, deletion of fluoride exporter genes (FEX) in S. cerevisiae resulted in over 1000-fold increased fluoride sensitivity. We used this FEX knockout strain to identify genes, that when overexpressed, are able to partially relieve the toxicity of fluoride exposure. Overexpression of five genes, SSU1, YHB1, IPP1, PHO87, and PHO90, increase fluoride tolerance by 2- to 10-fold. Overexpression of these genes did not provide improved fluoride resistance in wild-type yeast, suggesting that the mechanism is specific to low fluoride toxicity in yeast. Ssu1p and Yhb1p both function in nitrosative stress response, which is induced upon fluoride exposure along with metal influx. Ipp1p, Pho87p, and Pho90p increase intracellular orthophosphate. Consistent with this observation, fluoride toxicity is also partially mitigated by the addition of high levels of phosphate to the growth media. Fluoride inhibits phosphate import upon stress induction and causes nutrient starvation and organelle disruption, as supported by gene induction monitored through RNA-Seq. The combination of observations suggests that transmembrane nutrient transporters are among the most sensitized proteins during fluoride-instigated stress.
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Affiliation(s)
- Nichole R Johnston
- From the Department of Molecular Biophysics and Biochemistry , Yale University , New Haven , Connecticut 06520
| | - Scott A Strobel
- From the Department of Molecular Biophysics and Biochemistry , Yale University , New Haven , Connecticut 06520.,Department of Chemistry , Yale University , New Haven , Connecticut 06520
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12
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Elicharova H, Herynkova P, Zimmermannova O, Sychrova H. Potassium uptake systems of
Candida krusei. Yeast 2019; 36:439-448. [DOI: 10.1002/yea.3396] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 03/13/2019] [Accepted: 04/23/2019] [Indexed: 01/15/2023] Open
Affiliation(s)
- Hana Elicharova
- Department of Membrane TransportInstitute of Physiology of the Czech Academy of Sciences Prague Czech Republic
| | - Pavla Herynkova
- Department of Membrane TransportInstitute of Physiology of the Czech Academy of Sciences Prague Czech Republic
| | - Olga Zimmermannova
- Department of Membrane TransportInstitute of Physiology of the Czech Academy of Sciences Prague Czech Republic
| | - Hana Sychrova
- Department of Membrane TransportInstitute of Physiology of the Czech Academy of Sciences Prague Czech Republic
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13
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Llopis-Torregrosa V, Vaz C, Monteoliva L, Ryman K, Engstrom Y, Gacser A, Gil C, Ljungdahl PO, Sychrová H. Trk1-mediated potassium uptake contributes to cell-surface properties and virulence of Candida glabrata. Sci Rep 2019; 9:7529. [PMID: 31101845 PMCID: PMC6525180 DOI: 10.1038/s41598-019-43912-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 04/25/2019] [Indexed: 11/16/2022] Open
Abstract
The absence of high-affinity potassium uptake in Candida glabrata, the consequence of the deletion of the TRK1 gene encoding the sole potassium-specific transporter, has a pleiotropic effect. Here, we show that in addition to changes in basic physiological parameters (e.g., membrane potential and intracellular pH) and decreased tolerance to various cell stresses, the loss of high affinity potassium uptake also alters cell-surface properties, such as an increased hydrophobicity and adherence capacity. The loss of an efficient potassium uptake system results in diminished virulence as assessed by two insect host models, Drosophila melanogaster and Galleria mellonella, and experiments with macrophages. Macrophages kill trk1Δ cells more effectively than wild type cells. Consistently, macrophages accrue less damage when co-cultured with trk1Δ mutant cells compared to wild-type cells. We further show that low levels of potassium in the environment increase the adherence of C. glabrata cells to polystyrene and the propensity of C. glabrata cells to form biofilms.
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Affiliation(s)
- Vicent Llopis-Torregrosa
- Department of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, 14220, Prague 4, Czech Republic
| | - Catarina Vaz
- Department of Microbiology and Parasitology, Faculty of Pharmacy, Complutense University of Madrid and IRYCIS, Madrid, Spain
| | - Lucia Monteoliva
- Department of Microbiology and Parasitology, Faculty of Pharmacy, Complutense University of Madrid and IRYCIS, Madrid, Spain
| | - Kicki Ryman
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-10691, Stockholm, Sweden
| | - Ylva Engstrom
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-10691, Stockholm, Sweden
| | - Attila Gacser
- Department of Microbiology, University of Szeged Interdisciplinary Excellence Centre, Szeged, Hungary.,MTA-SZTE "Lendület" "Mycobiome" Research Group, University of Szeged, Szeged, Hungary
| | - Concha Gil
- Department of Microbiology and Parasitology, Faculty of Pharmacy, Complutense University of Madrid and IRYCIS, Madrid, Spain
| | - Per O Ljungdahl
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-10691, Stockholm, Sweden
| | - Hana Sychrová
- Department of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, 14220, Prague 4, Czech Republic.
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14
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Sasikumar AN, Killilea DW, Kennedy BK, Brem RB. Potassium restriction boosts vacuolar acidity and extends lifespan in yeast. Exp Gerontol 2019; 120:101-106. [PMID: 30742903 DOI: 10.1016/j.exger.2019.02.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 01/15/2019] [Accepted: 02/01/2019] [Indexed: 12/23/2022]
Abstract
Lysosome function is compromised during aging and in many disease states. Interventions that promote lysosomal activity and acidification are thus of prime interest as treatments for longevity and health. Intracellular pH can be controlled by the exchange of protons for inorganic ions, and in cells from microbes to man, when potassium is restricted in the growth medium, the cytoplasm becomes acidified. Here we use a yeast model to show that potassium limited-cells exhibit hallmarks of increased acidity in the vacuole, the analog of the lysosome, and live long by a mechanism that requires the vacuolar machinery. The emerging picture is one in which potassium restriction shores up vacuolar acidity and function, conferring health benefits early in life and extending viability into old age. Against the backdrop of well-studied protein and carbohydrate restrictions that extend lifespan and healthspan, our work establishes a novel pro-longevity paradigm of inorganic nutrient limitation.
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Affiliation(s)
- Arjun N Sasikumar
- Buck Institute for Research on Aging, Novato, CA, United States of America
| | - David W Killilea
- Nutrition & Metabolism Center and Elemental Analysis Facility, Children's Hospital Oakland Research Institute, Oakland, CA, United States of America
| | - Brian K Kennedy
- Buck Institute for Research on Aging, Novato, CA, United States of America; Departments of Biochemistry and Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Rachel B Brem
- Buck Institute for Research on Aging, Novato, CA, United States of America; Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, United States of America.
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15
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Lynch JH, Sa N, Saeheng S, Raffaelli N, Roje S. Characterization of a non-nudix pyrophosphatase points to interplay between flavin and NAD(H) homeostasis in Saccharomyces cerevisiae. PLoS One 2018; 13:e0198787. [PMID: 29902190 PMCID: PMC6002036 DOI: 10.1371/journal.pone.0198787] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 05/28/2018] [Indexed: 12/11/2022] Open
Abstract
The flavin cofactors FMN and FAD are required for a wide variety of biological processes, however, little is known about their metabolism. Here, we report the cloning and biochemical characterization of the Saccharomyces cerevisiae pyrophosphatase Fpy1p. Genetic and functional studies suggest that Fpy1p may play a key role in flavin metabolism and is the first-reported non-Nudix superfamily enzyme to display FAD pyrophosphatase activity. Characterization of mutant yeast strains found that deletion of fpy1 counteracts the adverse effects that are caused by deletion of flx1, a known mitochondrial FAD transporter. We show that Fpy1p is capable of hydrolyzing FAD, NAD(H), and ADP-ribose. The enzymatic activity of Fpy1p is dependent upon the presence of K+ and divalent metal cations, with similar kinetic parameters to those that have been reported for Nudix FAD pyrophosphatases. In addition, we report that the deletion of fpy1 intensifies the FMN-dependence of null mutants of the riboflavin kinase Fmn1p, demonstrate that fpy1 mutation abolishes the decreased fitness resulting from the deletion of the flx1 ORF, and offer a possible mechanism for the genetic interplay between fpy1, flx1 and fmn1.
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Affiliation(s)
- Joseph H. Lynch
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States of America
| | - Na Sa
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States of America
| | - Sompop Saeheng
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States of America
| | - Nadia Raffaelli
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università Politecnica delle Marche, Ancona, Italy
| | - Sanja Roje
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States of America
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16
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Olicón-Hernández DR, Uribe-Alvarez C, Uribe-Carvajal S, Pardo JP, Guerra-Sánchez G. Response of Ustilago maydis against the Stress Caused by Three Polycationic Chitin Derivatives. Molecules 2017; 22:molecules22121745. [PMID: 29215563 PMCID: PMC6149792 DOI: 10.3390/molecules22121745] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 10/09/2017] [Accepted: 10/13/2017] [Indexed: 12/25/2022] Open
Abstract
Chitosan is a stressing molecule that affects the cells walls and plasma membrane of fungi. For chitosan derivatives, the action mode is not clear. In this work, we used the yeast Ustilago maydis to study the effects of these molecules on the plasma membrane, focusing on physiologic and stress responses to chitosan (CH), oligochitosan (OCH), and glycol-chitosan (GCH). Yeasts were cultured with each of these molecules at 1 mg·mL−1 in minimal medium. To compare plasma membrane damage, cells were cultivated in isosmolar medium. Membrane potential (Δψ) as well as oxidative stress were measured. Changes in the total plasma membrane phospholipid and protein profiles were analyzed using standard methods, and fluorescence-stained mitochondria were observed. High osmolarity did not protect against CH inhibition and neither affected membrane potential. The OCH did produce higher oxidative stress. The effects of these molecules were evidenced by modifications in the plasma membrane protein profile. Also, mitochondrial damage was evident for CH and OCH, while GCH resulted in thicker cells with fewer mitochondria and higher glycogen accumulation.
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Affiliation(s)
- Dario Rafael Olicón-Hernández
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Departamento de Microbiología, Prolongación de Carpio y Plan de Ayala S/N, Col. Sto. Tomas, Del, Miguel Hidalgo, CP 11340 Ciudad de México, Mexico.
| | - Cristina Uribe-Alvarez
- Universidad Nacional Autónoma de México, Instituto de Fisiología Celular, Circuito exterior S/N, Ciudad Universitaria, CP 04510 Ciudad de México, Mexico.
| | - Salvador Uribe-Carvajal
- Universidad Nacional Autónoma de México, Instituto de Fisiología Celular, Circuito exterior S/N, Ciudad Universitaria, CP 04510 Ciudad de México, Mexico.
| | - Juan Pablo Pardo
- Universidad Nacional Autónoma de México, Facultad de Medicina, Departamento de Bioquímica, Circuito exterior S/N, Ciudad Universitaria, CP 04510 Ciudad de México, Mexico.
| | - Guadalupe Guerra-Sánchez
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Departamento de Microbiología, Prolongación de Carpio y Plan de Ayala S/N, Col. Sto. Tomas, Del, Miguel Hidalgo, CP 11340 Ciudad de México, Mexico.
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17
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Teunissen JHM, Crooijmans ME, Teunisse PPP, van Heusden GPH. Lack of 14-3-3 proteins in Saccharomyces cerevisiae results in cell-to-cell heterogeneity in the expression of Pho4-regulated genes SPL2 and PHO84. BMC Genomics 2017; 18:701. [PMID: 28877665 PMCID: PMC5588707 DOI: 10.1186/s12864-017-4105-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 08/31/2017] [Indexed: 01/16/2023] Open
Abstract
Background Ion homeostasis is an essential property of living organisms. The yeast Saccharomyces cerevisiae is an ideal model organism to investigate ion homeostasis at all levels. In this yeast genes involved in high-affinity phosphate uptake (PHO genes) are strongly induced during both phosphate and potassium starvation, indicating a link between phosphate and potassium homeostasis. However, the signal transduction processes involved are not completely understood. As 14-3-3 proteins are key regulators of signal transduction processes, we investigated the effect of deletion of the 14-3-3 genes BMH1 or BMH2 on gene expression during potassium starvation and focused especially on the expression of genes involved in phosphate uptake. Results Genome-wide analysis of the effect of disruption of either BMH1 or BMH2 revealed that the mRNA levels of the PHO genes PHO84 and SPL2 are greatly reduced in the mutant strains compared to the levels in wild type strains. This was especially apparent at standard potassium and phosphate concentrations. Furthermore the promoter of these genes is less active after deletion of BMH1. Microscopic and flow cytometric analysis of cells with GFP-tagged SPL2 showed that disruption of BMH1 resulted in two populations of genetically identical cells, cells expressing the protein and the majority of cells with no detectible expression. Heterogeneity was also observed for the expression of GFP under control of the PHO84 promoter. Upon deletion of PHO80 encoding a regulator of the transcription factor Pho4, the effect of the BMH1 deletion on SPL2 and PHO84 promoter was lost, suggesting that the BMH1 deletion mainly influences processes upstream of the Pho4 transcription factor. Conclusion Our data indicate that that yeast cells can be in either of two states, expressing or not expressing genes required for high-affinity phosphate uptake and that 14-3-3 proteins are involved in the process(es) that establish the activation state of the PHO regulon. Electronic supplementary material The online version of this article (10.1186/s12864-017-4105-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Janneke H M Teunissen
- Institute of Biology, Leiden University, Sylviusweg 72, NL-2333BE, Leiden, the Netherlands
| | - Marjolein E Crooijmans
- Institute of Biology, Leiden University, Sylviusweg 72, NL-2333BE, Leiden, the Netherlands
| | - Pepijn P P Teunisse
- Institute of Biology, Leiden University, Sylviusweg 72, NL-2333BE, Leiden, the Netherlands
| | - G Paul H van Heusden
- Institute of Biology, Leiden University, Sylviusweg 72, NL-2333BE, Leiden, the Netherlands.
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18
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Primo C, Ferri-Blázquez A, Loewith R, Yenush L. Reciprocal Regulation of Target of Rapamycin Complex 1 and Potassium Accumulation. J Biol Chem 2016; 292:563-574. [PMID: 27895122 DOI: 10.1074/jbc.m116.746982] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 11/16/2016] [Indexed: 12/19/2022] Open
Abstract
The proper maintenance of potassium homeostasis is crucial for cell viability. Among the major determinants of potassium uptake in the model organism Saccharomyces cerevisiae are the Trk1 high affinity potassium transporter and the functionally redundant Hal4 (Sat4) and Hal5 protein kinases. These kinases are required for the plasma membrane accumulation of not only Trk1 but also several nutrient permeases. Here, we show that overexpression of the target of rapamycin complex 1 (TORC1) effector NPR1 improves hal4 hal5 growth defects by stabilizing nutrient permeases at the plasma membrane. We subsequently found that internal potassium levels and TORC1 activity are linked. Specifically, growth under limiting potassium alters the activities of Npr1 and another TORC1 effector kinase, Sch9; hal4 hal5 and trk1 trk2 mutants display hypersensitivity to rapamycin, and reciprocally, TORC1 inhibition reduces potassium accumulation. Our results demonstrate that in addition to carbon and nitrogen, TORC1 also responds to and regulates potassium fluxes.
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Affiliation(s)
- Cecilia Primo
- From the Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Avd. de los Naranjos s/n, Valencia, Spain 46022 and
| | - Alba Ferri-Blázquez
- From the Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Avd. de los Naranjos s/n, Valencia, Spain 46022 and
| | - Robbie Loewith
- the Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), Swiss National Centre for Competence in Research in Chemical Biology, University of Geneva, 1211 Geneva, Switzerland
| | - Lynne Yenush
- From the Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Avd. de los Naranjos s/n, Valencia, Spain 46022 and
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19
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Petrényi K, Molero C, Kónya Z, Erdődi F, Ariño J, Dombrádi V. Analysis of Two Putative Candida albicans Phosphopantothenoylcysteine Decarboxylase / Protein Phosphatase Z Regulatory Subunits Reveals an Unexpected Distribution of Functional Roles. PLoS One 2016; 11:e0160965. [PMID: 27504636 PMCID: PMC4978486 DOI: 10.1371/journal.pone.0160965] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 07/27/2016] [Indexed: 11/24/2022] Open
Abstract
Protein phosphatase Z (Ppz) is a fungus specific enzyme that regulates cell wall integrity, cation homeostasis and oxidative stress response. Work on Saccharomyces cerevisiae has shown that the enzyme is inhibited by Hal3/Vhs3 moonlighting proteins that together with Cab3 constitute the essential phosphopantothenoylcysteine decarboxylase (PPCDC) enzyme. In Candida albicans CaPpz1 is also involved in the morphological changes and infectiveness of this opportunistic human pathogen. To reveal the CaPpz1 regulatory context we searched the C. albicans database and identified two genes that, based on the structure of their S. cerevisiae counterparts, were termed CaHal3 and CaCab3. By pull down analysis and phosphatase assays we demonstrated that both of the bacterially expressed recombinant proteins were able to bind and inhibit CaPpz1 as well as its C-terminal catalytic domain (CaPpz1-Cter) with comparable efficiency. The binding and inhibition were always more pronounced with CaPpz1-Cter, indicating a protective effect against inhibition by the N-terminal domain in the full length protein. The functions of the C. albicans proteins were tested by their overexpression in S. cerevisiae. Contrary to expectations we found that only CaCab3 and not CaHal3 rescued the phenotypic traits that are related to phosphatase inhibition by ScHal3, such as tolerance to LiCl or hygromycin B, requirement for external K+ concentrations, or growth in a MAP kinase deficient slt2 background. On the other hand, both of the Candida proteins turned out to be essential PPCDC components and behaved as their S. cerevisiae counterparts: expression of CaCab3 and CaHal3 rescued the cab3 and hal3 vhs3 S. cerevisiae mutations, respectively. Thus, both CaHal3 and CaCab3 retained the PPCDC related functions and have the potential for CaPpz1 inhibition in vitro. The fact that only CaCab3 exhibits its phosphatase regulatory potential in vivo suggests that in C. albicans CaCab3, but not CaHal3, acts as a moonlighting protein.
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Affiliation(s)
- Katalin Petrényi
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Cristina Molero
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
| | - Zoltán Kónya
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Ferenc Erdődi
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Joaquin Ariño
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
| | - Viktor Dombrádi
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
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Elicharová H, Hušeková B, Sychrová H. ThreeCandida albicanspotassium uptake systems differ in their ability to provideSaccharomyces cerevisiae trk1trk2mutants with necessary potassium. FEMS Yeast Res 2016; 16:fow039. [DOI: 10.1093/femsyr/fow039] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/14/2016] [Indexed: 12/31/2022] Open
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21
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Potassium Uptake Mediated by Trk1 Is Crucial for Candida glabrata Growth and Fitness. PLoS One 2016; 11:e0153374. [PMID: 27058598 PMCID: PMC4825953 DOI: 10.1371/journal.pone.0153374] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 03/29/2016] [Indexed: 12/20/2022] Open
Abstract
The maintenance of potassium homeostasis is crucial for all types of cells, including Candida glabrata. Three types of plasma-membrane systems mediating potassium influx with different transport mechanisms have been described in yeasts: the Trk1 uniporter, the Hak cation-proton symporter and the Acu ATPase. The C. glabrata genome contains only one gene encoding putative system for potassium uptake, the Trk1 uniporter. Therefore, its importance in maintaining adequate levels of intracellular potassium appears to be critical for C. glabrata cells. In this study, we first confirmed the potassium-uptake activity of the identified gene’s product by heterologous expression in a suitable S. cerevisiae mutant, further we generated a corresponding deletion mutant in C. glabrata and analysed its phenotype in detail. The obtained results show a pleiotropic effect on the cell physiology when CgTRK1 is deleted, affecting not only the ability of trk1Δ to grow at low potassium concentrations, but also the tolerance to toxic alkali-metal cations and cationic drugs, as well as the membrane potential and intracellular pH. Taken together, our results find the sole potassium uptake system in C. glabrata cells to be a promising target in the search for its specific inhibitors and in developing new antifungal drugs.
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22
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Mathematical Modelling of Cation Transport and Regulation in Yeast. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 892:291-305. [DOI: 10.1007/978-3-319-25304-6_12] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Volkov V. Quantitative description of ion transport via plasma membrane of yeast and small cells. FRONTIERS IN PLANT SCIENCE 2015; 6:425. [PMID: 26113853 PMCID: PMC4462678 DOI: 10.3389/fpls.2015.00425] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 05/26/2015] [Indexed: 05/21/2023]
Abstract
Modeling of ion transport via plasma membrane needs identification and quantitative understanding of the involved processes. Brief characterization of main ion transport systems of a yeast cell (Pma1, Ena1, TOK1, Nha1, Trk1, Trk2, non-selective cation conductance) and determining the exact number of molecules of each transporter per a typical cell allow us to predict the corresponding ion flows. In this review a comparison of ion transport in small yeast cell and several animal cell types is provided. The importance of cell volume to surface ratio is emphasized. The role of cell wall and lipid rafts is discussed in respect to required increase in spatial and temporary resolution of measurements. Conclusions are formulated to describe specific features of ion transport in a yeast cell. Potential directions of future research are outlined based on the assumptions.
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Affiliation(s)
- Vadim Volkov
- *Correspondence: Vadim Volkov, Faculty of Life Sciences, School of Human Sciences, London Metropolitan University, 166-220 Holloway Road, London N7 8DB, UK
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Anemaet IG, van Heusden GPH. Transcriptional response of Saccharomyces cerevisiae to potassium starvation. BMC Genomics 2014; 15:1040. [PMID: 25432801 PMCID: PMC4289377 DOI: 10.1186/1471-2164-15-1040] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 11/24/2014] [Indexed: 01/28/2023] Open
Abstract
Background Ion homeostasis is essential for every cell and aberrant cation homeostasis is related to diseases like Alzheimer’s disease and epilepsy. The mechanisms responsible for cation homeostasis are only partly understood. The yeast Saccharomyces cerevisiae is an excellent organism to study fundamental aspects of cation homeostasis. In this study we investigated the transcriptional response of this yeast to potassium starvation by using Serial Analysis of Gene Expression (SAGE)-tag sequencing. Results Comparison of transcript levels in cells grown for 60 min in media without potassium with those in cells grown under standard potassium concentrations showed that the mRNA levels of 105 genes were significantly (P < 0.01) up-regulated more than 2.0-fold during potassium starvation and the mRNA levels of 172 genes significantly down-regulated. These genes belong to several functional categories. Genes involved in stress response including HSP30, YRO2 and TPO2 and phosphate metabolism including PHO84, PHO5 and SPL2 were highly up-regulated. Analysis of the promoter of PHO84 encoding a high affinity phosphate transporter, revealed that increased PHO84 RNA levels are caused by both increased Pho4-dependent transcription and decreased RNA turnover. In the latter process antisense transcription may be involved. Many genes involved in cell cycle control, and to a lesser extent genes involved in amino acid transport, were strongly down-regulated. Conclusions Our study showed that yeast cells respond to potassium starvation in a complex way and reveals a direct link between potassium homeostasis and phosphate metabolism. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-1040) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - G Paul H van Heusden
- Institute of Biology, Leiden University, Sylviusweg 72, Leiden 2333BE, The Netherlands.
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25
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Coregulated expression of the Na+/phosphate Pho89 transporter and Ena1 Na+-ATPase allows their functional coupling under high-pH stress. Mol Cell Biol 2014; 34:4420-35. [PMID: 25266663 DOI: 10.1128/mcb.01089-14] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The yeast Saccharomyces cerevisiae has two main high-affinity inorganic phosphate (Pi) transporters, Pho84 and Pho89, that are functionally relevant at acidic/neutral pH and alkaline pH, respectively. Upon Pi starvation, PHO84 and PHO89 are induced by the activation of the PHO regulon by the binding of the Pho4 transcription factor to specific promoter sequences. We show that PHO89 and PHO84 are induced by alkalinization of the medium with different kinetics and that the network controlling Pho89 expression in response to alkaline pH differs from that of other members of the PHO regulon. In addition to Pho4, the PHO89 promoter is regulated by the transcriptional activator Crz1 through the calcium-activated phosphatase calcineurin, and it is under the control of several repressors (Mig2, Nrg1, and Nrg2) coordinately regulated by the Snf1 protein kinase and the Rim101 transcription factor. This network mimics the one regulating expression of the Na(+)-ATPase gene ENA1, encoding a major determinant for Na(+) detoxification. Our data highlight a scenario in which the activities of Pho89 and Ena1 are functionally coordinated to sustain growth in an alkaline environment.
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26
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Lulu L, Ling Z, Dongmei W, Xiaolian G, Hisanori T, Hidehiko K, Jiong H. Identification of a xylitol dehydrogenase gene from Kluyveromyces marxianus NBRC1777. Mol Biotechnol 2013; 53:159-69. [PMID: 22351371 DOI: 10.1007/s12033-012-9508-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Xylitol dehydrogenase (XDH) (EC 1.1.1.9) is one of the key enzymes in the xylose fermentation pathway in yeast and fungi. A xylitol dehydrogenase gene (XYL2) encoding a XDH was cloned from Kluyveromyces marxianus NBRC 1777, and the in vivo function was validated by disruption and complementation analysis. The highest activity of KmXDH could be observed at pH 9.5 during 55°C. The values of k(cat)/K(m) indicate that KmXDH prefers NAD(+) to NADP(+) (k(cat)/K(m NAD)(+) 3681/min mM and k(cat)/K(m NADP)(+) 1361/min mM). The different coenzyme preference between KmXR and KmXDH caused an accumulation of NADH in the xylose utilization pathway. The redox imbalance may be one of the reasons to cause the poor xylose fermentation under oxygen-limited conditions in K. marxianus NBRC1777.
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Affiliation(s)
- Li Lulu
- School of Life Science, University of Science and Technology of China, Hefei, 230027 Anhui, People's Republic of China
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27
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Mulet JM, Llopis-Torregrosa V, Primo C, Marqués MC, Yenush L. Endocytic regulation of alkali metal transport proteins in mammals, yeast and plants. Curr Genet 2013; 59:207-30. [PMID: 23974285 DOI: 10.1007/s00294-013-0401-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 07/24/2013] [Accepted: 07/29/2013] [Indexed: 12/30/2022]
Abstract
The relative concentrations of ions and solutes inside cells are actively maintained by several classes of transport proteins, in many cases against their concentration gradient. These transport processes, which consume a large portion of cellular energy, must be constantly regulated. Many structurally distinct families of channels, carriers, and pumps have been characterized in considerable detail during the past decades and defects in the function of some of these proteins have been linked to a growing list of human diseases. The dynamic regulation of the transport proteins present at the cell surface is vital for both normal cellular function and for the successful adaptation to changing environments. The composition of proteins present at the cell surface is controlled on both the transcriptional and post-translational level. Post-translational regulation involves highly conserved mechanisms of phosphorylation- and ubiquitylation-dependent signal transduction routes used to modify the cohort of receptors and transport proteins present under any given circumstances. In this review, we will summarize what is currently known about one facet of this regulatory process: the endocytic regulation of alkali metal transport proteins. The physiological relevance, major contributors, parallels and missing pieces of the puzzle in mammals, yeast and plants will be discussed.
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Affiliation(s)
- José Miguel Mulet
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, Avd. de los Naranjos s/n, 46022, Valencia, Spain
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28
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Ke R, Ingram PJ, Haynes K. An integrative model of ion regulation in yeast. PLoS Comput Biol 2013; 9:e1002879. [PMID: 23341767 PMCID: PMC3547829 DOI: 10.1371/journal.pcbi.1002879] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 11/27/2012] [Indexed: 12/03/2022] Open
Abstract
Yeast cells are able to tolerate and adapt to a variety of environmental stresses. An essential aspect of stress adaptation is the regulation of monovalent ion concentrations. Ion regulation determines many fundamental physiological parameters, such as cell volume, membrane potential, and intracellular pH. It is achieved through the concerted activities of multiple cellular components, including ion transporters and signaling molecules, on both short and long time scales. Although each component has been studied in detail previously, it remains unclear how the physiological parameters are maintained and regulated by the concerted action of all components under a diverse range of stress conditions. In this study, we have constructed an integrated mathematical model of ion regulation in Saccharomyces cerevisiae to understand this coordinated adaptation process. Using this model, we first predict that the interaction between phosphorylated Hog1p and Tok1p at the plasma membrane inhibits Tok1p activity and consequently reduces Na+ influx under NaCl stress. We further characterize the impacts of NaCl, sorbitol, KCl and alkaline pH stresses on the cellular physiology and the differences between the cellular responses to these stresses. We predict that the calcineurin pathway is essential for maintaining a non-toxic level of intracellular Na+ in the long-term adaptation to NaCl stress, but that its activation is not required for maintaining a low level of Na+ under other stresses investigated. We provide evidence that, in addition to extrusion of toxic ions, Ena1p plays an important role, in some cases alongside Nha1p, in re-establishing membrane potential after stress perturbation. To conclude, this model serves as a powerful tool for both understanding the complex system-level properties of the highly coordinated adaptation process and generating further hypotheses for experimental investigation. Ion regulation is fundamental to cell physiology. The concentrations of monovalent ions, such as H+, K+ and Na+, determine many physiological parameters such as cell volume, plasma membrane potential and intracellular pH. In yeast cells, these parameters are maintained within a narrow range during the adaptation to external perturbations, including ionic, osmotic and alkaline pH stress. This is achieved by the remarkably coordinated activities of ion transporters, regulatory molecules and signaling pathways. The response characteristics of individual components in adaptation have been studied extensively. However, a coherent understanding of the coordinated adaptation process is lacking. In this study, we address this gap by constructing a mathematical model that integrates the characteristics of the ion transporters, regulatory molecules, signaling pathways and changes in cell volume. Using this model, we characterize the impact of ionic, osmotic and alkaline pH stresses on cellular physiology and analyze the role that individual components play in the cellular adaptation processes. Our results also reveal system level properties achieved by the concerted regulatory responses. Therefore, this integrated model serves as a suitable tool to understand the coordinated processes of ion regulation in response to environmental stresses, and to make predictions that are experimentally testable.
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Affiliation(s)
- Ruian Ke
- Department of Mathematics, Imperial College London, London, United Kingdom.
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Gelis S, Curto M, Valledor L, González A, Ariño J, Jorrín J, Ramos J. Adaptation to potassium starvation of wild-type and K(+)-transport mutant (trk1,2) of Saccharomyces cerevisiae: 2-dimensional gel electrophoresis-based proteomic approach. Microbiologyopen 2012; 1:182-93. [PMID: 22950024 PMCID: PMC3426419 DOI: 10.1002/mbo3.23] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 03/29/2012] [Accepted: 05/03/2012] [Indexed: 01/20/2023] Open
Abstract
Saccharomyces cerevisiae wild-type (BY4741) and the corresponding mutant lacking the plasma membrane main potassium uptake systems (trk1,trk2) were used to analyze the consequences of K(+) starvation following a proteomic approach. In order to trigger high-affinity mode of potassium transport, cells were transferred to potassium-free medium. Protein profile was followed by two-dimensional (2-D) gels in samples taken at 0, 30, 60, 120, 180, and 300 min during starvation. We observed a general decrease of protein content during starvation that was especially drastic in the mutant strain as it was the case of an important number of proteins involved in glycolysis. On the contrary, we identified proteins related to stress response and alternative energetic metabolism that remained clearly present. Neural network-based analysis indicated that wild type was able to adapt much faster than the mutant to the stress process. We conclude that complete potassium starvation is a stressful process for yeast cells, especially for potassium transport mutants, and we propose that less stressing conditions should be used in order to study potassium homeostasis in yeast.
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Affiliation(s)
- Samuel Gelis
- Department of Microbiology, University of CórdobaCórdoba, Spain
| | - Miguel Curto
- Department of Biochemistry and Molecular Biology, Agricultural and Plant Biochemistry and Proteomics Research Group, University of CórdobaCórdoba, Spain
| | - Luis Valledor
- Molecular Systems Biology, University of ViennaVienna, Austria
| | - Asier González
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de BarcelonaBellaterra 08193, Barcelona, Spain
| | - Joaquín Ariño
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de BarcelonaBellaterra 08193, Barcelona, Spain
| | - Jesús Jorrín
- Department of Biochemistry and Molecular Biology, Agricultural and Plant Biochemistry and Proteomics Research Group, University of CórdobaCórdoba, Spain
| | - José Ramos
- Department of Microbiology, University of CórdobaCórdoba, Spain
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Kahm M, Navarrete C, Llopis-Torregrosa V, Herrera R, Barreto L, Yenush L, Ariño J, Ramos J, Kschischo M. Potassium starvation in yeast: mechanisms of homeostasis revealed by mathematical modeling. PLoS Comput Biol 2012; 8:e1002548. [PMID: 22737060 PMCID: PMC3380843 DOI: 10.1371/journal.pcbi.1002548] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 04/23/2012] [Indexed: 11/25/2022] Open
Abstract
The intrinsic ability of cells to adapt to a wide range of environmental conditions is a fundamental process required for survival. Potassium is the most abundant cation in living cells and is required for essential cellular processes, including the regulation of cell volume, pH and protein synthesis. Yeast cells can grow from low micromolar to molar potassium concentrations and utilize sophisticated control mechanisms to keep the internal potassium concentration in a viable range. We developed a mathematical model for Saccharomyces cerevisiae to explore the complex interplay between biophysical forces and molecular regulation facilitating potassium homeostasis. By using a novel inference method (“the reverse tracking algorithm”) we predicted and then verified experimentally that the main regulators under conditions of potassium starvation are proton fluxes responding to changes of potassium concentrations. In contrast to the prevailing view, we show that regulation of the main potassium transport systems (Trk1,2 and Nha1) in the plasma membrane is not sufficient to achieve homeostasis. Without potassium, all living cells will die; it has to be present in sufficient amounts for the proper function of most cell types. Disturbances in potassium levels in animal cells result in potentially fatal conditions and it is also an essential nutrient for plants and fungi. Cells have developed effective mechanisms for surviving under adverse environmental conditions of low external potassium. The question is how. Using the eukaryotic model organism, baker's yeast (Saccharomyces cerevisiae), we modeled how potassium homeostasis takes place. This is because, through mathematical modeling and experimentation, we found that the electro-chemical forces regulating potassium concentrations are coupled to proton fluxes, which respond to external conditions in order to maintain a viable potassium level within the cells. Our results challenge the current understanding of potassium homeostasis in baker's yeast, and could potentially be extended to other microorganisms, including non-conventional yeasts such as the pathogenic Candida albicans, and plant cells. In the future, the fundamental bases for this descriptive and predictive model might contribute to the development of new treatments for fungal infections, or developments in crop sciences.
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Affiliation(s)
- Matthias Kahm
- Department of Mathematics and Technology, RheinAhrCampus, University of Applied Sciences, Koblenz, Remagen, Germany
| | - Clara Navarrete
- Department of Microbiology, Campus de Rabanales, University of Córdoba, Córdoba, Spain
| | - Vicent Llopis-Torregrosa
- Instituto de Biologia Molecular y Celular de Plantas UPV-CSIC, Ciudad Politécnica de la Innovación, Universidad Politécnica de Valencia, Valencia, Spain
| | - Rito Herrera
- Department of Microbiology, Campus de Rabanales, University of Córdoba, Córdoba, Spain
| | - Lina Barreto
- Institut de Biotecnologia I Biomedicina & Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain
| | - Lynne Yenush
- Instituto de Biologia Molecular y Celular de Plantas UPV-CSIC, Ciudad Politécnica de la Innovación, Universidad Politécnica de Valencia, Valencia, Spain
| | - Joaquin Ariño
- Institut de Biotecnologia I Biomedicina & Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain
| | - Jose Ramos
- Department of Microbiology, Campus de Rabanales, University of Córdoba, Córdoba, Spain
| | - Maik Kschischo
- Department of Mathematics and Technology, RheinAhrCampus, University of Applied Sciences, Koblenz, Remagen, Germany
- * E-mail:
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Marquina M, González A, Barreto L, Gelis S, Muñoz I, Ruiz A, Álvarez MC, Ramos J, Ariño J. Modulation of yeast alkaline cation tolerance by Ypi1 requires calcineurin. Genetics 2012; 190:1355-64. [PMID: 22367039 PMCID: PMC3316648 DOI: 10.1534/genetics.112.138370] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 01/29/2012] [Indexed: 12/24/2022] Open
Abstract
Ypi1 was discovered as an essential protein able to act as a regulatory subunit of the Saccharomyces cerevisiae type 1 protein phosphatase Glc7 and play a key role in mitosis. We show here that partial depletion of Ypi1 causes lithium sensitivity and that high levels of this protein confer a lithium-tolerant phenotype to yeast cells. Remarkably, this phenotype was independent of the role of Ypi1 as a Glc7 regulatory subunit. Lithium tolerance in cells overexpressing Ypi1 was caused by a combination of increased efflux of lithium, mediated by augmented expression of the alkaline cation ATPase ENA1, and decreased lithium influx through the Trk1,2 high-affinity potassium transporters. Deletion of CNB1, encoding the regulatory subunit of the calcineurin phosphatase, blocked Ypi1-induced expression of ENA1, normalized Li(+) fluxes, and abolished the Li(+) hypertolerant phenotype of Ypi1-overexpressing cells. These results point to a complex role of Ypi1 on the regulation of cation homeostasis, largely mediated by the calcineurin phosphatase.
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Affiliation(s)
- Maribel Marquina
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra 08193, Barcelona, Spain
| | - Asier González
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra 08193, Barcelona, Spain
| | - Lina Barreto
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra 08193, Barcelona, Spain
| | - Samuel Gelis
- Departamento de Microbiología, Universidad de Córdoba, Campus Rabanales, 14071 Córdoba, Spain
| | - Iván Muñoz
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra 08193, Barcelona, Spain
| | - Amparo Ruiz
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra 08193, Barcelona, Spain
| | - Mari Carmen Álvarez
- Departamento de Microbiología, Universidad de Córdoba, Campus Rabanales, 14071 Córdoba, Spain
| | - José Ramos
- Departamento de Microbiología, Universidad de Córdoba, Campus Rabanales, 14071 Córdoba, Spain
| | - Joaquín Ariño
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra 08193, Barcelona, Spain
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A genomewide screen for tolerance to cationic drugs reveals genes important for potassium homeostasis in Saccharomyces cerevisiae. EUKARYOTIC CELL 2011; 10:1241-50. [PMID: 21724935 DOI: 10.1128/ec.05029-11] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Potassium homeostasis is crucial for living cells. In the yeast Saccharomyces cerevisiae, the uptake of potassium is driven by the electrochemical gradient generated by the Pma1 H(+)-ATPase, and this process represents a major consumer of the gradient. We considered that any mutation resulting in an alteration of the electrochemical gradient could give rise to anomalous sensitivity to any cationic drug independently of its toxicity mechanism. Here, we describe a genomewide screen for mutants that present altered tolerance to hygromycin B, spermine, and tetramethylammonium. Two hundred twenty-six mutant strains displayed altered tolerance to all three drugs (202 hypersensitive and 24 hypertolerant), and more than 50% presented a strong or moderate growth defect at a limiting potassium concentration (1 mM). Functional groups such as protein kinases and phosphatases, intracellular trafficking, transcription, or cell cycle and DNA processing were enriched. Essentially, our screen has identified a substantial number of genes that were not previously described to play a direct or indirect role in potassium homeostasis. A subset of 27 representative mutants were selected and subjected to diverse biochemical tests that, in some cases, allowed us to postulate the basis for the observed phenotypes.
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Identification of yeast genes involved in k homeostasis: loss of membrane traffic genes affects k uptake. G3-GENES GENOMES GENETICS 2011; 1:43-56. [PMID: 22384317 PMCID: PMC3276120 DOI: 10.1534/g3.111.000166] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 03/24/2011] [Indexed: 11/18/2022]
Abstract
Using the homozygous diploid Saccharomyces deletion collection, we searched for strains with defects in K(+) homeostasis. We identified 156 (of 4653 total) strains unable to grow in the presence of hygromycin B, a phenotype previously shown to be indicative of ion defects. The most abundant group was that with deletions of genes known to encode membrane traffic regulators. Nearly 80% of these membrane traffic defective strains showed defects in uptake of the K(+) homolog, (86)Rb(+). Since Trk1, a plasma membrane protein localized to lipid microdomains, is the major K(+) influx transporter, we examined the subcellular localization and Triton-X 100 insolubility of Trk1 in 29 of the traffic mutants. However, few of these showed defects in the steady state levels of Trk1, the localization of Trk1 to the plasma membrane, or the localization of Trk1 to lipid microdomains, and most defects were mild compared to wild-type. Three inositol kinase mutants were also identified, and in contrast, loss of these genes negatively affected Trk1 protein levels. In summary, this work reveals a nexus between K(+) homeostasis and membrane traffic, which does not involve traffic of the major influx transporter, Trk1.
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Martínez JL, Sychrova H, Ramos J. Monovalent cations regulate expression and activity of the Hak1 potassium transporter in Debaryomyces hansenii. Fungal Genet Biol 2011; 48:177-84. [DOI: 10.1016/j.fgb.2010.06.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 06/23/2010] [Accepted: 06/23/2010] [Indexed: 11/29/2022]
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Hal4 and Hal5 protein kinases are required for general control of carbon and nitrogen uptake and metabolism. EUKARYOTIC CELL 2010; 9:1881-90. [PMID: 20952580 DOI: 10.1128/ec.00184-10] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The yeast protein kinases Sat4/Hal4 and Hal5 are required for the plasma membrane stability of the K(+) transporter Trk1 and some amino acid and glucose permeases. The transcriptomic analysis presented here indicates alterations in the general control of the metabolism of both nitrogen and carbon. Accordingly, we observed reduced uptake of methionine and leucine in the hal4 hal5 mutant. This decrease correlates with activation of the Gcn2-Gcn4 pathway, as measured by expression of the lacZ gene under the control of the GCN4 promoter. However, with the exception of methionine biosynthetic genes, few amino acid biosynthetic genes are induced in the hal4 hal5 mutant, whereas several genes involved in amino acid catabolism are repressed. Concerning glucose metabolism, we found that this mutant exhibits derepression of respiratory genes in the presence of glucose, leading to an increased activity of mitochondrial enzymes, as measured by succinate dehydrogenase (SDH) activity. In addition, the reduced glucose consumption in the hal4 hal5 mutant correlates with a more acidic intracellular pH and with low activity of the plasma membrane H(+)-ATPase. As a compensatory mechanism for the low glycolytic rate, the hal4 hal5 mutant overexpresses the HXT4 high-affinity glucose transporter and the hexokinase genes. These results indicate that the hal4 hal5 mutant presents defects in the general control of nitrogen and carbon metabolism, which correlate with reduced transport of amino acids and glucose, respectively. A more acidic intracellular pH may contribute to some defects of this mutant.
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Regulation of Trk-dependent potassium transport by the calcineurin pathway involves the Hal5 kinase. FEBS Lett 2010; 584:2415-20. [DOI: 10.1016/j.febslet.2010.04.042] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Revised: 04/14/2010] [Accepted: 04/16/2010] [Indexed: 11/17/2022]
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