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Flynn MJ, Harper NW, Li R, Zhu LJ, Lee MJ, Benanti JA. Calcineurin promotes adaptation to chronic stress through two distinct mechanisms. Mol Biol Cell 2024; 35:ar123. [PMID: 39083354 DOI: 10.1091/mbc.e24-03-0122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2024] Open
Abstract
Adaptation to environmental stress requires coordination between stress-defense programs and cell cycle progression. The immediate response to many stressors has been well characterized, but how cells survive in challenging environments long term is unknown. Here, we investigate the role of the stress-activated phosphatase calcineurin (CN) in adaptation to chronic CaCl2 stress in Saccharomyces cerevisiae. We find that prolonged exposure to CaCl2 impairs mitochondrial function and demonstrate that cells respond to this stressor using two CN-dependent mechanisms-one that requires the downstream transcription factor Crz1 and another that is Crz1 independent. Our data indicate that CN maintains cellular fitness by promoting cell cycle progression and preventing CaCl2-induced cell death. When Crz1 is present, transient CN activation suppresses cell death and promotes adaptation despite high levels of mitochondrial loss. However, in the absence of Crz1, prolonged activation of CN prevents mitochondrial loss and further cell death by upregulating glutathione biosynthesis genes thereby mitigating damage from reactive oxygen species. These findings illustrate how cells maintain long-term fitness during chronic stress and suggest that CN promotes adaptation in challenging environments by multiple mechanisms.
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Affiliation(s)
- Mackenzie J Flynn
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
- Interdisciplinary Graduate Program, Morningside Graduate School of Biomedical Sciences, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Nicholas W Harper
- Interdisciplinary Graduate Program, Morningside Graduate School of Biomedical Sciences, University of Massachusetts Chan Medical School, Worcester, MA 01605
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Rui Li
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Lihua Julie Zhu
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
- Department of Genomics and Computational Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Michael J Lee
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Jennifer A Benanti
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
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Flynn MJ, Harper NW, Li R, Zhu LJ, Lee MJ, Benanti JA. Calcineurin promotes adaptation to chronic stress through two distinct mechanisms. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.19.585797. [PMID: 38562881 PMCID: PMC10983906 DOI: 10.1101/2024.03.19.585797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Adaptation to environmental stress requires coordination between stress-defense programs and cell cycle progression. The immediate response to many stressors has been well characterized, but how cells survive in challenging environments long-term is unknown. Here, we investigate the role of the stress-activated phosphatase calcineurin (CN) in adaptation to chronic CaCl2 stress in Saccharomyces cerevisiae. We find that prolonged exposure to CaCl2 impairs mitochondrial function and demonstrate that cells respond to this stressor using two CN-dependent mechanisms - one that requires the downstream transcription factor Crz1 and another that is Crz1-independent. Our data indicate that CN maintains cellular fitness by promoting cell cycle progression and preventing CaCl2-induced cell death. When Crz1 is present, transient CN activation suppresses cell death and promotes adaptation despite high levels of mitochondrial loss. However, in the absence of Crz1, prolonged activation of CN prevents mitochondrial loss and further cell death by upregulating glutathione (GSH) biosynthesis genes thereby mitigating damage from reactive oxygen species. These findings illustrate how cells maintain long-term fitness during chronic stress and suggest that CN promotes adaptation in challenging environments by multiple mechanisms.
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Affiliation(s)
- Mackenzie J. Flynn
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
- Interdisciplinary Graduate Program, Morningside Graduate School of Biomedical Sciences, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Nicholas W. Harper
- Interdisciplinary Graduate Program, Morningside Graduate School of Biomedical Sciences, University of Massachusetts Chan Medical School, Worcester, MA 01605
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Rui Li
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Lihua Julie Zhu
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
- Department of Genomics and Computational Biology, University of Massachusetts Chan Medical School, Worcester MA 01605
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester MA 01605
| | - Michael J. Lee
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Jennifer A. Benanti
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
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Saeki N, Yamamoto C, Eguchi Y, Sekito T, Shigenobu S, Yoshimura M, Yashiroda Y, Boone C, Moriya H. Overexpression profiling reveals cellular requirements in the context of genetic backgrounds and environments. PLoS Genet 2023; 19:e1010732. [PMID: 37115757 PMCID: PMC10171610 DOI: 10.1371/journal.pgen.1010732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 05/10/2023] [Accepted: 04/04/2023] [Indexed: 04/29/2023] Open
Abstract
Overexpression can help life adapt to stressful environments, making an examination of overexpressed genes valuable for understanding stress tolerance mechanisms. However, a systematic study of genes whose overexpression is functionally adaptive (GOFAs) under stress has yet to be conducted. We developed a new overexpression profiling method and systematically identified GOFAs in Saccharomyces cerevisiae under stress (heat, salt, and oxidative). Our results show that adaptive overexpression compensates for deficiencies and increases fitness under stress, like calcium under salt stress. We also investigated the impact of different genetic backgrounds on GOFAs, which varied among three S. cerevisiae strains reflecting differing calcium and potassium requirements for salt stress tolerance. Our study of a knockout collection also suggested that calcium prevents mitochondrial outbursts under salt stress. Mitochondria-enhancing GOFAs were only adaptive when adequate calcium was available and non-adaptive when calcium was deficient, supporting this idea. Our findings indicate that adaptive overexpression meets the cell's needs for maximizing the organism's adaptive capacity in the given environment and genetic context.
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Affiliation(s)
- Nozomu Saeki
- Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan
| | - Chie Yamamoto
- Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan
| | - Yuichi Eguchi
- Biomedical Business Center, RICOH Futures BU, Kanagawa, Japan
| | - Takayuki Sekito
- Graduate School of Agriculture, Ehime University, Matsuyama, Japan
| | | | - Mami Yoshimura
- RIKEN Center for Sustainable Resource Science, Wako, Japan
| | - Yoko Yashiroda
- RIKEN Center for Sustainable Resource Science, Wako, Japan
| | - Charles Boone
- RIKEN Center for Sustainable Resource Science, Wako, Japan
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Hisao Moriya
- Faculty of Environmental, Life, Natural Science and Technology, Okayama University, Okayama, Japan
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Kurakado S, Matsumoto Y, Yamada T, Shimizu K, Wakasa S, Sugita T. Tacrolimus inhibits stress responses and hyphal formation via the calcineurin signaling pathway in Trichosporon asahii. Microbiol Immunol 2023; 67:49-57. [PMID: 36398783 DOI: 10.1111/1348-0421.13039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 10/09/2022] [Accepted: 11/07/2022] [Indexed: 11/19/2022]
Abstract
The pathogenic fungus Trichosporon asahii causes fatal deep-seated mycosis in immunocompromised patients. Calcineurin, which is widely conserved in eukaryotes, regulates cell growth and various stress responses in fungi. Tacrolimus (FK506), a calcineurin inhibitor, induces sensitivity to compounds that cause stress on the cell membrane and cell wall integrity. In this study, we demonstrated that FK506 affects stress responses and hyphal formation in T. asahii. In silico structural analysis revealed that amino acid residues in the binding site of the calcineurin-FKBP12 complex that interact with FK506 are conserved in T. asahii. The growth of T. asahii was delayed by FK506 in the presence of SDS or Congo red but not in the presence of calcium chloride. FK506 also inhibited hyphal formation in T. asahii. A mutant deficient of the cnb gene, which encodes the regulatory subunit B of calcineurin, exhibited stress sensitivities on exposure to SDS and Congo red and reduced the hyphal forming ability of T. asahii. In the cnb-deficient mutant, FK506 did not increase the stress sensitivity or reduce hyphal forming ability. These results suggest that FK506 affects stress responses and hyphal formation in T. asahii via the calcineurin signaling pathway.
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Affiliation(s)
- Sanae Kurakado
- Department of Microbiology, Meiji Pharmaceutical University, Tokyo, Japan
| | - Yasuhiko Matsumoto
- Department of Microbiology, Meiji Pharmaceutical University, Tokyo, Japan
| | - Tsuyoshi Yamada
- Teikyo University Institute of Medical Mycology, Tokyo, Japan.,Asia International Institute of Infectious Disease Control, Teikyo University, Tokyo, Japan
| | - Kiminori Shimizu
- Department of Biological Science and Technology, Tokyo University of Science, Tokyo, Japan.,Medical Mycology Research Center, Chiba University, Chiba, Japan
| | - Shogo Wakasa
- Department of Microbiology, Meiji Pharmaceutical University, Tokyo, Japan
| | - Takashi Sugita
- Department of Microbiology, Meiji Pharmaceutical University, Tokyo, Japan
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Coordinated glucose-induced Ca 2+ and pH responses in yeast Saccharomyces cerevisiae. Cell Calcium 2021; 100:102479. [PMID: 34610487 DOI: 10.1016/j.ceca.2021.102479] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 09/23/2021] [Accepted: 09/24/2021] [Indexed: 12/13/2022]
Abstract
Ca2+ and pH homeostasis are closely intertwined and this interrelationship is crucial in the cells' ability to adapt to varying environmental conditions. To further understand this Ca2+-pH link, cytosolic Ca2+ was monitored using the aequorin-based bioluminescent assay in parallel with fluorescence reporter-based assays to monitor plasma membrane potentials and intracellular (cytosolic and vacuolar) pH in yeast Saccharomyces cerevisiae. At external pH 5, starved yeast cells displayed depolarized membrane potentials and responded to glucose re-addition with small Ca2+ transients accompanied by cytosolic alkalinization and profound vacuolar acidification. In contrast, starved cells at external pH 7 were hyperpolarized and glucose re-addition induced large Ca2+ transients and vacuolar alkalinization. In external Ca2+-free medium, glucose-induced pH responses were not affected but Ca2+ transients were abolished, indicating that the intracellular [Ca2+] increase was not prerequisite for activation of the two primary proton pumps, being Pma1 at the plasma membrane and the vacuolar and Golgi localized V-ATPases. A reduction in Pma1 expression resulted in membrane depolarization and reduced Ca2+ transients, indicating that the membrane hyperpolarization generated by Pma1 activation governed the Ca2+ influx that is associated with glucose-induced Ca2+ transients. Loss of V-ATPase activity through concanamycin A inhibition did not alter glucose-induced cytosolic pH responses but affected vacuolar pH changes and Ca2+ transients, indicating that the V-ATPase established vacuolar proton gradient is substantial for organelle H+/Ca2+ exchange. Finally, a systematic analysis of yeast deletion strains allowed us to reveal an essential role for both the vacuolar H+/Ca2+ exchanger Vcx1 and the Golgi exchanger Gdt1 in the dissipation of intracellular Ca2+.
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Fischer D, Gessner G, Fill TP, Barnett R, Tron K, Dornblut K, Kloss F, Stallforth P, Hube B, Heinemann SH, Hertweck C, Scherlach K, Brunke S. Disruption of Membrane Integrity by the Bacterium-Derived Antifungal Jagaricin. Antimicrob Agents Chemother 2019; 63:e00707-19. [PMID: 31235622 PMCID: PMC6709453 DOI: 10.1128/aac.00707-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 06/14/2019] [Indexed: 01/05/2023] Open
Abstract
Jagaricin is a lipopeptide produced by the bacterial mushroom pathogen Janthinobacterium agaricidamnosum, the causative agent of mushroom soft rot disease. Apart from causing lesions in mushrooms, jagaricin is a potent antifungal active against human-pathogenic fungi. We show that jagaricin acts by impairing membrane integrity, resulting in a rapid flux of ions, including Ca2+, into susceptible target cells. Accordingly, the calcineurin pathway is required for jagaricin tolerance in the fungal pathogen Candida albicans Transcriptional profiling of pathogenic yeasts further revealed that jagaricin triggers cell wall strengthening, general shutdown of membrane potential-driven transport, and the upregulation of lipid transporters, linking cell envelope integrity to jagaricin action and resistance. Whereas jagaricin shows hemolytic effects, it exhibited either no or low plant toxicity at concentrations at which the growth of prevalent phytopathogenic fungi is inhibited. Therefore, jagaricin may have potential for agricultural applications. The action of jagaricin as a membrane-disrupting antifungal is promising but would require modifications for use in humans.
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Affiliation(s)
- Daniel Fischer
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute, Jena, Germany
| | - Guido Gessner
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University Jena and Jena University Hospital, Jena, Germany
| | - Taicia Pacheco Fill
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute, Jena, Germany
| | - Robert Barnett
- Junior Research Group Chemistry of Microbial Communication, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute, Jena, Germany
| | - Kyrylo Tron
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University Jena and Jena University Hospital, Jena, Germany
| | - Katharina Dornblut
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute, Jena, Germany
| | - Florian Kloss
- Transfer Group Antiinfectives, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute, Jena, Germany
| | - Pierre Stallforth
- Junior Research Group Chemistry of Microbial Communication, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute, Jena, Germany
| | - Bernhard Hube
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute, Jena, Germany
- Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany
| | - Stefan H Heinemann
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University Jena and Jena University Hospital, Jena, Germany
| | - Christian Hertweck
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute, Jena, Germany
- Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany
| | - Kirstin Scherlach
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute, Jena, Germany
| | - Sascha Brunke
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute, Jena, Germany
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Compensatory Internalization of Pma1 in V-ATPase Mutants in Saccharomyces cerevisiae Requires Calcium- and Glucose-Sensitive Phosphatases. Genetics 2017; 208:655-672. [PMID: 29254995 PMCID: PMC5788529 DOI: 10.1534/genetics.117.300594] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 12/09/2017] [Indexed: 11/23/2022] Open
Abstract
Loss of V-ATPase activity in organelles triggers compensatory endocytic downregulation of the plasma membrane proton pump Pma1. Here, Velivela and Kane... Loss of V-ATPase activity in organelles, whether through V-ATPase inhibition or V-ATPase (vma) mutations, triggers a compensatory downregulation of the essential plasma membrane proton pump Pma1 in Saccharomyces cerevisiae. We have previously determined that the α-arrestin Rim8 and ubiquitin ligase Rsp5 are essential for Pma1 ubiquination and endocytosis in response to loss of V-ATPase activity. Here, we show that Pma1 endocytosis in V-ATPase mutants does not require Rim101 pathway components upstream and downstream of Rim8, indicating that Rim8 is acting independently in Pma1 internalization. We find that two phosphatases, the calcium-responsive phosphatase calcineurin and the glucose-sensitive phosphatase Glc7 (PP1), and one of the Glc7 regulatory subunits Reg1, exhibit negative synthetic genetic interactions with vma mutants, and demonstrate that both phosphatases are essential for ubiquitination and endocytic downregulation of Pma1 in these mutants. Although both acute and chronic loss of V-ATPase activity trigger the internalization of ∼50% of surface Pma1, a comparable reduction in Pma1 expression in a pma1-007 mutant neither compensates for loss of V-ATPase activity nor stops further Pma1 endocytosis. The results indicate that the cell surface level of Pma1 is not directly sensed and that internalized Pma1 may play a role in compensating for loss of V-ATPase-dependent acidification. Taken together, these results provide new insights into cross talk between two major proton pumps central to cellular pH control.
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Calcineurin controls hyphal growth, virulence, and drug tolerance of Candida tropicalis. EUKARYOTIC CELL 2014; 13:844-54. [PMID: 24442892 DOI: 10.1128/ec.00302-13] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Candida tropicalis, a species closely related to Candida albicans, is an emerging fungal pathogen associated with high mortality rates of 40 to 70%. Like C. albicans and Candida dubliniensis, C. tropicalis is able to form germ tubes, pseudohyphae, and hyphae, but the genes involved in hyphal growth machinery and virulence remain unclear in C. tropicalis. Recently, echinocandin- and azole-resistant C. tropicalis isolates have frequently been isolated from various patients around the world, making treatment difficult. However, studies of the C. tropicalis genes involved in drug tolerance are limited. Here, we investigated the roles of calcineurin and its potential target, Crz1, for core stress responses and pathogenesis in C. tropicalis. We demonstrate that calcineurin and Crz1 are required for hyphal growth, micafungin tolerance, and virulence in a murine systemic infection model, while calcineurin but not Crz1 is essential for tolerance of azoles, caspofungin, anidulafungin, and cell wall-perturbing agents, suggesting that calcineurin has both Crz1-dependent and -independent functions in C. tropicalis. In addition, we found that calcineurin and Crz1 have opposite roles in controlling calcium tolerance. Calcineurin serves as a negative regulator, while Crz1 plays a positive role for calcium tolerance in C. tropicalis.
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Abstract
Yeast prions are infectious proteins that spread exclusively by mating. The frequency of prions in the wild therefore largely reflects the rate of spread by mating counterbalanced by prion growth slowing effects in the host. We recently showed that the frequency of outcross mating is about 1% of mitotic doublings with 23–46% of total matings being outcrosses. These findings imply that even the mildest forms of the [PSI+], [URE3] and [PIN+] prions impart > 1% growth/survival detriment on their hosts. Our estimate of outcrossing suggests that Saccharomyces cerevisiae is far more sexual than previously thought and would therefore be more responsive to the adaptive effects of natural selection compared with a strictly asexual yeast. Further, given its large effective population size, a growth/survival detriment of > 1% for yeast prions should strongly select against prion-infected strains in wild populations of Saccharomyces cerevisiae.
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Affiliation(s)
- Amy C Kelly
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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10
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Calcineurin governs thermotolerance and virulence of Cryptococcus gattii. G3-GENES GENOMES GENETICS 2013; 3:527-39. [PMID: 23450261 PMCID: PMC3583459 DOI: 10.1534/g3.112.004242] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 01/12/2013] [Indexed: 12/26/2022]
Abstract
The pathogenic yeast Cryptococcus gattii, which is causing an outbreak in the Pacific Northwest region of North America, causes life-threatening pulmonary infections and meningoencephalitis in healthy individuals, unlike Cryptococcus neoformans, which commonly infects immunocompromised patients. In addition to a greater predilection for C. gattii to infect healthy hosts, the C. gattii genome sequence project revealed extensive chromosomal rearrangements compared with C. neoformans, showing genomic differences between the two Cryptococcus species. We investigated the roles of C. gattii calcineurin in three molecular types: VGIIa (R265), VGIIb (R272), and VGI (WM276). We found that calcineurin exhibits a differential requirement for growth on solid medium at 37°, as calcineurin mutants generated from R265 were more thermotolerant than mutants from R272 and WM276. We demonstrated that tolerance to calcineurin inhibitors (FK506, CsA) at 37° is linked with the VGIIa molecular type. The calcineurin mutants from the R272 background showed the most extensive growth and morphological defects (multivesicle and larger ring-like cells), as well as increased fluconazole susceptibility. Our cellular architecture examination showed that C. gattii and C. neoformans calcineurin mutants exhibit plasma membrane disruptions. Calcineurin in the C. gattii VGII molecular type plays a greater role in controlling cation homeostasis compared with that in C. gattii VGI and C. neoformans H99. Importantly, we demonstrate that C. gattii calcineurin is essential for virulence in a murine inhalation model, supporting C. gattii calcineurin as an attractive antifungal drug target.
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Xu YN, Xia XX, Zhong JJ. Induced effect of Na+on ganoderic acid biosynthesis in static liquid culture ofGanoderma lucidumvia calcineurin signal transduction. Biotechnol Bioeng 2013; 110:1913-23. [DOI: 10.1002/bit.24852] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2012] [Revised: 01/11/2013] [Accepted: 01/14/2013] [Indexed: 11/08/2022]
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Yeast Ist2 recruits the endoplasmic reticulum to the plasma membrane and creates a ribosome-free membrane microcompartment. PLoS One 2012; 7:e39703. [PMID: 22808051 PMCID: PMC3392263 DOI: 10.1371/journal.pone.0039703] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 05/24/2012] [Indexed: 11/19/2022] Open
Abstract
The endoplasmic reticulum (ER) forms contacts with the plasma membrane. These contacts are known to function in non-vesicular lipid transport and signaling. Ist2 resides in specific domains of the ER in Saccharomyces cerevisiae where it binds phosphoinositide lipids at the cytosolic face of the plasma membrane. Here, we report that Ist2 recruits domains of the yeast ER to the plasma membrane. Ist2 determines the amount of cortical ER present and the distance between the ER and the plasma membrane. Deletion of IST2 resulted in an increased distance between ER and plasma membrane and allowed access of ribosomes to the space between the two membranes. Cells that overexpress Ist2 showed an association of the nucleus with the plasma membrane. The morphology of the ER and yeast growth were sensitive to the abundance of Ist2. Moreover, Ist2-dependent effects on cytosolic pH and genetic interactions link Ist2 to the activity of the H(+) pump Pma1 in the plasma membrane during cellular adaptation to the growth phase of the culture. Consistently we found a partial colocalization of Ist2-containing cortical ER and Pma1-containing domains of the plasma membrane. Hence Ist2 may be critically positioned in domains that couple functions of the ER and the plasma membrane.
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13
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Convergent Evolution of Calcineurin Pathway Roles in Thermotolerance and Virulence in Candida glabrata. G3-GENES GENOMES GENETICS 2012; 2:675-91. [PMID: 22690377 PMCID: PMC3362297 DOI: 10.1534/g3.112.002279] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 04/02/2012] [Indexed: 12/31/2022]
Abstract
Candida glabrata is an emerging human fungal pathogen that is frequently drug tolerant, resulting in difficulties in treatment and a higher mortality in immunocompromised patients. The calcium-activated protein phosphatase calcineurin plays critical roles in controlling drug tolerance, hyphal growth, and virulence in diverse fungal pathogens via distinct mechanisms involving survival in serum or growth at host temperature (37° and higher). Here, we comprehensively studied the calcineurin signaling cascade in C. glabrata and found novel and uncharacterized functions of calcineurin and its downstream target Crz1 in governing thermotolerance, intracellular architecture, and pathogenesis in murine ocular, urinary tract, and systemic infections. This represents a second independent origin of a role for calcineurin in thermotolerant growth of a major human fungal pathogen, distinct from that which arose independently in Cryptococcus neoformans. Calcineurin also promotes survival of C. glabrata in serum via mechanisms distinct from C. albicans and thereby enables establishment of tissue colonization in a murine systemic infection model. To understand calcineurin signaling in detail, we performed global transcript profiling analysis and identified calcineurin- and Crz1-dependent genes in C. glabrata involved in cell wall biosynthesis, heat shock responses, and calcineurin function. Regulators of calcineurin (RCN) are a novel family of calcineurin modifiers, and two members of this family were identified in C. glabrata: Rcn1 and Rcn2. Our studies demonstrate that Rcn2 expression is controlled by calcineurin and Crz1 to function as a feedback inhibitor of calcineurin in a circuit required for calcium tolerance in C. glabrata. In contrast, the calcineurin regulator Rcn1 activates calcineurin signaling. Interestingly, neither Rcn1 nor Rcn2 is required for virulence in a murine systemic infection model. Taken together, our findings show that calcineurin signaling plays critical roles in thermotolerance and virulence, and that Rcn1 and Rcn2 have opposing functions in controlling calcineurin signaling in C. glabrata.
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Stein KC, True HL. The [RNQ+] prion: a model of both functional and pathological amyloid. Prion 2011; 5:291-8. [PMID: 22052347 DOI: 10.4161/pri.18213] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The formation of fibrillar amyloid is most often associated with protein conformational disorders such as prion diseases, Alzheimer disease and Huntington disease. Interestingly, however, an increasing number of studies suggest that amyloid structures can sometimes play a functional role in normal biology. Several proteins form self-propagating amyloids called prions in the budding yeast Saccharomyces cerevisiae. These unique elements operate by creating a reversible, epigenetic change in phenotype. While the function of the non-prion conformation of the Rnq1 protein is unclear, the prion form, [RNQ+], acts to facilitate the de novo formation of other prions to influence cellular phenotypes. The [RNQ+] prion itself does not adversely affect the growth of yeast, but the overexpression of Rnq1p can form toxic aggregated structures that are not necessarily prions. The [RNQ+] prion is also involved in dictating the aggregation and toxicity of polyglutamine proteins ectopically expressed in yeast. Thus, the [RNQ+] prion provides a tractable model that has the potential to reveal significant insight into the factors that dictate how amyloid structures are initiated and propagated in both physiological and pathological contexts.
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Affiliation(s)
- Kevin C Stein
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
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15
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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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Stein KC, True HL. The [RNQ+] prion: a model of both functional and pathological amyloid. Prion 2011; 5. [PMID: 22052347 PMCID: PMC4012398 DOI: 10.4161/pri.5.4.18213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The formation of fibrillar amyloid is most often associated with protein conformational disorders such as prion diseases, Alzheimer disease and Huntington disease. Interestingly, however, an increasing number of studies suggest that amyloid structures can sometimes play a functional role in normal biology. Several proteins form self-propagating amyloids called prions in the budding yeast Saccharomyces cerevisiae. These unique elements operate by creating a reversible, epigenetic change in phenotype. While the function of the non-prion conformation of the Rnq1 protein is unclear, the prion form, [RNQ+], acts to facilitate the de novo formation of other prions to influence cellular phenotypes. The [RNQ+] prion itself does not adversely affect the growth of yeast, but the overexpression of Rnq1p can form toxic aggregated structures that are not necessarily prions. The [RNQ+] prion is also involved in dictating the aggregation and toxicity of polyglutamine proteins ectopically expressed in yeast. Thus, the [RNQ+] prion provides a tractable model that has the potential to reveal significant insight into the factors that dictate how amyloid structures are initiated and propagated in both physiological and pathological contexts.
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Rodríguez C, Tejera P, Medina B, Guillén R, Domínguez A, Ramos J, Siverio JM. Ure2 is involved in nitrogen catabolite repression and salt tolerance via Ca2+ homeostasis and calcineurin activation in the yeast Hansenula polymorpha. J Biol Chem 2010; 285:37551-60. [PMID: 20880842 DOI: 10.1074/jbc.m110.146902] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Disruption of HpURE2 resulted in a low expression of genes encoding nitrate-assimilatory proteins; sensitivity to Li(+), Na(+), and Cd(2+); no induction of ENA1; low levels of the GATA-type transcription factor Gat1; and low intracellular Ca(2+) levels. Gat1 levels were also very low in a Δcnb1 mutant lacking the regulatory subunit of calcineurin. The strain Δure2 was very sensitive to the calcineurin inhibitor FK506 and displayed several phenotypes reminiscent of Δcnb1. The reporter 4xCDRE-lacZ, containing calcineurin-dependent response elements in its promoter, revealed that calcineurin activation was reduced in HpΔure2. Expression of ScURE2 in Δure2 rescued nitrogen catabolite repression and Cd(2+) tolerance but not those phenotypes depending on calcineurin activation, such as salt tolerance and nitrate assimilation gene derepression. HpΔure2 showed an increased expression of the gene PMR1 encoding the Golgi Ca(2+)-ATPase, whereas that of PMC1 encoding the vacuolar Ca(2+)-ATPase remained unaltered. PMR1 up-regulation was abolished by deletion of the GATA-type transcription factor GAT2 in a HpΔure2 genetic background, and normal Ca(2+) levels were recovered. Moreover, overexpression of GAT2 or PMR1 yielded strains mimicking the phenotype of the HpΔure2. This suggests that the low Ca(2+) levels in the HpΔure2 mutant are due to the high levels of Pmr1 that replenish the Golgi Ca(2+) content, thus acting as a negative signal for Ca(2+) entry into the cell. We conclude that HpUre2 is involved in salt tolerance and also in nitrate assimilation gene derepression via Ca(2+) homeostasis regulation and calcineurin activation, which control the levels of Gat1.
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Affiliation(s)
- Celia Rodríguez
- Department of Biochemistry and Molecular Biology, Institute of Biomedical Technologies, Nitrogen Metabolism Group, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Canarias, Spain
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18
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Abstract
The maintenance of appropriate intracellular concentrations of alkali metal cations, principally K(+) and Na(+), is of utmost importance for living cells, since they determine cell volume, intracellular pH, and potential across the plasma membrane, among other important cellular parameters. Yeasts have developed a number of strategies to adapt to large variations in the concentrations of these cations in the environment, basically by controlling transport processes. Plasma membrane high-affinity K(+) transporters allow intracellular accumulation of this cation even when it is scarce in the environment. Exposure to high concentrations of Na(+) can be tolerated due to the existence of an Na(+), K(+)-ATPase and an Na(+), K(+)/H(+)-antiporter, which contribute to the potassium balance as well. Cations can also be sequestered through various antiporters into intracellular organelles, such as the vacuole. Although some uncertainties still persist, the nature of the major structural components responsible for alkali metal cation fluxes across yeast membranes has been defined within the last 20 years. In contrast, the regulatory components and their interactions are, in many cases, still unclear. Conserved signaling pathways (e.g., calcineurin and HOG) are known to participate in the regulation of influx and efflux processes at the plasma membrane level, even though the molecular details are obscure. Similarly, very little is known about the regulation of organellar transport and homeostasis of alkali metal cations. The aim of this review is to provide a comprehensive and up-to-date vision of the mechanisms responsible for alkali metal cation transport and their regulation in the model yeast Saccharomyces cerevisiae and to establish, when possible, comparisons with other yeasts and higher plants.
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Zhao J, Lin W, Ma X, Lu Q, Ma X, Bian G, Jiang L. The protein kinase Hal5p is the high-copy suppressor of lithium-sensitive mutations of genes involved in the sporulation and meiosis as well as the ergosterol biosynthesis in Saccharomyces cerevisiae. Genomics 2010; 95:290-8. [PMID: 20206679 DOI: 10.1016/j.ygeno.2010.02.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2009] [Revised: 02/25/2010] [Accepted: 02/25/2010] [Indexed: 11/30/2022]
Abstract
From a genome-scale genetic screen, we have identified 114 lithium-sensitive and 6 lithium-tolerant gene mutations in Saccharomyces cerevisiae. Twenty-five of these identified lithium-sensitive mutations are of genes previously reported to be involved in sporulation and meiosis, whereas thirty-six of them are of genes involved in the vacuolar protein sorting (VPS) pathway, mainly functioning in the membrane docking and fusion. Accordingly, the lithium-sensitive phenotypes for one third of identified VPS mutants well correlate to their intracellular lithium contents in response to lithium stress. This indicates the integrity of the VPS pathway is critic for the ion homeostasis in yeast cells. The halotolerant protein kinase Hal5p, a regulator of the potassium transporter Trk1p, is shown to be the high-copy suppressor of nearly one third of identified lithium-sensitive mutations of genes involved in the sporulation and meiosis as well as in the biosynthesis of ergosterol. These results suggest that Hal5p-mediated ion homeostasis is important for these two biological processes.
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Affiliation(s)
- Jingwen Zhao
- Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, China
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20
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Lechauve C, Rezaei H, Celier C, Kiger L, Corral-Debrinski M, Noinville S, Chauvierre C, Hamdane D, Pato C, Marden MC. Neuroglobin and prion cellular localization: investigation of a potential interaction. J Mol Biol 2009; 388:968-77. [PMID: 19327369 DOI: 10.1016/j.jmb.2009.03.047] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Revised: 02/18/2009] [Accepted: 03/18/2009] [Indexed: 11/25/2022]
Abstract
Neuroglobin (Ngb) and the cellular prion protein (PrP(c)), proteins of unknown function in the nervous system, are known to be expressed in the retina and have been observed in different rat retinal cells. The retina is the site of the highest concentration for Ngb, a heme protein of similar size and conformation to myoglobin. In this study, we demonstrated by immunohistochemical analysis of retinal colocalization of Ngb and PrP(c) in the ganglion cell layer. Considering for these two a common protective role in relation to oxidative stress and a possible transient contact during migration of PrP(c) through the eye or upon neuronal degradation, we undertook in vitro studies of the interaction of the purified proteins. Mixing these two proteins leads to rapid aggregation, even at submicromolar concentrations. As observed with the use of dynamic light scattering, particles comprising both proteins evolve to hundreds of nanometers within several seconds, a first report showing that PrP(c) is able to form aggregates without major structural changes. The main effect would then appear to be a protein-protein interaction specific to the surface charge of the Ngb protein with PrP(c) N-terminal sequence. A dominant parameter is the solvent ionic force, which can significantly modify the final state of aggregation. PrP(c), normally anchored to the cell membrane, is toxic in the cytoplasm, where Ngb is present; this could suggest an Ngb function of scavenging proteins capable of forming deleterious aggregates considering a charge complementarity in the complex.
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Affiliation(s)
- Christophe Lechauve
- INSERM U779, Universités Paris VI et XI, Hopital de Bicêtre, Le Kremlin-Bicêtre, France
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21
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Ye T, Elbing K, Hohmann S. The pathway by which the yeast protein kinase Snf1p controls acquisition of sodium tolerance is different from that mediating glucose regulation. MICROBIOLOGY-SGM 2008; 154:2814-2826. [PMID: 18757815 DOI: 10.1099/mic.0.2008/020149-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
It recently became apparent that the highly conserved Snf1p protein kinase plays roles in controlling different cellular processes in the yeast Saccharomyces cerevisiae, in addition to its well-known function in glucose repression/derepression. We have previously reported that Snf1p together with Gis4p controls ion homeostasis by regulating expression of ENA1, which encodes the Ena1p Na(+) extrusion system. In this study we found that Snf1p is rapidly phosphorylated when cells are exposed to NaCl and this phosphorylation is required for the role of Snf1p in Na(+) tolerance. In contrast to activation by low glucose levels, the salt-induced phosphorylation of Snf1p promoted neither phosphorylation nor nuclear export of the Mig1p repressor. The mechanism that prevents Mig1p phosphorylation by active Snf1p under salt stress does not involve either hexokinase PII or the Gis4p regulator. Instead, Snf1p may mediate upregulation of ENA1 expression via the repressor Nrg1p. Activation of Snf1p in response to glucose depletion requires any of the three upstream protein kinases Sak1p, Tos3p and Elm1p, with Sak1p playing the most prominent role. The same upstream kinases were required for salt-induced Snf1p phosphorylation, and also under these conditions Sak1p played the most prominent role. Unexpectedly, however, it appears that Elm1p plays a dual role in acquisition of salt tolerance by activating Snf1p and in a presently unknown parallel pathway. Together, these results indicate that under salt stress Snf1p takes part in a different pathway from that during glucose depletion and this role is performed together as well as in parallel with its upstream kinase Elm1p. Snf1p appears to be part of a wider functional network than previously anticipated and the full complexity of this network remains to be elucidated.
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Affiliation(s)
- Tian Ye
- Department of Cell and Molecular Biology/Microbiology, University of Gothenburg, Box 462, S-40530 Göteborg, Sweden
| | - Karin Elbing
- Department of Cell and Molecular Biology/Microbiology, University of Gothenburg, Box 462, S-40530 Göteborg, Sweden
| | - Stefan Hohmann
- Department of Cell and Molecular Biology/Microbiology, University of Gothenburg, Box 462, S-40530 Göteborg, Sweden
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22
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Cramer RA, Perfect BZ, Pinchai N, Park S, Perlin DS, Asfaw YG, Heitman J, Perfect JR, Steinbach WJ. Calcineurin target CrzA regulates conidial germination, hyphal growth, and pathogenesis of Aspergillus fumigatus. EUKARYOTIC CELL 2008; 7:1085-97. [PMID: 18456861 PMCID: PMC2446674 DOI: 10.1128/ec.00086-08] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2008] [Accepted: 04/17/2008] [Indexed: 11/20/2022]
Abstract
The calcineurin pathway is a critical signal transduction pathway in fungi that mediates growth, morphology, stress responses, and pathogenicity. The importance of the calcineurin pathway in fungal physiology creates an opportunity for the development of new antifungal therapies that target this critical signaling pathway. In this study, we examined the role of the zinc finger transcription factor Crz1 homolog (CrzA) in the physiology and pathogenicity of the opportunistic human fungal pathogen Aspergillus fumigatus. Genetic replacement of the crzA locus in A. fumigatus resulted in a strain with significant defects in conidial germination, polarized hyphal growth, cell wall structure, and asexual development that are similar to but with differences from defects seen in the A. fumigatus DeltacnaA (calcineurin A) strain. Like the DeltacnaA strain, the DeltacrzA strain was incapable of causing disease in an experimental persistently neutropenic inhalational murine model of invasive pulmonary aspergillosis. Our results suggest that CrzA is an important downstream effector of calcineurin that controls morphology in A. fumigatus, but additional downstream effectors that mediate calcineurin signal transduction are likely present in this opportunistic fungal pathogen. In addition, the importance of CrzA to the production of disease is critical, and thus CrzA is an attractive fungus-specific antifungal target for the treatment of invasive aspergillosis.
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Affiliation(s)
- Robert A Cramer
- Duke University Medical Center, Box 3499, Pediatric Infectious Diseases, Durham, NC 27710, USA
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23
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Martínez-Muñoz GA, Kane P. Vacuolar and plasma membrane proton pumps collaborate to achieve cytosolic pH homeostasis in yeast. J Biol Chem 2008; 283:20309-19. [PMID: 18502746 DOI: 10.1074/jbc.m710470200] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vacuolar proton-translocating ATPases (V-ATPases) play a central role in organelle acidification in all eukaryotic cells. To address the role of the yeast V-ATPase in vacuolar and cytosolic pH homeostasis, ratiometric pH-sensitive fluorophores specific for the vacuole or cytosol were introduced into wild-type cells and vma mutants, which lack V-ATPase subunits. Transiently glucose-deprived wild-type cells respond to glucose addition with vacuolar acidification and cytosolic alkalinization, and subsequent addition of K(+) ion increases the pH of both the vacuole and cytosol. In contrast, glucose addition results in an increase in vacuolar pH in both vma mutants and wild-type cells treated with the V-ATPase inhibitor concanamycin A. Cytosolic pH homeostasis is also significantly perturbed in the vma mutants. Even at extracellular pH 5, conditions optimal for their growth, cytosolic pH was much lower, and response to glucose was smaller in the mutants. In plasma membrane fractions from the vma mutants, activity of the plasma membrane proton pump, Pma1p, was 65-75% lower than in fractions from wild-type cells. Immunofluorescence microscopy confirmed decreased levels of plasma membrane Pma1p and increased Pma1p at the vacuole and other compartments in the mutants. Pma1p was not mislocalized in concanamycin-treated cells, but a significant reduction in cytosolic pH under all conditions was still observed. We propose that short-term, V-ATPase activity is essential for both vacuolar acidification in response to glucose metabolism and for efficient cytosolic pH homeostasis, and long-term, V-ATPases are important for stable localization of Pma1p at the plasma membrane.
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Affiliation(s)
- Gloria A Martínez-Muñoz
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA.
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24
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Function and regulation of the Saccharomyces cerevisiae ENA sodium ATPase system. EUKARYOTIC CELL 2007; 6:2175-83. [PMID: 17951516 DOI: 10.1128/ec.00337-07] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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25
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Tate JJ, Cooper TG. Stress-responsive Gln3 localization in Saccharomyces cerevisiae is separable from and can overwhelm nitrogen source regulation. J Biol Chem 2007; 282:18467-18480. [PMID: 17439949 PMCID: PMC2269007 DOI: 10.1074/jbc.m609550200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Intracellular localization of Saccharomyces cerevisiae GATA family transcription activator, Gln3, is used as a downstream readout of rapamycin-inhibited Tor1,2 control of Tap42 and Sit4 activities. Gln3 is cytoplasmic in cells provided with repressive nitrogen sources such as glutamine and is nuclear in cells growing with a derepressive nitrogen source such as proline or those treated with rapamycin or methionine sulfoximine (Msx). Although gross Gln3-Myc13 phosphorylation levels in wild type cells do not correlate with nitrogen source-determined intracellular Gln3-Myc13 localization, the phosphorylation levels are markedly influenced by several environmental perturbations. Msx treatment increases Snf1-independent Gln3-Myc13 phosphorylation, whereas carbon starvation increases both Snf1-dependent and -independent Gln3-Myc13 phosphorylation. Here we demonstrate that a broad spectrum of environmental stresses (temperature, osmotic, and oxidative) increase Gln3-Myc13 phosphorylation. In parallel, these stresses elicit rapid (<5 min for NaCl) Gln3-Myc13 relocalization from the nucleus to the cytoplasm. The response of Gln3-Myc13 localization to stressful conditions can completely overwhelm its response to nitrogen source quality or inhibitor-generated disruption of the Tor1,2 signal transduction pathway. Adding NaCl to cells cultured under conditions in which Gln3-Myc13 is normally nuclear, i.e. proline-grown, nitrogen-starved, Msx-, caffeine-, and rapamycin-treated wild type cells, or ure2Delta cells, results in its prompt relocalization to the cytoplasm. Together these data identify a major new level of regulation to which Gln3 responds, and adds a new dimension to mechanistic studies of the regulation of this transcription factor.
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Affiliation(s)
- Jennifer J Tate
- Department of Molecular Sciences, University of Tennessee, Memphis, Tennessee 38163
| | - Terrance G Cooper
- Department of Molecular Sciences, University of Tennessee, Memphis, Tennessee 38163.
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26
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Krebs B, Wiebelitz A, Balitzki-Korte B, Vassallo N, Paluch S, Mitteregger G, Onodera T, Kretzschmar HA, Herms J. Cellular prion protein modulates the intracellular calcium response to hydrogen peroxide. J Neurochem 2007; 100:358-67. [PMID: 17241158 DOI: 10.1111/j.1471-4159.2006.04256.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The physiological function of the cellular prion protein (PrP(C)) is still under intense investigation. It has been suggested that PrP(C) has a protective role in neuronal cells, particularly against environmental stress caused by reactive oxygen species (ROS). Here we analysed the acute effect of a major ROS, hydrogen peroxide (H(2)O(2)), on intracellular calcium homeostasis in cultured cerebellar granule cells and immortalized hippocampal neuronal cells. Both neuronal cell culture models showed that the rise in intracellular calcium following application of H(2)O(2) was strongly dependent on the presence of PrP(C). Moreover, the N-terminal octapeptide repeats of PrP(C) were required for this effect, because neuronal cells expressing a PrP(C) lacking the N-terminus resembled the PrP(C)-deficient phenotype. Neurones deficient of fyn kinase, or pharmacological inhibition of fyn, also abrogated the calcium response to H(2)O(2) treatment, indicating that fyn activation is a critical step within the PrP(C) signalling cascade. Finally, we identified a possible role of this PrP(C) signalling pathway in the neuroprotective response of PrP(C) to oxidative stress. In conclusion, we put forward the hypothesis that PrP(C) functions as a sensor for H(2)O(2), thereby activating a protective signalling cascade involving fyn kinase that leads to calcium release from intracellular stores.
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Affiliation(s)
- Bjarne Krebs
- Centre for Neuropathology and Prion Research, Ludwig-Maximilians-University of Munich, Munich, Germany
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27
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Rodríguez-Vargas S, Sánchez-García A, Martínez-Rivas JM, Prieto JA, Randez-Gil F. Fluidization of membrane lipids enhances the tolerance of Saccharomyces cerevisiae to freezing and salt stress. Appl Environ Microbiol 2007; 73:110-6. [PMID: 17071783 PMCID: PMC1797130 DOI: 10.1128/aem.01360-06] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2006] [Accepted: 10/18/2006] [Indexed: 11/20/2022] Open
Abstract
Unsaturated fatty acids play an essential role in the biophysical characteristics of cell membranes and determine the proper function of membrane-attached proteins. Thus, the ability of cells to alter the degree of unsaturation in their membranes is an important factor in cellular acclimatization to environmental conditions. Many eukaryotic organisms can synthesize dienoic fatty acids, but Saccharomyces cerevisiae can introduce only a single double bond at the Delta(9) position. We expressed two sunflower (Helianthus annuus) oleate Delta(12) desaturases encoded by FAD2-1 and FAD2-3 in yeast cells of the wild-type W303-1A strain (trp1) and analyzed their effects on growth and stress tolerance. Production of the heterologous desaturases increased the content of dienoic fatty acids, especially 18:2Delta(9,12), the unsaturation index, and the fluidity of the yeast membrane. The total fatty acid content remained constant, and the level of monounsaturated fatty acids decreased. Growth at 15 degrees C was reduced in the FAD2 strains, probably due to tryptophan auxotrophy, since the trp1 (TRP1) transformants that produced the sunflower desaturases grew as well as the control strain did. Our results suggest that changes in the fluidity of the lipid bilayer affect tryptophan uptake and/or the correct targeting of tryptophan transporters. The expression of the sunflower desaturases, in either Trp(+) or Trp(-) strains, increased NaCl tolerance. Production of dienoic fatty acids increased the tolerance to freezing of wild-type cells preincubated at 30 degrees C or 15 degrees C. Thus, membrane fluidity is an essential determinant of stress resistance in S. cerevisiae, and engineering of membrane lipids has the potential to be a useful tool of increasing the tolerance to freezing in industrial strains.
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Affiliation(s)
- Sonia Rodríguez-Vargas
- Department of Biotechnology, Instituto de Agroquímica y Tecnología de los Alimentos, Consejo Superior de Investigaciones Científicas, E-46100 Burjassot, Valencia, Spain
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28
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Li M, Martin SJ, Bruno VM, Mitchell AP, Davis DA. Candida albicans Rim13p, a protease required for Rim101p processing at acidic and alkaline pHs. EUKARYOTIC CELL 2005; 3:741-51. [PMID: 15189995 PMCID: PMC420141 DOI: 10.1128/ec.3.3.741-751.2004] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Candida albicans is an important commensal of mucosal surfaces that is also an opportunistic pathogen. This organism colonizes a wide range of host sites that differ in pH; thus, it must respond appropriately to this environmental stress to survive. The ability to respond to neutral-to-alkaline pHs is governed in part by the RIM101 signal transduction pathway. Here we describe the analysis of C. albicans Rim13p, a homolog of the Rim13p/PalB calpain-like protease member of the RIM101/pacC pathway from Saccharomyces cerevisiae and Aspergillus nidulans, respectively. RIM13, like other members of the RIM101 pathway, is required for alkaline pH-induced filamentation and growth under extreme alkaline conditions. Further, our studies suggest that the RIM101 pathway promotes pH-independent responses, including resistance to high concentrations of lithium and to the drug hygromycin B. RIM13 encodes a calpain-like protease, and we found that Rim101p undergoes a Rim13p-dependent C-terminal proteolytic processing event at neutral-to-alkaline pHs, similar to that reported for S. cerevisiae Rim101p and A. nidulans PacC. However, we present evidence that suggests that C. albicans Rim101p undergoes a novel processing event at acidic pHs that has not been reported in either S. cerevisiae or A. nidulans. Thus, our results provide a framework to understand how the C. albicans Rim101p processing pathway promotes alkaline pH-independent processes.
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Affiliation(s)
- Mingchun Li
- Department of Microbiology, University of Minnesota, Minneapolis MN 55455, USA
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29
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Nakayashiki T, Kurtzman CP, Edskes HK, Wickner RB. Yeast prions [URE3] and [PSI+] are diseases. Proc Natl Acad Sci U S A 2005; 102:10575-80. [PMID: 16024723 PMCID: PMC1180808 DOI: 10.1073/pnas.0504882102] [Citation(s) in RCA: 205] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Viruses, plasmids, and prions can spread in nature despite being a burden to their hosts. Because a prion arises de novo in more than one in 10(6) yeast cells and spreads to all offspring in meiosis, its absence in wild strains would imply that it has a net deleterious effect on its host. Among 70 wild Saccharomyces strains, we found the [PIN+] prion in 11 strains, but the [URE3] and [PSI+] prions were uniformly absent. In contrast, the "selfish" 2mu DNA was in 38 wild strains and the selfish RNA replicons L-BC, 20S, and 23S were found in 8, 14, and 1 strains, respectively. The absence of [URE3] and [PSI+] in wild strains indicates that each prion has a net deleterious effect on its host.
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Affiliation(s)
- Toru Nakayashiki
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 8, Room 225, Bethesda, MD 20892-0830, USA
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30
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Lian T, Simmer MI, D'Souza CA, Steen BR, Zuyderduyn SD, Jones SJM, Marra MA, Kronstad JW. Iron-regulated transcription and capsule formation in the fungal pathogen Cryptococcus neoformans. Mol Microbiol 2005; 55:1452-72. [PMID: 15720553 DOI: 10.1111/j.1365-2958.2004.04474.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cryptococcus neoformans is the leading cause of fungal meningitis in humans. Production of a polysaccharide capsule is a key virulence property for the fungus and capsule synthesis is regulated by iron levels. Given that iron acquisition is an important aspect of virulence for many pathogens, we employed serial analysis of gene expression (SAGE) to examine the transcriptome under iron-limiting and iron-replete conditions. Initially, we demonstrated by SAGE and Northern analysis that iron limitation results in an elevated transcript level for the CAP60 gene that is required for capsule production. We also identified genes encoding putative components for iron transport and homeostasis, including the FTR1 (iron permease) gene, with higher transcript levels in the low-iron condition. An FTR1 disruption mutant grows more slowly than wild-type cells in low-iron medium, and shows delayed growth and altered capsule regulation in iron-replete medium. Iron deprivation also resulted in elevated SAGE tags for putative extracellular mannoproteins and the GPI8 gene encoding a glycosylphosphatidylinositol (GPI) transamidase. The GPI8 gene appears to be essential while disruption of the CIG1 gene encoding a mannoprotein resulted in impaired growth in low-iron medium and altered capsule response to the iron-replete condition. Additionally, we found that iron-replete conditions led to elevated transcripts for genes for iron storage, nitrogen metabolism, glycolysis, mitochondrial function, lipid metabolism and calmodulin-calcineurin signalling. Overall, these studies provide the first view of the C. neoformans transcriptional response to different iron levels.
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Affiliation(s)
- Tianshun Lian
- The Michael Smith Laboratories, Department of Microbiology and Immunology, and Faculty of Agricultural Sciences, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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31
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Wittenberg C, Reed SI. Cell cycle-dependent transcription in yeast: promoters, transcription factors, and transcriptomes. Oncogene 2005; 24:2746-55. [PMID: 15838511 DOI: 10.1038/sj.onc.1208606] [Citation(s) in RCA: 155] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the budding yeast, Saccharomyces cerevisiae, a significant fraction of genes (>10%) are transcribed with cell cycle periodicity. These genes encode critical cell cycle regulators as well as proteins with no direct connection to cell cycle functions. Cell cycle-regulated genes can be organized into 'clusters' exhibiting similar patterns of regulation. In most cases periodic transcription is achieved via both repressive and activating mechanisms. Fine-tuning appears to have evolved by the juxtaposition of regulatory motifs characteristic of more than one cluster within the same promoter. Recent reports have provided significant new insight into the role of the cyclin-dependent kinase Cdk1 (Cdc28) in coordination of transcription with cell cycle events. In early G1, the transcription factor complex known as SBF is maintained in a repressed state by association of the Whi5 protein. Phosphorylation of Whi5 by Cdk1 in late G1 leads to dissociation from SBF and transcriptional derepression. G2/M-specific transcription is achieved by converting the repressor Fkh2 into an activator. Fkh2 serves as a repressor during most of the cell cycle. However, phosphorylation of a cofactor, Ndd1, by Cdk1 late in the cell cycle promotes binding to Fkh2 and conversion into a transcriptional activator. Such insights derived from analysis of specific genes when combined with genome-wide analysis provide a more detailed and integrated view of cell cycle-dependent transcription.
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Affiliation(s)
- Curt Wittenberg
- Department of Molecular Biology, MB-3, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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32
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Kafadar KA, Cyert MS. Integration of stress responses: modulation of calcineurin signaling in Saccharomyces cerevisiae by protein kinase A. EUKARYOTIC CELL 2005; 3:1147-53. [PMID: 15470242 PMCID: PMC522609 DOI: 10.1128/ec.3.5.1147-1153.2004] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Calcineurin is a Ca2+/calmodulin-dependent protein phosphatase required for Saccharomyces cerevisiae to adapt to a variety of environmental stresses. Once activated, calcineurin dephosphorylates the Zn-finger transcription factor Crz1p/Tcn1p, causing it to accumulate in the nucleus where it activates gene expression. Here we show that cyclic AMP-dependent protein kinase A (PKA) phosphorylates and negatively regulates Crz1p activity by inhibiting its nuclear import. Activation of PKA in vivo decreases Crz1p-dependent transcription. PKA phosphorylates Crz1p in vitro, and we identify specific residues required for this phosphorylation, all of which reside in or adjacent to the nuclear localization signal. Mutation of these residues to alanine results in increased nuclear import of Crz1p and results in higher levels of both basal and Ca2+-induced Crz1p transcriptional activity. PKA regulates the general stress response in yeast and coordinates this response with nutrient availability. In contrast, calcineurin regulates the cellular response to a restricted set of environmental insults. Thus, these studies identify a specific biochemical mechanism through which the activities of multiple stress-activated signaling pathways are integrated in vivo.
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Affiliation(s)
- Kimberly A Kafadar
- Department of Biological Sciences, Stanford University, 337 Campus Dr., Lokey Building, Stanford, CA 94305-5020, USA
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33
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Watanabe Y, Oshima N, Tamai Y. Co-expression of the Na/H-antiporter and H-ATPase genes of the salt-tolerant yeast in. FEMS Yeast Res 2005; 5:411-7. [PMID: 15691746 DOI: 10.1016/j.femsyr.2004.11.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2004] [Revised: 10/21/2004] [Accepted: 11/09/2004] [Indexed: 11/15/2022] Open
Abstract
We cloned two genes from the salt-tolerant yeast Zygosaccharomyces rouxii: ZrSOD2 for the cell membrane Na(+)/H(+)-antiporter and ZrPMA1 for the cell membrane H(+)-ATPase. The products of these genes play cooperative roles in the salt-tolerance of Z. rouxii, and the function of the ZrPMA1 product is regulated at the transcription level. We constructed a yeast expression vector that is able to co-express the ZrSOD2 and ZrPMA1 genes. Single expression of ZrSOD2 was effective in conferring salt-tolerance, and although a slight synergic effect was observed with co-expression of ZrSOD2 and ZrPMA1, the usefulness of this co-expression is likely to be minimal with regard to salt-tolerance.
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Affiliation(s)
- Yasuo Watanabe
- Department of Biological Resources, Faculty of Agriculture, National University Corporation Ehime University, Matsuyama, Ehime 790-8566, Japan.
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34
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Munson AM, Haydon DH, Love SL, Fell GL, Palanivel VR, Rosenwald AG. Yeast ARL1 encodes a regulator of K+ influx. J Cell Sci 2005; 117:2309-20. [PMID: 15126631 DOI: 10.1242/jcs.01050] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A molecular genetic approach was undertaken in Saccharomyces cerevisiae to examine the functions of ARL1, encoding a G protein of the Ras superfamily. We show here that ARL1 is an important component of the control of intracellular K(+). The arl1 mutant was sensitive to toxic cations, including hygromycin B and other aminoglycoside antibiotics, tetramethylammonium ions, methylammonium ions and protons. The hygromycin-B-sensitive phenotype was suppressed by the inclusion of K(+) and complemented by wild-type ARL1 and an allele of ARL1 predicted to be unbound to nucleotide in vivo. The arl1 mutant strain internalized approximately 25% more [(14)C]-methylammonium ion than did the wild type, consistent with hyperpolarization of the plasma membrane. The arl1 strain took up 30-40% less (86)Rb(+) than did the wild type, showing an inability to regulate K(+) import properly, contributing to membrane hyperpolarity. By contrast, K(+) and H(+) efflux were undisturbed. The loss of ARL1 had no effect on the steady-state level or the localization of a tagged version of Trk1p. High copy suppressors of the hygromycin-B phenotype included SAP155, encoding a protein that interacts with the cell cycle regulator Sit4p, and HAL4 and HAL5, encoding Ser/Thr kinases that regulate the K(+)-influx mediators Trk1p and Trk2p. These results are consistent with a model in which ARL1, via regulation of HAL4/HAL5, governs K(+) homeostasis in cells.
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Affiliation(s)
- Amanda M Munson
- Department of Biology, 406 Reiss Science Center, Box 571229, Georgetown University, Washington, DC 20057, USA
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35
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Marín-Manzano MC, Rodríguez-Rosales MP, Belver A, Donaire JP, Venema K. Heterologously expressed protein phosphatase calcineurin downregulates plant plasma membrane H+-ATPase activity at the post-translational level. FEBS Lett 2004; 576:266-70. [PMID: 15474049 DOI: 10.1016/j.febslet.2004.09.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2004] [Revised: 09/04/2004] [Accepted: 09/04/2004] [Indexed: 11/23/2022]
Abstract
To investigate the effects of calcineurin expression on cellular ion homeostasis in plants, we have obtained a transgenic cell culture of tomato, expressing constitutively activated yeast calcineurin. Transgenic cells exhibited reduced growth rates and proton extrusion activity in vivo. We show that reduction of plasma membrane H+-ATPase activity by expression of calcineurin is the basis for the observed phenotypes. Transgenic calli and cell suspensions displayed also increased salt tolerance and contained slightly higher Ca2+ and K+ levels. This demonstrates that calcineurin can modulate ion homeostasis in plants as it does in yeast by affecting the activity of primary ion transporters.
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Affiliation(s)
- Mari Carmen Marín-Manzano
- Departamento de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín, Apartado 419, 18008 Granada, Spain
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36
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Kellermayer R, Szigeti R, Kellermayer M, Miseta A. The intracellular dissipation of cytosolic calcium following glucose re-addition to carbohydrate depleted Saccharomyces cerevisiae. FEBS Lett 2004; 571:55-60. [PMID: 15280017 DOI: 10.1016/j.febslet.2004.06.049] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2003] [Revised: 06/17/2004] [Accepted: 06/21/2004] [Indexed: 10/26/2022]
Abstract
Glucose re-addition to carbohydrate starved yeast cells leads to a transient elevation of eytosolic calcium (TECC). Concomitantly, a cytosolic proton extrusion occurs through the activation of the vacuolar H(+)-ATPase and the plasma membrane H(+)-ATPases. This study addressed the dissipation of the TECC through intracellular compartmentalization and the possible affects of the H(+)-ATPases on this process. Both the vacuole and the Golgi-ER apparatus were found to play important roles in distributing calcium to internal stores. Additionally, the inhibition of cytosolic proton extrusion augmented cytosolic calcium responses. A model where pH dependent cytosolic calcium buffering plays an important role in the dissipation of the TECC in Saccharomyces cerevisiae is proposed.
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Affiliation(s)
- Richard Kellermayer
- Department of Medical Genetics and Child Development Medicine, University of Pécs, Szigeti ut 12, 7623 Pécs, Hungary.
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37
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Mehlgarten C, Schaffrath R. After chitin docking, toxicity of Kluyveromyces lactis zymocin requires Saccharomyces cerevisiae plasma membrane H+-ATPase. Cell Microbiol 2004; 6:569-80. [PMID: 15104597 DOI: 10.1111/j.1462-5822.2004.00383.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Zymocin, a three-subunit (alpha beta gamma) toxin complex from Kluyveromyces lactis, imposes a cell cycle block on Saccharomyces cerevisiae. Phenotypic analysis of the resistant kti10 mutant implies a membrane defect, suggesting that KTI10 represents a gene involved early in the zymocin response. Consistently, KTI10 is shown here to be allelic to PMA1 encoding H(+)-ATPase, a plasma membrane H(+) pump vital for membrane energization (Delta Psi). Like pma1 mutants, kti10 cells lose viability at low pH, indicating a pH homeostasis defect, and resist the antibiotic hygromycin B, uptake of which is known to be Pma1 and Delta Psi sensitive. Similar to kti10 cells, pma1 mutants with reported H(+) pump defects survive in the presence of exozymocin but do not resist endogenous expression of its lethal gamma-toxin subunit. Based on DNA sequence data, kti10 cells are predicted to produce a malfunctional Pma1 variant with expression levels that are normal. Intriguingly, zymocin protection of kti10 cells is suppressed by excess H(+), a scenario ineffective in bypassing resistance of chitin or toxin target mutants. Together with unaltered zymocin docking and gamma-toxin import events in kti10 cells, our data suggest that Pma1's role in zymocin action is likely to involve activation of gamma-toxin in a step following its cellular uptake.
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Affiliation(s)
- Constance Mehlgarten
- Biologicum, Institut für Genetik, Martin-Luther-Universität Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany
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38
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Lisman Q, Urli-Stam D, Holthuis JCM. HOR7, a multicopy suppressor of the Ca2+-induced growth defect in sphingolipid mannosyltransferase-deficient yeast. J Biol Chem 2004; 279:36390-6. [PMID: 15208314 DOI: 10.1074/jbc.m406197200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Yeast mutants defective in sphingolipid mannosylation accumulate inositol phosphorylceramide C (IPC-C), which renders cells Ca(2+)-sensitive. A screen for loss of function suppressors of the Ca(2+)-sensitive phenotype previously led to the identification of numerous genes involved in IPC-C synthesis. To better understand the molecular basis of the Ca(2+)-induced growth defect in IPC-C-overaccumulating cells, we searched for genes whose overexpression restored Ca(2+) tolerance in a mutant lacking the IPC mannosyltransferases Csg1p and Csh1p. Here we report the isolation of HOR7 as a multicopy suppressor of the Ca(2+)-sensitive phenotype of Deltacsg1Deltacsh1 cells. HOR7 belongs to a group of hyperosmolarity-responsive genes and encodes a small (59-residue) type I membrane protein that localizes at the plasma membrane. Hor7p is not required for high Ca(2+) or Na(+) tolerance. Instead, we find that Hor7p-overproducing cells display an increased resistance to high salt, sensitivity to low pH, and a reduced uptake of methylammonium, an indicator of the plasma membrane potential. These phenotypes are induced through a mechanism independent of the plasma membrane H(+)-ATPase, Pma1p. Our findings suggest that induction of Hor7p causes a depolarization of the plasma membrane that may counteract a Ca(2+)-induced influx of toxic cations in IPC-C-overaccumulating cells.
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Affiliation(s)
- Quirine Lisman
- Department of Membrane Enzymology, Faculty of Chemistry, Utrecht University, H.R. Kruytgebouw N605, Padualaan 8, 3584 CH Utrecht, The Netherlands
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39
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Basu U, Southron JL, Stephens JL, Taylor GJ. Reverse genetic analysis of the glutathione metabolic pathway suggests a novel role of PHGPX and URE2 genes in aluminum resistance in Saccharomyces cerevisiae. Mol Genet Genomics 2004; 271:627-37. [PMID: 15133656 DOI: 10.1007/s00438-004-1015-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2003] [Accepted: 04/14/2004] [Indexed: 10/26/2022]
Abstract
We have taken a systematic genetic approach to study the potential role of glutathione metabolism in aluminum (Al) toxicity and resistance, using disruption mutants available in Saccharomyces cerevisiae. Yeast disruption mutants defective in phospholipid hydroperoxide glutathione peroxidases (PHGPX; phgpx1 Delta, phgpx2 Delta, and phgpx3Delta), were tested for their sensitivity to Al. The triple mutant, phgpx1 Delta/2Delta/3Delta, was more sensitive to Al (55% reduction in growth at 300 microM Al) than any single phgpx mutant, indicating that the PHGPX genes may collectively contribute to Al resistance. The hypersensitivity of phgpx3Delta to Al was overcome by complementation with PHGPX3, and all PHGPX genes showed increased expression in response to Al in the wild-type strain (YPH250), with maximum induction of approximately 2.5-fold for PHGPX3. Both phgpx3Delta and phgpx1Delta/2Delta/3Delta mutants were sensitive to oxidative stress (exposure to H(2)O(2) or diamide). Lipid peroxidation was also increased in the phgpx1Delta/2Delta/3Delta mutant compared to the parental strain. Disruption mutants defective in genes for glutathione S-transferases (GSTs) (gtt1Delta and gtt2Delta), glutathione biosynthesis (gsh1Delta and gsh2Delta), glutathione reductase (glr1Delta) and a glutathione transporter (opt1Delta) did not show hypersensitivity to Al relative to the parental strain BY4741. Interestingly, a strain deleted for URE2, a gene which encodes a prion precursor with homology to GSTs, also showed hypersensitivity to Al. The hypersensitivity of the ure2Delta mutant could be overcome by complementation with URE2. Expression of URE2 in the parental strain increased approximately 2-fold in response to exposure to 100 microM Al. Intracellular oxidation levels in the ure2Delta mutant showed a 2-fold (non-stressed) and 3-fold (when exposed-to 2 mM H(2)O(2)) increase compared to BY4741; however, the ure2Delta mutant showed no change in lipid peroxidation compared to the control. The phgpx1Delta/2Delta/3Delta and ure2Delta mutants both showed increased accumulation of Al. These findings suggest the involvement of PHGPX genes and a novel role of URE2 in Al toxicity/resistance in S. cerevisiae.
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Affiliation(s)
- U Basu
- Department of Biological Sciences, University of Alberta, T6G 2E9, Edmonton, Alberta, Canada.
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40
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Lefebvre B, Boutry M, Morsomme P. The yeast and plant plasma membrane H+ pump ATPase: divergent regulation for the same function. ACTA ACUST UNITED AC 2004; 74:203-37. [PMID: 14510077 DOI: 10.1016/s0079-6603(03)01014-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
Affiliation(s)
- Benoit Lefebvre
- Unité de biochimie physiologique, Institut des Sciences de la Vie, University of Louvain, B-1348 Louvain-la-Neuve, Belgium
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41
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Shitamukai A, Hirata D, Sonobe S, Miyakawa T. Evidence for antagonistic regulation of cell growth by the calcineurin and high osmolarity glycerol pathways in Saccharomyces cerevisiae. J Biol Chem 2003; 279:3651-61. [PMID: 14583627 DOI: 10.1074/jbc.m306098200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Because Ca(2+) signaling of budding yeast, through the activation of calcineurin and the Mpk1/Slt2 mitogen-activated protein kinase cascade, performs redundant function(s) in the events essential for growth, the simultaneous deletion of both these pathways (Delta cnb1 Delta mpk1) leads to lethality. A PTC4 cDNA that encodes a protein phosphatase belonging to the PP2C family was obtained as a high dosage suppressor of the lethality of Delta cnb1 Delta mpk1 strain. Overexpression of PTC4 led to a decrease in the high osmolarity-induced Hog1 phosphorylation, and HOG1 deletion remarkably suppressed the synthetic lethality, indicating an antagonistic role of the high osmolarity glycerol (HOG) pathway and the Ca(2+) signaling pathway in growth regulation. The calcineurin-Crz1 pathway was required for the down-regulation of the HOG pathway. Analysis of the time course of actin polarization, bud formation, and the onset of mitosis in synchronous cell cultures demonstrated that calcineurin negatively regulates actin polarization at the bud site, whereas the HOG pathway positively regulates bud formation at a later step after actin has polarized.
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Affiliation(s)
- Atsunori Shitamukai
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
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42
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Silva-Graça M, Neves L, Lucas C. Outlines for the definition of halotolerance/halophily in yeasts: Candida versatilis (halophila) CBS4019 as the archetype? FEMS Yeast Res 2003; 3:347-62. [PMID: 12748048 DOI: 10.1016/s1567-1356(02)00200-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Candida versatilis (halophila) CBS4019 was chosen to study the physiological reactions of long-term exposure to extremely high salt concentrations. In general, our results show a significant increase in enzyme expression during growth under stress conditions. Although glycerol and mannitol pathways are not under glucose repression, they were found to be metabolically regulated. Glycerol-3P-dehydrogenase used either of its cofactors NADPH or NADH, being in favor of NADPH during growth with high salt concentrations. This ability of interchanging cofactors, an increased fermentation rate, and the observed mannitol pathway activity are suggested to contribute to the yeasts' redox stability. Enzymes per se were not salt-tolerant in vitro. Consistently, intracellular sodium was low and intracellular potassium, a requirement for growth, was high. The concept of halophily and its applicability to yeasts is discussed.
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Affiliation(s)
- Magda Silva-Graça
- Department of Biology/Environmental Sciences Research Centre (CCA/B), University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal
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43
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Butcher RA, Schreiber SL. A small molecule suppressor of FK506 that targets the mitochondria and modulates ionic balance in Saccharomyces cerevisiae. CHEMISTRY & BIOLOGY 2003; 10:521-31. [PMID: 12837385 DOI: 10.1016/s1074-5521(03)00108-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
FK506 inhibits the evolutionarily conserved, Ca(2+)-dependent phosphatase calcineurin, which in yeast is essential for growth during sodium stress. We undertook a chemical genetic modifier screen to identify small molecules that suppress the ability of FK506 to inhibit yeast growth in high NaCl. One of these small molecule suppressors, SFK1 (suppressor of FK506 1), causes a mitochondrially induced death in low salt, concomitant with the release of reactive oxygen species. Biochemically, SFK1 interacts with Por1p, a channel protein in the outer mitochondrial membrane, suggesting that SFK1 interacts with the mitochondria directly. A genome-wide screen of yeast deletion strains for hypersensitivity to SFK1 yielded several strains with impaired mitochondrial function, as well as several with reduced sodium tolerance. Our data link ionic balance to mitochondrial function and suggest a role for calcineurin in mediating this signaling network.
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Affiliation(s)
- Rebecca A Butcher
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA
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44
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Abstract
Fungal prions are fascinating protein-based genetic elements. They alter cellular phenotypes through self-perpetuating changes in protein conformation and are cytoplasmically partitioned from mother cell to daughter. The four prions of Saccharomyces cerevisiae and Podospora anserina affect diverse biological processes: translational termination, nitrogen regulation, inducibility of other prions, and heterokaryon incompatibility. They share many attributes, including unusual genetic behaviors, that establish criteria to identify new prions. Indeed, other fungal traits that baffled microbiologists meet some of these criteria and might be caused by prions. Recent research has provided notable insight about how prions are induced and propagated and their many biological roles. The ability to become a prion appears to be evolutionarily conserved in two cases. [PSI(+)] provides a mechanism for genetic variation and phenotypic diversity in response to changing environments. All available evidence suggests that prions epigenetically modulate a wide variety of fundamental biological processes, and many await discovery.
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Affiliation(s)
- Susan M Uptain
- Howard Hughes Medical Institute, Department of Molecular Genetics and Cell Biology, University of Chicago, Illinois 60637, USA.
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45
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Forment J, Mulet JM, Vicente O, Serrano R. The yeast SR protein kinase Sky1p modulates salt tolerance, membrane potential and the Trk1,2 potassium transporter. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1565:36-40. [PMID: 12225850 DOI: 10.1016/s0005-2736(02)00503-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Protein kinases dedicated to the phosphorylation of SR proteins have been implicated in the processing and nuclear export of mRNAs. Here we demonstrate in Saccharomyces cerevisiae their participation in cation homeostasis. A null mutant of the single yeast SR protein kinase Sky1p is viable but exhibits increased tolerance to diverse toxic cations such as Na(+), Li(+), spermine, tetramethylammonium, hygromycin B and Mn(2+). This pleiotropic phenotype correlates with reduced accumulation of cations, suggesting a decrease in membrane electrical potential. Genetic analysis and Rb(+) uptake measurements indicate that Sky1p modulates Trk1,2, the high-affinity K(+) uptake system of yeast and a major determinant of membrane potential.
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Affiliation(s)
- Javier Forment
- Dept. de Biotecnologia, Instituto de Biologi;a Molecular y Celular de Plantas, Universidad Politécnica de Valencia-CSIC, Avenida de los Naranjos s/n, Camino de Vera, 46022, Valencia, Spain
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46
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Williams-Hart T, Wu X, Tatchell K. Protein phosphatase type 1 regulates ion homeostasis in Saccharomyces cerevisiae. Genetics 2002; 160:1423-37. [PMID: 11973298 PMCID: PMC1462070 DOI: 10.1093/genetics/160.4.1423] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Protein phosphatase type 1 (PP1) is encoded by the essential gene GLC7 in Saccharomyces cerevisiae. glc7-109 (K259A, R260A) has a dominant, hyperglycogen defect and a recessive, ion and drug sensitivity. Surprisingly, the hyperglycogen phenotype is partially retained in null mutants of GAC1, GIP2, and PIG1, which encode potential glycogen-targeting subunits of Glc7. The R260A substitution in GLC7 is responsible for the dominant and recessive traits of glc7-109. Another mutation at this residue, glc7-R260P, confers only salt sensitivity, indicating that the glycogen and salt traits of glc7-109 are due to defects in distinct physiological pathways. The glc7-109 mutant is sensitive to cations, aminoglycosides, and alkaline pH and exhibits increased rates of l-leucine and 3,3'-dihexyloxacarbocyanine iodide uptake, but it is resistant to molar concentrations of sorbitol or KCl, indicating that it has normal osmoregulation. KCl suppresses the ion and drug sensitivities of the glc7-109 mutant. The CsCl sensitivity of this mutant is suppressed by recessive mutations in PMA1, which encodes the essential plasma membrane H(+)ATPase. Together, these results indicate that Glc7 regulates ion homeostasis by controlling ion transport and/or plasma membrane potential, a new role for Glc7 in budding yeast.
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Affiliation(s)
- Tara Williams-Hart
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130, USA
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47
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Abstract
Calmodulin, a small, ubiquitous Ca2+-binding protein, regulates a wide variety of proteins and processes in all eukaryotes. CMD1, the single gene encoding calmodulin in S. cerevisiae, is essential, and this review discusses studies that identified many of calmodulin's physiological targets and their functions in yeast cells. Calmodulin performs essential roles in mitosis, through its regulation of Nuf1p/Spc110p, a component of the spindle pole body, and in bud growth, by binding Myo2p, an unconventional class V myosin required for polarized secretion. Surprisingly, mutant calmodulins that fail to bind Ca2+ can perform these essential functions. Calmodulin is also required for endocytosis in yeast and participates in Ca2+-dependent, stress-activated signaling pathways through its regulation of a protein phosphatase, calcineurin, and the protein kinases, Cmk1p and Cmk2p. Thus, calmodulin performs important physiological functions in yeast cells in both its Ca2+-bound and Ca2+-free form.
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Affiliation(s)
- M S Cyert
- Department of Biological Sciences, Stanford University, Stanford, California 94305-5020, USA.
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48
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Crespo JL, Daicho K, Ushimaru T, Hall MN. The GATA transcription factors GLN3 and GAT1 link TOR to salt stress in Saccharomyces cerevisiae. J Biol Chem 2001; 276:34441-4. [PMID: 11457832 DOI: 10.1074/jbc.m103601200] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
One of the most recent functions assigned to the TOR signaling pathway in yeast is the coordination of the transcription of genes involved in nutrient utilization. Here we show that transcription of ENA1, a gene encoding a lithium and sodium ion transporter essential for salt tolerance in yeast, is controlled by the TOR signaling pathway. First, ENA1 expression is strongly induced under TOR-inactivating conditions. Second, the absence of the TOR-controlled GATA transcription factors GLN3 and GAT1 results in reduced basal and salt-induced expression of ENA1. Third, a gln3 gat1 mutant displays a pronounced sensitivity to high concentrations of lithium and sodium. Fourth, TOR1, similar to ENA1, is required for growth under saline stress conditions. In summary, our results suggest that TOR plays a role in the general response to saline stress by regulating the transcription of ENA1 via GLN3 and GAT1.
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Affiliation(s)
- J L Crespo
- Division of Biochemistry, Biozentrum, University of Basel, Klingelbergstrasse 70, CH4056 Basel, Switzerland
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Edskes HK. Protein-based inheritance in Saccharomyces cerevisiae: [URE3] as a prion form of the nitrogen regulatory protein Ure2. Res Microbiol 2001; 152:605-12. [PMID: 11605980 DOI: 10.1016/s0923-2508(01)01239-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The [URE3] element of the yeast Saccharomyces cerevisiae results from the presence of an altered form of the nitrogen regulatory protein Ure2. This altered form acts as an infectious protein (prion). Genes affecting [URE3] initiation and propagation should give valuable information about prion diseases as well as other conformational diseases.
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Affiliation(s)
- H K Edskes
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0830, USA.
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Williams KE, Cyert MS. The eukaryotic response regulator Skn7p regulates calcineurin signaling through stabilization of Crz1p. EMBO J 2001; 20:3473-83. [PMID: 11432834 PMCID: PMC125528 DOI: 10.1093/emboj/20.13.3473] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
To survive ionic, pH and pheromone stress, the yeast Saccharomyces cerevisiae activates signaling through the Ca2+-activated phosphatase calcineurin to the transcription factor Crz1p/Tcn1p. We show that the overexpression of SKN7, a response-regulator transcription factor, activates transcription from a calcineurin/Crz1p-dependent response element (CDRE). Ca2+-induced, calcineurin/Crz1p-dependent activation of several genes is reduced in skn7 mutants. Skn7p modulates CDRE-dependent transcription by affecting Crz1p protein levels. Specifically, the rate of Crz1p turnover is increased in skn7 mutants. Calcineurin, but not its phosphatase activity, is required for Skn7p-mediated Crz1p stabilization. Skn7p binds to both calcineurin and Crz1p in vitro, and we suggest that this interaction is required for Skn7p regulation of Crz1p. The DNA-binding and internal coiled-coil domains, but not the response- regulator phosphorylation of Skn7p, are necessary for Crz1p-dependent transcriptional activation and Crz1p stabilization by Skn7 in vivo. The DNA-binding domain of Skn7p is also required for binding to Crz1p and calcineurin in vitro. Thus, we propose that Skn7p protects Crz1p from degradation by binding to it and calcineurin through its DNA-binding domain.
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Affiliation(s)
| | - Martha S. Cyert
- Department of Biological Science, Stanford University, Stanford, CA 94305-5020, USA
Corresponding author e-mail:
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