Cloning and Expression of Two Genes Coding for Sodium Pumps in the Salt-Tolerant Yeast
            <i>Debaryomyces hansenii</i>

Almagro, Anabel; Prista, Catarina; Benito, Begoña; Loureiro-Dias, Maria C.; Ramos, José

doi:10.1128/jb.183.10.3251-3255.2001

Cited by 82 publications

(65 citation statements)

References 30 publications

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“…At an OD 550 of 0.3 to 0.35, cells were collected on Millipore filters and rapidly washed with 20 mM MgCl 2 . The cells were then extracted with acid and analyzed by atomic emission spectrophotometry (2,15).…”

Section: Methodsmentioning

confidence: 99%

“…For determination of Na ϩ or Li ϩ efflux, cells were grown overnight in YEPD medium and incubated in the same medium plus 0.1 M NaCl or LiCl for 1.5 h. Cells were harvested, washed with cold water, and resuspended in assay buffer (10 mM MES [2-morpholinoethanesulfonic acid]) adjusted to pH 5.5 with Ca(OH) 2 and supplemented with 0.1 mM MgCl 2 , 2% (wt/vol) glucose, and 50 mM KCl to trigger the efflux process. Samples were taken in time intervals, filtered, and treated for determination of intracellular Na ϩ or Li ϩ content as described above (2, 15).…”

Section: Methodsmentioning

confidence: 99%

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Gis4, a New Component of the Ion Homeostasis System in the Yeast Saccharomyces cerevisiae

et al. 2006

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Gis4 is a new component of the system required for acquisition of salt tolerance in Saccharomyces cerevisiae. The gis4⌬ mutant is sensitive to Na ؉ and Li ؉ ions but not to osmotic stress. Genetic evidence suggests that Gis4 mediates its function in salt tolerance, at least partly, together with the Snf1 protein kinase and in parallel with the calcineurin protein phosphatase. When exposed to salt stress, mutants lacking gis4⌬ display a defect in maintaining low intracellular levels of Na ؉ and Li ؉ ions and exporting those ions from the cell. This defect is due to diminished expression of the ENA1 gene, which encodes the Na ؉ and Li ؉ export pump. The protein sequence of Gis4 is poorly conserved and does not reveal any hints to its molecular function. Gis4 is enriched at the cell surface, probably due to C-terminal farnesylation. The CAAX box at the C terminus is required for cell surface localization but does not seem to be strictly essential for the function of Gis4 in salt tolerance. Gis4 and Snf1 seem to share functions in the control of ion homeostasis and ENA1 expression but not in glucose derepression, the best known role of Snf1. Together with additional evidence that links Gis4 genetically and physically to Snf1, it appears that Gis4 may function in a pathway in which Snf1 plays a specific role in controlling ion homeostasis. Hence, it appears that the conserved Snf1 kinase plays roles in different pathways controlling nutrient as well as stress response.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Gis4, a New Component of the Ion Homeostasis System in the Yeast Saccharomyces cerevisiae

et al. 2006

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“…4 suggest that, like S. cerevisiae, F. oxysporum has at least two different Na ϩ (Li ϩ ) efflux systems: one functioning at pH 4.0 that is still present in the pacC ϩ/Ϫ loss-of-function mutant and the other one working at pH 8.0 that is not present in the mutant. Because the main alkaline Na ϩ and Li ϩ efflux system in yeast and filamentous fungi is based on P-type Na ϩ -ATPases encoded by the ENA genes (1,3,6,7,15), we decided to clone FIG. 6.…”

Section: Pacc Controls Salt Tolerance and Intacellular Cation Levelsmentioning

confidence: 99%

pH Response Transcription Factor PacC Controls Salt Stress Tolerance and Expression of the P-Type Na ⁺ -ATPase Ena1 in Fusarium oxysporum

Caracuel¹,

Casanova

Roncero³

et al. 2003

Eukaryot Cell

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Fungi possess efficient mechanisms of pH and ion homeostasis, allowing them to grow over a wide range of environmental conditions. In this study, we addressed the role of the pH response transcription factor PacC in salt tolerance of the vascular wilt pathogen Fusarium oxysporum. Loss-of-function pacC ؉/؊ mutants showed increased sensitivity to Li ؉ and Na ؉ and accumulated higher levels of these cations than the wild type. In contrast, strains expressing a dominant activating pacC c allele were more salt tolerant and had lower intracellular Li ؉ and Na ؉ concentrations. Although the kinetics of Li ؉ influx were not altered by mutations in pacC, we found that Li ؉ efflux at an alkaline, but not at an acidic, ambient pH was significantly reduced in pacCloss-of-function mutants. To explore the presence of a PacC-dependent efflux mechanism in F. oxysporum, we cloned ena1 encoding an orthologue of the yeast P-type Na ؉ -ATPase ENA1. Northern analysis revealed that efficient transcriptional activation of ena1 in F. oxysporum required the presence of high Na ؉ concentrations and alkaline ambient pH and was dependent on PacC function. We propose a model in which PacC controls ion homeostasis in F. oxysporum at a high pH by activating expression of ena1 coordinately with a second Na ؉ -responsive signaling pathway.Fungi are a versatile class of organisms that have successfully occupied numerous ecological niches, including those of plant and animal pathogenesis. A striking property of fungi and a major determinant of their evolutionary success is their capacity to adapt to an extremely wide range of environmental conditions. This ability depends crucially on the presence of cellular sensory networks that monitor the environment and mediate changes in gene expression in response to shifts in the external conditions. We use the vascular wilt pathogen Fusarium oxysporum as a model to understand how environmental signals regulate gene expression in fungi and how these regulatory mechanisms determine fungal virulence.A key factor in fungal growth and development is ambient pH. Fungi grow over a wide range of pH conditions and must thus be able to tailor gene expression to the particular pH of their growth environment. A conserved signaling cascade integrated by the products of the pal genes, whose terminal component is the zinc-finger transcription factor PacC/ Rim101p, regulates gene expression in response to ambient pH (18). Upon shift to alkaline pH, an inactive PacC precursor is posttranscriptionally activated by proteolytic processing into a shorter functional form that activates genes preferentially expressed at alkaline pH and represses genes expressed under acidic growth conditions (18). The pacC orthologue of F. oxysporum was recently cloned, and the encoded protein was shown to regulate pH-dependent gene expression and to function as a negative regulator of virulence on plants (11). Thus, pacC ϩ/Ϫ loss-of-function mutants of F. oxysporum mimic growth at acidic ambient pH and exhibit increased virulence, whereas pac...

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“…An important level of adaptation of the black yeasts to high salinity is seen in their extremophilic ecotype, which is characterized by a special meristematic morphology and changes in cell wall structure and pigmentation (27). Other fungal osmoadaptations include the accumulation of osmolytes (27,28,40), the extrusion of sodium (5), modification of the plasma membrane (44) and the cell wall, and even changes in fungal colony morphology (27).…”

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Morphological Response of the Halophilic Fungal Genus Wallemia to High Salinity

Kunčič

Kogej

Drobne

et al. 2010

Appl Environ Microbiol

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The basidiomycetous genus Wallemia is an active inhabitant of hypersaline environments, and it has recently been described as comprising three halophilic and xerophilic species: Wallemia ichthyophaga, Wallemia muriae, and Wallemia sebi. Considering the important protective role the fungal cell wall has under fluctuating physicochemical environments, this study was focused on cell morphology changes, with particular emphasis on the structure of the cell wall, when these fungi were grown in media with low and high salinities. We compared the influence of salinity on the morphological characteristics of Wallemia spp. by light, transmission, and focused-ion-beam/scanning electron microscopy. W. ichthyophaga was the only species of this genus that was metabolically active at saturated NaCl concentrations. W. ichthyophaga grew in multicellular clumps and adapted to the high salinity with a significant increase in cell wall thickness. The other two species, W. muriae and W. sebi, also demonstrated adaptive responses to the high NaCl concentration, showing in particular an increased size of mycelial pellets at the high salinities, with an increase in cell wall thickness that was less pronounced. The comparison of all three of the Wallemia spp. supports previous findings relating to the extremely halophilic character of the phylogenetically distant W. ichthyophaga and demonstrates that, through morphological adaptations, the eukaryotic Wallemia spp. are representative of eukaryotic organisms that have successfully adapted to life in extremely saline environments.

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Cloning and Expression of Two Genes Coding for Sodium Pumps in the Salt-Tolerant Yeast Debaryomyces hansenii

Cited by 82 publications

References 30 publications

Gis4, a New Component of the Ion Homeostasis System in the Yeast Saccharomyces cerevisiae

Gis4, a New Component of the Ion Homeostasis System in the Yeast Saccharomyces cerevisiae

pH Response Transcription Factor PacC Controls Salt Stress Tolerance and Expression of the P-Type Na ⁺ -ATPase Ena1 in Fusarium oxysporum

Morphological Response of the Halophilic Fungal Genus Wallemia to High Salinity

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Cloning and Expression of Two Genes Coding for Sodium Pumps in the Salt-Tolerant Yeast Debaryomyces hansenii

Cited by 82 publications

References 30 publications

Gis4, a New Component of the Ion Homeostasis System in the Yeast Saccharomyces cerevisiae

Gis4, a New Component of the Ion Homeostasis System in the Yeast Saccharomyces cerevisiae

pH Response Transcription Factor PacC Controls Salt Stress Tolerance and Expression of the P-Type Na + -ATPase Ena1 in Fusarium oxysporum

Morphological Response of the Halophilic Fungal Genus Wallemia to High Salinity

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pH Response Transcription Factor PacC Controls Salt Stress Tolerance and Expression of the P-Type Na ⁺ -ATPase Ena1 in Fusarium oxysporum