Role of the Nha1 antiporter in regulating K<sup>+</sup> influx in <i>Saccharomyces cerevisiae</i>

Bañuelos, María Antonia; Ruiz, Marta; Jiménez, Adriana; Souciet, Jean-Luc; Potier, Serge; Ramos, José

doi:10.1002/yea.799

Cited by 36 publications

(31 citation statements)

References 29 publications

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“…Potentially, yeast might provide a useful heterologous system for the study of animal CPA2 genes, because we were able to demonstrate a modest, but significant, rescue of exchangerdeficient mutants. Although it has been asserted that these genes are NHA homologues, and thus transport Na + , this is based on in silico analysis; such analysis is unlikely to be informative, because the ionic specificity of CPA2 family members is far from certain (Banuelos et al, 2002). It will also be interesting to explore the roles of CPA2 homologues (NHEDC1 and NHEDC2) in humans, in which this class of transporter remains surprisingly unexplored.…”

Section: Discussionmentioning

confidence: 99%

Identification of two partners from the bacterial Kef exchanger family for the apical plasma membrane V-ATPase of Metazoa

Day

Wan

Allan

et al. 2008

Journal of Cell Science

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The vital task of vectorial solute transport is often energised by a plasma membrane, proton-motive V-ATPase. However, its proposed partner, an apical alkali-metal/proton exchanger, has remained elusive. Here, both FlyAtlas microarray data and in situ analyses demonstrate that the bacterial kefB and kefC (members of the CPA2 family) homologues in Drosophila, CG10806 and CG31052, respectively, are both co-expressed with V-ATPase genes in transporting epithelia. Immunocytochemistry localises endogenous CG10806 and CG31052 to the apical plasma membrane of the Malpighian (renal) tubule. YFP-tagged CG10806 and CG31052 both localise to the plasma membrane of Drosophila S2 cells, and when driven in principal cells of the Malpighian tubule, they localise specifically to the apical plasma membrane. V-ATPase-energised fluid secretion is affected by overexpression of CG10806, but not CG31052; in the former case, overexpression causes higher basal rates, but lower stimulated rates, of fluid secretion compared with parental controls. Overexpression also impacts levels of secreted Na+ and K+. Both genes rescue exchanger-deficient (nha1 nhx1) yeast, but act differently; CG10806 is driven predominantly to the plasma membrane and confers protection against excess K+, whereas CG31052 is expressed predominantly on the vacuolar membrane and protects against excess Na+. Thus, both CG10806 and CG31052 are functionally members of the CPA2 gene family, colocalise to the same apical membrane as the plasma membrane V-ATPase and show distinct ion specificities, as expected for the Wieczorek exchanger.

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Section: Discussionmentioning

confidence: 99%

Identification of two partners from the bacterial Kef exchanger family for the apical plasma membrane V-ATPase of Metazoa

Day

Wan

Allan

et al. 2008

Journal of Cell Science

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“…Conversely, at an acidic ambient pH the Na ϩ efflux process would be mediated by a Na ϩ /H ϩ antiporter acting independently of PacC. In S. cerevisiae, a Na ϩ /H ϩ antiporter system encoded by the NHA1 gene mediates Na ϩ tolerance at acidic pH values (4,5,16). We have detected the existence in F. oxysporum of an orthologue of NHA, a plasma membrane Na ϩ /H ϩ antiporter from fungi and plants (Z. Caracuel et al, unpublished data).…”

Section: Vol 2 2003mentioning

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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“…Nha1 seems to be more involved, via its potassium-transporting capacity, in intracellular potassium and pH homeostases and, consequently, in the rapid response to changes of external osmolarity, to cell volume adjustment, and to maintenance of plasma membrane potential. Probably in all these physiological functions, the Nha1 antiporter is linked to the activity of the Trk1 (and/or Trk2) potassium uptake system, as it has been shown that the deletion of NHA1 affects the kinetics of high-affinity potassium uptake via Trk systems (16) and, vice versa, that deletion of TRK1,2 results in a diminished potassium efflux upon potassium starvation (J. Zahrádka and H. Sychrová, unpublished results).…”

Section: Sodium Effluxmentioning

confidence: 99%

Alkali Metal Cation Transport and Homeostasis in Yeasts

Ariño

Ramos

Sychrová

2010

Microbiol Mol Biol Rev

248

299

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SUMMARY 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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Role of the Nha1 antiporter in regulating K⁺ influx in Saccharomyces cerevisiae

Cited by 36 publications

References 29 publications

Identification of two partners from the bacterial Kef exchanger family for the apical plasma membrane V-ATPase of Metazoa

Identification of two partners from the bacterial Kef exchanger family for the apical plasma membrane V-ATPase of Metazoa

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

Alkali Metal Cation Transport and Homeostasis in Yeasts

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Role of the Nha1 antiporter in regulating K+ influx in Saccharomyces cerevisiae

Cited by 36 publications

References 29 publications

Identification of two partners from the bacterial Kef exchanger family for the apical plasma membrane V-ATPase of Metazoa

Identification of two partners from the bacterial Kef exchanger family for the apical plasma membrane V-ATPase of Metazoa

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

Alkali Metal Cation Transport and Homeostasis in Yeasts

Contact Info

Product

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About

Role of the Nha1 antiporter in regulating K⁺ influx in Saccharomyces cerevisiae

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