Arabidopsis thaliana CHX17 gene complements the kha1 deletion phenotypes in Saccharomyces cerevisiae

Marešová, Lydie; Sychrová, Hana

doi:10.1002/yea.1424

Cited by 41 publications

(35 citation statements)

References 14 publications

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“…[17][18][19] As expected, the host strain AXT3 transformed with the empty vector is unable to grow at 100 mM extracellular Na ϩ , at both extracellular pH of 4.0 and 7.4 ( Figure 7A). Expression of prevacuolar (Nhx1) and plasmalemmal (Nha1) S. cerevisiae NHE and human NHA2 all rescue the salt-sensitive phenotype at pH 4 but not at pH 7.4.…”

Section: Resultssupporting

confidence: 75%

Characterization of the Sodium/Hydrogen Exchanger NHA2

Fuster¹,

Zhang²,

Shi³

et al. 2008

Journal of the American Society of Nephrology

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Cation/proton exchange has been recognized for decades in mammalian mitochondria, but the exchanger proteins have eluded identification. In this study, a cDNA from a human brain library, previously designated NHA2 in the genome, was cloned and characterized. The NHA2 transcript bears more similarity to prokaryotic than known eukaryotic sodium/proton exchangers, but it was found to be expressed in multiple mammalian organs and cultured cells. A mAb to NHA2 was generated and found to label an approximately 55-kD native protein in multiple tissues and cell lines. The specificity of this antibody was confirmed by demonstrating the loss of the native NHA2 band on immunoblots when cultured cells were treated with NHA2-specific small interfering RNA. Although NHA2 protein was detected in multiple organs, within each, its expression was restricted to specific cell types. In the kidney, co-localization with calbindin 28k and reverse transcription-PCR of microdissected tubules revealed that NHA2 is limited to the distal convoluted tubule. In cell lines, native NHA2 was localized both to the plasma membrane and to the intracellular compartment; immunogold electron microscopy of rat distal convoluted tubule demonstrated NHA2 predominantly but not exclusively on the inner mitochondrial membrane. Furthermore, co-sedimentation of NHA2 antigen and mitochondrial membranes was observed with differential centrifugation, and two mitochondrial markers co-localized with NHA2 in cultured cells. Regarding function, human NHA2 reversed the sodium/hydrogen exchanger-null phenotype when expressed in sodium/hydrogen exchanger-deficient yeast and restored the ability to defend high salinity in the presence of acidic extracellular pH. In summary, NHA2 is a ubiquitous mammalian sodium proton/exchanger that is restricted to the distal convoluted tubule in the kidney.

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Section: Resultssupporting

confidence: 75%

Characterization of the Sodium/Hydrogen Exchanger NHA2

Fuster¹,

Zhang²,

Shi³

et al. 2008

Journal of the American Society of Nephrology

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“…novel subfamily (Mäser et al, 2001;Sze et al, 2004), although the biochemical properties of this family remained uncharacterized until recently (Maresova and Sychrova, 2006). Previous studies showed 18 CHXs are preferentially expressed in pollen and six AtCHXs are highly expressed in roots and/or shoots (Cellier et al, 2004;Sze et al, 2004;Hall et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

Participation of Endomembrane Cation/H+ Exchanger AtCHX20 in Osmoregulation of Guard Cells

et al. 2007

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Guard cell movement is induced by environmental and hormonal signals that cause changes in turgor through changes in uptake or release of solutes and water. Several transporters mediating these fluxes at the plasma membrane have been characterized; however, less is known about transport at endomembranes. CHX20, a member of a poorly understood cation/H+ exchanger gene family in Arabidopsis (Arabidopsis thaliana), is preferentially and highly expressed in guard cells as shown by promoter∷β-glucuronidase activity and by whole-genome microarray. Interestingly, three independent homozygous mutants carrying T-DNA insertions in CHX20 showed 35% reduction in light-induced stomatal opening compared to wild-type plants. To test the biochemical function of CHX20, cDNA was expressed in a yeast (Saccharomyces cerevisiae) mutant that lacks Na+(K+)/H+ antiporters (Δnhx1 Δnha1 Δkha1) and plasma membrane Na+ pumps (Δena1-4). Curiously, CHX20 did not enhance tolerance of mutants to moderate Na+ or high K+ stress. Instead, it restored growth of the mutant on medium with low K+ at slightly alkaline pH, but had no effect on growth at acidic pH. Green fluorescent protein-tagged CHX20 expressed in mesophyll protoplasts was localized mainly to membranes of the endosomal system. Furthermore, light-induced stomatal opening of the Arabidopsis mutants was insensitive to external pH and was impaired at high KCl. The results are consistent with the idea that, in exchanging K+ for H+, CHX20 maintains K+ homeostasis and influences pH under certain conditions. Together, these results provide genetic and biochemical evidence that one CHX protein plays a critical role in osmoregulation through K+ fluxes and possibly pH modulation of an active endomembrane system in guard cells.

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“…Yeast cells deleted for their endogenous exchangers are sensitive to external salt, and have proved useful for studies of heterologous CPA1 (Kang'ethe et al, 2007) and CPA2 genes (Maresova and Sychrova, 2006) by complementation. Accordingly, the ORFs encoding Drosophila CG10806::eYFP and CG31052::eYFP were expressed in nha1 nhx1 yeast.…”

Section: Drosophila Cpa2 Proteins Can Rescue Exchanger-deficient Yeastmentioning

confidence: 99%

“…However, it is clear that they are much more closely related to the prokaryote Kef (K + efflux) genes kefB and kefC (which were the first genes of the widespread CPA2 exchanger family to be discovered), and they have been named NHA1 and NHA2, respectively (Brett et al, 2005). Intriguingly, representatives of this family are present in yeast (Maresova and Sychrova, 2005;Ramirez et al, 1998), plants (Maresova and Sychrova, 2006; 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.…”

Section: Introductionmentioning

confidence: 99%

“…Quintero et al, 2000;Sze et al, 2004), insects (Pullikuth et al, 2006) and mammals; the family is designated CPA2, by contrast with the better-known CPA1 (the NHEs) (Brett et al, 2005). In yeast, ablation of K + /H + antiporter 1 (KHA1) causes salt sensitivity, and this can be rescued by homologous or heterologous expression of KHA candidates from yeast or plants (Maresova and Sychrova, 2006). A mosquito CPA2 was recently described (Rheault et al, 2007) and was named nha1, although it is not clear whether the protein transports Na + , K + or both.…”

Section: Introductionmentioning

confidence: 99%

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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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Arabidopsis thaliana CHX17 gene complements the kha1 deletion phenotypes in Saccharomyces cerevisiae

Cited by 41 publications

References 14 publications

Characterization of the Sodium/Hydrogen Exchanger NHA2

Characterization of the Sodium/Hydrogen Exchanger NHA2

Participation of Endomembrane Cation/H+ Exchanger AtCHX20 in Osmoregulation of Guard Cells

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

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