Steady-state free Ca2+ in the yeast endoplasmic reticulum reaches only 10 microM and is mainly controlled by the secretory pathway pump Pmr1

Strayle, Jochen; Pozzan, Tullio; Rudolph, Hans

doi:10.1093/emboj/18.17.4733

Cited by 130 publications

(132 citation statements)

References 51 publications

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“…1A shows that Mn tolerance of a pmr1⌬ strain was restored after transformation with the Arabidopsis CDF member AtMTP11 (At2g39450). The pmr1⌬ mutant is also unable to grow on Ca 2ϩ -depleted media because the Pmr1 protein is essential for loading of Ca 2ϩ into the ER and Golgi apparatus (32,33). Fig.…”

Section: Resultsmentioning

confidence: 99%

A secretory pathway-localized cation diffusion facilitator confers plant manganese tolerance

Peiter

Montanini

Gobert

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

253

262

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Manganese toxicity is a major problem for plant growth in acidic soils, but cellular mechanisms that facilitate growth in such conditions have not been clearly delineated. Established mechanisms that counter metal toxicity in plants involve chelation and cytoplasmic export of the metal across the plasma or vacuolar membranes out of the cell or sequestered into a large organelle, respectively. We report here that expression of the Arabidopsis and poplar MTP11 cation diffusion facilitators in a manganesehypersensitive yeast mutant restores manganese tolerance to wild-type levels. Microsomes from yeast expressing AtMTP11 exhibit enhanced manganese uptake. In accord with a presumed function of MTP11 in manganese tolerance, Arabidopsis mtp11 mutants are hypersensitive to elevated levels of manganese, whereas plants overexpressing MTP11 are hypertolerant. In contrast, sensitivity to manganese deficiency is slightly decreased in mutants and increased in overexpressing lines. Promoter-GUS studies showed that AtMTP11 is most highly expressed in root tips, shoot margins, and hydathodes, but not in epidermal cells and trichomes, which are generally associated with manganese accumulation. Surprisingly, imaging of MTP11-EYFP fusions demonstrated that MTP11 localizes neither to the plasma membrane nor to the vacuole, but to a punctate endomembrane compartment that largely coincides with the distribution of the trans-Golgi marker sialyl transferase. Golgi-based manganese accumulation might therefore result in manganese tolerance through vesicular trafficking and exocytosis. In accord with this proposal, Arabidopsis mtp11 mutants exhibit enhanced manganese concentrations in shoots and roots. We propose that Golgi-mediated exocytosis comprises a conserved mechanism for heavy metal tolerance in plants.Golgi ͉ heavy metal transport ͉ metal tolerance protein ͉ metal trafficking ͉ manganese transporter T ransition metals are required by living systems where they perform a wide variety of functions as cofactors for enzymes and transcription factors. Transition metals are also present in many environments at potentially toxic concentrations, and this has led to the evolution of mechanisms that counter toxicity. In plants exposed to high concentrations of transition metals in the soil, binding of the metals to phytochelatins in the cytosol lowers metal activity (1). Additionally, metals can be removed from the cytosol through the action of metal transporters. Transporters involved in metal tolerance localize to the plasma membrane, thereby removing metals from the cell, or to the vacuolar membrane, where the metal can be sequestered into a large and metabolically relatively inert intracellular compartment (2).Manganese is the second most prevalent transition metal, after iron, in the Earth's crust and an essential micronutrient for all organisms, including humans and plants (3). In addition to being a cofactor for a variety of enzymes (including various decarboxylases of the tricarboxylic acid cycle, RNA polymerases, and numerous glyco...

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Section: Resultsmentioning

confidence: 99%

A secretory pathway-localized cation diffusion facilitator confers plant manganese tolerance

Peiter

Montanini

Gobert

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

253

262

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“…An increase in cytosolic calcium can result from entry of the cation from the external medium or by release from internal stores, thus being the vacuole of the major calcium storage site in yeast (38,39). For instance, the initial increase of intracellular calcium upon hypotonic shock has been attributed to release from intracellular stores, whereas the sustained one would have an extracellular origin (7).…”

Section: Table V Evaluation By Dna Microarray and Quantitative Real Tmentioning

confidence: 99%

Characterization of the Calcium-mediated Response to Alkaline Stress in Saccharomyces cerevisiae

Viladevall¹,

Serrano²,

Ruiz³

et al. 2004

Journal of Biological Chemistry

189

212

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Exposure of the yeast Saccharomyces cerevisiae to alkaline stress resulted in adaptive changes that involved remodeling the gene expression. Recent evidence suggested that the calcium-activated protein phosphatase calcineurin could play a role in alkaline stress signaling. By using an aequorin luminescence reporter, we showed that alkaline stress resulted in a sharp and transient rise in cytoplasmic calcium. This increase was largely abolished by addition of EGTA to the medium or in cells lacking Mid1 or Cch1, components of the high affinity cell membrane calcium channel. Under these circumstances, the alkaline response of different calcineurin-sensitive transcriptional promoters was also blocked. Therefore, exposure to alkali resulted in entry of calcium from the external medium, and this triggered a calcineurin-mediated response. The involvement of calcineurin and Crz1/Tcn1, the transcription factor activated by the phosphatase, in the transcriptional response triggered by alkalinization has been globally assessed by DNA microarray analysis in a time course experiment using calcineurin-deficient (cnb1) and crz1 mutants. We found that exposure to pH 8.0 increased at least 2-fold the mRNA levels of 266 genes. In many cases (60%) the response was rather early (peak after 10 min). The transcriptional response of 27 induced genes (10%) was reduced or fully abolished in cnb1 cells. In general, the response of crz1 mutants was similar to that of calcineurin-deficient cells. By analysis of a systematic deletion library, we found 48 genes whose mutation resulted in increased sensitivity to the calcineurin inhibitor FK506. Twenty of these mutations (42%) also provoked alkaline pH sensitivity. In conclusion, our results demonstrated that calcium signaling and calcineurin activation represented a significant component of the yeast response to environmental alkalinization.Calcium-mediated signaling mechanisms are used by virtually every eukaryotic cell to regulate a wide variety or cellular processes, including gene expression. Transient increases in cytosolic calcium results in activation of diverse enzymes, such as the protein phosphatase calcineurin. Calcineurin is a heterodimer of catalytic subunit and regulatory subunits. In the yeast Saccharomyces cerevisiae, the catalytic subunit is encoded by two genes, CNA1 and CNA2 (1), whereas a single gene, CNB1, encodes the regulatory subunit (2). Cells lacking the catalytic subunits, or the regulatory subunit, are deficient in calcineurin activity.Exposure of yeast cells to a number of signals, such as ␣-factor (3, 4), glucose (5), sphingosine (6), and certain stress conditions (7-9), triggers a rise in cytoplasmic calcium. This increase in calcium can be a consequence of external calcium influx or release from internal stores, such as the vacuole, and results in activation of calcineurin. For instance, hyperosmotic shock has been reported to provoke calcium release from vacuolar stores (8) through Yvc1, a member of the transient receptor potential channel family, and to trig...

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“…Under normal conditions, the yeast [Ca 2+ ] cyt is maintained between 50 and 200 nM (10). The maintenance of this basal level and the return to normal levels after stimulation are achieved by a series of Ca 2+ pumps and exchangers located in different compartments of the cell: Pmr1p, the P-type Ca 2+ / Mn 2+ -ATPase localized in the medial-Golgi apparatus and responsible for the Ca 2+ supply for the secretory pathway (11)(12)(13), and Pmc1p (14), a P-type Ca 2+ -ATPase, and Vcx1p (15, 16), a Ca 2+ /H + exchanger (CAX), both responsible for the uptake of Ca 2+ through the vacuolar membrane.…”

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confidence: 99%

Newly characterized Golgi-localized family of proteins is involved in calcium and pH homeostasis in yeast and human cells

Demaegd

Foulquier

Colinet

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

134

190

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Defects in the human protein TMEM165 are known to cause a subtype of Congenital Disorders of Glycosylation. Transmembrane protein 165 (TMEM165) belongs to an uncharacterized family of membrane proteins called Uncharacterized Protein Family 0016, which are well conserved throughout evolution and share characteristics reminiscent of the cation/Ca 2+ exchanger superfamily. Gcr1 dependent translation factor 1 (Gdt1p), the budding yeast member of this family, contributes to Ca 2+ homeostasis via an uncharacterized Ca 2+ transport pathway localized in the Golgi apparatus. The gdt1Δ mutant was found to be sensitive to high concentrations of Ca 2+ , and interestingly, this sensitivity was suppressed by expression of TMEM165, the human ortholog of Gdt1p, indicating conservation of function among the members of this family. Patch-clamp analyses on human cells indicated that TMEM165 expression is linked to Ca 2+ ion transport. Furthermore, defects in TMEM165 affected both Ca 2+ and pH homeostasis. Based on these results, we propose that Gdt1p and TMEM165 could be members of a unique family of Golgi-localized Ca 2+ /H + antiporters and that modification of the Golgi Ca 2+ and pH balance could explain the glycosylation defects observed in TMEM165-deficient patients. CDGs are a family of inborn metabolic diseases affecting the glycosylation pathway. Most of these mutations are found in genes directly involved in glycosylation, however unique types of CDG have been found to be caused by deficiencies in vesicular Golgi trafficking (2-6) and Golgi pH homeostasis (7). TMEM165 belongs to a well-conserved, but uncharacterized, family of membrane proteins named UPF0016 (Uncharacterized Protein Family 0016; Pfam PF01169) and is localized in the Golgi apparatus (1). The members of this family are well conserved and are found in many organisms-for example, 919 different species of bacteria and 409 different eukaryotes.Gcr1 dependent translation factor 1 (Gdt1p) the yeast ortholog of TMEM165, is a 280-residue membrane protein and is involved in tolerance to high concentrations of calcium (Ca 2+ ) (8). In eukaryotic cells, Ca 2+ is a ubiquitous intracellular messenger involved in many different biological processes (9). To allow the increases in cytosolic calcium concentration ([Ca 2+ ] cyt ) required for these signaling mechanisms, it is absolutely necessary that the resting Ca 2+ levels are maintained below a certain threshold. Under normal conditions, the yeast [Ca 2+ ] cyt is maintained between 50 and 200 nM (10). The maintenance of this basal level and the return to normal levels after stimulation are achieved by a series of Ca 2+ pumps and exchangers located in different compartments of the cell: Pmr1p, the P-type Ca 2+ / Mn 2+ -ATPase localized in the medial-Golgi apparatus and responsible for the Ca 2+ supply for the secretory pathway (11-13), and Pmc1p (14), a P-type Ca 2+ -ATPase, and Vcx1p (15, 16), a Ca 2+ /H + exchanger (CAX), both responsible for the uptake of Ca 2+ through the vacuolar membrane.Yeast is a simple and conv...

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Steady-state free Ca2+ in the yeast endoplasmic reticulum reaches only 10 microM and is mainly controlled by the secretory pathway pump Pmr1

Cited by 130 publications

References 51 publications

A secretory pathway-localized cation diffusion facilitator confers plant manganese tolerance

A secretory pathway-localized cation diffusion facilitator confers plant manganese tolerance

Characterization of the Calcium-mediated Response to Alkaline Stress in Saccharomyces cerevisiae

Newly characterized Golgi-localized family of proteins is involved in calcium and pH homeostasis in yeast and human cells

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