Intracellular Pi-Compartmentation during Phosphate Starvation-Triggered Induction of an Extracellular Ribonuclease in Tomato Cell Culture

Glund, Konrad; Nürnberger, Thorsten; Abel, Steffen; Jost, Wolfgang H.; Preisser, Joachim; Komor, Ewald

doi:10.1007/978-94-009-2103-0_51

Cited by 7 publications

(5 citation statements)

References 13 publications

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“…These results are consistent with results obtained for tomato cells, where a depletion of phosphate in the medium caused loss of phosphate from the vacuoles but not from the cytosol (Glund et al 1990). Similar effects were observed in maize roots where cytosolic phosphate was kept constant but vacuolar phosphate increased after perfusion of root tips with a phosphate-containing medium (Tu et al 1990), and in barley leaves where vacuolar phosphate changed with nutrient conditions but cytosolic phosphate was kept within a narrow range (Mimura et al 1990).…”

Section: Compartmentation Of Ionssupporting

confidence: 93%

Solute distribution between vacuole and cytosol of sugarcane suspension cells: Sucrose is not accumulated in the vacuole

Preisser

Sprügel

Komor

1992

Planta

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The compartmentation of solutes in suspension cells of Saccharum sp. during different growth phases in batch culture was determined using CuCl2 to permeabilize the plasma membrane of the cells. The efflux of cytosolic and vacuolar pools of sugars, cations and phosphate was monitored, and the efflux data for phosphate were compared and corrected using data from compartmentation analysis of phosphate as determined by (31)P-nuclear magnetic resonance spectroscopy. The results show that sucrose is not accumulated in the vacuoles at any phase of the growth cycle. On the other hand, glucose and fructose are usually accumulated in the vacuole, except at the end of the cell-culture cycle when equal distribution of glucose and fructose between the cytosol and the vacuole is found. Both Na(+) and Mg(2+) are preferentially located in the vacuoles, but follow the same tendency as glucose and fructose with almost complete location in the vacuole in the early culture phases and increasing cytosolic concentration with increasing age of the cell culture. Potassium ions are always clearly accumulated in the cytosol at a concentration of about 80 mM; only about 20% of the cellular K(+) is located inside the vacuole. Cytosolic phosphate is little changed during the cell cycle, whereas the vacuolar phosphate pool changes according to total cellular phosphate. In general there are two different modes of solute compartmentation in sugarcane cells. Some solutes, fructose, glucose, Mg(2+) and Na(+), show high vacuolar compartmentation when the total cellular content of the respective solute is low, whereas in the case of ample supply the cytosolic pools increase. For other solutes, phosphate and K(+), the cytosolic concentration tends to be kept constant, and only excess solute is stored in the vacuole and remobilized under starvation conditions. The behaviour of sucrose is somewhat intermediate and it appears to equilibrate easily between cytosol and vacuole.

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Section: Compartmentation Of Ionssupporting

confidence: 93%

Solute distribution between vacuole and cytosol of sugarcane suspension cells: Sucrose is not accumulated in the vacuole

Preisser

Sprügel

Komor

1992

Planta

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“…Recently, we (21) purified to homogeneity a RNase from the medium of cultured tomato cells and showed by in vivo labeling that its synthesis is induced upon phosphate starvation. It is an intriguing feature of this system that induction of synthesis and secretion occurs rapidly (<3 h after transferring tomato cells from +Pi to -Pi) and under conditions in which the intracellular Pi pool changes only slightly (11). Functionally, RNase LE4 may be involved in extracellular degradation of remnant RNA which, in concert with secreted extracellular phosphodiesterase (our unpublished results) and acid phosphatase (14), may provide Pi to the cells.…”

mentioning

confidence: 80%

Phosphate-Regulated Induction of Intracellular Ribonucleases in Cultured Tomato (Lycopersicon esculentum) Cells

Löffler¹,

Abel²,

Jost³

et al. 1992

Plant Physiol.

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Four intracellular RNases were found to be induced in cultured tomato (Lycopersicon esculentum) cells upon phosphate starvation. Localization studies revealed three (RNases LV 1-3) in the vacuoles and one (RNase LX) outside these organelles. All of these RNases were purified to homogeneity and were shown to be type I RNases on the basis of type of splitting, substrate, and base specificity at the cleavage site, molecular weight, isoelectric point, and pH optimum. Moreover, RNase LV 3 was shown by fingerprinting of tryptic digests on reversed-phase high-performance liquid chromatography and sequencing the N terminus and two tryptic peptides to be structurally very similar to a recently characterized extracellular RNase LE which is also phosphate regulated (Nürnberger et al. [1990] Plant Physiol 92: 970-976; Jost et al. [1991] Eur J Biochem 198: 1-6). Expression of the four intracellular RNases is induced by depleting the cells of phosphate and repressed by adding phosphate. Our studies indicate that higher plants, in addition to secreting enzymes for scavanging phosphate under starvation conditions, also induce intracellularly emergency rescue systems.

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“…Here it is shown that, in higher plants, this induction correlates with an increase in m R N A levels. Since it is the extracellular, rather than the intracellular, Pi concentration that induces RNase LE [15], it has been suggested that the signal is transduced at the plasma membrane [14]. 3).…”

Section: Discussionmentioning

confidence: 99%

“…One of the most thoroughly studied systems in that respect is induction of extra-and intracellular RNases by Pi starvation in cultured tomato cells [1,2,3,14,22,31]. Toward this goal one has to characterize both, access to and in vivo behaviour of the RNA substrate, and properties and regulation of synthesis of the respective proteins.…”

Section: Introductionmentioning

confidence: 99%

cDNA structure and regulatory properties of a family of starvation-induced ribonucleases from tomato

et al. 1995

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In previous work we have determined the primary structure of two of the five ribonucleases which are induced by phosphate starvation in cultured tomato cells. Here, we present the isolation and characterization of the cDNAs for the extracellular ribonuclease LE and the intracellular, but extravacuolar ribonuclease LX. Structural analysis of these cDNAs together with partial protein-sequencing of vacuolar ribonucleases LV1, LV2 and LV3 revealed a family of very similar ribonucleases. From these data we assume identify between ribonucleases LE and LV3 for which the targeting mechanism has to be shown. Furthermore, RNase LV1 and RNase LV2 might be posttranslational processing products of RNase LX which travel to the vacuoles after splitting off the putative ER retention signal present at RNase LX. Additionally, we show by northern blot analysis that phosphate starvation in plant cells leads to an increase in the steady-state level of this type of enzymes revealing close similarities of the plant response to a limited supply of inorganic phosphate with the PHO regulation in bacteria and fungi.

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Intracellular Pi-Compartmentation during Phosphate Starvation-Triggered Induction of an Extracellular Ribonuclease in Tomato Cell Culture

Cited by 7 publications

References 13 publications

Solute distribution between vacuole and cytosol of sugarcane suspension cells: Sucrose is not accumulated in the vacuole

Solute distribution between vacuole and cytosol of sugarcane suspension cells: Sucrose is not accumulated in the vacuole

Phosphate-Regulated Induction of Intracellular Ribonucleases in Cultured Tomato (Lycopersicon esculentum) Cells

cDNA structure and regulatory properties of a family of starvation-induced ribonucleases from tomato

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