ATP-dependent acidification and tonoplast hyperpolarization in isolated vacuoles from green suspension cells of
            <i>Chenopodium rubrum</i>
            L

Bentrup, Friedrich‐Wilhelm; Gogarten-Boekels, Maria; Hoffmann, Bernhard; Gogarten, J. Peter; Baumann, Christian

doi:10.1073/pnas.83.8.2431

Cited by 42 publications

(23 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In molar terms, solute flux -notably K + -from the vacuole predominates during stomatal closure (MacRobbie 1981(MacRobbie , 1988. Thus, and appreciable contribution from the vacuolar H +-ATPase (Bentrup et al 1986;Rea and Sanders 1987;Hedfich et al 1989) could account for the pHi change through charge balance by H + transport across the tonoplast. This same explanation might also accommodate the temporal characteristics of the phi rise by virtue of its mechanistic separation from the K § flux.…”

Section: Effecting Cytoplasmic Alkalinisation In Abamentioning

confidence: 96%

K+ channels of stomatal guard cells: Abscisic-acid-evoked control of the outward rectifier mediated by cytoplasmic pH

Blatt

Armstrong

1993

Planta

268

239

View full text Add to dashboard Cite

Abstract.The activation by abscisic acid (ABA) of current through outward-rectifying K + channels and its dependence on cytoplasmic pH (pHi) was examined in stomatal guard cells of Vicia faba L. Intact guard cells were impaled with multibarrelled and H+-selective microelectrodes to record membrane potentials and pH i during exposures to ABA and the weak acid butyrate. Potassium channel currents were monitored under voltage clamp and, in some experiments, guard cells were loaded with pH buffers by iontophoresis to suppress changes in pH i . Following impalements, stable pH i values ranged between 7.53 and 7.81 (7.67_+ 0.04, n = 17). On adding 20 gM ABA, pHi rose over periods of 5-8 min to values 0.27_+0.03 pH units above the pH i before ABA addition, and declined slowly thereafter. Concurrent voltage-clamp measurements showed a parallel rise in the outward-rectifying K + channel current (IK,out) and, once evoked, both pH i and IK, out responses were unaffected by ABA washout. Acid loads, imposed with external butyrate, abolished the ABA-evoked rise in IK, out. Butyrate concentrations of 10 and 30 mM (pH 0 6.1) caused pH i to fall to values near 7.0 and below, both before and after adding ABA, consistent with a cytoplasmic buffer capacity of 128_+ 12 mM per pH unit (n = 10) near neutrality. Butyrate washout was characterised by an appreciable alkaline overshoot in pH i and concomitant swell in the steady-state conductance of IK,ou t . The rise in pH i and IK,ou t in ABA were also virtually eliminated when guard cells were first loaded with pH buffers to raise the cytoplasmic buffer capacity four-to sixfold; however, buffer loading was without appreciable effect on the ABAevoked inactivation of a second, inward-rectifying class of K + channels (IK,in). The pH i dependence of IK,ou t was (233) 8131 40 consistent with a cooperative binding of at least 2H + (apparent pKa=8.3 ) to achieve a voltage-independent block of the channel. These results establish a causal link previously implicated between cytoplasmic alkalinisation and the activation of IK, out in ABA and, thus, affirm a role for H + in signalling and transport control in plants distinct from its function as a substrate in H+-coupled transport. Additional evidence implicates a coordinate control of IK,in by cytoplasmic-free [Ca 2+] and pH i.

show abstract

Section: Effecting Cytoplasmic Alkalinisation In Abamentioning

confidence: 96%

K+ channels of stomatal guard cells: Abscisic-acid-evoked control of the outward rectifier mediated by cytoplasmic pH

Blatt

Armstrong

1993

Planta

268

239

View full text Add to dashboard Cite

show abstract

“…Movement of Cl-and NO3-into the vacuole partially neutralizes positive charges inside, and could account for the low potential difference (+10 to +20 mV [2,18,19]) in the vacuole relative to the cytoplasm. These results are consistent with high concentrations of Cl-found in the vacuole (17,21) and its role as a possible storage compartment for N03 (19)(20)(21).…”

Section: Methodsmentioning

confidence: 99%

Potential-Dependent Anion Transport in Tonoplast Vesicles from Oat Roots

Kaestner¹,

Sze²

1987

Plant Physiol.

View full text Add to dashboard Cite

ABSTRACrPotential-dependent anion movement into tonoplast vesicles from oat roots (Avena sati'a L. var Lang) was monitored as dissipation of membrane potentials (A4O) using the fluorescence probe Oxonol V. The potentials (positive inside) were generated with the H'-pumping pyrophosphatase, which is Kg stimulated and anion insensitive. The relative rate of A4, dissipation by anions was used to estimate the relative permeabilities of the anions. In decreasing order they were: SCN-(100) > NO3-(72) = Cl-(70) > Br-(62) > S042- (5) In this paper, we generated membrane potentials in right-side out tonoplast vesicles with the anion-insensitive H+-pyrophosphatase in order to exclude side effects of the anions on the enzyme activity, which might occur with the anion-sensitive H+-ATPase. The membrane potential provides one driving force for anion uptake into the vesicles. We used the rate of dissipation of membrane potentials by anions to show their different permeabilities. Our evidence suggests that the potential-dependent C1-and NO3-transport into the vacuole is via proteinaceous porters. We also try to elucidate further a putative Cl-conductance on the tonoplast H+-pumping ATPase. A preliminary report ofthese results has been presented (1 1). Preparation of Low Density Microsomal Vesicles. The procedure of Churchill and Sze (6, 7) was used with some modifications. A microsomal preparation was obtained using differential centrifugation. This fraction was further purifiedby use ofdensity gradient centrifugation. Low density vesicles, enriched in tonoplast membranes, were collected from the interface over a 6% MATERIALS AND METHODS

show abstract

“…value as large as the one described for Chenopodium rubrum vacuoles (5). Addition of FCCP (10 uM) to the vacuolar preparations partially abolished the ATP-induced acidification of the vacuoles.…”

mentioning

confidence: 48%

Regulation of Vacuolar pH of Plant Cells

Guern

Mathieu²,

Kurkdjian³

et al. 1989

Plant Physiol.

View full text Add to dashboard Cite

The vacuolar pH and the trans-tonoplast ApH modifications induced by the activity of the two proton pumps H+-ATPase and H -PPase and by the proton exchanges catalyzed by the Na+/H+ and Ca2+/H+ antiports at the tonoplast of isolated intact vacuoles prepared from Catharanthus roseus cells enriched in inorganic phosphate (Y Mathieu et al 1988 Plant Physiol [in press]) were measured using the 31P NMR technique. The H+-ATPase induced an intravacuolar acidification as large as 0.8 pH unit, building a trans-tonoplast ApH up to 2.2 pH units. The hydrolysis of the phosphorylated substrate and the vacuolar acidification were monitored simultaneously to estimate kinetically the apparent stoichiometry between the vectorial proton pumping and the hydrolytic activity of the H+-ATPase. A ratio of H+ translocated/ ATP hydrolyzed of 1.97 ± 0.06 (mean ± standard error) was calculated. Pyrophosphate-treated vacuoles were also acidified to a significant extent. The H+-PPase at 2 millimolar PPi displayed hydrolytic and vectorial activities comparable to those of the HATPase, building a steady state ApH of 2.1 pH units. Vacuoles incubated in the presence of 10 millimolar Na+ were alkalinized by 0.4 to 0.8 pH unit. It has been shown by using 23Na NMR that sodium uptake was coupled to the H+ efflux and occurred against rather large concentration gradients. For the first time, the activity of the Ca2+/H+ antiport has been measured on isolated intact vacuoles. Ca2+ uptake was strongly inhibited by NH4CI or gramicidin. mulation and anion retrieval (6). However, aside the relatively well studied tonoplast proton pumping ATPase (26, 28 and references therein), our knowledge of the other ionic exchanges involving fluxes of protons or proton-equivalents is more limited. A second proton pump, the H+-PPase, present on tonoplast-enriched microsomal vesicles, has been described several times as distinct from the H+-ATPase (12,25,31). Its hydrolytic activity has also been measured on isolated intact vacuoles of beet roots (32) and tulipa petals (31) but, in these few cases, the possible effect of PPi hydrolysis on the vacuolar pH has not been determined.The study of H+-coupled secondary transport of cations through the functioning of Na+/H+ or Ca2+/H' antiports has been restricted to tonoplast vesicles isolated from beet (8, 9) carrot (1 1), or oat (27) Figure 1 illustrates the evolution with time of 31P NMR spectra of a vacuolar suspension incubated with Mg-ATP. The extravacuolar and intravacuolar inorganic phosphate peaks were clearly distinct from the peaks corresponding to the three phosphate groups of ATP. As ATP was hydrolyzed, the two ADP peaks appeared along with a weak AMP signal. The main interest of using 31P NMR was that it allowed simultaneously (a) the measurement of ATP hydrolysis, (b) the measurement ofvacuolar pH modifications linked to ATP hydrolysis, and (c) the estimation of the apparent stoichiometry between vectorial H+-pumping and the hydrolytic activities of the H+-ATPase.The rate of ATP hydrolysis was measured from...

show abstract

ATP-dependent acidification and tonoplast hyperpolarization in isolated vacuoles from green suspension cells of Chenopodium rubrum L

Cited by 42 publications

References 12 publications

K+ channels of stomatal guard cells: Abscisic-acid-evoked control of the outward rectifier mediated by cytoplasmic pH

K+ channels of stomatal guard cells: Abscisic-acid-evoked control of the outward rectifier mediated by cytoplasmic pH

Potential-Dependent Anion Transport in Tonoplast Vesicles from Oat Roots

Regulation of Vacuolar pH of Plant Cells

Contact Info

Product

Resources

About