An electrogenic uniport mediates light‐dependent Ca<sup>2+</sup> influx into intact spinach chloroplasts

Kreimer, Georg; Melkonian, Michael; Latzko, Erwin

doi:10.1016/0014-5793(85)81081-4

Cited by 75 publications

(32 citation statements)

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“…Several years later, when it was apparent that plant cells maintained very low [Ca 21 ] i, the role of the chloroplast in the regulation of this ion received further attention. Different laboratories using chloroplasts from wheat (Muto et al, 1982) and spinach (Kreimer et al, 1985a(Kreimer et al, , 1985b confirmed the dramatic light-dependent uptake of Ca 21 . Kreimer et al (1985aKreimer et al ( , 1985b further concluded that photosynthetic electron transport was essential and that it was the membrane potential rather than pH that drove Ca 21 uptake.…”

Section: Ca 21 and Chloroplastsmentioning

confidence: 85%

Calcium: A Central Regulator of Plant Growth and Development

2005

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Section: Ca 21 and Chloroplastsmentioning

confidence: 85%

Calcium: A Central Regulator of Plant Growth and Development

2005

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“…To investigate whether light-induced Ca>2 influx causes the stimulation of FBPase activation, we also examined the effect of ruthenium red, an inhibitor of light-induced Ca2+ influx (11), on activation of FBPase (Fig. 2).…”

Section: Resultsmentioning

confidence: 99%

“…After Chl and Protein Determination. Chl and protein was determined as previously described (11,13).…”

Section: Methodsmentioning

confidence: 99%

Stromal Free Calcium Concentration and Light-Mediated Activation of Chloroplast Fructose-1,6-Bisphosphatase

Kreimer¹,

Melkonian²,

Holtum³

et al. 1988

Plant Physiol.

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Light-mediated activation of fructose-1,6-bisphosphatase (EC 3.13.11) in intact spinach chloroplasts (Spinacia okracea L.) is enhanced in the presence of 10-' molar external free Ca2. The most pronounced effect is observed during the first minutes of illumination. Ruthenium red, an inhibitor of light-induced Ca2" influx, inhibits this Ca2" stimulated activation. In isolated stromal preparations, the activation of fructose-1,6-bisphosphatase is already enhanced by 2 minutes of exposure to elevated Ca2" concentrations in the presence of physiological concentrations of Mg2" and fructose-1,6-bisphosphate. (20), suggesting that the stromal free Ca2" concentration is strictly controlled. This control could be achieved by binding of Ca2+ to thylakoids (6) and stromal proteins (13). Ca2" binding was also reported for purified FBPase (9) and for ferredoxin (29). Ca2" exhibits dual 'This work was supported by grants from the Deutsche Forschungsgemeinschaft.2Abbreviations: FBPase, fructose-1,6-bisphosphatase (EC 3.1.3.11); FBP, fructose-1,6-bisphosphate; Io.s, concentration of modulator that is required to obtain half inhibition of the maximum specific activity; SBPase, sedoheptulose-1 ,7-bisphosphatase; Ao.5, concentration of modulator in the preincubation that is required to obtain half of the maximum specific activity. effects on purified FBPase: the rate of activation in vitro is accelerated by an increase in free Ca2" during activation, whereas catalysis is inhibited at similar concentrations of free Ca2" (2,3,8,9). It is, however, still controversial whether Ca2+ is involved in the regulation of FBPase in vivo (23). Therefore we have investigated the effect of light-induced Ca2+ influx on lightmediated activation of FBPase in intact chloroplasts. We have also studied the effects of elevating Ca2+ concentrations for short periods on FBPase activation in stromal preparations in the presence of physiological concentrations of Mg2+ and FBP. The steady-state concentration of free Ca2+ in the stroma of darkkept chloroplasts has also been determined. MATERIALS AND METHODSChemicals. Antipyrylazo III, ATP, and nigericin were obtained from Sigma; Chelex-100 from Bio-Rad; ruthenium red from Serva; Percoll from Pharmacia, and A 23187 from CalBiochem. CaCl2-standard solutions, KCI Suprapur and all other chemicals (analytical grade) were from Merck. Stromal Preparations and Chloroplast Isolation. Spinach (Spinacia oleracea L.) was either purchased at the local market (stroma isolation) or grown as described in Kreimer et al. (1 1). Stromal preparations were isolated and purified as previously described (13), except that the Sephadex G-25/Chelex-100 column step was omitted. Intact chloroplasts were prepared from fully developed leaves according to Kreimer et al. (1 1) with the following modifications: intact chloroplasts used for the determination of the stromal free Ca2" concentration were collected from Percoll gradients with a pasteur pipette, diluted 1:5 with a Chelex-100 treated medium containing 330 mm sorbitol a...

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“…Photosynthetic intermediates (7), calcium (22,23), and diacylglycerol (21) are putative candidates for second messengers. The vanadate sensitivity of blue light-stimulated proton pumping also implicates a H+-ATPase at the guard cell plasma membrane (24).…”

Section: Discussionmentioning

confidence: 99%

Close correspondence between the action spectra for the blue light responses of the guard cell and coleoptile chloroplasts, and the spectra for blue light-dependent stomatal opening and coleoptile phototropism.

Quiñones

Zhang

Zeiger

1996

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

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Fluorescence spectroscopy was used to characterize blue light responses from chloroplasts of adaxial guard cells from Pima cotton (Gossypium barbadense) and coleoptile tips from corn (Zea mays). The chloroplast response to blue light was quantified by measurements of the blue light-induced enhancement of a red light-stimulated quenching of chlorophyll a fluorescence. In adaxial (upper) guard cells, low fluence rates of blue light applied under saturating fluence rates of red light enhanced the red light-stimulated fluorescence quenching by up to 50%. In contrast, added blue light did not alter the red light-stimulated quenching from abaxial (lower) guard cells. This response pattern paralleled the blue light sensitivity of stomatal opening in the two leaf surfaces. An action spectrum for the blue light-induced enhancement of the red light-stimulated quenching showed a major peak at 450 nm and two minor peaks at 420 and 470 nm. This spectrum matched closely an action spectrum for blue light-stimulated stomatal opening. Coleoptile chloroplasts also showed an enhancement by blue light ofred light-stimulated quenching. The action spectrum of this response, showing a major peak at 450 nm, a minor peak at 470 nm, and a shoulder at 430 nm, closely matched an action spectrum for blue lightstimulated coleoptile phototropism. Both action spectra match the absorption spectrum of zeaxanthin, a chloroplastic carotenoid recently implicated in blue light photoreception of both guard cells and coleoptiles. The remarkable similarity between the action spectra for the blue light responses of guard cells and coleoptile chloroplasts and the spectra for blue light-stimulated stomatal opening and phototropism, coupled to the recently reported evidence on a role of zeaxanthin in blue light photoreception, indicates that the guard cell and coleoptile chloropfasts specialize in sensory transduction.

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An electrogenic uniport mediates light‐dependent Ca²⁺ influx into intact spinach chloroplasts

Cited by 75 publications

References 31 publications

Calcium: A Central Regulator of Plant Growth and Development

Calcium: A Central Regulator of Plant Growth and Development

Stromal Free Calcium Concentration and Light-Mediated Activation of Chloroplast Fructose-1,6-Bisphosphatase

Close correspondence between the action spectra for the blue light responses of the guard cell and coleoptile chloroplasts, and the spectra for blue light-dependent stomatal opening and coleoptile phototropism.

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An electrogenic uniport mediates light‐dependent Ca2+ influx into intact spinach chloroplasts

Cited by 75 publications

References 31 publications

Calcium: A Central Regulator of Plant Growth and Development

Calcium: A Central Regulator of Plant Growth and Development

Stromal Free Calcium Concentration and Light-Mediated Activation of Chloroplast Fructose-1,6-Bisphosphatase

Close correspondence between the action spectra for the blue light responses of the guard cell and coleoptile chloroplasts, and the spectra for blue light-dependent stomatal opening and coleoptile phototropism.

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An electrogenic uniport mediates light‐dependent Ca²⁺ influx into intact spinach chloroplasts