The Cupric Ion as an Inhibitor of Photosynthetic Electron Transport in Isolated Chloroplasts

Cedeño-Maldonado, Arturo; Swader, J. A.; Heath, Robert L.

doi:10.1104/pp.50.6.698

Cited by 116 publications

(71 citation statements)

References 19 publications

(27 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The earliest report stated the proximity of a Cu binding site to the oxygen evolving complex (OEC) [6]. Further studies confirmed the existence of a highly sensitive site for Cu-inhibition on the oxidizing side of PSII [7][8][9]. Copper ions have been even suggested to substitute calcium and manganese ions in the OEC [10].…”

Section: Introductionmentioning

confidence: 98%

Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b₅₅₉in a Chlamydomonas reinhardtii PSI Minus Mutant

et al. 2006

View full text Add to dashboard Cite

Mössbauer spectroscopy was applied, for the first time, to study the interaction of copper ions with the non-heme iron and the heme iron of cytochrome b559 in photosystem II thylakoids isolated from a Chlamydomonas reinhardtii photosystem I minus mutant. We showed that copper ions oxidize the heme iron and change its low spin state into a high spin state. This is probably due to deprotonation of the histidine coordinating the heme. We also found that copper preserves the non-heme iron in a low spin ferrous state, enhancing the covalence of iron bonds as compared to the untreated sample. We suggest that a disruption of hydrogen bonds stabilizing the quinone-iron complex by Cu 2+ is the mechanism responsible for a new arrangement of the binding site of the non-heme iron leading to its more "tense" structure. Such a diamagnetic state of the non-heme iron induced by copper results in a magnetic decoupling of iron from the primary quinone acceptor. These results indicate that Cu does not cause removal of the non--heme iron from its binding site. The observed Cu 2+ action on the non--heme iron and cytochrome b 559 is similar to that previously observed for α-tocopherol quinone.

show abstract

Section: Introductionmentioning

confidence: 98%

Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b₅₅₉in a Chlamydomonas reinhardtii PSI Minus Mutant

et al. 2006

View full text Add to dashboard Cite

show abstract

“…Copper is an essential micronutrient for algae and higher plants and is an essential constituent of a number of plant enzymes (21). Copper at concentrations higher than I ,UM is increasingly toxic to algal and higher plant tissues (10,23 (10,19,26) and to inhibit photosynthetic electron transport in isolated chloroplasts (6,12). The basis for Cu toxicity in plants is largely unknown.…”

Section: Methodsmentioning

confidence: 99%

Stimulation of Ethylene Production in the Mung Bean Hypocotyls by Cupric Ion, Calcium Ion, and Kinetin

Lau¹,

Yang²

1976

Plant Physiol.

View full text Add to dashboard Cite

The synergistic stimulation of ethylene production by kinetin and Ca2l in hypocotyl segments of mung bean (Phaseolus aureus Roxb.) seedling was further studied. The requirement for Ca2l in this system was specific. Except for Sr", which mimicked the effect of Ca2", none of the following divalent cations, including Ba2+, Mg6", Cu2l, Hg2+, Co2+, Ni2+, Sn2+, and Zn2+, showed synergism with kinetin on ethylene production. Fe2+, however, showed a slight synergism with kinetin. Some of them (Hg2+, Co2l, and Ni2+) had a strong inhibitory effect, while others (Zn2+, Mg2+, Sn2+, and Ba2l) had a slight or no inhibitory effect on ethylene production in the absence or presence of kinetin.Cu2+ alone, depending on the concentration applied, stimulated ethylene production with a lag period of about 2 hours and had no synergism with kinetin on ethylene production. When Cu2+ was applied with Ca2l, a remarkable synergistic stimulation of ethylene production was observed.Tracer experiments indicated that Cu2l enhanced the uptake of 45Ca2+ into the tissues during the first few hours of incubation, and this increase of 45Ca2+ uptake paralleled the enhancement of ethylene production. When Ca2+ was applied together with kinetin plus Cu2+, both the ethylene production and the 45Ca2+ uptake were greatly increased over those from the segments treated with Cu2l or kinetin alone. The increase in ethylene production as a result of kinetin plus Ca2l plus Cu2+ treatment is equal to the combined increases caused by kinetin plus Ca2l and Cu2l plus Ca2l. A possible mechanism accounting for such cooperative effects of Cu2+, Ca2l, and kinetin on ethylene production is discussed. MATERIALS AND METHODSSeeds of mung bean (Phaseolus aureus Roxb.) were grown in vermiculite for 3.5 days in darkness at 24 C. Segments 2 cm long were cut from hypocotyls at a point I cm below the hook, as previously described (14). Lots of 20 segments were incubated in 5 ml of a medium consisting of 50 mm potassium phosphate buffer, pH 6, 2% sucrose, various concentrations of different divalent cations, kinetin, or labeled 45Ca2+ (100 ,uCi, 50 ,umoles) as indicated, in a 50-mi Erlenmeyer flask. A plastic center well containing 0.2 ml of 40% KOH was hung in the flask to absorb CO2 evolved. The flasks were sealed with rubber serum caps and incubated in a shaker at 27 C in darkness.At time intervals indicated, 1-ml gas samples were withdrawn by hypodermic syringe, and ethylene was assayed with a gas chromatograph equipped with an alumina column and a flame ionization detector. The flasks were flushed with air and recapped for the next ethylene determination.For 45Ca2+ uptake studies, the hypocotyls, incubated for a given time interval, were washed with 10 changes of distilled H20, and then ground with a glass homogenizer in 9 ml of 80% ethyl alcohol. The debris was pelleted by centrifugation, and the supernatant was collected. The pellet was serially extracted three times with 5 ml of 20 mm HCI. The radioactivity in each extract and in the debris was determined with a ...

show abstract

“…Cu2+ introduced as a trace contaminant from distilled or deionized H20 would also be highly effective. This effect and those described previously (5,22) mayr well be of significance in areas of high natural abundance of Cu + or in areas where it is present as a pollutant.…”

Section: Resultsmentioning

confidence: 77%

“…shown that it can inhibit election transport at the oxidizing side of PSII (5) and through a direct inactivation of ferredoxin (22). A preliminary report (25) has delineated the effect of Cu2+ on CF1-dependent reactions of spinach chloroplasts.…”

mentioning

confidence: 99%

Inhibition of Photosynthetic Energy Conversion by Cupric Ion

Uribe¹,

Stark²

1982

Plant Physiol.

View full text Add to dashboard Cite

in a volume of 1.5 ml; CuCl2, MgC12, NaKHPO4, and other additions were included in the mixtures as indicated. The 1-min phosphorylation was initiated immediately (no preincubation control) or at the end of a preincubation in light (preilluminated) or darkness (dark controls) bl adding 2.5 mm ADP; 5 mM MgC12, and 5 mm NaKHPO4, and Pi containing 5 x I05 cpm in a volume of 0.5 ml to the reactions for cyclic phosphorylation and the same plus 1 mm FeCN to reactions for noncycic electron flow and coupled phosphorylation to bring the final volume to 2.0 ml.Inhibition by Cu2+ is also a function of light intensity and illumination of copper-treated chloroplasts with less than 104 ergs cm-2 s-' white light does not produce significant inhibition. The inhibition is maximal above 3 x 105 ergs cm-2 S-1 (data not included). The nature of the light response allowed us to handle control chloroplasts in subdued room light of less than 104 ergs cm-2 s-' intensity. Preillumination was with heat-filtered white light of intensity 3.5 to 4.0 x 105 ergs cm-2 s-1. The completed phosphorylation reaction mixtures were then illuminated for an additional min with light of the same quality and intensity used in the preillumination and then terminated by making to 2% in TCA. ATP synthesis was determined by the method of Avron (2) and ferricyanide reduction as described by Avron, Krogmann, and Jagendorf (3). In other experiments using protocol B, the preincubation stage was identical but containing 75 ,ug Chl. After preincubation in light or dark, 0.5-ml aliquots were removed to a completed phosphorylation mix of 1.5 ml volume containing ADP, NaKHPO4, and MgCl2 at the concentration shown for protocol A. These proto-.ols are schematically described by Uribe (25

show abstract

The Cupric Ion as an Inhibitor of Photosynthetic Electron Transport in Isolated Chloroplasts

Cited by 116 publications

References 19 publications

Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b₅₅₉in a Chlamydomonas reinhardtii PSI Minus Mutant

Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b₅₅₉in a Chlamydomonas reinhardtii PSI Minus Mutant

Stimulation of Ethylene Production in the Mung Bean Hypocotyls by Cupric Ion, Calcium Ion, and Kinetin

Inhibition of Photosynthetic Energy Conversion by Cupric Ion

Contact Info

Product

Resources

About

The Cupric Ion as an Inhibitor of Photosynthetic Electron Transport in Isolated Chloroplasts

Cited by 116 publications

References 19 publications

Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b559in a Chlamydomonas reinhardtii PSI Minus Mutant

Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b559in a Chlamydomonas reinhardtii PSI Minus Mutant

Stimulation of Ethylene Production in the Mung Bean Hypocotyls by Cupric Ion, Calcium Ion, and Kinetin

Inhibition of Photosynthetic Energy Conversion by Cupric Ion

Contact Info

Product

Resources

About

Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b₅₅₉in a Chlamydomonas reinhardtii PSI Minus Mutant

Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b₅₅₉in a Chlamydomonas reinhardtii PSI Minus Mutant