Stimulation of thylakoid energization and ribulose‐bisphosphate carboxylase/oxygenase activation in <i>Arabidopsis</i> leaves by methyl viologen

Salvucci, Michael E.; Portis, Archie R.; Heber, U.; Ogren, William L.

doi:10.1016/0014-5793(87)80928-6

Cited by 25 publications

(25 citation statements)

References 22 publications

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“…Since high rates of electron transport still occur when nigericin is used (8), inhibition of the light activation of rubisco seems to be the result of collapse of the pH gradient. Previous reports (21,23) suggested involvement of a transthylakoid pH gradient in light activation of rubisco by rubisco activase. Since the thylakoid pH gradient is utilized to synthesize ATP in the chloroplast ( 13), the requirement for a pH gradient appeared to be synonymous with the requirement for ATP in the activation of rubisco by rubisco activase (26).…”

Section: Discussionmentioning

confidence: 92%

“…479 concentration within the chloroplast stroma (9,14). An Previous studies (23,27,30) suggested a role for thylakoid membranes in the activation ofrubisco, and early experiments with the rubisco activase system (20,24) required the presence ofthylakoid membranes and light in reconstituted chloroplast assays. However, considering the rubisco activase requirement for ATP, the role of the thylakoid membrane seemed to be defined.…”

mentioning

confidence: 99%

“…Rubisco, in vivo, is activated by the rubisco activase system in an ATP-dependent process ( 19). Before the discovery of rubisco activase (24), the role of light in rubisco activation was proposed to be the establishment of an alkaline pH and an increase in Mg2' Previous studies (23,27,30) suggested a role for thylakoid membranes in the activation ofrubisco, and early experiments with the rubisco activase system (20, 24) required the presence ofthylakoid membranes and light in reconstituted chloroplast assays. However, considering the rubisco activase requirement for ATP, the role of the thylakoid membrane seemed to be defined.…”

Section: Introductionmentioning

confidence: 99%

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Electron Transport through photosystem I Stimulates Light Activation of Ribulose Bisphosphate Carboxylase/Oxygenase (Rubisco) by Rubisco Activase

Campbell¹,

Ogren²

1990

Plant Physiol.

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The activation state of ribulose bisphosphate carboxylase/ oxygenase (rubisco) in a lysed chloroplast system is increased by light in the presence of a saturating concentration of ATP and a physiological concentration of CO2 (10 micromolar). Electron transport inhibitors and artificial electron donors and acceptors were used to determine in which region of the photosynthetic electron transport chain this light-dependent reaction occurred. In the presence of DCMU and methyl viologen, the artificial donors durohydroquinone and 2,6-dichlorophenolindophenol (DCPIP) plus ascorbate both supported light activation of rubisco at saturating ATP concentrations. No light activation occurred when DCPIP was used as an acceptor with water as electron donor in the presence of ATP and dibromothymoquinone, even though photosynthetic electron transport was observed. Nigericin completely inhibited the light-dependent activation of rubisco. Based on these results, we conclude that stimulation of light activation of rubisco by rubisco activase requires electron transport through PSI but not PSII, and that this light requirement is not to supply the ATP needed by the rubisco activase reaction. Furthermore, a pH gradient across the thylakoid membrane appears necessary for maximum light activation of rubisco even when ATP is provided exogenously.Light activation ofrubisco' has been demonstrated in leaves (15,18,25,29) and intact chloroplasts (2, 10). The light responses of the activation of rubisco, the enzyme which catalyzes photosynthetic CO2 assimilation (16), and the rate of CO2 assimilation have been shown to proceed in tandem (18,25,29). Several enzymes involved in C3 photosynthetic carbon metabolism in addition to rubisco are also light activated, but unlike rubisco these enzymes are activated by the ferredoxin/thioredoxin system (5). Rubisco, in vivo, is activated by the rubisco activase system in an ATP-dependent process ( 19). Before the discovery of rubisco activase (24), the role of light in rubisco activation was proposed to be the establishment of an alkaline pH and an increase in Mg2' Previous studies (23,27,30) suggested a role for thylakoid membranes in the activation ofrubisco, and early experiments with the rubisco activase system (20, 24) required the presence ofthylakoid membranes and light in reconstituted chloroplast assays. However, considering the rubisco activase requirement for ATP, the role of the thylakoid membrane seemed to be defined. Recently we demonstrated a requirement for light and photosynthetic electron transport for full activation of rubisco by rubisco activase in lysed chloroplasts at physiological concentrations of C02, even though ATP was supplied exogenously at saturating concentrations (6). Activation occurred in the presence of MV, indicating the ferredoxin/ thioredoxin system was not involved. These results implied a more direct involvement of the thylakoid membrane in the activation of rubisco in vivo.The objectives of the present study were to determine the location of the light-...

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Section: Discussionmentioning

confidence: 92%

mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electron Transport through photosystem I Stimulates Light Activation of Ribulose Bisphosphate Carboxylase/Oxygenase (Rubisco) by Rubisco Activase

Campbell¹,

Ogren²

1990

Plant Physiol.

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“…The small decreases in rublose bisphosphate carboxylase at low irradiance in these experimentsalso suggestthe absence ofan inhibitor. However, the activation state is probably maintained via the 'activase' system (15) which requires ATP (20)(21)(22). Changes in the activation state of the ribulose bisphosphate carboxylase may, therefore, respond to changes in the ATP/ADP ratio of the stroma.…”

Section: Biophysical Measurementsmentioning

confidence: 99%

“…However, changes in RuBP carboxylase activation state can be observed in leaves in the absence of any large change in adenylate concentrations (2). There are, therefore, undoubtedly other factors involved in the regulation of RuBP carboxylase activation in vivo that, thus far, remain unresolved (21,22). We have no explanation for the difference between the relationship between J,, and ribulose-1,5-bisphosphate activity under conditions of varying irradiance in air, and varying CO2 concentrations in 2% 02 in N2.…”

Section: Biophysical Measurementsmentioning

confidence: 99%

Relationship between Photosynthetic Electron Transport and Stromal Enzyme Activity in Pea Leaves

Harbinson¹,

Genty²,

Foyer³

1990

Plant Physiol.

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The responses of the quantum efficiencies of photosystem (PS) II and PSI measured in vivo simultaneously with estimations of the activities and activation states of NADP-malate dehydrogenase, chloroplast fructose-1,6-bisphosphatase, and nbulose-1,5-bisphosphate carboxylase were used to study the relationship between electron transport and carbon metabolism. The effects of varying irradiance and CO2 partial pressure on the relationship between the quantum efficiencies of PSI and 11, and the activity of these enzymes shows that the interrelationships vary according to the limitations placed on the system. The relationship between the quantum efficiencies of PSII and PSI was linear in most situations. In response to increasing irradiance, the activity of all three enzymes increased. In the case of NADP-malate dehydrogenase this increase was well correlated with the estimated flux of electrons through PSI and PSII. The other two enzymes showed a more complex relationship with the estimated flux of electrons through both photosystems. These relationships are consistent with the known interactions between these stromal enzymes and the thylakoids. The response to varying CO2 partial pressure is more complex. The efficiencies of PSI and 11 declined with decreasing CO2 partial pressure and the activity of each enzyme varied uniquely. However, there are clear correlations between the activities of the enzymes and the flux of electrons through the photosystems. In contrast to the data obtained under conditions of varying irradiance, there is clear evidence of photosynthetic control of electron transport when the CO2 (13,29,30). It has been suggested that FBP and thioredoxin act sequentially to activate FBPase (12,13). That substrate is required for activation in vivo has been demonstrated via work with isolated intact chloroplasts (13) where, in contrast to NADP-MDH, which showed significant light activation in the presence or absence of oxygen, FBPase was inactive in anaerobic conditions. Activation of the latter enzyme was stimulated in this situation by dihydroxyacetone phosphate which enters the chloroplast via the phosphate translocator and is converted into the substrate FBP by the reactions of the Benson-Calvin cycle (13

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Photosynthesis. Carbon Metabolism: New Regulators of CO2 Fixation, the New Importance of Pyrophosphate, and the Old Problem of Oxygen Involvement Revisited

Kelly

Holtum²,

Latzko

Thirty Years of Photosynthesis 1974–2004

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Stimulation of thylakoid energization and ribulose‐bisphosphate carboxylase/oxygenase activation in Arabidopsis leaves by methyl viologen

Cited by 25 publications

References 22 publications

Electron Transport through photosystem I Stimulates Light Activation of Ribulose Bisphosphate Carboxylase/Oxygenase (Rubisco) by Rubisco Activase

Electron Transport through photosystem I Stimulates Light Activation of Ribulose Bisphosphate Carboxylase/Oxygenase (Rubisco) by Rubisco Activase

Relationship between Photosynthetic Electron Transport and Stromal Enzyme Activity in Pea Leaves

Photosynthesis. Carbon Metabolism: New Regulators of CO2 Fixation, the New Importance of Pyrophosphate, and the Old Problem of Oxygen Involvement Revisited

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