Photosynthetic protein phosphorylation in intact chloroplasts

Allen, John F.; Bennett, John

doi:10.1016/0014-5793(81)80021-x

Cited by 49 publications

(7 citation statements)

References 17 publications

(11 reference statements)

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“…2b). This appears to be contrary to the situation reported for intact pea chloroplasts [22], where the initiation of 02 evolution was accompanied by a net decrease in the level of phosphorylation of LHCP. Despite the large differences in Calvin-cycle activity that accompanied changes in CO2 availability in intact spinach chloroplasts, there was little difference in the level of thylakoid protein phosphorylation.…”

Section: Resultscontrasting

confidence: 99%

Stromal protein phosphorylation in spinach (Spinacia oleracea) chloroplasts

Foyer¹

1985

Biochemical Journal

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When intact spinach chloroplasts were supplied with [32P]Pi, stromal protein phosphorylation was found to occur in the dark. On illumination the thylakoid protein kinase was activated and the amount of label found in thylakoid proteins quickly exceeded that incorporated into stromal protein, such that the latter was found to account for only 10-15% of the total radioactivity bound to chloroplast proteins after 5 min illumination. The rate of phosphorylation of stromal polypeptides was unchanged by light. After SDS/polyacrylamide-gel electrophoresis, more than 15 labelled polypeptides of stromal origin were observed. A polypeptide with an Mr of approx. 70 000 had the highest specific activity of labelling. Both the large and small subunits of the ribulose-1,5-bisphosphate carboxylase were phosphorylated. The level of phosphorylation of stromal protein was increased by CO2 fixation in intact chloroplasts. This increase was not observed in the absence of NaHCO3 or in the presence of the phosphoribulokinase inhibitor DL-glyceraldehyde. These effects appeared to be largely due to changes in the phosphorylation state of the large and small subunits of ribulose-1,5-bisphosphate carboxylase. Studies with the reconstituted chloroplast system showed that the thylakoid protein kinase(s) played no part in the phosphorylation of stromal protein. The rate and level of phosphorylation of stromal protein was unaffected by the activation state of the thylakoid protein kinase and was unchanged when thylakoids were omitted from the reaction medium. The phosphorylation of stromal proteins is therefore catalysed by a discrete soluble protein kinase.

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Section: Resultscontrasting

confidence: 99%

Stromal protein phosphorylation in spinach (Spinacia oleracea) chloroplasts

Foyer¹

1985

Biochemical Journal

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“…Thus, it would be predicted that protein kinase activity would also vary under these conditions. Indeed, the level of protein phosphorylation was maximal during the induction period of CO2 fixation, but decreased as the rate of CO2 fixation increased [48]. Recently, this work has been extended using a reconstituted chloroplast system and clear effects of light intensity and capacity for carbon assimilation on protein phosphorylation were observed [49].…”

Section: Control Of Electron Transport -A Wider Perspectivementioning

confidence: 73%

Control of chloroplast electron transport by phosphorylation of thylakoid proteins

Horton

1983

FEBS Letters

130

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Several chloroplast membrane proteins can become phosphorylated by a membrane protein kinase. The kinase is activated when the electron carriers (plastoquinone) between photosystem II and photosystem I are reduced. Phosphorylation of the light harvesting complex of photosytem II causes a decrease in energy transferred to photosystem II and an increase in the rate of excitation of photosystem I. This process, which is mediated by lateral diffusion of the phosphorylated complex serves to regulate the relative rates of electron transfer through the two photosystems. Phosphorylation may also have an important role in balancing the rate of excitation of photosystem II with the capacity for photosynthetic carbon metabolism and in controlling the functional state of photosystem II. Chloroplast Protein kinase Light harvesting complex Thylakoid membrane Electron transport

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“…Intact chloroplasts were isolated from shoots of lo-day-old peas as in [14], except that an isotonic sorbitol medium was used both for homogenization and for resuspension of the chloroplast pellet. This medium contained sorbitol (0.33 M), EDTA (2 mM), MgClz (5 mM), NaCl (5 mM), ascorbate (10 mM) and Hepes (50 mM) at pH 7.6.…”

Section: Methodsmentioning

confidence: 99%

Photosynthesis and phosphorylation of light‐harvesting chlorophyll a/b—protein in intact chloroplasts

Allen

1984

FEBS Letters

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Protein phosphorylationin isolated, intact pea chloroplasts was measured during the onset of COZ-dependent 02 evolution. Total incorporation of 32P (from 32Pi) into light-harvesting chlorophyll a/b-protein was found to be less sensitive than 02 evolution to inhibition by the uncouplers FCCP and NH&l. It is concluded that changes in the rate of ATP synthesis cannot affect protein phosphorylation without also affecting the rate of COz-fixation in this system. The ATP/ADP ratio is therefore unlikely to regulate photosynthetic protein phosphorylation under normal physiological conditions. Photosynthesis Protein phosphorylation Uncoupler COZ-fixation Electron transport Chloroplast

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Photosynthetic protein phosphorylation in intact chloroplasts

Cited by 49 publications

References 17 publications

Stromal protein phosphorylation in spinach (Spinacia oleracea) chloroplasts

Stromal protein phosphorylation in spinach (Spinacia oleracea) chloroplasts

Control of chloroplast electron transport by phosphorylation of thylakoid proteins

Photosynthesis and phosphorylation of light‐harvesting chlorophyll a/b—protein in intact chloroplasts

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