Effects of bicarbonate on thylakoid protein phosphorylation

Sundby, Cecilia; Larsson, Ulla K.; Henrysson, Tomas

doi:10.1016/s0005-2728(89)80259-2

Cited by 21 publications

(11 citation statements)

References 30 publications

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“…However, if 20 mM sodium bicarbonate (NaHCO3) was added to the thylakoid membrane suspension prior to the photo-inhibitory treatment, nearly 90% of the activity has remained after the same treatment. As was concluded already in [1], this shows that the thylakoid membranes are protected against photo-inhibition by the addition of 20 mM NaHCO3.…”

Section: Bicarbonate Added To the Medium Protects Against Photo-inhibsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 61%

“…Sometimes we noticed a decrease in the PS2 activity after this illumination (photo-inhibition) and we also discovered that in samples, to which 20 mM NaHCO3 was added before illumination, there was no such decrease in the PS2 activity. We therefore concluded, that this observation indicated a protection against photo-inhibition by added sodium bicarbonate [1,2].In the present study, I have further investigated the bicarbonate effects on photo-inhibition. Not only do these data confirm that indeed 20 mM sodium bicarbonate (NaHCO3) protects thylakoid membranes against photo-inhibition, under anaerobic as well as…”

mentioning

confidence: 56%

“…Before the photo-inhibitory treatment, the thylakoid membranes were pretreated in different ways (details are directly taken from [1], where the effect of bicarbonate on photo-inhibition was first seen). The thylakoid membranes were suspended at a concentration of 600 #g chl/ml in 50 mM Hepes, pH 7.4/5 mM sodium chloride/5 mM magnesium chloride/100 mM sucrose.…”

Section: Pretreatment Of Thylakoid Membranesmentioning

confidence: 99%

“…Since carbon dioxide is the ultimate substrate for photosynthesis, bicarbonate ions may well be an important regulating factor, acting on the thylakoid membranes of the chloroplasts in vivo. The background to the investigations presented in this paper, is that in an earlier study [1], isolated thylakoid membranes were slightly illuminated in absence of an electron acceptor in order to evoke phosphorylation of the thylakoid membrane polypeptides. Sometimes we noticed a decrease in the PS2 activity after this illumination (photo-inhibition) and we also discovered that in samples, to which 20 mM NaHCO3 was added before illumination, there was no such decrease in the PS2 activity.…”

Section: Introductionmentioning

confidence: 99%

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Bicarbonate effects on photo‐inhibition

1990

FEBS Letters

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Isolated thylakoid membranes were found to be efficiently protected against photo-inhibition by sodium bicarbonate (20 mM NaHCO3) under both anaerobic and aerobic conditions. Furthermore, data are presented which indicate that the pronounced sensitivity to photo-inhibition under anaerobic compared to aerobic conditions is due to the removal of protecting bicarbonate, rather than oxygen, from the medium. A second type of bicarbonate effect on photo-inhibition, in apparent contradiction to the protective effect of added NaHCO 3, is that thylakoid membranes that were depleted in their endogenous bicarbonate by treatment with formate were found to be less susceptible to photo-inhibition than thylakoids in the normal non-depleted state.Photo-inhibition; Bicarbonate; Carbon dioxide; Regulation of photosynthesis; Spinach thylakoid membranes; Mehler reaction .INTRODUCTIONThis paper is concerned with effects of bicarbonate ions on photo-inhibition. Since carbon dioxide is the ultimate substrate for photosynthesis, bicarbonate ions may well be an important regulating factor, acting on the thylakoid membranes of the chloroplasts in vivo. The background to the investigations presented in this paper, is that in an earlier study [1], isolated thylakoid membranes were slightly illuminated in absence of an electron acceptor in order to evoke phosphorylation of the thylakoid membrane polypeptides. Sometimes we noticed a decrease in the PS2 activity after this illumination (photo-inhibition) and we also discovered that in samples, to which 20 mM NaHCO3 was added before illumination, there was no such decrease in the PS2 activity. We therefore concluded, that this observation indicated a protection against photo-inhibition by added sodium bicarbonate [1,2].In the present study, I have further investigated the bicarbonate effects on photo-inhibition. Not only do these data confirm that indeed 20 mM sodium bicarbonate (NaHCO3) protects thylakoid membranes against photo-inhibition, under anaerobic as well asCorrespondence address: C. Sundby, Dept. of Biochemistry, University of Lund, P.O. Box 124, S-221 00 Lund, SwedenAbbreviations: LHC2 -light-harvesting chlorophyll a/b complex of photosystem 2; PpBQ phenyl-p-benzoquinone; Hepes N-2-hydroxyet hylpiperazine-N2-et hane sulfonic acid; chl chlorophyll aerobic conditions. These data also suggest, that the long known increased sensitivity to photo-inhibition under anaerobic conditions [3] is at least partly explained by a bicarbonate depletion of the medium. Data are also presented which indicate that, in apparent contradiction to the effect of added sodium bicarbonate in protection against photo-inhibition, there is also an other, different type of bicarbonate effect on photoinhibition, manifested when not only the medium, but also the thylakoid membranes themselves, are depleted in their content of endogenous bicarbonate. MATERIALS AND METHODS Preparation of thylakoid membranesThylakoid membranes were prepared from spinach as in [4]. Pretreatment of thylakoid membranesBefore the photo-i...

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Section: Bicarbonate Added To the Medium Protects Against Photo-inhibsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 61%

mentioning

confidence: 56%

Section: Pretreatment Of Thylakoid Membranesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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