Inhibition of photophosphorylation and photosynthetic carbon cycle reactions by fatty acids and esters

Pedersen, T. A.; Kirk, Martha; Bassham, James A.

doi:10.1016/0926-6585(66)90320-7

Cited by 67 publications

(20 citation statements)

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“…Experiments with crude extracts from chloroplasts have shown, however, that linolenic acid has no effect on six key enzymes of the Calvin-Benson cycle (25): ribulose 5-P-isomerase, ribulose 5-P-kinase, ribulose 1,5-bisP-carboxylase, 3-phosphoglycerate-kinase, glyceraldehyde 3-phosphate dehydrogenase and phosphotriose-isomerase. Similar results were also reported by Pedersen et al (29) using shorter chain fatty acids.…”

Section: Resultssupporting

confidence: 81%

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Effect of linolenate on photosynthesis by intact spinach chloroplasts I. Inhibition of orthophosphate uptake and of 3-P-glyceraldehyde efflux across the chloroplast envelope

Siegenthaler

Akamba

1979

Plant and Cell Physiology

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Linolenic acid (Cis:3) inhibited photosynthesis by intact spinach chloroplasts. This inhibition was due neither to a lack of NADPH in chloroplasts nor to a direct inhibition of the enzyme activities in the Calvin-Benson cycle. Linolenate inhibited CO2 fixation and oxygen evolution more effectively than NADP+ photoreduction but did not inhibit the activity of several key enzymes of the Calvin cycle. Linolenate inhibited phosphate influx and 3-phosphoglyceraldehyde efflux across the chloroplast envelope. A hypothesis explaining the inhibition of photosynthesis by linolenate is presented. Key words: Chloroplasts -Linolenic acid treatment -3-P-glyceraldehyde effluxPhosphate uptake -Photosynthesis -Spinach -Transport.The release of fatty acids during aging processes in vitro has been demonstrated in several cells and organelles such as human erythrocytes (30), mitochondria (10) and chloroplasts (8,16,22,39,41). In chloroplasts, the main fatty acids released in the course of aging are Cis-unsaturated fatty acids (8,16,39), particularly linolenic acid; these acids are the most abundant in the thylakoid (8, 39) and envelope (21) membrane lipids. So far, the action of endogenous (31, 38,39) and exogenous (26,(35)(36)(37)(38) fatty acids has been mainly studied in relation to the photochemical reactions of the thylakoid. It has been shown that such unsaturated fatty acids inhibit electron flow in photosystems II and I and the associated photophosphorylation (35,37), light-induced shrinkage in chloroplasts (35), and the light-generated ZlpH across thyalkoid membranes in a sequential fashion (37). In addition, fatty acids modify the physicochemical properties of the thylakoid membrane in such a way that swelling occurs (27,34) and that the JpH is diminished and pHi increased, inducing a shift of the pH optimum of electron flow towards acidity (37)(38)(39).In order to elucidate further the control of photosynthetic activities by these fatty acids, we have now studied the action of linolenate on the photosynthetic apparatus at a higher level of structural integrity. The initial point of interest was: Would free fatty acids influence photosynthetic carbon metabolism in intact chloro-1 This work is part of a doctoral program which is carried out by L. Mv6 Akamba in this laboratory. 395

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Section: Resultssupporting

confidence: 81%

“…1 and Table 1). Moreover, in agreement with Pedersen et al (29), we observed that fatty acids did not inhibit six key enzymatic activities of the Calvin-Benson cycle (ref. 25, cf.…”

Section: Discussionsupporting

confidence: 80%

Effect of linolenate on photosynthesis by intact spinach chloroplasts I. Inhibition of orthophosphate uptake and of 3-P-glyceraldehyde efflux across the chloroplast envelope

Siegenthaler

Akamba

1979

Plant and Cell Physiology

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“…At Dusseldorf the products of 14C fixation were measured after two-dimensional paper chromatography on paper 2043 b Mg 1 from Schleicher and Schuell as described by Pedersen (29).…”

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confidence: 99%

Role of Orthophosphate and Other Factors in the Regulation of Starch Formation in Leaves and Isolated Chloroplasts

et al. 1977

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Starch synthesis in leaves was increased by phosphate starvation or by treatments which decreased cytoplasmic orthophosphate levels (such as mannose feeding). Usally less than 30% of the total carbon fixed during CO2 assimlation was incorporated into starch in spinach (Spinacia oleracca L.), spinach beet (Beta vulgaris), and tobacco (Nicotiana tabacum) leaves.In isolated spinach chloroplasts, formation of starch from CO2 was usualy less than in leaves.

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“…Pederson et al (13) have sh'own that methyl octonoate or octan'oic acid can inhibit carboxylation of ribulose 1,5-diP, photophostphorylation, and the epho,sphorylajtion of both frtuctose 1,6-diP and sedoheptulose 1,7-diP. The influence of higher fatty acid's has not yet been examined.…”

Section: Discussionmentioning

confidence: 99%

Release of Free Fatty Acids and Loss of Hill Activity by Aging Spinach Chloroplasts

Constantopoulos

Kenyon

1968

Plant Physiol.

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A bstract. The free fatty acid content of spinach chloroplasts, isolated at pH 5.8 to 8.0, has been found to vary between 3.1 and 5.5 % of the total chloroplast fatty acids. When chloroplasts were incubated at room temperature for 2 hours, the free fatty acids increased by 42 land the Hill activity decreased by 70 g. After 2 hours of incubation at 370, the free fatty acids increased about 3-fold and the Hill activity decreased to almost 0. The addition of crystalline bovine serum albumin largely prevented the loss of Hill activity at room temperature and at 50, but had little effect during incubation at 370. Both the release of free fatty acids and the loss of Hill activity were pH dependent. The losses were the least during incubation at pH 5.8 and the greatest during incubation at pH 8.0. The major free fatty acids released at pH 5.8 were saturated, while those released at pH 7.0 or 8.0 were mainly the unsaturated acids, a-linolenic acid and hexadecatrienoic acid.Approximately 50 % (w/w) of the dry weight of spinach chloroplasts is lipid (9). Almost 40 % (w/w) of these lipids are fatty acids (G. Constanitopouilos, unpublished results). However, aside from a paper written by Speer et al. in 1929 (15) in which the free faitty acids of spinach chloroplasts were said to be 53 % (w/w) of the total fatty acids, no distinction between the free fatty acids ancI lipid-boutnd fatty acids has been reported. Thus, both the amount and the chemical composition of the free fatty acids remain uncertain.\WVhile studying the effect of hydrolytic enzymes on the structure and function of chloroplasts (G. Constanto,poulos and K. Bloch, manuscript in preparation), we noticed a rapid loss of Hill activity of the chloro'plasts after short incubations at 370 or even at roolm temperature. An inhibitory effect on the Hilll relaction by unsatturated fatty acids had been found by Krogmann and Jagendorf (8) ing isolation varies between 3.1 and 5.5 % of the total fatty acids of chloroplasts, depending on the method of preparation. Incubation of chlo,roplasts ait 370 results in the release of bound fatty acids. The rate of release and chemical composition of the released fatty acids is dependent on the pH of the reaction mixture. Under some conditions, addtition of bovine serum albumin (BSA) to the chloroplasit stuspension la,rgely prevents the loss of Hill activity. Materials and MethodsPreptaratioa of Chloroplaist Sutspensionts. Spinach was ptuirchased at the local market. Several different procedures were used for the preparation of chloroplasts from fresh spinach leaves (6,12,17). Chlorophyll was deitermined by the method of Arnon (1). Chloropla,sts were aged in 20 mm potassitum phosphate buffer, pH 7.0, containing 6.7 mM KOl, at a concentration of 1 to 2 mg chlorophyll/ml of suispension.

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Inhibition of photophosphorylation and photosynthetic carbon cycle reactions by fatty acids and esters

Cited by 67 publications

References 15 publications

Effect of linolenate on photosynthesis by intact spinach chloroplasts I. Inhibition of orthophosphate uptake and of 3-P-glyceraldehyde efflux across the chloroplast envelope

Effect of linolenate on photosynthesis by intact spinach chloroplasts I. Inhibition of orthophosphate uptake and of 3-P-glyceraldehyde efflux across the chloroplast envelope

Role of Orthophosphate and Other Factors in the Regulation of Starch Formation in Leaves and Isolated Chloroplasts

Release of Free Fatty Acids and Loss of Hill Activity by Aging Spinach Chloroplasts

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