Localization of sulfolipid labeling within cells and chloroplasts

Haas, R.; Siebertz, Heinz Peter; Wrage, Käthe; Heinz, Ernst

doi:10.1007/bf00380033

Cited by 65 publications

(25 citation statements)

References 22 publications

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“…Chloroplasts were isolated and purified from pea and spinach leaves, as described before (9). Purified chloroplasts were osmotically ruptured in 5 mm Tris-HCl (pH 7.8) and centrifuged for 20 min at 40,000g.…”

Section: Methodsmentioning

confidence: 99%

Positional Specificity and Fatty Acid Selectivity of Purified sn-Glycerol 3-Phosphate Acyltransferases from Chloroplasts

Bertrams¹,

Heinz²

1981

Plant Physiol.

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Soluble acyl-CoAsn-glycerol 3-phosphate acyltransferases (EC 23.1.15) which are localized in chloroplasts were purified from leaves of Pisum sativum and Spinacia oke.aca and obtained free from interfering activities. The purification raised the specific activities by factors of about 1,000 for pea and 200 for spinach preparations. In pea chloroplasts, acyltransferase activity occurs in two soluble forms with apparent isoelectric points of 6.3 and 6.6. For both forms, the same molecular weight of about 42,000 was determined. The enzyme from spinach chloroplasts showed a slightly higher molecular weight and a lower isoelectric point of 5.2.The enriched enzyme fractions possessed a specificity for glycerol 3-phosphate as acyl acceptor and did not use dihydroxyacetone phosphate. Besides acyl-CoA, acyl-acyl carrier protein also can function as acyl donor. With acyl-CoA as acyl donor, the enzyme shows a high positional specificity, since the predominant product is 1-acylglycerol 3-phosphate.Different acyl-CoAs, when offered separately, were all accepted as substrates, whereas incubations with mixtures of palmitoyl-, stearoyl-, and oleoyl-CoA demonstrated a preference for olec acid. The acyltransferase from spinach displays higher selectivity than does the enzyme from pea and, therefore, may be responsible for the preferred esterification of oleic acid at the C-1 position in chloroplast lipids and the exclusion of palmitic acid from this position as observed during in vivo labeling experiments.When membrane lipids contain different fatty acids, they are usually distributed asymmetrically between positions C-1 and C-2 of the glycerol backbone. In leaf lipids, palmitic acid and unsaturated C18-fatty acids such as linoleic and linolenic acid predominate. In so-called 16:3-plants, in addition to linolenic acid, the lower homologue hexadecatrienoic acid is present and accumulates specifically in monogalactosyl diacylglycerol (13). Positional analyses have shown that this acid is confined to C-2 in this glycolipid, whereas linolenic acid is found in both positions (12). When these analyses were extended to labeled lipids from leaves or chloroplasts of 16:3-plants, common patterns were observed in all chloroplast lipids. After short labeling times, they carried mainly oleate at C-I and palmitate at C-2 (16,22,26,27), which suggests a common diacylglycerol precursor. The only exception in chloroplasts is phosphatidyl choline, which carries palmitate esterified at the C-1 position.The discovery that, apart from other organelles also chloroplasts (3, 15) contain acyl-CoA:glycerol 3-P acyltransferase activity suggested that this enzyme may be involved in the control of fatty acid distribution in chloroplast lipids, since it catalyzes the first acylation step in the de novo synthesis ofcomplex lipids. Therefore, we purified this chloroplast enzyme to investigate its general 'This work was supported by the Deutsche Forschungsgemeinschaft.properties as well as its positional and fatty acid specificity. The results show tha...

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Section: Methodsmentioning

confidence: 99%

Positional Specificity and Fatty Acid Selectivity of Purified sn-Glycerol 3-Phosphate Acyltransferases from Chloroplasts

Bertrams¹,

Heinz²

1981

Plant Physiol.

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“…Previous research has shown the autonomy of the chloroplast for the synthesis of SQDG2 from 35SO42- (15,20). A light requirement for the synthesis of SQDG from sulfate has been indicated (1,16,20).…”

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confidence: 99%

Biosynthesis of Sulfoquinovosyldiacylglycerol in Higher Plants

Kleppinger-Sparace¹,

Mudd²

1987

Plant Physiol.

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“…As already mentioned before, intact chloroplasts are able to label sulfolipid from added radioactive sulfate [4,. This was taken as evidence for the operation of the complete pathway of sulfolipid biosynthesis within the organelle.…”

Section: Biochemical Studiesmentioning

confidence: 74%

“…Intact chloroplasts and envelope membranes were isolated i;-orn hydroponically grown spinach as described before [4]. Radioactive compounds on TLC plates were detected by scanning the plates with a Berthold automatic TLC linear analyzer; liquid scintillation counting was carried out in a Beckman LS 1801 instrument using a commercially available cocktail (Quickszint 701, Zinsser).…”

Section: Materials and General Methomentioning

confidence: 99%

“…With regard to the sulfur budget of plants, the sulfolipid represents a major component which accounts for about half of the organic sulfur in leaves [3]. In higher plants this unique glycolipid is confined to plastids [4]. In these organelles it is located in the two surrounding envelopes as well as in the inner thylakoid membranes [5], where part of it may be firmly bound to specific protein complexes [6 -81. After application of radioactive sulfate to plants, the sulfolipid is rapidly labelled [I, 2, 91.…”

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confidence: 99%

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Synthesis of different nucleoside 5′‐diphospho‐sulfoquinovoses and their use for studies on sulfolipid biosynthesis in chloroplasts

Heinz

Schmidt

Hoch

et al. 1989

European Journal of Biochemistry

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6-Su~fo-a-~-quinovopyranosyl phosphate was reacted with different nucleoside monophosphate morpholidates to form ADP-, CDP-, GDP-and UDP-sulfoquinovose. Analytical and preparative HPLC of these nucleotides was performed on reversed-phase columns using volatile buffer systems as eluant. The isolated compounds were characterized by NMR spectroscopy (except the CDP derivative) and used for an investigation of sulfolipid biosynthesis by chloroplasts. For this purpose intact spinach chloroplasts were biosynthetically preloaded with radioactive diacylglycerol to provide a sulfoquinovosyl acceptor. When sulfosugar nucleotides were added to such prelabelled intact organelles, the background levels of sulfolipid biosynthesis did not rise. On the other hand, after osmotic shock of prelabelled chloroplasts sulfolipid labelling was significantly increased by the addition of UDP-or GDP-sulfoquinovose. The same stimulation was observed with isolated envelope membranes, and UDP-sulfoquinovose proved to be twice as active as the GDP derivative. From these results it was concluded that the final step in sulfolipid biosynthesis is catalyzed by a UDP-sulfoquinovose: 1,2-diacylglycero13-0-a-D-sulfoquinovosyltransferase. This chloroplast enzyme cannot use exogenously supplied sulfosugar nucleotides, which as membrane-impermeable compounds are expected to be formed in viwo within chloroplasts.The plant sulfolipid 1 ',2'-di-0-acyl-3'-0-(6-deoxy-6-sulfoa-D-glucopyranosy1)-sn-glycerol [I] is a membrane lipid found in higher plants, cyanobacteria and some other photosynthetic procaryotes [2]. With regard to the sulfur budget of plants, the sulfolipid represents a major component which accounts for about half of the organic sulfur in leaves [3]. In higher plants this unique glycolipid is confined to plastids [4]. In these organelles it is located in the two surrounding envelopes as well as in the inner thylakoid membranes [5], where part of it may be firmly bound to specific protein complexes [6 -81.After application of radioactive sulfate to plants, the sulfolipid is rapidly labelled [I, 2, 91. Despite this specific and easy labelling, several steps in sulfolipid biosynthesis have not been resolved and at present two alternative routes are discussed. It has been suggested that a sulfoglycolytic sequencc [lo -121 produces 3-sulfo-~-lactaldehyde which instead of 3-phospho-~-glyceraldehyde can be used by aldolase [lo] to form 6-deoxy-6-sulfo-~-fructofuranosyl 1-phosphate. Subsequent hydrolysis and isomerisation to 6-sulfoquinovose (quinovose = 6-deoxy-~-glucose), rephosphorylation at C-I and activation by a corresponding pyrophosphorylase could result in a nucleoside diphospho-sulfoquinovose. Such a com-

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Localization of sulfolipid labeling within cells and chloroplasts

Cited by 65 publications

References 22 publications

Positional Specificity and Fatty Acid Selectivity of Purified sn-Glycerol 3-Phosphate Acyltransferases from Chloroplasts

Positional Specificity and Fatty Acid Selectivity of Purified sn-Glycerol 3-Phosphate Acyltransferases from Chloroplasts

Biosynthesis of Sulfoquinovosyldiacylglycerol in Higher Plants

Synthesis of different nucleoside 5′‐diphospho‐sulfoquinovoses and their use for studies on sulfolipid biosynthesis in chloroplasts

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