Synthesis of Long-Chain Acyl-CoA in Chloroplast Envelope Membranes

Joyard, Jacques; Stumpf, P.K.

doi:10.1104/pp.67.2.250

Cited by 74 publications

(35 citation statements)

References 18 publications

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“…Subsequent experiments showed that ACP-dependent fatty acid synthesis was entirely a chloroplast function (Ohlrogge et al, 1979), implying that the acyl-ACP thioesterase was a stromal enzyme activity. Acyl-CoA synthetase was demonstrated as an activity of the chloroplast envelope (Roughan and Slack, 1977;Joyard and Stumpf, 1981), and later more specifically of the outer envelope (Andrews and Keegstra, 1983;Block et al, 1983). The assumption is that free fatty acids are the intermediates, although the mechanism by which such intermediates move is unknown.…”

mentioning

confidence: 99%

Testing Models of Fatty Acid Transfer and Lipid Synthesis in Spinach Leaf Using in Vivo Oxygen-18 Labeling

Pollard

Ohlrogge

1999

Plant Physiology

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Testing Models of Fatty Acid Transfer and Lipid Synthesis in Spinach Leaf Using in Vivo Oxygen-18 Labeling

Pollard

Ohlrogge

1999

Plant Physiology

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“…The role of the plastid envelope acyl-CoA thioesterase, which is a separate enzyme from the synthetase (16), is still unknown. Because of its preference for shorter-chain acyl groups, it has been suggested to prevent either the export out of the chloroplast or the improper insertion into plastid-synthesized lipids of fatty acids with less than 16 carbons (15 Chloroplast envelope membranes were then isolated and subfractionated as previously described (7).…”

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confidence: 99%

Acyl-CoA Synthetase Is Located in the Outer Membrane and Acyl-CoA Thioesterase in the Inner Membrane of Pea Chloroplast Envelopes

Andrews

Keegstra²

1983

Plant Physiol.

102

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Both acyl-CoA synthetase and acyl-CoA thioesterase activities are present in chloroplast envelope membranes. The functions of these enzymes in lipid metabolism remains unresolved, although the synthetase has been proposed to be involved in either plastid galactolipid synthesis or the export of plastid-synthesized fatty acids to the cytoplasm. We have examined the locations of both enzymes within the two envelope membranes of pea (Pisum sativum var Laxton's Progress No. 9) chloroplasts. Inner and outer envelope membranes were purified from unfractionated envelope preparations by linear density sucrose gradient centrifugation. Acyl-CoA synthetase was located in the outer envelope membrane while acyl-CoA thioesterase was located in the inner envelope membrane. Thus, it seems unlikely that the synthetase is directly involved in galactolipid assembly. Instead, its localization supports the hypothesis that it functions in the transport of plastid-synthesized fatty acids to the endoplasmic reticulum.

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“…Most polyunsaturated 18-carbon plant fatty acids, however, appear to be formed in the cytosol by ER-bound enzymes. Fatty acids that are transported out of the chloroplast are thought to be converted to CoA esters and subsequently incorporated into glycerolipids by the eukaryotic route (2,6,18,26). These lipids characteristically contain 18-carbon fatty acids in the sn-2 position.…”

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Expression of the Yeast Δ-9 Fatty Acid Desaturase in Nicotiana tabacum

Polashock¹,

Chin²,

Martin³

1992

Plant Physiol.

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To examine the processes of plant cytoplasmic fatty acid desaturation and glycerolipid biosynthesis, the protein coding sequence of the endoplasmic reticulum cytochrome b5-dependent, A-9 fatty acid desaturase gene from Saccharomyces cerevisiae was introduced into Nicotiana tabacum via Agrobacterium transformation. All transformed plants expressing the yeast gene at the mRNA level exhibited an approximately 10-fold increase in the levels of palmitoleic acid (16:1) in leaf tissue. This fatty acid species is found in very low levels (less than 2%) in wild-type plants. These results indicate that the yeast desaturase can function in plants, presumably by using a leaf microsomal cytochrome b5-mediated electron transport system. Lipid analysis demonstrated that the overproduced 16:1 is incorporated into most of the major polar lipid classes, including the cytoplasmically produced "eukaryotic" fraction of the chloroplast galactolipids. 16:1 was not found, however, in phosphatidyl glycerol, which is considered to be produced almost exclusively in the chloroplast. Despite these changes in membrane lipid composition, no obvious phenotypic differences were apparent in the transformed plants. Positional analysis shows that the cytoplasmically produced 16:1 is found primarily in the sn-2 position of phosphatidylcholine, phosphatidylethanolamine, monogalactosyldiacylglycerol, and digalactosyldiacylglycerol. The positional data suggest that the sn-2 acyltransferases responsible for the "eukaryotic" arrangement of 16-and 18-carbon fatty acids in glycerolipids are selective for unsaturated fatty acids rather than chain length.In plants, unsaturated fatty acids are formed and incorporated into complex lipids in two distinct cellular compartments. The initial products of de novo fatty acid synthesis, which occurs almost exclusively in the plastids (12), are the saturated species 16:0-ACP2 and 18:0-ACP. 18:1-ACP is

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Synthesis of Long-Chain Acyl-CoA in Chloroplast Envelope Membranes

Cited by 74 publications

References 18 publications

Testing Models of Fatty Acid Transfer and Lipid Synthesis in Spinach Leaf Using in Vivo Oxygen-18 Labeling

Testing Models of Fatty Acid Transfer and Lipid Synthesis in Spinach Leaf Using in Vivo Oxygen-18 Labeling

Acyl-CoA Synthetase Is Located in the Outer Membrane and Acyl-CoA Thioesterase in the Inner Membrane of Pea Chloroplast Envelopes

Expression of the Yeast Δ-9 Fatty Acid Desaturase in Nicotiana tabacum

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