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Weigle AT, Carr M, Shukla D. Impact of Increased Membrane Realism on Conformational Sampling of Proteins. J Chem Theory Comput 2021; 17:5342-5357. [PMID: 34339605 DOI: 10.1021/acs.jctc.1c00276] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The realism and accuracy of lipid bilayer simulations through molecular dynamics (MD) are heavily dependent on the lipid composition. While the field is pushing toward implementing more heterogeneous and realistic membrane compositions, a lack of high-resolution lipidomic data prevents some membrane protein systems from being modeled with the highest level of realism. Given the additional diversity of real-world cellular membranes and protein-lipid interactions, it is still not fully understood how altering membrane complexity affects modeled membrane protein functions or if it matters over long-timescale simulations. This is especially true for organisms whose membrane environments have little to no computational study, such as the plant plasma membrane. Tackling these issues in tandem, a generalized, realistic, and asymmetric plant plasma membrane with more than 10 different lipid species is constructed herein. Classical MD simulations of pure membrane constructs were performed to evaluate how altering the compositional complexity of the membrane impacted the plant membrane properties. The apo form of a plant sugar transporter, OsSWEET2b, was inserted into membrane models where lipid diversity was calculated in either a size-dependent or size-independent manner. An adaptive sampling simulation regime validated by Markov-state models was performed to capture the gating dynamics of OsSWEET2b in each of these membrane constructs. In comparison to previous OsSWEET2b simulations performed in a pure POPC bilayer, we confirm that simulations performed within a native-like membrane composition alter the stabilization of apo OsSWEET2b conformational states by ∼1 kcal/mol. The free-energy barriers of intermediate conformational states decrease when realistic membrane complexity is simplified, albeit roughly within sampling error, suggesting that protein-specific responses to membranes differ due to altered packing caused by compositional fluctuations. This work serves as a case study where a more realistic bilayer composition makes unbiased conformational sampling easier to achieve than with simplified bilayers.
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Affiliation(s)
- Austin T Weigle
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Matthew Carr
- Independent Software Development Provider310 East Marlette Avenue, Phoenix, Arizona 85012, United States
| | - Diwakar Shukla
- Department of Chemical & Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Cancer Center at Illinois, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Center for Digital Agriculture, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,NIH Center for Macromolecular Modeling and Bioinformatics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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Kuttenreich H, Hinz HJ, Incźedy-Marcsek M, Koynova R, Tenchov B, Laggner P. Polymorphism of synthetic 1,2-O-β-dialkyl-3-O-β-D-galactosyl-sn-glycerols of different alkyl chain lengths. Chem Phys Lipids 1988. [DOI: 10.1016/0009-3084(88)90048-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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4
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Edman K, Ericson I. Phospholipid and fatty acid composition in mitochondria from spinach (Spinacia oleracea) leaves and petioles. A comparative study. Biochem J 1987; 243:575-8. [PMID: 3632635 PMCID: PMC1147893 DOI: 10.1042/bj2430575] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Essentially chlorophyll-free mitochondria from photosynthetic (leaf) and non-photosynthetic tissue (petiole) were isolated from spinach (Spinacia oleracea). Leaf mitochondria were found to contain more phosphatidylcholine than phosphatidylethanolamine compared with petiole mitochondria. Galactolipids were found in small and equal amounts (5 mol of galactolipids/100 mol of galactolipids and phospholipids) in both leaf and petiole mitochondria. Fatty acid composition showed a significant difference in the amounts of C18:2 and C18:3 acids. The C18:2/C18:3 ratio was more than twice as high in all of the phospholipids studied from petiole mitochondria compared with the ratio in leaf mitochondria. More than 50% (mol/100 mol) of the fatty acids in the major lipids (phosphatidylcholine, phosphatidylethanolamine and cardiolipin) in petiole mitochondria were C18:2. In the minor lipids (phosphatidylinositol and phosphatidylglycerol), C16:0 dominated in both leaf and petiole mitochondria.
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5
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Hartmann MA, Benveniste P. [58] Plant membrane sterols: Isolation, identification, and biosynthesis. Methods Enzymol 1987. [DOI: 10.1016/0076-6879(87)48060-9] [Citation(s) in RCA: 115] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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7
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Douce R, Block MA, Dorne AJ, Joyard J. The plastid envelope membranes: their structure, composition, and role in chloroplast biogenesis. Subcell Biochem 1984; 10:1-84. [PMID: 6382702 DOI: 10.1007/978-1-4613-2709-7_1] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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8
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Optimal conditions for post-translational uptake of proteins by isolated chloroplasts. In vitro synthesis and transport of plastocyanin, ferredoxin-NADP+ oxidoreductase, and fructose-1,6-bisphosphatase. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(19)68228-1] [Citation(s) in RCA: 132] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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9
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Nishihara M, Yokota K, Kito M. Lipid molecular species composition of thylakoid membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 617:12-9. [PMID: 7188732 DOI: 10.1016/0005-2760(80)90219-2] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Lipid molecular species compositions of chloroplast thylakoid membranes of mesophyll cells from Spinacia oleracea, Glycine max, Oryza sativa and Zea mays and of bundle sheath cells from Zea mays have been quantitatively determined. No significant difference in the lipid molecular species composition was found among the five membrane sources. The predominant molecular species of monogalactosyldiacylglycerol was the 1-linolenoyl parallel to 2-linolenoyl species. The 1-linolenoyl parallel to 2-linoenoyl and 1-palmitoyl parallel to 2-linolenoyl species were the major molecular species of digalactosyldiacylglycerol. 6-Sulfoquinovosyldiacylglycerol was mainly composed of the palmitoyl parallel to linolenoyl and palmitoyl parallel to lineolyl species. Almost all of the C-2 position of phosphatidylglycerol were esterified with the palmitoyl or delta 3-trans-hexadecenoyl residue. The molecular species compositions of phosphatidylcholine and phosphatidylinositol were basically similar to those of membranes in non-photosynthetic tissues.
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10
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[11] Isolation of chloroplast envelople membranes. Methods Enzymol 1980. [DOI: 10.1016/s0076-6879(80)69013-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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11
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12
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Siebertz HP, Heinz E, Linscheid M, Joyard J, Douce R. Characterization of lipids from chloroplast envelopes. EUROPEAN JOURNAL OF BIOCHEMISTRY 1979; 101:429-38. [PMID: 520307 DOI: 10.1111/j.1432-1033.1979.tb19736.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The major neutral, glycolipids and phospholipids from envelopes of spinach chloroplasts were analyzed with respect to proportions, positional distribution and pairing of fatty acids. All specificities in the diacylglycerol portions of lipids known from previous analyses of lipids from whole leaves were also found in envelope lipids. Diacylglycerols and galactolipids share a common diacylglycerol portion. The only exception is digalactosyl diacylglycerol, which contains 18:3/16:0 but lacks 18:3/16:3 species reverting the distribution in other galactolipids. Phosphatidylcholine, phosphatidylglycerol and sulfoquinovosyl diacylglycerol are distinct from the galactolipids, because each one has a unique diacylglycerol profile. The diacylglycerol species present in phosphatidylcholine and galactolipids or free diacylglycerols do not provide evidence for a biogenetic relation between phosphatidylcholine and galactolipids at the level of envelopes.
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Blee E, Schantz R. Biosynthesis of galactolipids in Euglena gracilis: I, incorporation of UDP galactose into galactosyldiglycerides. ACTA ACUST UNITED AC 1978. [DOI: 10.1016/0304-4211(78)90103-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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van Besouw A, Wintermans JF. Galactolipid formation in chloroplast envelopes. I. Evidence for two mechanisms in galactosylation. BIOCHIMICA ET BIOPHYSICA ACTA 1978; 529:44-53. [PMID: 638180 DOI: 10.1016/0005-2760(78)90102-9] [Citation(s) in RCA: 124] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Two different enzymes for galactosylation occur in isolated chloroplast envelopes of spinach leaves, UDPgalactose-diglyceride galactosyltransferase and galactolipid-galactolipid galactosyltransferase. The first enzyme is responsible for the biosynthesis of monogalactosyldiglyceride, UDPgalactose being donor of the galactosyl moiety. The second enzyme is responsible for the biosynthesis of digalactosyldiglyceride and higher homologues. The optimum pH for monogalactosyldiglyceride synthesis was found to be 7.5, for digalactosyldiglyceride synthesis 6.5. After incubation at pH 7.4 a Lineweaver-Burk plot indicated two binding sites for UDPgalactose on the UDPgalactose-diglyceride galactosyltransferase with different affinities for UDPgalactose and different activities. Indirectly the galactolipid-galactolipid galactosyltransferase was shown to respond similarly to various UDPgalactose concentrations. However, the second reaction also proceeds in absence of UDPgalactose. It was concluded that the second enzyme does not require the presence of UDPgalactose, but that galactosyl transfer proceeds by direct exchange of galactosyl groups between molecules of galactolipids, or via unknown lipid intermediates, not detected in our system. Results of other investigations will be discussed in the light of the present data.
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Murakami S, Strotmann H. Adenylate kinase bound to the envelope membranes of spinach chloroplasts. Arch Biochem Biophys 1978; 185:30-8. [PMID: 203230 DOI: 10.1016/0003-9861(78)90140-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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17
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Kleinig H, Kopp C. Lipids, lipid turnover, and phospholipase D in plant suspension culture cells (Daucus carota). PLANTA 1978; 139:61-65. [PMID: 24414107 DOI: 10.1007/bf00390811] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/1977] [Accepted: 11/02/1977] [Indexed: 06/03/2023]
Abstract
The lipid pattern of Daucus carota L. suspension culture cells and other plant cell strains was analyzed. Phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and triacylglycerol were the main components. The characteristic plastidal and mitochondrial lipids could also be identified. All strains tested exhibited a phospholipase D activity. Several lipid precursors were found to be well utilized by the cells and to be special markers for certain lipids or parts of the lipid molecules. The half life times of the major lipids ranged at about half a generation time of the cells.
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Affiliation(s)
- H Kleinig
- Lehrstuhl für Zellbiologie, Institut für Biologie II, Schänzlestr. 1, D-7800, Freiburg i.Br., Federal Republic of Germany
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Beck JC, Levine RP. Synthesis of chloroplast membrane lipids and chlorophyll in synchronous cultures of Chlamydomonas reinhardi. BIOCHIMICA ET BIOPHYSICA ACTA 1977; 489:360-9. [PMID: 588577 DOI: 10.1016/0005-2760(77)90156-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Chloroplast membrane lipid synthesis has been studied in synchronously growing cultures of Chlamydomonas reinhardi. The synthesis of sulfolipid and phospholipid were measured by incorporation of 35SO4(2-) and 32PO4(3-) during a 1-h pulse. Galactolipid synthesis was measured by H14CO3- incorporation into lipid fractions separated by thin layer chromatography. Lipid synthesis occurs principally during the light portion of the synchronous cycle. Phosphatidylglycerol is synthesized between 3-4 h in the light and sulfolipid is labeled between 7-9 h in the light. Galactolipid synthesis appears to reach maximal rates shortly after the lights go on and again at 7 h. Chlorophyll reaches maximal rates of synthesis after 7 h. These lipids are made and inserted into the chloroplast membrane prior to major increases in photosynthetic capacity. Our results also show that chloroplast membrane lipids are synthesized in a sequential or multistep process.
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Roughan PG, Slack CR. Long-chain acyl-coenzyme A synthetase activity of spinach chloroplasts is concentrated in the envelope. Biochem J 1977; 162:457-9. [PMID: 849293 PMCID: PMC1164620 DOI: 10.1042/bj1620457] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Purified chloroplasts were disrupted and then fractionated by discontinuous sucrose-density-gradient centrifugation. Envelopes contained long-chain acyl-CoA synthetase at a specific activity 80 times the activity in the lamellae or the stroma. Acetyl-CoA synthetase was concentrated in the stroma, and chlorophyll was confined to the lamellae membranes. Phospholipase D was not detected in any fraction.
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20
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Liedvogel B, Kleinig H. Lipid metabolism in chromoplast membranes from the daffodil: Glycosylation and acylation. PLANTA 1977; 133:249-253. [PMID: 24425258 DOI: 10.1007/bf00380685] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/1976] [Accepted: 10/07/1976] [Indexed: 06/03/2023]
Abstract
The non-photosynthetic chromoplast membranes from the corona ofNarcissus pseudonarcissus L. were investigated for their lipid synthetic capabilities. The following activities were detected: galactosylation of diacylglycerol and galactosydiacylglycerols, glycosylation of sterols, acylation of monogalactosyldiacylglycerol and steryl glycosides from an unknown endogenous donor, acylation of phospholipids from acyl-CoA, and acylation of phosphatidyl inositol from phosphatidyl choline. Furthermore, activities of an acyl thioesterase, a sugar epimerase, and a phospholipase A2 were measured.
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Affiliation(s)
- B Liedvogel
- Lehrstuhl für Zellbiologie, Institut für Biologie II, Schänzlestraße 9-15, D-7800, Freiburg i.Br., Germany
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Bahl J. Chlorophyll, carotenoid, and lipid content in Triticum sativum L. plastid envelopes, prolamellar bodies, stroma lamellae, and grana. PLANTA 1977; 136:21-24. [PMID: 24420221 DOI: 10.1007/bf00387919] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/1977] [Accepted: 04/25/1977] [Indexed: 06/03/2023]
Abstract
The pigment and lipid content, expressed on a protein basis, is compared in wheat etioplast and chloroplast membrane fractions. Chloroplast envelopes contain less carotenoid and 1/3 more lipid than etioplast envelopes. The minute amount of chlorophyll and carotenoid found in chloroplast envelopes could be due to thylakoid contamination. Prolamellar bodies and grana have nearly the same amount of total lipid and total carotenoid per mg of protein although their respective compositions differ. On a protein basis, the lipid, chlorophyll, and carotenoid contents are lower (2.3, 10, and 20 times, respectively) in stroma lamellae than in grana membranes, but the latter contains a higher proportion of β-carotene, chlorophyll a, and sulfolipid.
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Affiliation(s)
- J Bahl
- Laboratoire de Régulations Métaboliques et Différenciation des Plastes , Institut de Biologie Végétale, Université Paris VI, Tour 53, 4, Place Jussieu, F-75230, Paris Cedex 05, France
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GIVAN BCURTISV, HARWOOD JOHNL. BIOSYNTHESIS OF SMALL MOLECULES IN CHLOROPLASTS OF HIGHER PLANTS. Biol Rev Camb Philos Soc 1976. [DOI: 10.1111/j.1469-185x.1976.tb01061.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Westrin H, Albertsson PA, Johansson G. Hydrophobic affinity partition of spinach chloroplasts in aqueous two-phase systems. BIOCHIMICA ET BIOPHYSICA ACTA 1976; 436:696-706. [PMID: 952914 DOI: 10.1016/0005-2736(76)90451-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The surface properties of spinach chloroplasts, both of intact chloroplasts with surrounding envelope and broken chloroplasts consisting of the inner lamellar system, have been studied by partitioning them between two aqueous phases, especially using counter-current distribution technique. The two-phase system consists of poly(ethyleneglycol), dextran and water. The two polymers are enriched in opposite phases and by binding deoxycholate or palmitate to one of the polymers the affinity of chloroplasts for the corresponding phase is strongly enhanced. The partition of the two classes of chloroplasts, however, is not affected to the same degree and the affinity of the chloroplast envelope for deoxycholate and palmitate is stronger than that of the lamellar system. This has been correlated to the chemical composition of the two types of membranes. By studying the effect of salts on the partition it has been found that the lamellar system bears a larger number of negative charges as compared to the envelope of the intact chloroplast.
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Sprey B, Laetsch W. Chloroplast Envelopes of Spinacia oleracea L. III. Freeze-Fracturing of Chloroplast Envelopes. ACTA ACUST UNITED AC 1976. [DOI: 10.1016/s0044-328x(76)80107-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Sprey B, Laetsch W. Chloroplast Envelopes of Spinacia oleracea L. II. Ultrastructure of Chloroplast Envelopes and Lamellae. ACTA ACUST UNITED AC 1976. [DOI: 10.1016/s0044-328x(78)80186-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Joyard J, Douce R. [Separation and role of diacylglycerols in the envelope of spinach chloroplasts (author's transl)]. BIOCHIMICA ET BIOPHYSICA ACTA 1976; 424:125-31. [PMID: 1252476 DOI: 10.1016/0005-2760(76)90057-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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27
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Bahl J, Francke B, Monéger R. Lipid composition of envelopes, prolamellar bodies and other plastid membranes in etiolated, green and greening wheat leaves. PLANTA 1976; 129:193-201. [PMID: 24430956 DOI: 10.1007/bf00398257] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/1975] [Accepted: 11/24/1975] [Indexed: 05/25/2023]
Abstract
Comparative studies of lipid composition were made on prolamellar bodies, envelopes and other plastid membranes separately extracted from etiolated, green or greening (intermittent or continuous light) wheat (Triticum sativum L.) leaves. The different membrane fractions were examined by electron microscopy.The major lipid was digalactosyldiglyceride in the envelopes and prolamellar bodies and monogalactosyldiglyceride in stroma lamellae and grana. Phosphatidylcholine represented 60% of total phospholipids in the envelopes, 30% in prolamellar bodies and 14% in grana. All types of envelopes had the same lipid proportions.For all lipids the lowest fatty acid unsaturation was always found in the envelope membranes. The relative amount of {ie193-1} acid in the phosphatidylglycerol of envelopes increased from 4% (etioplasts) to an average of 15% (etiochloroplasts and chloroplasts).
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Affiliation(s)
- J Bahl
- Laboratoire de Régulations Métaboliques et Différenciation des Plastes, Institut de Biologie Végétale, Université Paris 6, Tour 53, 4 Place Jussieu, 75230, Paris Cedex 05, France
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28
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Biochemische und cytologische untersuchungen zur chloroplastenentwicklung I. Die chemische Charakterisierung der Prolamellarkörper aus Etioplasten von Avena sativa L. ACTA ACUST UNITED AC 1975. [DOI: 10.1016/s0044-328x(75)80100-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Van Hummel HC, Hulsebos TH, Wintermans JF. Biosynthesis of galactosyl diglycerides by non-green fractions from chloroplasts. BIOCHIMICA ET BIOPHYSICA ACTA 1975; 380:219-26. [PMID: 1120142 DOI: 10.1016/0005-2760(75)90008-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
When either mitochondria, chloroplast stroma lamellae, or osmotically shocked chloroplasts were centrifuged through sucrose gradients, zones were always obtained at the 0.6 M-0.9 M boundary which were highly active in galactosyltransferase. These activities did not coincide with maxima for chlorophyll or cytochrome c oxidase activity. A second chlorophyll-free fraction was obtained at lower density, showing high galactosyltransferase activity when incubated after isolation. The results indicate that the highly active fractions originate from chloroplast envelopes.
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31
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Joy KW, Ellis RJ. Protein synthesis in chloroplasts. IV. Polypeptides of the chloroplast envelope. BIOCHIMICA ET BIOPHYSICA ACTA 1975; 378:143-51. [PMID: 1120134 DOI: 10.1016/0005-2787(75)90145-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Envelope membranes were isolated from washed chloroplasts of pea seedlings. As judged by the protein-to-chlorophyll ratio, average preparations contain less than 8 percent contamination with internal lamellar membranes. Electrophoresis on sodium dodecylsulphate polyacrylamide gels shows that the envelope membranes contain at least 25 polypeptides. The molecular weight distribution of the envelope polypeptides is different from that of the lamellar polypeptides, there being more polypeptides of molecular weights above 50 000 in the envelopes. Two envelope polypeptides become labelled when isolated intact chloroplasts are incubated in the light with (35S) methionine. One of these is similar in molecular weight to the main polypeptide labelled in lamellae, but the other is unique to the envelope fraction. Incorporation of label into both polypeptides is totally light-dependent and is inhibited by chloramphenicol. When (35S) methionine is fed to detached pea shoots with and without cycloheximide, the labelling of other envelope polypeptides is inhibited. We conclude that two polypeptides of the chloroplast envelop are synthesised by chloroplast ribosomes.
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32
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Krause GH, Santarius KA. Relative thermostability of the chloroplast envelope. PLANTA 1975; 127:285-99. [PMID: 24430479 DOI: 10.1007/bf00380726] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/1975] [Accepted: 08/03/1975] [Indexed: 05/18/2023]
Abstract
Intact isolated chloroplasts from leaves of Spinacia oleracea L. were subjected to heat treatment. After heating, the integrity of the chloroplast envelopes and the activities of various light-dependent chloroplast reactions were tested. The integrity of the chloroplast envelopes, as judged from rates of ferricyanide reduction, enzyme compartmentation and visual appearance of the chloroplasts in the light microscope with phase optics, was affected much less by heat stress than the photochemical reactions of thylakoids. This indicates a comparatively high thermostability of the chloroplast envelope membranes. It is also evidence of a differential thermostability of different biomembranes. Photophosphorylation was highly susceptible to thermal stress. Heat treatment that partly inactivated phosphorylation stimulated light-dependent quenching of 9-aminoacridine fluorescence, which served as an indicator of proton transfer from stroma to thylakoids in intact chloroplasts. Drastic changes in the characteristics of chlorophyll a fluorescence emission caused by heating were probably due to structural alterations of the thylakoid system.
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Affiliation(s)
- G H Krause
- Botanisches Institute der Universität Düsseldorf, D-4000, Düsseldorf 1, Germany
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33
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Mendiola-Morgenthaler LR, Morgenthaler JJ. Proteins of the envelope and thylakoid membranes of spinach chloroplasts. FEBS Lett 1974; 49:152-5. [PMID: 4442597 DOI: 10.1016/0014-5793(74)80499-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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34
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35
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Cobb AH, Wellburn AR. Changes in plastid envelope polypeptides during chloroplast development. PLANTA 1974; 121:273-282. [PMID: 24442806 DOI: 10.1007/bf00389327] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/1974] [Indexed: 06/03/2023]
Abstract
A quantitative estimation of sodium dodecyl sulphate-extractable plastid envelope polypeptides during greening of Avena sativa L. laminae is described, combined with protein distribution and plastid number studies over the same period.A primary light-dependent and cytoplasm-dependent increase in both total plastid protein and envelope associated protein during the first 30 minutes of greening was observed, followed by a period during which release of envelope-associated protein either into the plastid or into the cytoplasm, or both, takes place. After 8 hours greening an increase in plastid envelope protein reflects a requirement for an increased plastid surface area during chloroplast maturation.A comparison of the behaviour of envelope membranes during illuminated in vitro incubation of isolated etio-plasts with plastids isolated from tissue given similar illumination pre-treatments, indicates that the early increase in envelope-associated protein is real and requires the participation of the cytoplasm.
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Affiliation(s)
- A H Cobb
- Department of Biological Sciences, University of Lancaster, LA1 4YQ, Lancaster, UK
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