Phase equilibria of mixtures of plant galactolipids. The formation of a bicontinuous cubic phase

Brentel, Ingvar; Selstam, Eva; Lindblom, Göran

doi:10.1016/0005-2736(85)90277-9

Cited by 102 publications

(56 citation statements)

References 50 publications

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“…2 A) and f m,TEMPO (Fig. 3A) was expected in a membrane whose major lipid [MGDG with 18:3͞18:3 acyl chains (8,9)] adapts an inverted hexagonal (H II ) phase under normal conditions (48)(49)(50). However, because f m,TEMPO and sym CH 2 are to increase upon increasing fluidity (16,22), the upward shift in sym CH 2 ( Fig.…”

Section: Discussionmentioning

confidence: 93%

Protein assembly and heat stability in developing thylakoid membranes during greening

Kóta

Horváth

Droppa

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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The development of the thylakoid membrane was studied during illumination of dark-grown barley seedlings by using biochemical methods, and Fourier transform infrared and spin label electron paramagnetic resonance spectroscopic techniques. Correlated, gross changes in the secondary structure of membrane proteins, conformation, composition, and dynamics of lipid acyl chains, SDS͞PAGE pattern, and thermally induced structural alterations show that greening is accompanied with the reorganization of membrane protein assemblies and the protein-lipid interface. Changes in overall membrane fluidity and noncovalent proteinlipid interactions are not monotonic, despite the monotonic accumulation of chlorophyll, LHCII [light-harvesting chlorophyll a͞b-binding (polypeptides) associated with photosystem II] apoproteins, and 18:3 fatty acids that follow a similar time course with highest rates between 12-24 h of greening. The 18:3 fatty acid content increases 2.8-fold during greening. This appears to both compensate for lipid immobilization by membrane proteins and facilitate packing of larger protein assemblies. The increase in the amount of protein-solvating immobile lipids, which reaches a maximum at 12 h, is caused by 40% decrease in the membranous mean diameter of protein assemblies at constant protein͞lipid mass ratio. Alterations in the SDS͞PAGE pattern are most significant between 6 -24 h. The size of membrane protein assemblies increases Ϸ4.5-fold over the 12-48-h period, likely caused by the 2-fold gain in LHCII apoproteins. The thermal stability of thylakoid membrane proteins increases monotonically, as detected by an increasing temperature of partial protein unfolding during greening. Our data suggest that a structural coupling between major protein and lipid components develops during greening. This protein-lipid interaction is required for the development and protection of thylakoid membrane protein assemblies.barley (Hordeum vulgare) ͉ FTIR ͉ photosynthesis ͉ protein-lipid interaction ͉ spin label EPR

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Section: Discussionmentioning

confidence: 93%

Protein assembly and heat stability in developing thylakoid membranes during greening

Kóta

Horváth

Droppa

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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“…1 A and B, was indeed higher for T8 protoplasts (18,33,34, and 31%) than the RLD protoplasts (12,22,22, and 23%). However, the difference in the incidence of EIL between T8 and RLD could be eliminated by increasing the osmolality of the suspending medium in which the protoplasts were isolated and subsequently frozen from 0.400 to 0.413 ( Fig.…”

Section: Resultsmentioning

confidence: 98%

Mode of action of the COR15a gene on the freezing tolerance of Arabidopsis thaliana

Steponkus

Uemura

Joseph

et al. 1998

Proc. Natl. Acad. Sci. U.S.A.

378

252

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Constitutive expression of the cold-regulated COR15a gene of Arabidopsis thaliana results in a significant increase in the survival of isolated protoplasts frozen over the range of ؊4.5 to ؊7°C. The increased freezing tolerance is the result of a decreased incidence of freeze-induced lamellar-tohexagonal II phase transitions that occur in regions where the plasma membrane is brought into close apposition with the chloroplast envelope as a result of freeze-induced dehydration. Moreover, the mature polypeptide encoded by this gene, COR15am, increases the lamellar-to-hexagonal II phase transition temperature of dioleoylphosphatidylethanolamine and promotes formation of the lamellar phase in a lipid mixture composed of the major lipid species that comprise the chloroplast envelope. We propose that COR15am, which is located in the chloroplast stroma, defers freeze-induced formation of the hexagonal II phase to lower temperatures (lower hydrations) by altering the intrinsic curvature of the inner membrane of the chloroplast envelope.The ability to endure low temperatures and freezing is a major determinant of the geographical distribution and productivity of agricultural crops. Even in areas considered suitable for the cultivation of a given species or cultivar, decreases in yield and crop failure frequently occur as a result of aberrant, freezing temperatures. In spite of attempts to minimize damage to freezing-sensitive crops-primarily by using energy-costly practices to modify the microclimate-substantial economic losses resulting from freezing are incurred annually in a diverse array of agricultural crops.Only modest increases (1-2°C) in the freezing tolerance of crop species would have a dramatic impact on agricultural productivity and profitability. The development of genotypes with increased freezing tolerance would provide a more reliable means to minimize crop losses from freezing stresses and greatly diminish the use of energy-costly practices to modify the microclimate. However, there has been little progress in improving the freezing tolerance of crop species by using classical plant breeding approaches. For example, the freezing tolerance of the best wheat varieties today is essentially the same as the most freezing-tolerant varieties developed in the early part of this century (1). Currently, there is considerable interest in the use of genetic engineering techniques for increasing the freezing tolerance of agricultural crop species.Since 1985, when Guy et al.(2) first reported that gene expression is altered during cold acclimation, remarkable progress has been made in identifying an ever-increasing number of genes that are regulated by low temperatures (3, 4). Many of these genes encode hydrophilic polypeptides with little or no homology with previously described polypeptides. These include the COR and LTI genes of Arabidopsis thaliana (5-7), the COR and pao86 genes of barley (8, 9), and the A͞ES genes of alfalfa (10). It is widely speculated that these genes might have roles in freezing tolera...

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“…The presence of H II phase has been detected in the native photosynthetic membranes [5,28] as well as in model systems containing MGDG [29]. Moreover, in mixtures of MGDG and DGDG and in the mixtures of all thylakoid lipids, cubic phase structures are formed [30,31]. In this type of structure, the water forms two independent and interwoven branched channels.…”

Section: Discussionmentioning

confidence: 95%

Maturation Process of Photosynthetic Membranes Observed by Proton Magnetic Relaxation and Sorption Isotherm

et al. 2009

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Mild rehydration from the gaseous phase of the developing and mature lyophilized wheat photosynthetic membranes was investigated using hydration kinetics, adsorption isotherm and high power proton relaxometry. Hydration time courses are single exponential for all target air humidities; the hydration time t h equals to (11.9 ± 3.6) h for the mature membranes, and (17.0 ± 3.2) h for the developing membranes. The sorption isotherm is sigmoidal in form and well fitted using the Dent model; the mass of water saturating primary binding sites equals ∆M/m 0 = 0.033 ± 0.013 and 0.025 ± 0.007 for the mature and for the developing membranes, respectively, where m 0 is the dry mass of the sample, and ∆M is mass of water taken up. Proton free induction decays distinguish: (i) an immobilized proton (Gaussian) component, S 0 , originating from protons of solid matrix of lyophilizate; (ii) a Gaussian component, S 1 , from water bound to the primary water binding sites and localized in proximity of paramagnetic ions; (iii) an exponentially decaying contribution, L 1 , from water tightly bound to lyophilizate surface; and (iv) exponentially decaying loosely bound water pool, L 2 . A significant contribution of water "sealed" in the structure of lyophilized membrane (from the fraction S 1 and L 1 ) is detected. The mass of "sealed" water fraction is ∆M S /m 0 = 0.047 ± 0.023 and 0.072 ± 0.021 for the mature and for the developing membranes, respectively.

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Phase equilibria of mixtures of plant galactolipids. The formation of a bicontinuous cubic phase

Cited by 102 publications

References 50 publications

Protein assembly and heat stability in developing thylakoid membranes during greening

Protein assembly and heat stability in developing thylakoid membranes during greening

Mode of action of the COR15a gene on the freezing tolerance of Arabidopsis thaliana

Maturation Process of Photosynthetic Membranes Observed by Proton Magnetic Relaxation and Sorption Isotherm

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