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Lipid polymorphism in chloroplast thylakoid membranes - as revealed by 31P-NMR and time-resolved merocyanine fluorescence spectroscopy.


ABSTRACT: Chloroplast thylakoid membranes contain virtually all components of the energy-converting photosynthetic machinery. Their energized state, driving ATP synthesis, is enabled by the bilayer organization of the membrane. However, their most abundant lipid species is a non-bilayer-forming lipid, monogalactosyl-diacylglycerol; the role of lipid polymorphism in these membranes is poorly understood. Earlier 31P-NMR experiments revealed the coexistence of a bilayer and a non-bilayer, isotropic lipid phase in spinach thylakoids. Packing of lipid molecules, tested by fluorescence spectroscopy of the lipophilic dye, merocyanine-540 (MC540), also displayed heterogeneity. Now, our 31P-NMR experiments on spinach thylakoids uncover the presence of a bilayer and three non-bilayer lipid phases; time-resolved fluorescence spectroscopy of MC540 also reveals the presence of multiple lipidic environments. It is also shown by 31P-NMR that: (i) some lipid phases are sensitive to the osmolarity and ionic strength of the medium, (ii) a lipid phase can be modulated by catalytic hydrogenation of fatty acids and (iii) a marked increase of one of the non-bilayer phases upon lowering the pH of the medium is observed. These data provide additional experimental evidence for the polymorphism of lipid phases in thylakoids and suggest that non-bilayer phases play an active role in the structural dynamics of thylakoid membranes.

SUBMITTER: Garab G 

PROVIDER: S-EPMC5645462 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

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Lipid polymorphism in chloroplast thylakoid membranes - as revealed by <sup>31</sup>P-NMR and time-resolved merocyanine fluorescence spectroscopy.

Garab Győző G   Ughy Bettina B   Waard Pieter de P   Akhtar Parveen P   Javornik Uroš U   Kotakis Christos C   Šket Primož P   Karlický Václav V   Materová Zuzana Z   Špunda Vladimír V   Plavec Janez J   van Amerongen Herbert H   Vígh László L   As Henk Van HV   Lambrev Petar H PH  

Scientific reports 20171017 1


Chloroplast thylakoid membranes contain virtually all components of the energy-converting photosynthetic machinery. Their energized state, driving ATP synthesis, is enabled by the bilayer organization of the membrane. However, their most abundant lipid species is a non-bilayer-forming lipid, monogalactosyl-diacylglycerol; the role of lipid polymorphism in these membranes is poorly understood. Earlier <sup>31</sup>P-NMR experiments revealed the coexistence of a bilayer and a non-bilayer, isotropi  ...[more]

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