Phase behavior of phosphatidylglycerol in spinach thylakoid membranes as revealed by 31P-NMR

S.K.B. Krumova, C. Dijkema, P. de Waard, H. van As, G. Garab, H. van Amerongen

Research output: Contribution to journalArticleAcademicpeer-review

32 Citations (Scopus)

Abstract

Non-bilayer lipids account for about half of the total lipid content in chloroplast thylakoid membranes. This lends high propensity of the thylakoid lipid mixture to participate in different phases which might be functionally required. It is for instance known that the chloroplast enzyme violaxanthin de-epoxidase (VDE) requires a non-bilayer phase for proper functioning in vitro but direct evidence for the presence of non-bilayer lipid structures in thylakoid membranes under physiological conditions is still missing. In this work, we used phosphatidylglycerol (PG) as an intrinsic bulk lipid label for 31P-NMR studies to monitor lipid phases of thylakoid membranes. We show that in intact thylakoid membranes the characteristic lamellar signal is observed only below 20 °C. But at the same time an isotropic phase is present, which becomes even dominant between 14 and 28 °C despite the presence of fully functional large membrane sheets that are capable of generating and maintaining a transmembrane electric field. Tris-washed membranes show a similar behavior but the lamellar phase is present up to higher temperatures. Thus, our data show that the location of the phospholipids is not restricted to the bilayer phase and that the lamellar phase co-exists with a non-bilayer isotropic phase.
Original languageEnglish
Pages (from-to)997-1003
JournalBiochimica et Biophysica Acta. Biomembranes
Volume1778
Issue number4
DOIs
Publication statusPublished - 2008

Keywords

  • violaxanthin de-epoxidase
  • photosystem-ii
  • photosynthetic membranes
  • structural flexibility
  • lipid polymorphism
  • nonbilayer lipids
  • protein complexes
  • deepoxidation
  • temperature
  • particles

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