TY - JOUR
T1 - Self-assembly of large, ordered lamellae from non-bilayer lipids and integral membrane proteins in vitro
AU - Simidjiev, Ilian
AU - Stoylova, Svetla
AU - Amenitsch, Heinz
AU - Jávorfi, Tamás
AU - Mustárdy, László
AU - Laggner, Peter
AU - Holzenburg, Andreas
AU - Garab, Gyozo
PY - 2000/2/15
Y1 - 2000/2/15
N2 - In many biological membranes, the major lipids are 'non-bilayer lipids,' which in purified form cannot be arranged in a lamellar structure. The structural and functional roles of these lipids are poorly understood. This work demonstrates that the in vitro association of the two main components of a membrane, the non-bilayer lipid monogalactosyldiacylglycerol (MGDG) and the chlorophyll-a/b light-harvesting antenna protein of photosystem II (LHCII) of pea thylakoids, leads to the formation of large, ordered lamellar structures: (i) thin-section electron microscopy and circular dichroism spectroscopy reveal that the addition of MGDG induces the transformation of isolated, disordered macroaggregates of LHCII into stacked lamellar aggregates with a long-range chiral order of the complexes; (ii) small-angle x-ray scattering discloses that LHCII perturbs the structure of the pure lipid and destroys the inverted hexagonal phase; and (iii) an analysis of electron micrographs of negatively stained 2D crystals indicates that in MGDG-LHCII the complexes are found in an ordered macroarray. It is proposed that, by limiting the space available for MGDG in the macroaggregate, LHCII inhibits formation of the inverted hexagonal phase of lipids; in thylakoids, a spatial limitation is likely to be imposed by the high concentration of membrane-associated proteins.
AB - In many biological membranes, the major lipids are 'non-bilayer lipids,' which in purified form cannot be arranged in a lamellar structure. The structural and functional roles of these lipids are poorly understood. This work demonstrates that the in vitro association of the two main components of a membrane, the non-bilayer lipid monogalactosyldiacylglycerol (MGDG) and the chlorophyll-a/b light-harvesting antenna protein of photosystem II (LHCII) of pea thylakoids, leads to the formation of large, ordered lamellar structures: (i) thin-section electron microscopy and circular dichroism spectroscopy reveal that the addition of MGDG induces the transformation of isolated, disordered macroaggregates of LHCII into stacked lamellar aggregates with a long-range chiral order of the complexes; (ii) small-angle x-ray scattering discloses that LHCII perturbs the structure of the pure lipid and destroys the inverted hexagonal phase; and (iii) an analysis of electron micrographs of negatively stained 2D crystals indicates that in MGDG-LHCII the complexes are found in an ordered macroarray. It is proposed that, by limiting the space available for MGDG in the macroaggregate, LHCII inhibits formation of the inverted hexagonal phase of lipids; in thylakoids, a spatial limitation is likely to be imposed by the high concentration of membrane-associated proteins.
KW - Chloroplast thylakoid membranes
KW - Circular dichroism
KW - Electron microscopy
KW - Light-harvesting complex
KW - Lipid-protein interactions
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U2 - 10.1073/pnas.97.4.1473
DO - 10.1073/pnas.97.4.1473
M3 - Article
C2 - 10677486
AN - SCOPUS:0034652259
SN - 0027-8424
VL - 97
SP - 1473
EP - 1476
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 4
ER -