Fluorescence depolarization studies of phase transitions and fluidity in phospholipid bilayers. 2. Two-component phosphatidylcholine liposomes

Lentz, Barry R.; Barenholz, Yechezkel; Thompson, T. E.

doi:10.1021/bi00665a030

Cited by 504 publications

(294 citation statements)

References 33 publications

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“…It was shown that DOPC and DPPC are not miscible at room temperature (23). As shown above, our imaging study has provided new details about the miscibility.…”

Section: Resultssupporting

confidence: 60%

Coexisting Stripe- and Patch-Shaped Domains in Giant Unilamellar Vesicles

Cheng

2006

Biochemistry

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We report a new type of gel-liquid phase segregation in giant unilamellar vesicles (GUVs) of mixed lipids. Coexisting patch and stripe shaped gel domains in GUV bilayers composed of DOPC/DPPC or DLPC/DPPC are observed by confocal fluorescence microscopy. The lipids in stripe domains are shown to be tilted according to the DiIC18 fluorescence intensity dependence on the excitation polarization. The patch domains are found to be mainly composed of d62-DPPC according to the coherent anti-Stokes Raman scattering (CARS) images of DOPC/d62-DPPC bilayers. When cooling GUVs from above the miscibility temperature, the patch domains start to appear between the chain melting and the pretransition temperature of DPPC. In GUVs containing high molar percentage of DPPC, the stripe domains form below the pretransition temperature. Our observations suggest that the patch and stripe domains are in the P β′ and L β′ gel phases, respectively. According to the thermoelastic properties of GUVs described by Needham and Evans (Biochemistry,27,[8261][8262][8263][8264][8265][8266][8267][8268][8269], the P β′ and L β′ phases are formed at relatively low and high membrane tensions respectively. GUVs with high DPPC percentage have high membrane surface tension and thus mainly exhibit L β′ domains, while GUVs with low DPPC percentage have low membrane surface tension and form P β′ domains accordingly. Adding negatively charged lipid to the lipid mixtures or applying an osmotic pressure to GUVs using sucrose solutions releases the surface tension and leads to the disappearance of L β′ gel phase. The relationship between the observed domains in free-standing GUV bilayers in and those in supported bilayers is discussed.Phase segregation plays important roles in membrane organization and intracellular trafficking (1-5). Phase behavior of lipid mixtures has been extensively studied using different welldefined model membrane systems. GUVs which mimic the plasma membrane with controlled lipid compositions and similar size as cells have been widely used to study the mechanisms of membrane phase segregation, fusion, and fission (6-10). In GUVs composed of a saturated lipid, an unsaturated lipid, and cholesterol, the observation of coexisting ordered and disordered liquid phases below miscibility transition temperature has provided supports for the existence of lipid rafts in cell membranes (11). Despite these advances, the lipid phase behavior in GUVs is far away from being well understood, even for binary lipid mixtures. Patch and stripe shaped domains in GUVs composed of DPPC and another phospholipid have been reported in different papers (7,8,12,13). However, the composition and lipid organization properties of these domains have not been well characterized. The relations between these two types of domains and the different gel phases (P β′ and L β′ ) observed in pure DPPC bilayers are elusive. In addition, the forces that govern the formation of these two types of domains are poorly investigated.To whom correspondence should be addressed....

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“…It was shown that DOPC and DPPC are not miscible at room temperature (23). As shown above, our imaging study has provided new details about the miscibility.…”

Section: Resultssupporting

confidence: 60%

Coexisting Stripe- and Patch-Shaped Domains in Giant Unilamellar Vesicles

Cheng

2006

Biochemistry

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“…In contrast, molecular dynamics (MD) simulations pointed to an increasing diffusion coefficient with increasing vesicles size with the highest value for planar bilayers (7). Other properties, such as fusion rate (18, 23), phase transition temperature (19,24,25), and elasticity (20), have been shown to vary for vesicles of different sizes.NMR studies can provide a great deal of information on bilayer dynamics and order parameters. They have been used to investigate the effect of vesicle curvature on the dynamics of lipid acyl chains.…”

mentioning

confidence: 99%

Size-dependent ultrafast structural dynamics inside phospholipid vesicle bilayers measured with 2D IR vibrational echoes

Kel

Tamimi

Fayer

2014

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

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The ultrafast structural dynamics inside the bilayers of dilauroylphosphatidylcholine (DLPC) and dipalmitoylphosphatidylcholine vesicles with 70, 90, and 125 nm diameters were directly measured with 2D IR vibrational echo spectroscopy. The antisymmetric CO stretch of tungsten hexacarbonyl was used as a vibrational probe and provided information on spectral diffusion (structural dynamics) in the alkyl region of the bilayers. Although the CO stretch absorption spectra remain the same, the interior structural dynamics become faster as the size of the vesicles decrease, with the size dependence greater for dipalmitoylphosphatidylcholine than for DLPC. As DLPC vesicles become larger, the interior dynamics approach those of the planar bilayer.vesicle bilayer dynamics | vesicle size dependent dynamics | vesicles chainlength dependent dynamics T he plasma membrane provides a boundary between a living cell and its surroundings and between cellular compartments, providing organizational control of proteins and small molecules that are critical for achieving the complexity of biological systems. In addition to a permeability barrier, the second role of the plasma membrane is serving as the solvent for membrane proteins and other biomolecules. The lipid environment of membrane proteins can influence their function (1-5), and so impact cell signaling, metabolism, growth, defense, and a myriad of other biological functions.Membranes have a bilayer structure where the nonpolar chains of the lipids form the interior of bilayer, with zwitterionic or ionic head groups at the interfaces with water. Artificial lipid bilayers are frequently used as models of cell membranes for investigation of membrane properties and in studies of transmembrane proteins. Although a good deal is known about the structure of artificial membranes (6-12) and orientational and translational diffusion of lipids and other molecules (7, 13-16), much less is known about the fast interior structural dynamics of the bilayers, which serve as the dynamic bath modes that can impact membrane processes.Unilamellar vesicles (ULVs) of different sizes, as well as multilamellar vesicles (MLVs), are used as model membranes owing to their ease of preparation and handling. It has been shown that their properties depend on the curvature (size) (8,9,13,(17)(18)(19)(20). Aligned planar multi-bilayers (21) are membrane models that do not have curvature, yet they are less attractive for routine use because they are substantially more difficult to prepare than vesicles.Numerous experiments have been performed to determine which type of model bilayers most closely represents the properties of the plasma membrane. However, no consensus exists because the results obtained by different methods and groups are not in agreement. Some small-angle X-ray scattering and small-angle neutron scattering (SANS) experiments indicate that the structural properties of ULVs and MLVs are curvature independent, the overall bilayer thickness does not dependent on vesicle size, and the thicknesses of...

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“…However, in a biological membrane, microenvironments of different dielectric constants could also be formed along the membrane plane due to the presence of cholesterol and protein molecules and to microdomains of specific phospholipid composition. In this respect, DPH is a useful probe, since it partitions equally between fluid and solid environments, insuring a homogeneous distribution in the membrane plane [40]. The DPH lifetime distribution width as a function of temperature in liposomes of extracted phospholipids showed a pattern similar to that of the erythrocyte membrane.…”

Section: Discussionmentioning

confidence: 90%

Fluorescence lifetime distributions of 1,6-diphenyl-1,3,5-hexatriene reveal the effect of cholesterol on the microheterogeneity of erythrocyte membrane

Fiorini

Valentino

Gläser

et al. 1988

Biochimica et Biophysica Acta (BBA) - Biomembranes

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Fluorescence lifetime distributions of 1,6-diphenyl-1,3,5-hexatriene reveal the effect of cholesterol on the microheterogeneity of erythrocyte membrane The fluorescence decay of 1,6 diphenyl-l,3,5-hexatriene (DPH) has been used to characterize aspects of the erythrocyte membrane structure related to the microheterogeneity of the lipid bilayer. The DPH decay has been studied using frequency domain fluorometry and the data analyzed either by a model of discrete exponential components or a model that assumes a continuous distribution of lifetime values. The main intensity fraction was associated with a lifetime value centered at about 11 ns in the erythrocyte membrane, but a short component of very low fractional intensity had to be considered to obtain a good fit to the data. The lifetime value of the long component was insensitive to temperature, while the width of the distribution decreased with increasing temperature. In multilamellar liposomes prepared from phospholipids extracted from the erythrocytes, the long lifetime component showed a temperature dependence. The depletion of 27% of the cholesterol in the erythocyte membrane induced a broadening of the distribution, suggesting a homogenizing effect of cholesterol. This effect has also been detected in egg phosphatidylcholine at a very low cholesterol/phospholipid molar ratio. The role of cholesterol on membrane heterogeneity is discussed in relation to the effect of cholesterol on water penetration.

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Fluorescence depolarization studies of phase transitions and fluidity in phospholipid bilayers. 2. Two-component phosphatidylcholine liposomes

Cited by 504 publications

References 33 publications

Coexisting Stripe- and Patch-Shaped Domains in Giant Unilamellar Vesicles

Coexisting Stripe- and Patch-Shaped Domains in Giant Unilamellar Vesicles

Size-dependent ultrafast structural dynamics inside phospholipid vesicle bilayers measured with 2D IR vibrational echoes

Fluorescence lifetime distributions of 1,6-diphenyl-1,3,5-hexatriene reveal the effect of cholesterol on the microheterogeneity of erythrocyte membrane

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