Interaction of apolipoprotein A-I in three different conformations with palmitoyl oleoyl phosphatidylcholine vesicles

Tricerri, M. Alejandra; Sánchez, Susana A.; Arnulphi, Cristina; Durbin, Diane M.; Gratton, Enrico; Jonas, Ana

doi:10.1016/s0022-2275(20)30160-7

Cited by 35 publications

(17 citation statements)

References 51 publications

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“…No significant change in protein migration was detected in any case, indicating that there is no lipid solubilization from these vesicles. These results are in total agreement with previous experiments performed by our group analyzing the binding of different apoA-I conformations to POPC SUVs and giant unilamellar vesicles (9). Lipid-free apoA-I was neither able to solubilize lipids, as indicated by PAGGE, nor able to change the morphology of the giant vesicles, in clear contrast with the ability of apoA-I to rearrange when reconstituted in small lipid complexes (9).…”

Section: Resultssupporting

confidence: 92%

“…The aim of this work is to understand how the interaction of apoA-I with cell membranes is influenced by the presence of cholesterol. In a previous work we examined, using gel electrophoresis and two-photon fluorescence microscopy, the effect of three distinct conformations of apoA-I on its ability to bind and extract lipids from POPC membrane vesicles (9). We found that apoA-I binds reversibly to the vesicles with high affinity but does not extract significant amounts of lipid nor perturb the vesicle structure under the experimental conditions used.…”

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confidence: 98%

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Enthalpy-Driven Apolipoprotein A-I and Lipid Bilayer Interaction Indicating Protein Penetration upon Lipid Binding

et al. 2004

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The interaction of lipid-free apolipoprotein A-I (apoA-I) with small unilamellar vesicles (SUVs) of 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) with and without free cholesterol (FC) was studied by isothermal titration calorimetry and circular dichroism spectroscopy. Parameters reported are the affinity constant (K(a)), the number of protein molecules bound per vesicle (n), enthalpy change (DeltaH degrees), entropy change (DeltaS degrees ), and the heat capacity change (DeltaC(p) degrees). The binding process of apoA-I to SUVs of POPC plus 0-20% (mole) FC was exothermic between 15 and 37 degrees C studied, accompanied by a small negative entropy change, making enthalpy the main driving force of the interaction. The presence of cholesterol in the vesicles increased the binding affinity and the alpha-helix content of apoA-I but lowered the number of apoA-I bound per vesicle and the enthalpy and entropy changes per bound apoA-I. Binding affinity and stoichiometry were essentially invariant of temperature for binding to SUVs of POPC/FC at a molar ratio of 6/1 at (2.8-4) x 10(6) M(-1) and 2.4 apoA-I molecules bound per vesicle or 1.4 x 10(2) phospholipids per bound apoA-I. A plot of DeltaH degrees against temperature displayed a linear behavior, from which the DeltaC(p) degrees per mole of bound apoA-I was calculated to be -2.73 kcal/(mol x K). These results suggested that binding of apoA-I to POPC vesicles is characterized by nonclassical hydrophobic interactions, with alpha-helix formation as the main driving force for the binding to cholesterol-containing vesicles. In addition, comparison to literature data on peptides suggested a cooperativity of the helices in apoA-I in lipid interaction.

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Section: Resultssupporting

confidence: 92%

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confidence: 98%

Enthalpy-Driven Apolipoprotein A-I and Lipid Bilayer Interaction Indicating Protein Penetration upon Lipid Binding

et al. 2004

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“…In the process of cholesterol esterification by lecithin/cholesterol acyltransferase, the particles acquire an apolar core and undergo transformation to form mature spherical HDLs . Discoidal HDLs are lipid−apoA-I complexes in which two or more apoA-I molecules surround the hydrophobic edge of the lipid bilayer in a beltlike manner. , The reported size of these discs ranges from 7 to 15 nm, depending on the lipid/protein composition. − ApoA-I contains a series of highly homologous 11- and 22-residue amphipathic α-helices, which are responsible for its lipid-associating properties. , In recent years, discoidal complexes have also attracted researchers’ attention as new pharmaceutical applications − or as an attractive alternative protein solubilization system over micelles and vesicles. − …”

Section: Introductionmentioning

confidence: 99%

“…6,7 The reported size of these discs ranges from 7 to 15 nm, depending on the lipid/protein composition. [8][9][10][11] ApoA-I contains a series of highly homologous 11-and 22-residue amphipathic R-helices, which are responsible for its lipid-associating properties. 12,13 In recent years, discoidal complexes have also attracted researchers' attention as new pharmaceutical applications [14][15][16] or as an attractive alternative protein solubilization system over micelles and vesicles.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic and Kinetic Stability of Discoidal High-Density Lipoprotein Formation from Phosphatidylcholine/Apolipoprotein A-I Mixture

et al. 2010

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Nascent high-density lipoproteins (HDLs), which are also known as discoidal HDLs, are formed by the interaction of apolipoprotein A-I (apoA-I) with transmembrane ATP-binding cassette transporter A1 (ABCA1). However, the molecular mechanism governing disc formation is not fully understood. Here, we evaluated the thermodynamic and kinetic stability of disc formation from mixtures of 1-palmitoyl-2-oleoylphosphatidylcholine and apoA-I by quantifying the discs and vesicles produced. Sodium cholate dialysis experiments revealed that the discs are thermodynamically more stable than the vesicle/apoA-I mixture (Delta*G = -52 kJ/disc mol at 37.0 degrees C) because the decrease in enthalpy (Delta*H = -620 kJ/disc mol) exceeds the decrease in entropy (TDelta*S = -570 kJ/disc mol). Circular dichroism spectral measurements ascribed 68% of the decrease in enthalpy during disc formation to the formation of helices in apoA-I. Fluorescence measurements suggested that phospholipids enclosed in the discs are more closely packed than those in the vesicles so that they are entropically destabilized. To determine if the disc could be spontaneously produced from vesicles, we measured the decrease in the turbidity of vesicles in response to the addition of apoA-I. However, the rate of disc formation was very slow, suggesting that the large kinetic barrier against disc formation makes the vesicle/apoA-I mixtures metastable. These results raise the possibility that ABCA1 may act to lower the activation energy, thereby facilitating disc formation.

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“…Activation of the GTPase activity of dynamin II by pure POPC was then shown. Alejandra Tricerri and Ana Jonas 35 from the Biochemistry Department of UIUC complemented standard biochemistry studies such as chromatography and differential calorimetry with two-photon microscopy to show differential binding of apo A-I and two different sizes of HDL particles to POPC vesicles.…”

Section: Applicationsmentioning

confidence: 99%

Lipid−Protein Interactions Revealed by Two-Photon Microscopy and Fluorescence Correlation Spectroscopy

Sánchez

Gratton

2005

Acc. Chem. Res.

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Cellular processes involve a multitude of chemical reactions that must be kept in delicate equilibrium to maintain cellular homeostasis. Powerful biophysical techniques are needed to measure the localization and concentration of target molecules as well as to quantify complex molecular processes in model and in vivo systems. Two-photon microscopy and fluorescence correlation spectroscopy (FCS) can measure association and dynamics of appropriate molecules under equilibrium conditions. FCS provides information on motility (diffusion coefficients), concentration (number of particles), association (molecular brightness), and localization (image) of the target molecules. All of this information, in conjunction with computational modeling techniques, can help us to better understand the network of complex molecular interactions, which are at the basis of cellular processes. Fluorescence imaging techniques add the beauty of visualization to the scientific information. Photons emitted by a fluorescent dye are digitized, and the associated spatial information and intensity can be translated into different colors and shades providing the researcher not only with quantitative intensity information but also with spatial resolution and visual comprehension of two-or threedimensional images. In this Account, we review the use of twophoton excitation microscopy and FCS in the study of lipidprotein interactions. We discuss these new methodologies and techniques, and we present examples of different complexity from qualitative to quantitative, from simple model systems to studies in living cells.

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Interaction of apolipoprotein A-I in three different conformations with palmitoyl oleoyl phosphatidylcholine vesicles

Cited by 35 publications

References 51 publications

Enthalpy-Driven Apolipoprotein A-I and Lipid Bilayer Interaction Indicating Protein Penetration upon Lipid Binding

Enthalpy-Driven Apolipoprotein A-I and Lipid Bilayer Interaction Indicating Protein Penetration upon Lipid Binding

Thermodynamic and Kinetic Stability of Discoidal High-Density Lipoprotein Formation from Phosphatidylcholine/Apolipoprotein A-I Mixture

Lipid−Protein Interactions Revealed by Two-Photon Microscopy and Fluorescence Correlation Spectroscopy

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