Acyl Chain Disorder and Azelaoyl Orientation in Lipid Membranes Containing Oxidized Lipids

Ferreira, Tiago Mendes; Sood, Rohit; Bärenwald, Ruth; Carlström, Göran; Topgaard, Daniel; Saalwächter, Kay; Kinnunen, Paavo K.J.; Ollila, O. H. Samuli

doi:10.1021/acs.langmuir.6b00788

Cited by 24 publications

(22 citation statements)

References 81 publications

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“…Fig. S3 and references 20 , 23 , 36 , 43 – 49 ). The carbons of the crowded spectral region at 29–31 ppm were assigned having the previous assignment for 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) by Ferreira et al .…”

Section: Methodsmentioning

confidence: 99%

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Cholesterol-like effects of a fluorotelomer alcohol incorporated in phospholipid membranes

Jbeily

Bärenwald

Kreßler

et al. 2018

Sci Rep

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Fluorocarbon amphiphiles are anthropogenic substances widely used in diverse applications such as food packaging, clothing or cookware. Due to their widespread use and non-biodegradability, these chemicals are now ubiquitous in the natural world with high propensity to bioaccumulate in biological membranes, wherein they may affect microscopic properties. Here, we test the hypothesis that a typical fluorocarbon amphiphile can affect lipid membranes similarly to cholesterol by investigating the effect of 1H,1H,2H,2H-perfluoro-1-decanol (8:2 FTOH) on 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) membranes. Using solid-state nuclear magnetic resonance spectroscopy, differential scanning calorimetry and confocal microscopy, we present a consistent set of independent experimental evidences supporting this hypothesis, namely that upon incorporation of 8:2 FTOH, (i) a condensing effect on the acyl chains occurs in the fluid phase, (ii) coexistence of two membrane phases is observed below melting, and (iii) the melting temperature of DPPC varies no more than approximately ±1 °C up to a concentration of 40 mol% of 8:2 FTOH. The condensing effect is quantified by means of advanced dipolar recoupling solid-state NMR experiments and is found to be of approximately half the magnitude of the cholesterol effect at the same concentration.

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Section: Methodsmentioning

confidence: 99%

“…ref. 20 ). It was also suggested that highly fluorinated alcohols such as CF 3 (CF 2 ) 7 (CH 2 ) 5 OH (8:5 FTOH) may have similar properties to cholesterol in 1,2-dipalmitoyl- sn -glycero-3-phosphocholine (DPPC) monolayers 21 .…”

Section: Introductionmentioning

confidence: 99%

Cholesterol-like effects of a fluorotelomer alcohol incorporated in phospholipid membranes

Jbeily

Bärenwald

Kreßler

et al. 2018

Sci Rep

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“…36,37 In this study, we investigate how polymer structure dictates the polymer-lipid membrane association by quantitative measurements of polymer binding via pulsed-field-gradient NMR (PFG-NMR). Liposomes, or more specifically, large unilamellar vesicles (LUVs), were used as the model membrane system.…”

Section: Introductionmentioning

confidence: 99%

Quantifying Binding of Ethylene Oxide–Propylene Oxide Block Copolymers with Lipid Bilayers

et al. 2017

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Block copolymers composed of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) have been widely used in cell membrane stabilization and permeabilization. To explore the mechanism of interaction between PPO-PEO block copolymers and lipid membranes, we have investigated how polymer structure influences the polymer-lipid bilayer association by varying the overall molecular weight, the hydrophobic and hydrophilic block lengths, and the endgroup structure systematically, using 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) unilamellar liposomes as model membranes. Pulsed-field-gradient NMR (PFG-NMR) was employed to probe polymer diffusion in the absence and presence of liposomes. The echo decay curves of free polymers in the absence of liposomes are single exponentials, indicative of simple translational diffusion, while in the presence of liposomes, the decays were biexponential, with the slower decay corresponding to polymers bound to liposomes. The binding percentage of polymer to the liposome was quantified by fitting the echo decay curves to a biexponential model. The NMR experiments showed that increasing the total molecular weight and hydrophobicity of the polymer can significantly enhance the polymer-lipid bilayer association, as the binding percentage and liposome surface coverage both increase. We hypothesize that the hydrophobic PPO block inserts into the lipid bilayer, due to the fact that little molecular exchange between bound and free polymers occurs on the time scale of the diffusion experiments. Additionally, as polymer concentration increases, the liposome surface coverage increases and approaches a limit. These results demonstrate that PFG-NMR is a simple yet powerful method to quantify interactions between polymers and lipid bilayers.

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“…5; (29)). These assays also showed that the types of OxPl species present in the membrane strongly affect this process and that the effect of PoxnoPC (which has an aldehyde group at its sn-2 chain) opposes that of OxPls with carboxylic sn-2 moieties (29,55). This in turn indicates that the perturbation of membrane organization resulting from OxPl formation in vivo is one of the most important factors governing Bax translocation to the mitochondrial membrane, and that the subsequent membrane perforation process is controlled by the specific types of OxPl that are generated.…”

Section: Dynamic Organization Of the Membrane Interfacementioning

confidence: 91%

Apoptotic Bax at Oxidatively Stressed Mitochondrial Membranes: Lipid Dynamics and Permeabilization

Dingeldein

Pokorná

Lidman

et al. 2017

Biophysical Journal

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Mitochondria are crucial compartments of eukaryotic cells because they function as the cellular power plant and play a central role in the early stages of programmed cell death (apoptosis). To avoid undesired cell death, this apoptotic pathway is tightly regulated by members of the Bcl-2 protein family, which interact on the external surface of the mitochondria, i.e., the mitochondrial outer membrane (MOM), and modulate its permeability to apoptotic factors, controlling their release into the cytosol. A growing body of evidence suggests that the MOM lipids play active roles in this permeabilization process. In particular, oxidized phospholipids (OxPls) formed under intracellular stress seem to directly induce apoptotic activity at the MOM. Here we show that the process of MOM pore formation is sensitive to the type of OxPls species that are generated. We created MOM-mimicking liposome systems, which resemble the cellular situation before apoptosis and upon triggering of oxidative stress conditions. These vesicles were studied using P solid-state magic-angle-spinning nuclear magnetic resonance spectroscopy and differential scanning calorimetry, together with dye leakage assays. Direct polarization and cross-polarization nuclear magnetic resonance experiments enabled us to probe the heterogeneity of these membranes and their associated molecular dynamics. The addition of apoptotic Bax protein to OxPls-containing vesicles drastically changed the membranes' dynamic behavior, almost completely negating the previously observed effect of temperature on the lipids' molecular dynamics and inducing an ordering effect that led to more cooperative membrane melting. Our results support the hypothesis that the mitochondrion-specific lipid cardiolipin functions as a first contact site for Bax during its translocation to the MOM in the onset of apoptosis. In addition, dye leakage assays revealed that different OxPls species in the MOM-mimicking vesicles can have opposing effects on Bax pore formation.

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Acyl Chain Disorder and Azelaoyl Orientation in Lipid Membranes Containing Oxidized Lipids

Cited by 24 publications

References 81 publications

Cholesterol-like effects of a fluorotelomer alcohol incorporated in phospholipid membranes

Cholesterol-like effects of a fluorotelomer alcohol incorporated in phospholipid membranes

Quantifying Binding of Ethylene Oxide–Propylene Oxide Block Copolymers with Lipid Bilayers

Apoptotic Bax at Oxidatively Stressed Mitochondrial Membranes: Lipid Dynamics and Permeabilization

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