Effect of Triton X-100 on Raft-Like Lipid Mixtures: Phase Separation and Selective Solubilization

Effect of Triton X-100 on Raft-Like Lipid Mixtures: Phase Separation and Selective Solubilization

Author Carita, Amanda Autor UNIFESP Google Scholar
Autor UNIFESP Google Scholar
Domingues, Cleyton C. Google Scholar
de Paula, Eneida Google Scholar
Riske, Karin A. Autor UNIFESP Google Scholar
Abstract Under certain conditions, biological membranes exhibit resistance to solubilization, even at high detergent concentration. These insoluble fragments are enriched in sphingolipids, cholesterol, and certain proteins having a preference for more organized environments. Here we investigated the effect of detergent Triton X-100 (TX-100) on raft-like lipid mixtures composed of POPC (palmitoyl oleoyl phosphatidylcholine, an unsaturated lipid), SM (sphingomyelin, a saturated lipid), and cholesterol, focusing on the detergent-induced phase separation at subsolubilizing concentration and the extent of solubilization at higher concentration. Giant unilamellar vesicles (GUVs) of POPC/SM/chol containing a fluorescent probe known to prefer the liquid-disordered phase were prepared and observed with fluorescence microscopy. A phase diagram constructed in the presence and absence of 0.1 mM TX-100 showed that the detergent induces macroscopic liquid-ordered/liquid-disordered (Lo/Ld) phase separation over a wide range of membrane composition, indicating that TX-100 has the ability to rearrange the lateral heterogeneity of the lipid mixture. The extent of solubilization of the POPC/SM/chol GUVs was quantified by measuring the vesicle size before and after the injection of a high concentration of TX-100. In parallel, the solubilization extent of large unilamellar vesicles (LUVs) was assessed by turbidity measurements. The extent of solubilization decreases significantly as the fractions of SM and cholesterol in the mixture increase. The origin of the detergent resistance is the low partitioning of TX-100 in cholesterol-rich membranes, especially in SM-containing ones, as evidenced by isothermal titration calorimetry experiments on LUVs. Our results provide a guide to future research on the effects of TX-100 on raft-like lipid mixtures.
xmlui.dri2xhtml.METS-1.0.item-coverage Washington
Language English
Sponsor FAPESP
Grant number FAPESP
Date 2017
Published in Langmuir. Washington, v. 33, n. 29, p. 7312-7321, 2017.
ISSN 0743-7463 (Sherpa/Romeo, impact factor)
Publisher Amer Chemical Soc
Extent 7312-7321
Origin http://dx.doi.org/10.1021/acs.langmuir.7b01134
Type Article
Web of Science ID WOS:000406573400013
URI https://repositorio.unifesp.br/handle/11600/53435

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