Journal article
Cholesterol affects divalent cation-induced fusion and isothermal phase transitions of phospholipid membranes
Biochimica et biophysica acta. Biomembranes, v 946(2), pp 405-416
22 Dec 1988
PMID: 3207754
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
The influence of cholesterol on divalent cation-induced fusion and isothermal phase transitions of large unilamellar vesicles composed of phosphatidylserine (PS) was investigated. Vesicle fusion was monitored by the terbium/dipicolinic acid assay for the intermixing of internal aqueous contents, in the temperature range 10–40°C. The fusogenic activity of the cations decreases in the sequence Ca
2+ > Ba
2+ > Sr
2+ ⪢ Mg
2+ for cholesterol concentrations in the range 20–40 mol%, and at all temperatures. Increasing the cholesterol concentration decreases the initial rate of fusion in the presence of Ca
2+ and Ba
2+ at 25°C, reaching about 50% of the rate for pure PS at a mole fraction of 0.4. From 10 to 25°C, Mg
2+ is ineffective in causing fusion at all cholesterol concentrations. However, at 30°C, Mg
2+-induced fusion is observed with vesicles containing cholesterol. At 40°C, Mg
2+ induces slow fusion of pure PS vesicles, which is enhanced by the presence of cholesterol. Increasing the temperature also causes a monotonic increase in the rate of fusion induced by Ca
2+, Ba
2+ and Sr
2+. The enhancement of the effect of cholesterol at high temperatures suggests that changes in hydrogen bonding and interbilayer hydration forces may be involved in the modulation of fusion by cholesterol. The phase behavior of PS/cholesterol membranes in the presence of Na
+ and divalent cations was studied by differential scanning calorimetry. The temperature of the gel-liquid crystalline transition (
T
m) in Na
+ is lowered as the cholesterol content is increased, and the endotherm is broadened. Addition of divalent cations shifts the
T
m upward, with a sequence of effectiveness Ba
2+ > Sr
2+ > Mg
2+. The
T
m of these complexes decreases as the cholesterol content is increased. Although the transition is not detectable for cholesterol concentrations of 40 and 50 mol% in the presence of Na
+, Sr
2+ or Mg
2+, the addition of Ba
2+ reveals endotherms with
T
m progressively lower than that observed at 30 mol%. Although the presence of cholesterol appears to induce an isothermal gel-liquid crystalline transition by decreasing the
T
m, this change in membrane fluidity does not enhance the rate of fusion, but rather decreases it. The effect of cholesterol on the fusion of PS/phosphatidylethanolamine (PE) vesicles was investigated by utilizing a resonance energy transfer assay for lipid mixing. The initial rate of fusion of PS/PE and PS/PE/cholesterol vesicles is saturated at high Mg
2+ concentrations. With Ca
2+, saturation is not observed for cholesterol-containing vesicles. The highest rate of fusion for both Ca
2+- and Mg
2+-induced fusion is observed with vesicles containing 30 mol% cholesterol.
Metrics
Details
- Title
- Cholesterol affects divalent cation-induced fusion and isothermal phase transitions of phospholipid membranes
- Creators
- Sergei A. Shavnin - University of California, San FranciscoMaria C. Pedroso de Lima - University of California, San FranciscoJane Fedor - Cancer Research InstitutePeriann Wood - Cancer Research InstituteJoe Bentz - University of California, San FranciscoNejat Düzgüneş - University of California, San Francisco
- Publication Details
- Biochimica et biophysica acta. Biomembranes, v 946(2), pp 405-416
- Publisher
- Elsevier
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Biology
- Web of Science ID
- WOS:A1988R693400026
- Scopus ID
- 2-s2.0-0024262811
- Other Identifier
- 991021463422904721
UN Sustainable Development Goals (SDGs)
This publication has contributed to the advancement of the following goals:
InCites Highlights
Data related to this publication, from InCites Benchmarking & Analytics tool:
- Web of Science research areas
- Biochemistry & Molecular Biology
- Biophysics