On the Miscibility of Cardiolipin with the Major Lipid Components of the Bacterial Inner Membrane

MARIA FRIAS; MATTHEW G. K. BENESCH; RUTHVEN N. A. H.LEWIS; RONALD N. MCELHANEY

San Francisco, Califorrnia

Congreso; 54th Annual Meeting Biophysical Society; 2010

Biophysical Society

Abstract: The thermotropic phase behavior and organization of model membranes derived from binary mixtures of tetramyristoylcardiolipin (TMCL) with dimyristoyl phosphatidylethanolamine (DMPE) and dimyristoyl phosphatidylglycerol (DMPG) were studied by differential scanning calorimetry (DSC) and fourier transform infrared (FTIR) spectroscopy. Cardiolipin-containing DMPE and DMPG model membranes all exhibit complex multi-component hydrocarbon chain-melting (Lâ/Lá) phase transitions upon heating and cooling. This suggests that TMCL is poorly miscible with both DMPE and DMPG and that the domains formed prior to the onset of the Lâ/Lá phase transitions are probably retained in the liquidcrystalline state. For all mixtures, the temperatures of the Lâ/Lá phase transitions are generally higher than those predicted by an ideal mixing of the components, and the enthalpies of these phase transitions seem to be better correlated with the component mol fraction of hydrocarbon chains than with the molar composition of the mixture per se. Finally, when cooled to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. transitions are generally higher than those predicted by an ideal mixing of the components, and the enthalpies of these phase transitions seem to be better correlated with the component mol fraction of hydrocarbon chains than with the molar composition of the mixture per se. Finally, when cooled to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. state. For all mixtures, the temperatures of the Lâ/Lá phase transitions are generally higher than those predicted by an ideal mixing of the components, and the enthalpies of these phase transitions seem to be better correlated with the component mol fraction of hydrocarbon chains than with the molar composition of the mixture per se. Finally, when cooled to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. transitions are generally higher than those predicted by an ideal mixing of the components, and the enthalpies of these phase transitions seem to be better correlated with the component mol fraction of hydrocarbon chains than with the molar composition of the mixture per se. Finally, when cooled to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. transitions upon heating and cooling. This suggests that TMCL is poorly miscible with both DMPE and DMPG and that the domains formed prior to the onset of the Lâ/Lá phase transitions are probably retained in the liquidcrystalline state. For all mixtures, the temperatures of the Lâ/Lá phase transitions are generally higher than those predicted by an ideal mixing of the components, and the enthalpies of these phase transitions seem to be better correlated with the component mol fraction of hydrocarbon chains than with the molar composition of the mixture per se. Finally, when cooled to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. transitions are generally higher than those predicted by an ideal mixing of the components, and the enthalpies of these phase transitions seem to be better correlated with the component mol fraction of hydrocarbon chains than with the molar composition of the mixture per se. Finally, when cooled to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. state. For all mixtures, the temperatures of the Lâ/Lá phase transitions are generally higher than those predicted by an ideal mixing of the components, and the enthalpies of these phase transitions seem to be better correlated with the component mol fraction of hydrocarbon chains than with the molar composition of the mixture per se. Finally, when cooled to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. transitions are generally higher than those predicted by an ideal mixing of the components, and the enthalpies of these phase transitions seem to be better correlated with the component mol fraction of hydrocarbon chains than with the molar composition of the mixture per se. Finally, when cooled to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. â/Lá) phase transitions upon heating and cooling. This suggests that TMCL is poorly miscible with both DMPE and DMPG and that the domains formed prior to the onset of the Lâ/Lá phase transitions are probably retained in the liquidcrystalline state. For all mixtures, the temperatures of the Lâ/Lá phase transitions are generally higher than those predicted by an ideal mixing of the components, and the enthalpies of these phase transitions seem to be better correlated with the component mol fraction of hydrocarbon chains than with the molar composition of the mixture per se. Finally, when cooled to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. transitions are generally higher than those predicted by an ideal mixing of the components, and the enthalpies of these phase transitions seem to be better correlated with the component mol fraction of hydrocarbon chains than with the molar composition of the mixture per se. Finally, when cooled to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. state. For all mixtures, the temperatures of the Lâ/Lá phase transitions are generally higher than those predicted by an ideal mixing of the components, and the enthalpies of these phase transitions seem to be better correlated with the component mol fraction of hydrocarbon chains than with the molar composition of the mixture per se. Finally, when cooled to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. transitions are generally higher than those predicted by an ideal mixing of the components, and the enthalpies of these phase transitions seem to be better correlated with the component mol fraction of hydrocarbon chains than with the molar composition of the mixture per se. Finally, when cooled to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. â/Lá phase transitions are probably retained in the liquidcrystalline state. For all mixtures, the temperatures of the Lâ/Lá phase transitions are generally higher than those predicted by an ideal mixing of the components, and the enthalpies of these phase transitions seem to be better correlated with the component mol fraction of hydrocarbon chains than with the molar composition of the mixture per se. Finally, when cooled to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. transitions are generally higher than those predicted by an ideal mixing of the components, and the enthalpies of these phase transitions seem to be better correlated with the component mol fraction of hydrocarbon chains than with the molar composition of the mixture per se. Finally, when cooled to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. â/Lá phase transitions are generally higher than those predicted by an ideal mixing of the components, and the enthalpies of these phase transitions seem to be better correlated with the component mol fraction of hydrocarbon chains than with the molar composition of the mixture per se. Finally, when cooled to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications. per se. Finally, when cooled to low temperatures, cardiolipin-rich (i.e., > 30 mol % TMCL) membranes tend to form lamellar-crystalline phases which exhibit spectroscopic characteristics comparable to those exhibited by the lamellar crystalline phases of pure cardiolipin. Together, our experimental observations indicate that cardiolipin is poorly miscible with major lipid components of one of the biological membrane systems (Escherichia coli) in which it occurs naturally. The possibility that it may also be poorly miscible in the biologically relevant liquid-crystalline phase also has interesting structural and functional implications.