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. 2000 Jul;79(1):416–425. doi: 10.1016/S0006-3495(00)76303-X

Two-photon fluorescence microscopy studies of bipolar tetraether giant liposomes from thermoacidophilic archaebacteria Sulfolobus acidocaldarius.

L Bagatolli 1, E Gratton 1, T K Khan 1, P L Chong 1
PMCID: PMC1300945  PMID: 10866967

Abstract

The effects of temperature and pH on Laurdan (6-lauroyl-2-(dimethylamino)naphthalene) fluorescence intensity images of giant unilamellar vesicles (GUVs) ( approximately 20-150 microm in diameter) composed of the polar lipid fraction E (PLFE) from the thermoacidophilic archaebacteria Sulfolobus acidocaldarius have been studied using two-photon excitation. PLFE GUVs made by the electroformation method were stable and well suited for microscopy studies. The generalized polarization (GP) of Laurdan fluorescence in the center cross section of the vesicles has been determined as a function of temperature at pH 7.23 and pH 2.68. At all of the temperatures and pHs examined, the GP values are low (below or close to 0), and the GP histograms show a broad distribution width (> 0.3). When excited with light polarized in the y direction, Laurdan fluorescence in the center cross section of the PLFE GUVs exhibits a photoselection effect showing much higher intensities in the x direction of the vesicles, a result opposite that previously obtained on monopolar diester phospholipids. This result indicates that the chromophore of Laurdan in PLFE GUVs is aligned parallel to the membrane surface. The x direction photoselection effect and the low GP values lead us to further propose that the Laurdan chromophore resides in the polar headgroup region of the PLFE liposomes, while the lauroyl tail inserts into the hydrocarbon core of the membrane. This unusual L-shaped disposition is presumably caused by the unique lipid structures and by the rigid and tight membrane packing in PLFE liposomes. The GP exhibited, at both pH values, a small but abrupt decrease near 50 degrees C, suggesting a conformational change in the polar headgroups of PLFE. This transition temperature fully agrees with the d-spacing data recently measured by small-angle x-ray diffraction and with the pyrene-labeled phosphatidylcholine and perylene fluorescence data previously obtained from PLFE multilamellar vesicles. Interestingly, the two-photon Laurdan fluorescence images showed snowflake-like lipid domains in PLFE GUVs at pH 7.23 and low temperatures (<20 degrees C in the cooling scan and <24 degrees C in the heating scan). These domains, attributable to lipid lateral separation, were stable and laterally immobile at low temperatures (<23 degrees C), again suggesting tight membrane packing in the PLFE GUVs.

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Selected References

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  1. Bagatolli L. A., Gratton E., Fidelio G. D. Water dynamics in glycosphingolipid aggregates studied by LAURDAN fluorescence. Biophys J. 1998 Jul;75(1):331–341. doi: 10.1016/S0006-3495(98)77517-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bagatolli L. A., Gratton E. Two photon fluorescence microscopy of coexisting lipid domains in giant unilamellar vesicles of binary phospholipid mixtures. Biophys J. 2000 Jan;78(1):290–305. doi: 10.1016/S0006-3495(00)76592-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Bagatolli L. A., Gratton E. Two-photon fluorescence microscopy observation of shape changes at the phase transition in phospholipid giant unilamellar vesicles. Biophys J. 1999 Oct;77(4):2090–2101. doi: 10.1016/S0006-3495(99)77050-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Bagatolli L. A., Parasassi T., Fidelio G. D., Gratton E. A model for the interaction of 6-lauroyl-2-(N,N-dimethylamino)naphthalene with lipid environments: implications for spectral properties. Photochem Photobiol. 1999 Oct;70(4):557–564. [PubMed] [Google Scholar]
  5. Chang E. L. Unusual thermal stability of liposomes made from bipolar tetraether lipids. Biochem Biophys Res Commun. 1994 Jul 29;202(2):673–679. doi: 10.1006/bbrc.1994.1983. [DOI] [PubMed] [Google Scholar]
  6. Chong P. L., Wong P. T. Interactions of Laurdan with phosphatidylcholine liposomes: a high pressure FTIR study. Biochim Biophys Acta. 1993 Jul 4;1149(2):260–266. doi: 10.1016/0005-2736(93)90209-i. [DOI] [PubMed] [Google Scholar]
  7. Choquet C. G., Patel G. B., Beveridge T. J., Sprott G. D. Stability of pressure-extruded liposomes made from archaeobacterial ether lipids. Appl Microbiol Biotechnol. 1994 Nov;42(2-3):375–384. doi: 10.1007/BF00902745. [DOI] [PubMed] [Google Scholar]
  8. De Rosa M., Gambacorta A., Gliozzi A. Structure, biosynthesis, and physicochemical properties of archaebacterial lipids. Microbiol Rev. 1986 Mar;50(1):70–80. doi: 10.1128/mr.50.1.70-80.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. De Rosa M., Gambacorta A. The lipids of archaebacteria. Prog Lipid Res. 1988;27(3):153–175. doi: 10.1016/0163-7827(88)90011-2. [DOI] [PubMed] [Google Scholar]
  10. Elferink M. G., De Wit J. G., Driessen A. J., Konings W. N. Energy-transducing properties of primary proton pumps reconstituted into archaeal bipolar lipid vesicles. Eur J Biochem. 1993 Jun 15;214(3):917–925. doi: 10.1111/j.1432-1033.1993.tb17995.x. [DOI] [PubMed] [Google Scholar]
  11. Elferink M. G., de Wit J. G., Demel R., Driessen A. J., Konings W. N. Functional reconstitution of membrane proteins in monolayer liposomes from bipolar lipids of Sulfolobus acidocaldarius. J Biol Chem. 1992 Jan 15;267(2):1375–1381. [PubMed] [Google Scholar]
  12. Elferink M. G., de Wit J. G., Driessen A. J., Konings W. N. Stability and proton-permeability of liposomes composed of archaeal tetraether lipids. Biochim Biophys Acta. 1994 Aug 3;1193(2):247–254. doi: 10.1016/0005-2736(94)90160-0. [DOI] [PubMed] [Google Scholar]
  13. Gabriel J. L., Chong P. L. Molecular modeling of archaebacterial bipolar tetraether lipid membranes. Chem Phys Lipids. 2000 Apr;105(2):193–200. doi: 10.1016/s0009-3084(00)00126-2. [DOI] [PubMed] [Google Scholar]
  14. In't Veld G., Elferink M. G., Driessen A. J., Konings W. N. Reconstitution of the leucine transport system of Lactococcus lactis into liposomes composed of membrane-spanning lipids from Sulfolobus acidocaldarius. Biochemistry. 1992 Dec 15;31(49):12493–12499. doi: 10.1021/bi00164a028. [DOI] [PubMed] [Google Scholar]
  15. Jarrell H. C., Zukotynski K. A., Sprott G. D. Lateral diffusion of the total polar lipids from Thermoplasma acidophilum in multilamellar liposomes. Biochim Biophys Acta. 1998 Mar 2;1369(2):259–266. doi: 10.1016/s0005-2736(97)00228-9. [DOI] [PubMed] [Google Scholar]
  16. Kao Y. L., Chang E. L., Chong P. L. Unusual pressure dependence of the lateral motion of pyrene-labeled phosphatidylcholine in bipolar lipid vesicles. Biochem Biophys Res Commun. 1992 Nov 16;188(3):1241–1246. doi: 10.1016/0006-291x(92)91364-v. [DOI] [PubMed] [Google Scholar]
  17. Khan T. K., Chong P. L. Studies of archaebacterial bipolar tetraether liposomes by perylene fluorescence. Biophys J. 2000 Mar;78(3):1390–1399. doi: 10.1016/S0006-3495(00)76692-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Komatsu H., Chong P. L. Low permeability of liposomal membranes composed of bipolar tetraether lipids from thermoacidophilic archaebacterium Sulfolobus acidocaldarius. Biochemistry. 1998 Jan 6;37(1):107–115. doi: 10.1021/bi972163e. [DOI] [PubMed] [Google Scholar]
  19. Lo S. L., Chang E. L. Purification and characterization of a liposomal-forming tetraether lipid fraction. Biochem Biophys Res Commun. 1990 Feb 28;167(1):238–243. doi: 10.1016/0006-291x(90)91756-i. [DOI] [PubMed] [Google Scholar]
  20. Parasassi T., De Stasio G., Ravagnan G., Rusch R. M., Gratton E. Quantitation of lipid phases in phospholipid vesicles by the generalized polarization of Laurdan fluorescence. Biophys J. 1991 Jul;60(1):179–189. doi: 10.1016/S0006-3495(91)82041-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Parasassi T., De Stasio G., d'Ubaldo A., Gratton E. Phase fluctuation in phospholipid membranes revealed by Laurdan fluorescence. Biophys J. 1990 Jun;57(6):1179–1186. doi: 10.1016/S0006-3495(90)82637-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Parasassi T., Gratton E., Yu W. M., Wilson P., Levi M. Two-photon fluorescence microscopy of laurdan generalized polarization domains in model and natural membranes. Biophys J. 1997 Jun;72(6):2413–2429. doi: 10.1016/S0006-3495(97)78887-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Tomioka K., Kii F., Fukuda H., Katoh S. Homogeneous immunoassay of antibody by use of liposomes made of a model lipid of archaebacteria. J Immunol Methods. 1994 Nov 10;176(1):1–7. doi: 10.1016/0022-1759(94)90345-x. [DOI] [PubMed] [Google Scholar]
  24. Weber G., Farris F. J. Synthesis and spectral properties of a hydrophobic fluorescent probe: 6-propionyl-2-(dimethylamino)naphthalene. Biochemistry. 1979 Jul 10;18(14):3075–3078. doi: 10.1021/bi00581a025. [DOI] [PubMed] [Google Scholar]
  25. Yu W., So P. T., French T., Gratton E. Fluorescence generalized polarization of cell membranes: a two-photon scanning microscopy approach. Biophys J. 1996 Feb;70(2):626–636. doi: 10.1016/S0006-3495(96)79646-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Zeng J., Chong P. L. Effect of ethanol-induced lipid interdigitation on the membrane solubility of Prodan, Acdan, and Laurdan. Biophys J. 1995 Feb;68(2):567–573. doi: 10.1016/S0006-3495(95)80218-3. [DOI] [PMC free article] [PubMed] [Google Scholar]

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