Structure-Function Relationship of Thermoacidophilic Archaebacterial Membranes

本研究从嗜热嗜酸古细菌Sulfolobus acidocalarius中分离出四醚极性脂质组分E （PLFE）组成脂质体，研究其物理性质。具体目的是确定PLFE脂质体的等温压缩性、热膨胀性、质子渗透率、脂质旋转和侧向扩散。假设是：(i) PLFE脂质体是刚性的，但包装松散；（ii） PLFE极性头基的糖部分对维持古细菌质膜上的pH梯度起着至关重要的作用。荧光探针技术以及化学修饰和高压方法将被采用。这项研究的总体目的是为了更好地了解古细菌膜的结构-功能关系。本研究结果将为今后进一步研究酸碱硫虫膜结合蛋白与PLFE脂质的相互作用奠定坚实的基础。古细菌是一种奇特而非凡的生物。嗜热嗜酸古细菌Sulfolobus acidocalarius的原生栖息地是高温（65-75℃）和酸性（pH 2-3）硫泉。此外，磺胺在生物技术方面也有广泛的应用，尤其是在分子生物学研究中使用其DNA聚合酶和-半乳糖苷酶。此外，由古细菌型脂质制成的脂质体具有显著的热稳定性，这可能在纳米级人工离子通道和膜受体的设计中具有潜在的用途。＊＊＊

9513669 Chong This research is to study physical properties of liposomes composed of the tetraether polar lipid fraction E (PLFE) isolated from thermoacidophilic archaebacteria Sulfolobus acidocaldarius. The specific aims are to determine isothermal compressibility, thermal expansivity, proton permeability, lipid rotational and lateral diffusion of PLFE liposomes. The hypotheses are: (i) PLFE liposomes are rigid but loosely packed and (ii) the sugar moieties at the PLFE polar headgroups play a crucial role for maintaining a pH gradient across the archaebacterial plasma membrane. Fluorescence probe techniques as well as chemical modifications and high pressure methodologies will be employed. %%% The general purpose of this research is to gain a better understanding of the structure-function relationship of the archaebacterial membrane. The results obtained in this research will set a solid basis for the future studies of interactions between Sulfolobus acidocaldarius membrane-bound proteins and PLFE lipids. Archaebacteria are curios and remarkable organisms. The native habitat of the thermoacidophilic archaebacterium Sulfolobus acidocaldarius is hot (65-75 0C) and acidic (pH 2-3) sulfur springs. Besides, Sulfolobus has found wide use in biotechnology, most notably in the use of its DNA polymerase and (-galactosidase for molecular biology research. Also, liposomes made from archaebacteria-type lipids show remarkable thermostability, which may have potential use in the nanoscale design of artificial ion channels and membrane receptors. ***