Structure-Function Relationship of Thermoacidophilic Archaebacterial Membranes

9513669本研究旨在研究嗜热嗜酸古细菌硫化叶菌（Sulfolobus acidocaldarius）四醚极性脂质组分E（PLFE）脂质体的物理性质。 具体的目的是确定PLFE脂质体的等温压缩性，热膨胀性，质子渗透性，脂质旋转和侧向扩散。 假设是：（i）PLFE脂质体是刚性的但松散地堆积，以及（ii）PLFE极性头基处的糖部分对于维持跨古细菌质膜的pH梯度起着至关重要的作用。 将采用荧光探针技术以及化学修饰和高压方法。 本研究的总体目的是更好地了解古细菌膜的结构-功能关系。 本研究结果为进一步研究酸热硫化叶菌膜结合蛋白与PLFE脂质的相互作用奠定了基础。 古细菌是一种奇特的生物。 嗜热嗜酸古细菌酸热硫化叶菌（Sulfolobus acidocaldarius）的原生栖息地是高温（65-75 ℃）和酸性（pH 2-3）的硫磺泉。 此外，硫化叶菌在生物技术中也有广泛的用途，最显著的是利用其DNA聚合酶和β-半乳糖苷酶进行分子生物学研究。 此外，由古细菌型脂质制成的脂质体显示出显著的热稳定性，这可能在人工离子通道和膜受体的纳米级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. ***