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Molecular Assembly of Protein with Liquid-Liquid Phase Separation : Structure, Mechanism, and Function of Elastic Fiber Protein Aggregates

液-液相分离蛋白质分子组装：弹性纤维蛋白质聚集体的结构、机制和功能

基本信息

批准号：
02804031
负责人：
KAIBARA Kozue
金额：
$ 1.22万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

The essential and key step for the biosynthesis of elastic fiber protein is a self-assembly process of tropoelastin, biogenic precursor protein of elastin. Multiple functions of elastin as an extracellular matrix are derived from the molecular structures established during these 'molecular aggregation process. These important biological processes in the extracellular space are equivalent to the temperature-dependent coacervation of soluble elastin-related peptides. In the present research project, structure, mechanism, and function of elastin coacervate composed of a-elastin or synthetic model polypeptide were investigated.(1)Examination of the liquid-liquid phase separation of elastin water system.Turbidity measurements were employed to survey primarily the characteristics of temperature-dependent coacervation of elastin peptides. Static and dynamic light scattering experiments were also carried out to further investigate the early stage of molecular assembly process. It was shown that the elastin coacervate formation process was affected specifically by metal cations.(2)Elastin coacervate as a protein liquid membrane.Macrocoacervate layer of elastin peptides was stable enough to utilize as a liquid ion-exchange membrane. Selective and specific transport processes for Ca^<2+> ions were observed. It was also demonstrated that the present system is useful to investigate the interactions between protein and metal cations.(3)Structure, mechanism, and function of elastin coacervate.Selective interactions of Ca^<2+> ions with pentapeptide, Val-Pro-Gly-Val-Gly, backbone were observed in a variety of measurements including CD and NMR sppectroscopy. It was suggested that the fundamental molecular structure responsible to generate elastomeric function of elastin is inevitably subjected to selective interaction of Ca^<2+>.

弹性蛋白的生物前体蛋白原弹性蛋白的自组装过程是弹性纤维蛋白生物合成的关键步骤。弹性蛋白作为细胞外基质的多种功能来自于在这些分子聚集过程中建立的分子结构。这些在细胞外空间的重要生物过程相当于可溶弹性蛋白相关多肽的温度依赖凝聚。本研究对由α-弹性蛋白或合成模型多肽组成的弹性蛋白凝聚体的结构、机理和功能进行了研究。(1)弹性蛋白水体系液-液分离的考察。为了进一步研究分子组装过程的早期阶段，还进行了静态和动态光散射实验。结果表明，弹性蛋白凝聚体的形成过程受金属离子的特异性影响。(2)弹性蛋白凝聚体是一种蛋白质液膜，弹性蛋白多肽的大凝聚层足够稳定，可以作为液体离子交换膜使用。观察到了Ca~(2+)~(2+)和Gt~(2+)选择性和特异性的输运过程。(3)弹性蛋白凝聚体的结构、机理和功能。通过CD和核磁共振波谱等多种测量手段，观察到Ca~(2+)~(2+)和Gt~(2+)离子与五肽、Val-Pro-Gly-Val-Gly、骨架的选择性相互作用。结果表明，决定弹性蛋白弹性功能的基本分子结构不可避免地受到Ca~(2+)和~(2+)的选择性作用。