CRYSTALLOGRAPHIC STUDIES OF TRANSPORT PROTEINS FROM ESCHERICHIA COLI

这个子项目的目标是提纯足够量的两个 大肠埃希氏菌的内源性膜蛋白--OmpA蛋白 外膜和多亚单位麦芽糖转运体复合体 内，细胞膜，并进行电子 这些膜蛋白的结晶学研究。选择了OmpA 因为它属于一个新的蛋白家族，有着异常低的 渗透性，这种特性的结构基础是完全未知的。 对该蛋白的通道结构的阐明有望 帮助设计更好的化疗药物，这样会更有效 针对铜绿假单胞菌，这是机会主义的主要来源 感染，因为它有OmpA同源物，一种低渗透性的孔蛋白，如 它的主要角色是。之所以选择麦芽糖转运体复合体，是因为 是广泛传播的运输者家族中研究最深入的成员之一 ABC(“三磷酸腺苷结合盒”)转运蛋白，并且有很多知识可用 关于这种转运蛋白的生理学和遗传学。ABC运输商 包括哺乳动物细胞的多药耐药系统，它产生抗癌 来自癌细胞细胞质的试剂。因此，对 麦芽糖转运蛋白的分子结构和作用机制 ABC运输机的范例，预计将有助于设计 即使在表达该基因的细胞中也可能保持活性的抗癌药物 MDR系统处于高水平。

The goal of this subproject is to purify in sufficient amounts two intrinsic membrane proteins of Escherichia coli, the OmpA protein of the outer membrane and the multi-subunit, maltose transporter complex of the inner, cytoplasmic membrane, and to carry out the electron crystallographic studies of these membrane proteins. OmpA was chosen because it belongs to a family of novel porins, with unusually low permeability, and the structural basis for this property is total unknown. The elucidation of the channel structure of this protein is expected to help design better chemotherapeutic agents, which would be more effective against Pseudomonas aeruginosa, that is a major source of opportunistic infections because it has an OmpA homolog, a low permeability porin, as its main porin. The maltose transporter complex was chosen because it is one of the best-studied members of a widespread transporter family, the ABC ("ATP-binding cassette") transporters, and much knowledge is available on the physiology and genetics of this transporter. The ABC transporters include the MDR system of mammalian cells, which pumps out anti-cancer agents from the cytoplasm of cancer cells. Thus the understanding of the molecular structure and mechanism of action of maltose transporter, as a paradigm of the ABC transporters, is expected to contribute to the design of anti-cancer agents that may remain active even in cells expressing the MDR system at a high level.