BIOSYNTHESIS OF ENTEROBACTERIAL COMMON ANTIGEN

这项研究的长期目标是阐明 参与外膜生物发生和组装的机制 革兰氏阴性菌据估计，这一知识 这一过程将为新的发展提供合理的基础。 抗菌剂，也提供了深入了解的过程， 参与真核细胞中的膜生物发生和组装， 细胞器 本研究的具体重点是确定 肠杆菌共同抗原（ECA）的生物合成和组装。ECA 是一种外膜糖脂， 肠杆菌科，它发生在所有细菌属于这 家人我们研究了ECA合成在鼠伤寒沙门氏菌 和大肠杆菌，并且体内和体外系统都已被 成功开发并用于此目的。我们希望 继续我们的研究，并为所要求的时期的具体目标， 支持是（a）证明Fuc 4 NAc- ManNAcA-GlcNAc-焦磷酸十一肾上腺素是ECA的前体 （B）确定“杂多糖链”中涉及的机制。 ECA链的组装;（c）确定 磷酸甘油酯连接的ECA链（ECApG）的合成;（d） 确定参与合成的机制 脂多糖连接的ECA（ECALPS）;和（3）分离和 结构表征涉及聚类异戊二烯连接的中间体 在ECA合成中。 拟议的研究将利用分子生物学技术， 生物化学，包括体内脉冲标记，酶学， 生物合成中间体的分离和结构表征。

The long-term goals of this research are directed at elucidating the mechanisms involved in the biogenesis and assembly of the outer membrane of gram-negative bacteria. It is anticipated that a knowledge of this process will provide a rational basis for the development of new antimicrobial agents and also provide insights into the processes involved in membrane biogenesis and assembly in eukaryotic cells and cell organelles. The specific focus of this research is to define the mechanism of biosynthesis and assembly of enterobacterial common antigen (ECA). ECA is an outer membrane glycolipid that is unique to the Enterobacteriaceae, and it occurs in all bacteria belonging to this family. We have investigated ECA synthesis in Salmonella tymphimurium and Escherichia coli, and both in vivo and in vitro systems have been successfully developed and employed for this purpose. We wish to continue our studies, and the specific aims for the requested period of support are (a) to demonstrate that Fuc4NAc- ManNAcA-GlcNAc-pyrophosphorylundecaprenol is a precursor of ECA heteropolysaccharide chains; (b) to determine the mechanism involved in' the assembly of ECA chains; (c) to determine the mechanism involved in the synthesis of phosphoglyceride-linked ECA chains (ECApG); (d) to determine the mechanism involved in the synthesis of lipopolysaccharide-linked ECA (ECALPS); and (3) to isolate and structurally characterize polyisoprenoid-linked intermediates involved in ECA synthesis. The proposed research will utilize techniques of molecular biology and biochemistry including in vivo pulse-labeling, enzymology, and the isolation and structural characterization of biosynthetic intermediates.