BIOSYNTHESIS OF ENTEROBACTERIAL COMMON ANTIGEN

这项研究的长期目标旨在阐明 外膜的生物发生和组装的机制 革兰氏阴性细菌。预计对此的了解 流程将为新的发展提供合理的基础 抗菌剂，还提供了对过程的洞察 参与真核细胞膜的生物发生和组装 细胞器。 本研究的具体重点是明确心力衰竭的发病机制。 肠道细菌共同抗原(ECA)的生物合成和组装非洲经委会 是一种外膜糖脂，它是 肠杆菌科，它存在于属于该细菌的所有细菌中 一家人。我们研究了鼓膜沙门氏菌Eca的合成。 和大肠杆菌，体内和体外系统都已经被 为此目的成功地开发和使用了。我们希望 继续我们的学习，以及所要求的时期的具体目标 支持是(A)证明Fuc4NAc- 甘露醇-谷氨酰胺-焦磷十一烯醇是ECA的前体 杂多糖链；(B)确定‘ 非洲经委会链的组装；(C)确定所涉机制 磷酸甘油酯连接的ECA链(ECApG)的合成；(D)至 确定与合成有关的机理 (3)分离、分离和鉴定 涉及的聚异戊二烯连接中间体的结构表征 在ECA合成中。 拟议的研究将利用分子生物学和 生物化学，包括体内脉冲标记，酶学和 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.