BIOSYNTHESIS OF ENTEROBACTERIAL COMMON ANTIGEN

这项研究的长期目标是阐明机制， 参与外膜成分的生物发生和功能 革兰氏阴性菌 为了实现这一目标，我们进行了调查。 肠杆菌共同抗原（ECA）的生物化学和遗传学 在大肠杆菌和鼠伤寒沙门氏菌中合成。ECA是一个外部 肠杆菌科特有的膜糖脂，它存在于 所有的细菌都属于这个家族。 将特别强调 确定ECA的生物合成机制， 描述了参与这一过程的基因。 这一奋进一直是 通过分离和鉴定E.杆菌 和S.鼠伤寒沙门氏菌的几个遗传决定因子缺陷， 非洲经委会。这些突变体的特征导致了 鉴定ECA合成中涉及的生物合成中间体， 开发体外和体内实验系统， ECA组装中涉及的特定酶促步骤的证明。 我们在这里建议继续我们的研究实验， 所请求的支助期的具体目标是：㈠确定 磷脂连接的ECA合成机制 多糖链（ECA-PL），（ii）确定参与的机制 ECA多糖链的组装，（iii）确定机制 参与ECA多糖链转移到 脂多糖受体形成ECA-LP，和（iv）研究 开放式阅读框o348在ECA装配中的可能作用 分子。 拟议中的研究将利用分子生物学技术， 生物化学和遗传学。 据了解， 非洲经委会大会的机制将提供深入了解的过程， 细菌中的膜生物发生和组装。这些信息将 为新型抗菌药物的开发提供合理依据， 它还将提供有关的机制， 真核细胞和细胞膜的生物发生和组装 细胞器

The long term goals of this research are to elucidate the mechanisms involved in the biogenesis and function of outer membrane components of gram-negative bacteria. As an approach to this goal, we have investigated the biochemistry and genetics of enterobacterial common antigen (ECA) synthesis in Escherichia coli and Salmonella typhimurium. ECA is an outer membrane glycolipid unique to the Enterobacteriaceae, and it is present in all bacteria belonging to this family. Specific emphasis will be placed on determining the mechanism of biosynthesis of ECA and on identifying and characterizing the genes involved in this process. This endeavor has been facilitated by the isolation and characterization of mutants of E. coli and S. typhimurium defective in several of the genetic determinants of ECA. The characterization of these mutants has resulted in the identification of biosynthetic intermediates involved in ECA synthesis and the development of in vitro and in vivo experimental systems that allow demonstration of specific enzymatic steps involved in ECA assembly. We propose here experiments for the continuation of our studies, and the specific aims for the requested period of support are to (i) determine the mechanism involved in the synthesis of phospholipid-linked ECA polysaccharide chains (ECA-PL), (ii) determine the mechanism involved in the assembly of ECA polysaccharide chains, (iii) determine the mechanism involved in the transfer of ECA polysaccharide chains to lipopolysaccharide acceptors to form ECA-LPs, and (iv) investigate the possible function of open reading frame o348 in the assembly of ECA molecules. The proposed research will utilize techniques of molecular biology, biochemistry, and genetics. It is anticipated that a knowledge of the mechanism of ECA assembly will provide insights into the processes of membrane biogenesis and assembly in bacteria. Such information will provide a rational basis for the development of new antimicrobial agents, and it will also provide insights into the mechanisms involved in the biogenesis and assembly of membranes in eukaryotic cells and cell organelles.