BACTERIAL CELL SURFACE STRUCTURE FUNCTIONS & BIOGENESIS

具有共价连接的脂质和脂肪酸的膜脂蛋白是 无处不在的生物膜成分。 在细菌中， 蛋白质，其含有N-酰基甘油酯-半胱氨酸作为氨基末端， 被合成为称为前脂蛋白的前体蛋白。 前脂蛋白经过广泛的翻译后修饰， 处理反应以形成成熟脂蛋白。 的生物发生 细菌中的脂蛋白与它们的分泌密切相关。 我们 长期目标是研究脂蛋白的生物化学 成熟，阐明其出口和组装成 细菌细胞包膜，并了解这些调节 流程. 我们建议继续进行脂蛋白的生化和遗传学研究 革兰氏阴性和革兰氏阳性细菌的生物发生。 我们的具体 目的包括（1）前脂蛋白的鉴定和表征 通过酶纯化修饰酶，分离突变体 在这些酶的纯化，分离的活性缺陷， 这些酶的活性缺陷的突变体，以及克隆这些酶的突变体。 编码这些酶的基因;（2）结构，膜 前脂蛋白信号肽酶（信号肽酶）的拓扑结构和组装 II）在大肠杆菌的细胞质膜中;和（3） x-ileS-lsp-orf 149-orf 316操纵子在大肠杆菌中的特性。杆菌和 其他细菌。 所采用的技术包括分子遗传学、重组DNA 基因融合、膜生物化学和细菌生理学技术 问题研究

Membrane lipoprotein with covalently linked lipids and fatty acids are ubiquitous components of biological membranes. In bacteria, lipid-modified proteins, which contain N-acyl glyceride-cysteine as the amino terminus, are synthesized as precursor proteins called prolipoproteins. Prolipoproteins undergo extensive posttranslational modification and processing reactions to form the mature lipoproteins. The biogenesis of lipoproteins in bacteria is intimately related to their secretion. Our long-term objectives are to study the biochemistry of lipoprotein maturation, to elucidate its mechanism of export and assembly into the bacterial cell envelope and to understand the regulation of these processes. We propose to continue our biochemical and genetic studies of lipoprotein biogenesis in both gram-negative and gram-positive bacteria. Our specific aims include (1) identification and characterization of prolipoprotein modification enzymes through enzyme purification, isolation of mutants defective in the activities of these enzyme purification, isolation of mutants defective in the activities of these enzymes, and cloning of the genes encoding these enzymes; (2) studies of the structures, membrane topology and assembly of prolipoprotein signal peptidase (signal peptidase II) in the cytoplasmic membrane of Escherichia coli; and (3) characterization of the x-ileS-lsp-orf149-orf316 operon in E. coli and other bacteria. Techniques to be employed include molecular genetics, recombinant DNA technology gene fusion, membrane biochemistry and bacterial physiological studies.