BACTERIAL CELL SURFACE/STRUCTURE, FUNCTIONS & BIOGENESIS

膜脂蛋白与共价连接的脂质普遍存在 生物膜的组成部分。 在革兰阴性和革兰阳性 细菌，越来越多的膜蛋白已被发现， 含有甘油酯-半胱氨酸。 我们的长期目标是了解 膜脂蛋白的结构、功能和组装方式 细菌 最近的研究表明，脂蛋白的输出， 细菌在输出过程的起始中具有共同的步骤。 在这个过程的后期， Leu-Ala-Gly-Cys，其存在于前脂蛋白的切割位点， 为前脂蛋白修饰提供独特的识别位点， 加工酶 前脂蛋白信号对前脂蛋白的加工 肽酶（SPase II）需要预先修饰前脂蛋白， 甘油酯，并被球霉素特异性抑制。 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。 我们的目标 将是（1）鉴定前脂蛋白修饰酶，分离 这些酶的活性缺陷的突变体，并克隆 编码这些酶的结构基因;（2）阐明 x-ileS-lsp操纵子在E.大肠杆菌;（3） 从B中克隆1 sp基因（以及该途径中的其他结构基因）。 枯草杆菌或其他细菌，以便进一步了解 SPase II的结构和1 sp（和ileS）的基因组组织 细菌 所采用的技术包括微生物遗传学、重组DNA 技术、膜生物化学和细菌生理学研究。 我们 将继续在E. coli和B.地衣 青霉素酶在B中。subtilis为模型系统。 我们还将比较 蛋白质分泌一般与脂蛋白输出进一步定义 这两种途径的分歧，从一个共同的启动出口 过程

Membrane lipoproteins with covalently linked lipids are ubiquitous components of biological membrane. In both gram-negative and gram-positive bacteria, an increasing number of membrane proteins have been found to contain glyceride-cysteine. Our long-term goal is to undertand the structures, functions and mode of assembly of membrane lipoproteins in bacteria. Recent studies have revealed that the export of lipoproteins in bacteria shares common step(s) in the initiation of the export process. Later in this process, the consensus tetrapeptide sequence of Leu-Ala-Gly-Cys which is present at the cleavage site of prolipoproteins, provides a unique recognition site for prolipoprotein modification and processing enzymes. Processing of prolipoprotein by prolipoprotein signal peptidase (SPase II) requires prior modification of prolipoprotein with glyceride and is specifically inhibited by globomycin. We propose to continue our biochemical and genetic studies of lipoprotein biogenesis in both gram-negative and gram-positive bacteria. Our goals will be (1) to identify prolipoprotein modification enzymes, to isolate mutants defective in the activities of these enzymes and to clone the structural genes encoding these enzymes; (2) to elucidate the mechanism of regulation of the expression of the x-ileS-lsp operon in E. coli; and (3) to clone 1sp gene (and other structural genes in this pathways) from B. subtilis or other bacteria in order to gain further insights into the structures of SPase II and genomic organization of 1sp (and ileS) in other bacteria. Techniques to be employed include microbial genetics, recombinant DNA technology, membrane biochemistry and bacterial physiological studies. We will continue to use Braun's lipoprotein in E. coli, and B. licheniformis penicillinase in B. subtilis as our model systems. We will also compare protein secretion in general with lipoprotein export to further define divergence of these two pathways from a common initiation of the export process.