BACTERIAL CELL SURFACE/STRUCTURE, FUNCTIONS & BIOGENESIS

具有共价连接脂类的膜脂蛋白是普遍存在的 生物膜组分。在革兰氏阴性和革兰氏阳性中 细菌中，越来越多的膜蛋白被发现可以 含有甘油三酯-半胱氨酸。我们的长期目标是了解和 膜脂蛋白的结构、功能和组装方式 细菌。最近的研究表明，脂蛋白在体内的输出 细菌在启动出口过程中有共同的步骤(S)。 在这个过程的后期，共识的四肽序列 亮氨酸-丙氨酸-甘氨酸-半胱氨酸，存在于前脂蛋白的裂解部位， 为前脂蛋白修饰提供独特的识别位点 加工酶。利用前脂蛋白信号对前脂蛋白进行加工 多肽酶(Spase II)需要对原脂蛋白进行预先修饰 甘油三酯，并被球霉素特异性地抑制。 我们建议继续我们对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(1)鉴定前脂蛋白修饰酶，以分离 这些酶活性有缺陷的突变体并克隆 编码这些酶的结构基因；(2)阐明这些酶的机制 X-ILES-LSP操纵子在大肠杆菌中的表达调控；以及(3) 从B.S.中克隆1SP基因(以及其他结构基因)。 枯草杆菌或其他细菌，以便进一步了解 异育银杏Spase II的结构和1SP(和ILE)的基因组结构 细菌。 将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 将继续在大肠杆菌和地衣芽孢杆菌中使用布劳恩脂蛋白 以枯草杆菌中的青霉素酶为模型系统。我们还将比较 蛋白质分泌一般随脂蛋白输出而进一步明确 这两条路径与共同的出口起点不同 进程。

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.