BIOSYNTHESIS OF BACTERIAL CELL WALLS AND MEMBRANES

我们将继续研究生物合成，组装和 细菌细胞壁的降解，特别是在关系 细胞生长和细胞分裂。 重点将放在 屎链球菌ATCC 9790作为“模型系统”的研究， 特别是由于其相对简单的形状和模式 师. 下一个5年资助期内的研究将 旨在研究两个独立的， SF在表面组装和分裂中的独特的胞壁酶。 因此 我们建议：（一）研究两个非常重要的性质， SF不常见的自溶性胞壁酶。 将包括以下研究： 探讨了胞壁酶-2（E- 2）。 E-2是转糖苷酶的可能性是 特别值得注意的是，E-2可能是一个“两个... 以“为首”型转糖苷酶-转肽酶，类似于at 大肠杆菌属的至少两种青霉素结合蛋白（PBP） 杆菌 此外，我们将研究和比较的约束力和 E-I和E-2两者对许多不同的催化性质 可溶性和不溶性底物。 这些项目的最终目标 研究的目的是深入了解 这两种活动在细菌生长和分裂中的作用。 （二） 研究这两个可能的体内功能，冗余，PG 细胞壁组装、表面扩大和/或细胞中水解酶 师. 为了实现这一目标，我们将获得和表征 同基因对，其中一个将包含突变， E-1或E-2结构基因。 E-I和E-2的基因将是 克隆于E.大肠杆菌中表达，并对两个基因进行测序。 （三） 进一步的研究将包括调查的关系， 的E-2的PBPs，并研究细胞壁组织使用 针对细胞壁PG中存在的表位的单克隆抗体。

We will continue to study aspects of the biosynthesis, assembly and degradation of the bacteria cell wall, especially in relationship to cell growth and cell division. Emphasis will be placed on studies of Streptococcus faecium ATCC 9790 as a "model system," particularly because of its relatively simple shape and mode of division. Studies during the next 5-year grant period will be directed towards studies of the possible roles of two separate and distinct muramidases of SF in surface assembly and division. Thus we propose to: (i) Study several of the properties of the two very unusual autolytic murasidases of SF. Included will be studies of the molecular mechanism of hydrolysis of PGs by muramidase-2 (E- 2). The possibility that E-2 is a transglycosidase is of particular interest, as is the possibility that E-2 is a "two- headed" type of transglycosidase-transpeptidase, similar to at least two of the penicillin-binding proteins (PBPs) of Escherichia coli. Additionally we will study and compare the binding of and catalytic properties of both E-l and E-2 on a number of different soluble and insoluble substrates. The ultimate goal of these studies is to obtain an insight into the action of and regulation of these two activities in growing and dividing bacteria. (ii) Study the possible in vivo functions of these two, redundant, PG hydrolases in cell wall assembly, surface enlargement and/or cell division. Towards this goal we will obtain and characterize isogenic pairs, one of which will contain a mutation in the structural gene for E-1 or E-2. The genes for E-l and E-2 will be cloned in E. coli and the two genes will be sequenced. (iii) Additional studies will include investigations of the relationship of E-2 to PBPs, and studies of cell wall organization using monoclonal antibodies to epitopes present in the cell wall PG.