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 对细胞生长和细胞分裂的影响。重点将放在 以屎链球菌ATCC 9790为“模型系统”的研究 尤其是因为它的形状和模式相对简单 组织。在下一个五年资助期内的研究将是 旨在研究两个独立的和 SF在表面组装和分裂过程中有明显的溶菌酶。因此， 我们建议：(I)研究这两个非常重要的性质 罕见的SF自溶性壁壁糖苷酶。将包括以下研究： 胞壁酰胺酶-2(E-2)降解PGs的分子机制 2)。E-2是一种转糖苷酶的可能性是 尤其令人感兴趣的是，E-2可能是一个“两个- 标题“型转糖苷酶-转肽酶，类似于At 至少两种青霉素结合蛋白(PBPs) Coli.此外，我们还将研究和比较和 E-L和E-2在几种不同催化剂上的催化性能 可溶和不溶的底物。这些项目的最终目标是 研究是为了洞察和调控的行动 在生长和分裂细菌的这两个活动中。(Ii) 研究这两个冗余的PG在体内可能的功能 水解酶在细胞壁组装、表面扩大和/或细胞中的作用 组织。为了实现这一目标，我们将获得并描述 等基因对，其中一个将包含突变 E-1或E-2的结构基因。E-L和E-2的基因将是 在大肠杆菌中克隆，并对这两个基因进行测序。(Iii) 其他研究将包括对这一关系的调查 E-2对多氯联苯的抑制作用，并研究了利用 存在于细胞壁PG中的针对表位的单抗。

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.