Studies on biosynthesis of biological macromolecules using mutants of Escherichia coli.

我们研究了大肠杆菌中大分子的生物合成反应和控制大分子生物合成的基因，这是一个理想的基础细胞研究系统，旨在了解细胞复制的机制及其遗传调控。鉴于大肠杆菌中的基因总数假设为数千个，如果我们分离出1万个突变，预计每个基因至少有一个突变。广田随机分离了5000多个独立来源的温度敏感突变株。我们利用在Hirota突变体中发现的突变体研究了大分子的生物合成过程及其遗传控制。Hara和Hirota证明了青霉素结合蛋白(PBP)-3是细胞分裂所必需的酶，是一种跨膜转移(分泌)的蛋白质，部分是脂蛋白。他们发现突变体在PBP-3的加工过程中存在缺陷，并研究了加工反应。伊藤鉴定了与分泌物…有关的Secy基因产物进一步研究了细胞表面蛋白，阐明了其结构和功能。他发现并分析了在分泌过程中有缺陷的新突变体。通过测定外膜蛋白启动子区的结构和分析外膜蛋白的控制因子OmpR和EnvZ蛋白，揭示了外膜蛋白基因OmpF和OMPC的表达调控机制。西野发现突变株在参与细胞壁合成的异戊二烯类化合物的生物合成方面存在缺陷，并显示了每个突变株中缺乏哪种酶，并进行了遗传分析。铃木证实，在参与细胞表面生长的PBP-1b的三种成分中，参与细胞表面生长的PBP-1b的&lt；α&gt；和&lt；γ&gt；是主要的基因产物，并且&lt；β&gt；是在膜组分制备过程中产生的。他在-lt；α&gt；-&&gt；-β&gt；转换中发现了一个突变缺陷，并确定了这些成分的结构。较少

We studied the biosynthetic reactions of macromolecules and the genes controlling them in Escherichia coli, an ideal system for the basic cell research, aiming at understanding the mechanisms of cell replication and their genetic regulations.Scince the total number of genes is supposed to be several thousands in E. coli, we can expect to get at least one mutant for every gene if we isolate ten thousand mutants. Hirota isolated more than five thousand temperature-sensitive mutants of independent origin at random. We studied biosynthetic processes of macromolecules and their genetic controls using mutants found in Hirota's mutant collection.Hara and Hirota demonstrated that penicillin-binding protein (PBP)-3, an indispensable enzyme for cell division, is a protein translocated (secreted) across the membrane and is a lipoprotein in part. They found mutants defective in the processing of PBP-3 and studied the processing reaction. Ito identified the secY gene product involved in the secreti … More on of cell surface proteins and clarified its structure and function. He found and analyzed novel mutants defective in secretion process. Mizushima revealed the regulatory mechanism of expression of ompF and ompC, genes encoding the outer membrane proteins whose relative amounts are changed in response to the medium osmolarity, by determining the structures of their promoter regions and by analyzing their controlling factors, OmpR and EnvZ proteins. Nishino found mutants defective in biosynthesis of isoprenoids involved in the synthesis of cell wall, showed which enzyme is deficient in each mutant, and performed genetic analyses. Suzuki confirmed that, among the three components, <alpha> , <beta> and <gamma> of PBP-1b participating in the growth of cell surface, <alpha> and <gamma> are the primary gene products and that <beta> is generated from <alpha> during preparation of the membrane fraction. He found a mutant defective in the <alpha> -> <beta> conversion and determined the structures of these components. Less