MODE OF ACTION OF A BACTERIAL FUNCTION INVOLVED IN CELL GROWTH CONTROL

我们一直在研究蛋白质降解在 通过对突变体的研究，调节细胞生长控制 依赖于ATP和独立的蛋白质周转存在缺陷。E. 大肠杆菌突变株在细胞分裂调控中存在缺陷 DNA损伤，并过度产生荚膜多糖。我们有 此前显示一种不稳定的正性调节剂胶囊 合成，RCSA，在Lon突变体中稳定。RCSA函数 似乎在许多革兰氏阴性原核生物中是常见的， 提出了一种共同的机制来调节不同的胶囊 这些菌株。RCSC是胶囊合成的负调控因子， 是一种膜蛋白，可以作为环境的感应器 控制胶囊合成的信号。三磷酸腺苷的基因- 一种新的双组分ATP依赖的蛋白水解酶的结合亚基 基因中的染色体突变，称为clpA， 已经产生了。虽然缺乏clpA的细胞是健康的，但 CLP蛋白水解酶在降解异常中似乎是对Lon的支持 蛋白质。第三种蛋白水解酶的功能已经被确定，并且 负责的基因在大肠杆菌上被定位到56分钟 染色体。

We have been studying the role that protein degradation plays in regulating cell growth control, through the study of mutants defective in ATP-dependent and independent protein turnover. E. coli lon mutants are defective in cell division regulation after DNA damage, and overproduce capsular polysaccharide. We have previously shown that an unstable positive regulator of capsule synthesis, RcsA, is stabilized in lon mutants. The rcsA function seems to be common to a number of gram-negative prokaryotes, suggesting a common mechanism for regulating different capsules in these strains. RcsC, a negative regulator of capsule synthesis, is a membrane protein which may act as a sensor for environmental signals controlling capsule synthesis. The gene for the ATP- binding subunit of a new two component ATP-dependent protease has been isolated, and chromosomal mutations in the gene, called clpA, have been generated. While cells devoid of clpA are healthy, the Clp protease seems to act as a back-up to lon in degrading abnormal proteins. A third protease function has been identified, and the gene responsible has been mapped to 56 minutes on the E. coli chromosome.