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的蛋白质周转有缺陷。大肠杆菌Lon突变体 DNA损伤后，细胞分裂调节存在缺陷，以及 我们之前已经证明，该缺陷是由于 高度不稳定的细胞分裂抑制因子Sula的稳定性。 Lon突变体也会过度生产荚膜多糖；我们有 确定了一种不稳定的胶囊合成正性调节因子， RCSA，稳定在Lon突变体中。按顺序排列的 RCSA基因与其他离子底物没有明显的相似性。 我们已经分离的RCSA-Lac融合将使我们能够检查 该基因的转录和翻译控制。vbl.使用 缺乏离子活性的细胞，我们已经在生化上确定了一种 新型双组分、依赖于ATP的蛋白水解酶。使用氨基酸 来自纯化组分之一的序列数据，即质粒 携带该基因的人正在被确认。使用基因筛查，我们 还标识并部分映射了一个函数，该函数 能够代替Lon，并且可能用代码来代替另一个 在大肠杆菌中具有潜在调节功能的蛋白酶。

We have been studying the role that protein degradation plays in regulating cell growth control, through the study of mutants defective in ATP-dependent protein turnover. E. coli lon mutants are defective in cell division regulation after DNA damage, and we have previously demonstrated that this defect is due to stabilization of the highly unstable cell division inhibitor, SulA. lon mutants also overproduce capsular polysaccharide; we have identified an unstable positive regulator of capsule synthesis, RcsA, which is stabilized in lon mutants. The sequence of the rcsA gene shows no striking similarities to other lon substrates. rcsA-lac fusions which we have isolated will allow us to examine the transcriptional and translational control of this gene. Using cells devoid of lon activity, we have biochemically identified a novel two-component, ATP-dependent protease. Using amino acid sequence data from one of the purified components, plasmids carrying the gene are being identified. Using genetic screens, we have also identified and partially mapped a function which is capable of substituting for lon, and presumably codes for another protease with potential regulatory functions in E. coli.