BACTERIAL FUNCTION INVOLVED IN CELL GROWTH CONTROL

我们一直在研究蛋白质降解在 调节基因表达，并继续研究 细胞分裂过程中染色体的合成和分配 师. Lon ATP依赖的天然底物的周转 蛋白酶，N和苏拉，已被证明是独立的热休克 蛋白DnaJ的活性，而Lon的另一种底物， 多糖正调节因子RcsA，已经显示依赖于 DnaJ活性在大多数情况下。这些结果表明 热休克蛋白不是依赖于Lon的 天然底物在体内的降解。的温度敏感性 胶囊合成似乎是由于RcsA在体内的错误折叠;类似的 错误折叠可能在DnaJ不存在的情况下发生。的调控研究 rcsA转录导致了小RNA的鉴定，DsrA 核糖核酸增加DsrA RNA的量导致转录增加， rcsA，显然是因为DsrA RNA参与打开沉默的 rcsA启动子。组蛋白样蛋白HNS是沉默所必需的。 我们继续研究Clp能量的体内功能- 依赖性蛋白酶这种蛋白酶在体内的特异性似乎是 由ATP酶亚基决定。我们已经发现ClpX，一种替代品， ATP酶亚基和ClpP也介导λ O蛋白的降解 如许多其它衬底。另一种可能的ATP酶亚基是 通过序列比较发现，其在体内降解中的作用正在研究中。 考察我们也一直在研究细胞的调节事件 使用mbr突变体进行循环，每个突变体的DNA含量都有变化。 cell.我们一直专注于mbrA，它影响DNA的偶联 复制到细胞伸长，并确定了几个基因所需的 才能发挥作用此外，我们已经克隆了mbrA，并开始 分析基因的物理结构。的进一步表征 mbrA及其抑制因子应该阐明它在 细胞周期调控

We have been studying the role that protein degradation plays in regulating gene expression and have continued with studies on the linkages between chromosome synthesis and partition of chromosomes during cell division. Turnover of the natural substrates of the Lon ATP-dependent protease, N and SulA, has been shown to be independent of the heat shock protein DnaJ, while the activity of another substrate of Lon, the capsular polysaccharide positive regulator RcsA, has been shown to be dependent on DnaJ activity under most circumstances. These results suggest that the heat shock proteins are not an essential component of Lon-dependent degradation of natural substrates in vivo. The temperature sensitivity of capsule synthesis appears to be due to misfolding of RcsA in vivo; similar misfolding may occur in the absence of DnaJ. Studies on the regulation of rcsA transcription have led to the identification of a small RNA, DsrA RNA. Increased amounts of DsrA RNA lead to increased transcription of rcsA, apparently because the DsrA RNA participates in opening a silenced rcsA promoter. The histone-like protein, HNS, is necessary for silencing. We have continued to investigate the in vivo function of the Clp energy- dependent protease. The specificity of this protease in vivo seems to be dictated by the ATPase subunit. We have found that ClpX, an alternate ATPase subunit, and ClpP mediate degradation of lambda O protein, as well as a number of other substrates. Another possible ATPase subunit has been found by sequence comparisons and its role in in vivo degradation is being examined. We have also been studying the regulatory events of the cell cycle using the mbr mutants, which have an alteration in DNA content per cell. We have been focusing on mbrA, which affects the coupling of DNA replication to cell elongation and have identified several genes required for mbrA to function. In addition, we have cloned mbrA and begun to analyze the physical structure of the gene. Further characterization of mbrA and its suppressors should elucidate the critical role it plays in cell cycle regulation.