A DNA segment conferring stable maintenance on R6K gamma-origin core replicons.
A DNA segment conferring stable maintenance on R6K gamma-origin core replicons.
复制标题
赋予 R6K 伽马起源核心复制子稳定维持的 DNA 片段。
DOI：
10.1128/jb.177.22.6338-6345.1995
复制
发表时间：
1995
影响因子：
3.2
通讯作者：
Filutowicz,M
中科院分区：
文献类型：
--
作者：
Wu,F;Levchenko,I;Filutowicz,M
R6K伽马源由两个相邻的模块组成，即增强子和核心，需要R6K启动子蛋白pi进行复制。虽然核心细胞本身可以在低水平的野生型pi蛋白下复制，但我们在这里表明，宿主细胞并不稳定地维持核心质粒。增强子片段的存在使核心质粒具有稳定的遗传，而不会显著改变平均质粒拷贝数。缺失和定点突变表明，核心质粒的稳定性不是由Dna A、pi蛋白、旋转酶、FIS或DCM甲基酶增强子中的结合位点或共同序列介导的。核心质粒的正确分离只需要R6K STB或稳定性相关区域，包括与核心相邻的100-BP增强子的20-BP片段。Pi 116突变蛋白的使用使质粒拷贝数增加了四倍，但不能稳定缺乏增强子的核心质粒。我们还表明，在野生型pi水平升高时，伽马起源的质粒是不稳定的，即使在增强子存在的情况下也是如此。我们讨论了R6K稳定系统与其他质粒中发现的那些不同和相似之处。
The plasmid R6K gamma origin consists of two adjacent modules, the enhancer and the core, and requires R6K initiator protein pi for replication. While the core alone can replicate at a low level of wild-type pi protein, we show here that host cells do not stably maintain core plasmids. The presence of the enhancer segment confers stable inheritance on core plasmids without a significant change in average plasmid copy number. Deletions and site-directed mutagenesis indicated that the stability of core plasmids is not mediated by binding sites or consensus sequences in the enhancer for DnaA, pi protein, gyrase, Fis, or Dcm methylase. Proper segregation of core plasmids requires only the R6K stb or stability-related region, which includes the 20-bp segment of the 100-bp enhancer adjacent to the core. The use of the pi 116 mutant protein, which increases plasmid copy number fourfold, does not stabilize core plasmids lacking the enhancer. We also show that at an elevated level of wild-type pi, the gamma-origin plasmid is unstable, even in the presence of the enhancer. We discuss the differences and similarities between the R6K stability system and those found in other plasmids.