Ruiz-Echevarría M J, de Torrontegui G, Giménez-Gallego G, Díaz-Orejas R
Centro de Investigaciones Biológicas (C.S.I.C.), Velázquez, Madrid, Spain.
Mol Gen Genet. 1991 Mar;225(3):355-62. doi: 10.1007/BF00261674.
The stability determined by the systems ParD of plasmid R1 and Ccd of plasmid F is due to the concerted action of two proteins, a cytotoxin and an antagonist of this function. In this paper we report that CcdA and Kis proteins, the antagonists of the Ccd and ParD systems respectively, share significant sequence homologies at both ends. In Kis, these regions seem to correspond to two different domains. Despite the structural similarities, Kis and CcdA are not interchangeable. In addition we have shown that the cytotoxins of these systems, the Kid and CcdB proteins, do not share structural homologies. In contrast to CcdB, the Kid protein of the ParD system induces RecA-dependent cleavage of the cI repressor of bacteriophage lambda very inefficiently or not at all. The functional implications of these results are discussed.
质粒R1的ParD系统和质粒F的Ccd系统所决定的稳定性，是由于两种蛋白质的协同作用，一种是细胞毒素，另一种是该功能的拮抗剂。在本文中，我们报道CcdA蛋白和Kis蛋白，分别作为Ccd和ParD系统的拮抗剂，在两端具有显著的序列同源性。在Kis蛋白中，这些区域似乎对应于两个不同的结构域。尽管结构相似，但Kis和CcdA不能互换。此外，我们还表明，这些系统的细胞毒素，即Kid蛋白和CcdB蛋白，不具有结构同源性。与CcdB不同，ParD系统的Kid蛋白非常低效地诱导或根本不诱导噬菌体λ的cI阻遏物的RecA依赖性切割。本文讨论了这些结果的功能意义。
