Van Melderen L, Bernard P, Couturier M
Département de Biologie Moléculaire, Université Libre de Bruxelles, Rhode Saint Genèse.
Mol Microbiol. 1994 Mar;11(6):1151-7. doi: 10.1111/j.1365-2958.1994.tb00391.x.
The ccd locus contributes to the stability of plasmid F by post-segregational killing of plasmid-free bacteria. The ccdB gene product is a potent cell-killing protein and its activity is negatively regulated by the CcdA protein. In this paper, we show that the CcdA protein is unstable and that the degradation of CcdA is dependent on the Lon protease. Differences in the stability of the killer CcdB protein and its antidote CcdA are the key to post-segregational killing. Because the half-life of active CcdA protein is shorter than that of active CcdB protein, persistence of the CcdB protein leads to the death of plasmid-free bacterial segregants.
ccd位点通过对无质粒细菌的后分离杀伤作用来促进质粒F的稳定性。ccd B基因产物是一种强效的细胞杀伤蛋白，其活性受到Ccd A蛋白的负调控。在本文中，我们表明Ccd A蛋白不稳定，且Ccd A的降解依赖于Lon蛋白酶。杀伤性Ccd B蛋白与其解毒剂Ccd A稳定性的差异是后分离杀伤的关键。由于活性Ccd A蛋白的半衰期短于活性Ccd B蛋白，Ccd B蛋白的持续存在会导致无质粒细菌分离菌死亡。
