Intracellular localization of P1 ParB protein depends on ParA and par<i>S</i>

作     者：Erdmann, N Petroff, T Funnell, BE 

作者机构：Univ Toronto Dept Mol & Med Genet Toronto ON M5S 1A8 Canada 

出 版 物：《PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA》 (美国国家科学院汇刊)

年 卷 期：1999年第96卷第26期

页      面：14905-14910页

核心收录：

学科分类：07[理学] 08[工学] 

主　　题：细菌蛋白质类/分离和提纯 细菌噬菌体P1/遗传学 细胞区室化 细胞周期 大肠杆菌/细胞学 大肠杆菌/遗传学 荧光抗体技术 整合宿主因子类 质粒/遗传学 原病毒/遗传学 

摘      要：The P1 partition system promotes faithful plasmid segregation during the Escherichia coli cell cycle. This system consists of two proteins, ParA and ParB, that act on a plasmid site called parS, By immunofluorescence microscopy, we observed that ParB localizes to discrete foci that are most often located close to the one-quarter and three-quarters positions of cell length, The visualization of ParB foci depended completely on the presence of parS, although their visualization was independent of the chromosomal context of pars (in P1 or the bacterial chromosome). In integration host factor-defective mutants, in which ParB binding to parS is weakened, only a fraction of the total pool of ParB had converged into foci, Taken together, these results indicate that pars recruits a pool of ParB into foci and that the resulting ParB-parS complexes serve as substrates for the segregation reaction. In the absence of ParA, the position of ParB foci in cells is perturbed, indicating that at least one of the roles of ParA is to direct ParB-parS complexes to the proper one-quarter positions from a cell pole. Finally, inhibition of cell division did not inhibit localization of ParB foci in cells, indicating that the positioning signals in the E. coli host that are needed for P1 partition do not depend on early division events.