Intracellular localization of P1 ParB protein depends on ParA and parS
AUTOR(ES)
Erdmann, Natalie
FONTE
The National Academy of Sciences
RESUMO
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.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=24746Documentos Relacionados
- Mini-P1 plasmid partitioning: excess ParB protein destabilizes plasmids containing the centromere parS.
- ParB of Pseudomonas aeruginosa: Interactions with Its Partner ParA and Its Target parS and Specific Effects on Bacterial Growth
- P1 ParB Domain Structure Includes Two Independent Multimerization Domains
- Recognition of the P1 plasmid centromere analog involves binding of the ParB protein and is modified by a specific host factor.
- P1 and P7 plasmid partition: ParB protein bound to its partition site makes a separate discriminator contact with the DNA that determines species specificity.
