Determinants of segregational stability of the linear plasmid-prophage N15of Escherichia coli

Citation
Ps. Grigoriev et Mb. Lobocka, Determinants of segregational stability of the linear plasmid-prophage N15of Escherichia coli, MOL MICROB, 42(2), 2001, pp. 355-368
Citations number
52
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
MOLECULAR MICROBIOLOGY
ISSN journal
0950-382X → ACNP
Volume
42
Issue
2
Year of publication
2001
Pages
355 - 368
Database
ISI
SICI code
0950-382X(200110)42:2<355:DOSSOT>2.0.ZU;2-V
Abstract
N15 is a bacteriophage of Escherichia coli that resembles lambda, but, unli ke lambda, it lysogenizes as a linear plasmid. We show that stable maintena nce of this unusual plasmid-prophage depends on the parA and parB genes, re latives of the partition genes of F and P1 plasmids. ParB of N15, like its F- and Pl-encoded homologues, destabilizes plasmids carrying its target cen tromere, when present in excess. Within the genome of N15, we identified fo ur unlinked, palindromic sequences that can promote the ParB-mediated desta bilization of a moderate-copy vector in cis. They are distant from the parA B operon, unlike the centromeric sites of F and P1. Each of these palindrom es could interact in vivo and in vitro with ParB. Each, when cloned separat ely, had properties characteristic of centromeric sites: exerted incompatib ility against the N15 prophage and mini-N15 plasmids, and stabilized a mini -P1 plasmid depleted of its own partition genes when ParA and ParB of N15 w ere supplied. A pair of sites was more effective than a single site. Two of the centromeric sites are located in the proximity of promoters of phage g enes, suggesting that, in addition to their function in partitioning of N15 prophage, they may control expression of N15 lytic functions.