Sequential strand exchange by XerC and XerD during site-specific recombination at dif

Citation
Gw. Blakely et al., Sequential strand exchange by XerC and XerD during site-specific recombination at dif, J BIOL CHEM, 275(14), 2000, pp. 9930-9936
Citations number
37
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biochemistry & Biophysics
Journal title
JOURNAL OF BIOLOGICAL CHEMISTRY
ISSN journal
0021-9258 → ACNP
Volume
275
Issue
14
Year of publication
2000
Pages
9930 - 9936
Database
ISI
SICI code
0021-9258(20000407)275:14<9930:SSEBXA>2.0.ZU;2-M
Abstract
Successful segregation of circular chromosomes in Escherichia coli requires that dimeric replicons, produced by homologous recombination, are converte d to monomers prior to cell division. The Xer site-specific recombination s ystem uses two related tyrosine recombinases, XerC and XerD, to catalyze re solution of circular dimers at the chromosomal site, dif, A 33-base pair DN A fragment containing the 28-base pair minimal dif site is sufficient for t he recombinases to mediate both inter- and intramolecular site-specific rec ombination in vivo. We show that Xer-mediated intermolecular recombination in vitro between nicked linear dif "suicide" substrates and supercoiled pla smid DNA containing dif is initiated by XerC, Furthermore, on the appropria te substrate, the nicked Holliday junction intermediate formed by XerC is c onverted to a linear product by a subsequent single XerD-mediated strand ex change. We also demonstrate that a XerC homologue from Pseudomonas aerugino sa stimulates strand cleavage by XerD on a nicked linear substrate and prom otes initiation of strand exchange by XerD in an intermolecular reaction be tween linear and supercoiled DNA, thereby reversing the normal order of str and exchanges.