A hand-off mechanism for primosome assembly in replication restart.

TitleA hand-off mechanism for primosome assembly in replication restart.
Publication TypeJournal Article
Year of Publication2007
AuthorsLopper M, Boonsombat R, Sandler SJ, Keck JL
JournalMol Cell
Volume26
Issue6
Pagination781-93
Date Published2007 Jun 22
ISSN1097-2765
KeywordsBinding Sites, DNA Helicases, DNA Replication, DNA, Bacterial, DNA, Single-Stranded, DNA-Binding Proteins, DNA-Directed DNA Polymerase, Escherichia coli, Escherichia coli Proteins, Genome, Bacterial, Models, Biological, Multienzyme Complexes, Protein Binding, Replication Origin
Abstract

Collapsed DNA replication forks must be reactivated through origin-independent reloading of the replication machinery (replisome) to ensure complete duplication of cellular genomes. In E. coli, the PriA-dependent pathway is the major replication restart mechanism and requires primosome proteins PriA, PriB, and DnaT for replisome reloading. However, the molecular mechanisms that regulate origin-independent replisome loading are not fully understood. Here, we demonstrate that assembly of primosome protein complexes represents a key regulatory mechanism, as inherently weak PriA-PriB and PriB-DnaT interactions are strongly stimulated by single-stranded DNA. Furthermore, the binding site on PriB for single-stranded DNA partially overlaps the binding sites for PriA and DnaT, suggesting a dynamic primosome assembly process in which single-stranded DNA is handed off from one primosome protein to another as a repaired replication fork is reactivated. This model helps explain how origin-independent initiation of DNA replication is restricted to repaired replication forks, preventing overreplication of the genome.

DOI10.1016/j.molcel.2007.05.012
Alternate JournalMol. Cell
PubMed ID17588514