Replication terminus for DNA polymerase I during initiation of pAMβ1 replication: role of the plasmid-encoded resolution system |
| |
Authors: | L Jannière V Bidnenko S McGovern S D Ehrlich & M A Petit |
| |
Institution: | Laboratoire de Génétique Microbienne, Institut National de la Recherche Agronomique, 78352 Jouy-en-Josas, Cedex, France. |
| |
Abstract: | Replication of plasmid pAMβ1 is initiated by DNA polymerase I (Pol I) and completed by DNA polymerase III holoenzyme contained in the replisome machinery. In this study we report that initiation of DNA replication generates D-loop structures containing the nascent leading strand paired to its template, and that D-loop extension is arrested ≈230 bp from the initiation site of DNA synthesis in the presence of the plasmid-encoded resolvase. In vitro and in vivo data suggest that this arrest is caused by a collision between Pol I and the resolvase bound to its target. As the arrested D-loop replication intermediates carry a single-stranded primosome-assembly site, we hypothesize that the biological role of the replication arrest is to limit the region replicated by Pol I and to promote the replacement of Pol I by the replisome in order to initiate concerted synthesis of the leading and lagging strands. |
| |
Keywords: | |
|
|