Replication terminus for DNA polymerase I during initiation of pAM beta 1 replication: role of the plasmid-encoded resolution system.
Replication of plasmid pAM beta 1 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 approximately 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.
Jannière
L
L
Laboratoire de Génétique Microbienne, Institut National de la Recherche Agronomique, Jouy-en-Josas, France. janniere@biotec.jouy.inra.fr
Bidnenko
V
V
McGovern
S
S
Ehrlich
S D
SD
Petit
M A
MA
D001412:Bacillus subtilis / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology; D001483:Base Sequence; D002474:Cell-Free System; D002874:Chromosome Mapping; D004256:DNA Polymerase I / Q000502:physiology*; D004261:DNA Replication / Q000502:physiology; D004268:DNA-Binding Proteins / Q000737:chemistry; D005786:Gene Expression Regulation / Q000502:physiology; D018257:Helix-Loop-Helix Motifs; D008969:Molecular Sequence Data; D010443:Peptide Chain Termination, Translational; D010957:Plasmids / Q000235:genetics* / Q000502:physiology; D011485:Protein Binding
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C087014:Res beta protein, Enterococcus faecalis; D004256:DNA Polymerase I