Cells defective for replication restart undergo replication fork reversal.
We have studied the fate of blocked replication forks with the use of the Escherichia coli priA mutant, in which spontaneously arrested replication forks persist owing to the lack of the major replication restart pathway. Such blocked forks undergo a specific reaction named replication fork reversal, in which newly synthesized strands anneal to form a DNA double-strand end adjacent to a four-way junction. Indeed, (i) priA recB mutant chromosomes are linearized by a reaction that requires the presence of the Holliday junction resolvase RuvABC, and (ii) RuvABC-dependent linearization is prevented by the presence of RecBC. Replication fork reversal in a priA mutant occurs independently of the recombination proteins RecA and RecR. recBC inactivation does not affect priA mutant viability but prevents priA chronic SOS induction. We propose that, in the absence of PriA, RecBC action at reversed forks does not allow replication restart, which leads to the accumulation of SOS-inducing RecA filaments. Our results suggest that types of replication blockage that cause replication fork reversal occur spontaneously.
Grompone
Gianfranco
G
Laboratoire de Génétique Microbienne, Institut National de la Recherche Agronomique, Jouy en Josas, France.
Ehrlich
Dusko
D
Michel
Bénédicte
B
D000251:Adenosine Triphosphatases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004265:DNA Helicases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication / Q000235:genetics / Q000502:physiology*; D045566:DNA, Cruciform / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D043211:Exodeoxyribonuclease V / Q000235:genetics / Q000378:metabolism*; D045565:Holliday Junction Resolvases / Q000378:metabolism*; D009154:Mutation; D013014:SOS Response, Genetics / Q000235:genetics / Q000502:physiology
D001426:Bacterial Proteins; D045566:DNA, Cruciform; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C061260:RuvB protein, Bacteria; C069806:ruvC protein, E coli; D004247:DNA; D004706:Endodeoxyribonucleases; D043211:Exodeoxyribonuclease V; C468322:exodeoxyribonuclease V, E coli; D045565:Holliday Junction Resolvases; C071059:Holliday junction DNA helicase, E coli; D000251:Adenosine Triphosphatases; C506743:priA protein, E coli; D004265:DNA Helicases