Requirement for RecFOR-mediated recombination in priA mutant.
Restart of arrested replication forks is an important process and PriA, the main Escherichia coli replication restart protein, is essential for viability under any condition that increases the frequency of fork arrest. In priA mutant, replication forks are arrested by spontaneously occurring roadblocks and blocked replication forks persist as a result of the defect in replication restart. In the present work, we analysed how recombination proteins contribute to the viability of the priA mutant. RecFOR-mediated homologous recombination occurs in a large fraction of priA mutant cells, indicating a frequent formation of DNA single strand gaps and their recombinational repair. This high level of homologous recombination renders the proteins that resolve Holliday junctions recombination intermediates essential for viability. When homologous recombination is blocked at early steps by recFOR or recA inactivation, exonuclease V-mediated DNA degradation is required for full viability of priA mutants, indicating that unrepaired gaps are broken and that DNA degradation of the broken DNA allows the formation of viable cells. Models for the formation of single strand DNA gaps consequently to a replication restart defect and for gap processing are proposed.
Grompone
Gianfranco
G
Génétique Microbienne, Institut National de la Recherche Agronomique, Domaine de Vilvert 78350 Jouy en Josas, France.
Sanchez
Nicolas
N
Dusko Ehrlich
S
S
Michel
Bénédicte
B
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D004249:DNA Damage; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair; D004261:DNA Replication; D004269:DNA, Bacterial / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism; D005798:Genes, Bacterial; D005821:Genetic Techniques; D009154:Mutation; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C081006:RecO protein, E coli; C489318:RecR protein, E coli; C065831:RecR protein, Bacteria; D011938:Rec A Recombinases; D004265:DNA Helicases