title: Completion of DNA replication in Escherichia coli.
abstract: The mechanism by which cells recognize and complete replicated regions at their precise doubling point must be remarkably efficient, occurring thousands of times per cell division along the chromosomes of humans. However, this process remains poorly understood. Here we show that, in Escherichia coli, the completion of replication involves an enzymatic system that effectively counts pairs and limits cellular replication to its doubling point by allowing converging replication forks to transiently continue through the doubling point before the excess, over-replicated regions are incised, resected, and joined. Completion requires RecBCD and involves several proteins associated with repairing double-strand breaks including, ExoI, SbcDC, and RecG. However, unlike double-strand break repair, completion occurs independently of homologous recombination and RecA. In some bacterial viruses, the completion mechanism is specifically targeted for inactivation to allow over-replication to occur during lytic replication. The results suggest that a primary cause of genomic instabilities in many double-strand-break-repair mutants arises from an impaired ability to complete replication, independent from DNA damage.
authors.affiliation: Department of Biology, Portland State University, Portland, OR 97201 bwendel@pdx.edu.
authors.forename: Brian M
authors.initials: BM
authors.lastname: Wendel
authors.affiliation: Department of Biology, Portland State University, Portland, OR 97201.
authors.forename: Charmain T
authors.initials: CT
authors.lastname: Courcelle
authors.affiliation: Department of Biology, Portland State University, Portland, OR 97201.
authors.forename: Justin
authors.initials: J
authors.lastname: Courcelle
mesh_terms: D001433:Bacteriolysis; D010582:Bacteriophage lambda / Q000502:physiology; D002876:Chromosomes, Bacterial / Q000235:genetics / Q000648:ultrastructure; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004261:DNA Replication / Q000502:physiology*; D004269:DNA, Bacterial / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000821:virology; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D043211:Exodeoxyribonuclease V / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D059014:High-Throughput Nucleotide Sequencing; D059765:Homologous Recombination / Q000235:genetics; D008957:Models, Genetic; D010957:Plasmids / Q000235:genetics; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D014779:Virus Replication
chemical_list: D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C489340:recF protein, E coli; C071446:RecG protein, E coli; D011938:Rec A Recombinases; D043211:Exodeoxyribonuclease V; C468322:exodeoxyribonuclease V, E coli
keywords: RecBCD; SbcDC; double-strand break repair; homologous recombination; replication completion