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Replication arrests during a single round of replication of the Escherichia coli chromosome in the absence of DnaC activity
Author(s) -
MaisnierPatin Sophie,
Nordström Kurt,
Dasgupta Santanu
Publication year - 2001
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2001.02718.x
Subject(s) - dnab helicase , biology , pre replication complex , control of chromosome duplication , dna replication , dnaa , replication factor c , seqa protein domain , origin recognition complex , genetics , origin of replication , microbiology and biotechnology , eukaryotic dna replication , helicase , dna , gene , rna
We used a flow cytometric assay to determine the frequency of replication fork arrests during a round of chromosome replication in Escherichia coli . After synchronized initiation from oriC in a dnaC (Ts) strain, non‐permissive conditions were imposed, such that active DnaC was not available during elongation. Under these conditions, about 18% of the cells failed to complete chromosome replication. The sites of replication arrests were random and occurred on either arm of the bidirectionally replicating chromosome, as stalled forks accumulated at the terminus from both directions. The forks at the terminal Ter sites disappeared in the absence of Tus protein, as the active forks could then pass through the terminus to reach the arrest site, and the unfinished rounds of replication would be completed without DnaC. In a dnaC2 (Ts) rep double mutant, almost all cells failed to complete chromosome replication in the absence of DnaC activity. As inactivation of Rep helicase (the rep gene product) has been shown to cause frequent replication arrests inducing double‐strand breaks (DSBs) in a replicating chromosome, DnaC activity appears to be essential for replication restart from DSBs during elongation.