Premium
Replication restart in UV‐irradiated Escherichia coli involving pols II, III, V, PriA, RecA and RecFOR proteins
Author(s) -
Rangarajan Savithri,
Woodgate Roger,
Goodman Myron F.
Publication year - 2002
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.1365-2958.2002.02747.x
Subject(s) - repressor lexa , biology , sos response , dna replication , escherichia coli , mutant , microbiology and biotechnology , dna , dna repair , genetics , gene , repressor , gene expression
Summary In Escherichia coli , UV‐irradiated cells resume DNA synthesis after a transient inhibition by a process called replication restart. To elucidate the role of several key proteins involved in this process, we have analysed the time dependence of replication restart in strains carrying a combination of mutations in lexA , recA , polB (pol II), umuDC (pol V), priA , dnaC , recF , recO or recR . We find that both pol II and the origin‐independent primosome‐assembling function of PriA are essential for the immediate recovery of DNA synthesis after UV irradiation. In their absence, translesion replication or ‘replication readthrough’ occurs ≈ 50 min after UV and is pol V‐dependent. In a wild‐type, lexA + background, mutations in recF , recO or recR block both pathways. Similar results were obtained with a lexA (Def) recF strain. However, lexA (Def) recO or lexA (Def) recR strains, although unable to facilitate PriA‐pol II‐dependent restart, were able to perform pol V‐dependent readthrough. The defects in restart attributed to mutations in recF , recO or recR were suppressed in a recA730 lexA (Def) strain expressing constitutively activated RecA (RecA*). Our data suggest that in a wild‐type background, RecF, O and R are important for the induction of the SOS response and the formation of RecA*‐dependent recombination intermediates necessary for PriA/Pol II‐dependent replication restart. In con‐trast, only RecF is required for the activation of RecA that leads to the formation of pol V (UmuD ′ 2 C) and facilitates replication readthrough.