The RdgC protein of Escherichia coli binds DNA and counters a toxic effect of RecFOR in strains lacking the replication restart protein PriA.
PriA protein provides a means to load the DnaB replicative helicase at DNA replication fork and D loop structures, and is therefore a key factor in the rescue of stalled or broken forks and subsequent replication restart. We show that the nucleoid-associated RdgC protein binds non-specifically to single-stranded (ss) DNA and double-stranded DNA. It is also essential for growth of a strain lacking PriA, indicating that it might affect replication fork progression or fork rescue. dnaC suppressors of priA overcome this inviability, especially when RecF, RecO or RecR is inactivated, indicating that RdgC avoids or counters a toxic effect of these proteins. Mutations modifying ssDNA-binding (SSB) protein also negate this toxic effect, suggesting that the toxicity reflects inappropriate loading of RecA on SSB-coated ssDNA, leading to excessive or untimely RecA activity. We suggest that binding of RdgC to DNA limits RecA loading, avoiding problems at replication forks that would otherwise require PriA to promote replication restart. Mutations in RNA polymerase also reduce the toxic effect of RecFOR, providing a further link between DNA replication, transcription and repair.
Moore
Timothy
T
Institute of Genetics, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK.
McGlynn
Peter
P
Ngo
Hien-Ping
HP
Sharples
Gary J
GJ
Lloyd
Robert G
RG
D002455:Cell Division / Q000502:physiology; D048429:Cell Size; D004247:DNA / Q000378:metabolism*; D004265:DNA Helicases / Q000378:metabolism*; D004261:DNA Replication / Q000502:physiology*; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D019143:Evolution, Molecular; D005798:Genes, Bacterial; D009154:Mutation; D010802:Phylogeny; D011485:Protein Binding; D051716:Replication Protein A
D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; C071702:DnaC protein, E coli; D029968:Escherichia coli Proteins; C103478:RdgC protein, E coli; D051716:Replication Protein A; D004247:DNA; D012321:DNA-Directed RNA Polymerases; D004265:DNA Helicases