Journal article
DnaC inactivation in Escherichia coli K-12 induces the SOS response and expression of nucleotide biosynthesis genes
Background: Initiation of chromosome replication in E. coli requires the DnaA and DnaC proteins and conditionally-lethal dnaA and dnaC mutants are often used to synchronize cell populations. Methodology/Principal Findings: DNA microarrays were used to measure mRNA steady-state levels in initiation-deficient dnaA46 and dnaC2 bacteria at permissive and non-permissive temperatures and their expression profiles were compared to MG1655 wildtype cells.
For both mutants there was altered expression of genes involved in nucleotide biosynthesis at the non-permissive temperature. Transcription of the dnaA and dnaC genes was increased at the non-permissive temperature in the respective mutant strains indicating auto-regulation of both genes. Induction of the SOS regulon was observed in dnaC2 cells at 38 degrees C and 42 degrees C.
Flow cytometric analysis revealed that dnaC2 mutant cells at non-permissive temperature had completed the early stages of chromosome replication initiation. Conclusion/Significance: We suggest that in dnaC2 cells the SOS response is triggered by persistent open-complex formation at oriC and/or by arrested forks that require DnaC for replication restart.
Language: | English |
---|---|
Publisher: | Public Library of Science |
Year: | 2008 |
Pages: | e2984 |
ISSN: | 19326203 |
Types: | Journal article |
DOI: | 10.1371/journal.pone.0002984 |
Bacterial Proteins Chromosomes, Bacterial DNA Replication DNA-Binding Proteins DnaA protein, Bacteria DnaC protein, E coli Escherichia coli K12 Escherichia coli Proteins Flow Cytometry Gene Expression Profiling Gene Expression Regulation, Bacterial Genes, Bacterial Genes, Lethal Heat-Shock Proteins Medicine Nucleotides Oligonucleotide Array Sequence Analysis Q R RNA, Bacterial RNA, Messenger SOS Response, Genetics Science Thermodynamics Transcription, Genetic