Abstract
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.
| Original language | English |
|---|---|
| Journal | PLoS ONE |
| Volume | 3 |
| Issue number | 8 |
| Pages (from-to) | e2984 |
| ISSN | 1932-6203 |
| DOIs | |
| Publication status | Published - 20 Aug 2008 |
Keywords
- Bacterial Proteins/genetics
- Chromosomes, Bacterial/genetics
- DNA Replication/genetics
- DNA-Binding Proteins/genetics
- Escherichia coli K12/genetics
- Escherichia coli Proteins/antagonists & inhibitors
- Flow Cytometry
- Gene Expression Profiling
- Gene Expression Regulation, Bacterial
- Genes, Bacterial
- Genes, Lethal
- Heat-Shock Proteins/genetics
- Nucleotides/biosynthesis
- Oligonucleotide Array Sequence Analysis
- RNA, Bacterial/genetics
- RNA, Messenger/genetics
- SOS Response (Genetics)
- Thermodynamics
- Transcription, Genetic