Critical Analysis of DNA Packaging Models at Different Types of Stress

DNA compaction in Escherichia coli cells was studied by synchrotron radiation diffraction and transmission electron microscopy. The aim was to identify DNA structure when bacteria are exposed to the action of antibiotic ciprofloxacin. DNA structure after the action of ciprofloxacin resembles the structure of DNA in the anabiotic dormant state. The Dps null mutant strain (K-12 Δdps) experiment allows us to make a critical analysis of DNA packaging models under different types of stress and draw conclusions: peaks at 44.5, 22.2 and 14.8 Å resolutions are associated with the ordered arrangement of DNA. Such an order must be considered in any further model of DNA compaction. The in vitro DNA-Dps packaging model gives an incorrect picture of DNA-Dps packaging in the cell.