Transient enhanced cell division by blocking DNA synthesis in Escherichia coli

Area of Science:

• Microbiology
• Cell Biology
• Bacterial Physiology

Background:

• Bacterial cell division requires nucleoid duplication.
• Inhibition of DNA replication leads to filamentation and cell division arrest.
• Existing models suggest temporal and spatial coupling between DNA replication and cell division machinery.

Purpose of the Study:

• To investigate the immediate effects of DNA replication inhibition on bacterial cell division dynamics.
• To explore the relationship between nucleoid status and cell morphology changes during early stages of division arrest.
• To provide further evidence for the coordination between the bacterial nucleoid/replisome and the cell envelope/divisome.

Main Methods:

• Treatment of *Escherichia coli* with a DNA replication inhibitor.
• Microscopic observation and quantification of cell division events (constriction).
• Analysis of nucleoid morphology and cell dimensions (length and width).

Main Results:

• Within the first 10 minutes of replication inhibition, *Escherichia coli* exhibited enhanced residual cell divisions, with the proportion of constricted cells doubling to 40%.
• Nucleoids contracted, and cells underwent dimensional remodeling, decreasing in length and increasing in width.
• These rapid changes indicate a complex interplay between DNA replication status and the cell division machinery.

Conclusions:

• The study demonstrates a rapid, transient enhancement of cell division and cell remodeling in *Escherichia coli* upon immediate inhibition of DNA replication.
• Preliminary data support the existence of tight temporal and spatial couplings between the nucleoid/replisome and the sacculus/divisome.
• Results are consistent with the hypothesis that rod-shaped bacteria actively modulate cell width during the division process.