Interrogating the Escherichia coli cell cycle by cell dimension perturbations

Area of Science:

• Microbiology
• Cell Biology
• Biophysics

Background:

• Bacteria coordinate cell cycle events for accurate duplication and size control.
• Escherichia coli growth follows Schaechter's growth law, relating cell volume to growth rate.
• Cell dimensions are critical for understanding bacterial cell cycle regulation.

Purpose of the Study:

• To investigate the robustness of Schaechter's growth law under perturbed cell dimensions.
• To explore how altering mreB and ftsZ expression affects cell shape and growth.
• To test the relationship between DNA replication initiation and cell division timing.

Main Methods:

• Systematic perturbation of cell dimensions by varying mreB and ftsZ expression levels in Escherichia coli.
• Measurement of cell length, width, and cell cycle timing parameters.
• Analysis of bacterial growth and cell division under altered conditions.

Main Results:

• Decreasing mreB increased cell width; decreasing ftsZ increased cell length.
• The time from replication termination to cell division increased with perturbed dimensions.
• Schaechter's growth law remained valid across various growth conditions and dimension perturbations.

Conclusions:

• The robustness of Schaechter's growth law supports models linking cell division timing to DNA replication initiation.
• Cell volume is a key factor governing replication initiation timing.
• Findings support the "adder-per-origin" model of bacterial cell division.