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Updated: Jun 27, 2026
12:08
Multi-scale Analysis of Bacterial Growth Under Stress Treatments
Published on: November 28, 2019
The stringent response and cell cycle arrest in Escherichia coli.
Daniel J Ferullo1, Susan T Lovett
1Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA, USA.
Plos Genetics
|December 17, 2008
Summary
The bacterial stringent response halts DNA replication and chromosome segregation during nutrient starvation. This arrest, regulated by ppGpp and DNA methylation, ensures cells contain an integer number of chromosomes before resuming growth.
Area of Science:
- Bacteriology
- Molecular Biology
- Genetics
Background:
- The bacterial stringent response is a global regulatory mechanism triggered by environmental stresses like nutrient deprivation.
- This response leads to the accumulation of alarmones, guanosine tetra- and pentaphosphate (ppGpp and pppGpp), which alter cellular physiology.
- Understanding the precise effects of the stringent response on DNA replication and chromosome segregation is crucial for bacterial survival.
Purpose of the Study:
- To characterize the replication arrest occurring during the stringent response in Escherichia coli.
- To investigate the role of ppGpp and DNA methylation in enforcing this arrest.
- To determine how the stringent response impacts bacterial chromosome segregation.
Main Methods:
- Induction of the stringent response using serine hydroxamate in wild-type E. coli.
- Analysis of nucleoid structure and chromosome segregation using microscopy.
- Assessment of replication initiation and chromosome segregation in various mutant strains (e.g., relA, seqA, dam).
Main Results:
- Wild-type cells arrest replication with an integer number of chromosomes and a specific origin-to-terminus ratio during the stringent response.
- Nucleoid decondensation is observed, and chromosome segregation is arrested at a specific point, with origins segregating but termini remaining colocalized.
- The stringent arrest is partially relieved in seqA and dam mutants, suggesting a role for DNA methylation and SeqA binding in enforcing the complete arrest.
Conclusions:
- The bacterial stringent response, mediated by ppGpp accumulation, arrests both DNA replication and chromosome segregation.
- DNA methylation and SeqA binding are necessary for a complete stringent arrest, impacting replication initiation and segregation.
- This study reveals that bacterial chromosome segregation can be regulated in response to environmental conditions, offering new insights into its mechanism.
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