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Escherichia coli cell cycle control genes affect chromosome superhelicity
T Weitao1, K Nordström, S Dasgupta
1Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, Sweden.
EMBO Reports
|March 27, 2001
Summary
Mutations in Escherichia coli cell cycle genes mukB and seqA alter DNA supercoiling. This study directly demonstrates mukB and seqA
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- DNA topology, specifically supercoiling, is crucial for various cellular processes in bacteria.
- The cell cycle genes mukB and seqA are known to be involved in DNA replication and segregation, but their direct role in DNA topology was unclear.
Purpose of the Study:
- To directly measure and demonstrate the impact of mukB and seqA mutations on the superhelicity of the Escherichia coli chromosome.
- To investigate whether these cell cycle genes influence plasmid DNA topology as well.
Main Methods:
- Ethidium bromide titration was employed for direct measurement of DNA supercoiling.
- Superhelicity of both the bacterial chromosome and plasmids was assessed in wild-type and mutant strains (mukB and seqA).
Main Results:
- mukB mutants exhibited reduced negative supercoiling compared to wild-type E. coli.
- seqA mutants showed increased negative supercoiling relative to wild-type E. coli.
- Similar, though less pronounced, topological changes were observed in plasmids within these mutant strains.
Conclusions:
- The cell cycle genes mukB and seqA directly modulate the topological state (superhelicity) of the Escherichia coli chromosome.
- The influence of mukB and seqA extends to plasmid DNA topology, suggesting interaction with broader DNA topology maintenance factors.
- This study provides the first direct evidence linking mukB and seqA gene function to E. coli chromosome superhelicity.