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Replication of lambda plasmid DNA in the Escherichia coli cell cycle
A Herman-Antosiewicz1, G Wegrzyn
1Department of Molecular Biology, University of Gdańsk, Poland.
Biochemical and Biophysical Research Communications
|July 2, 1998
Summary
Lambda plasmids can replicate without the Cro repressor, showing cell cycle-dependent initiation. Host DnaA protein is involved in this regulation, offering a simple model for DNA replication studies.
Area of Science:
- Molecular Biology
- Microbiology
Background:
- The Cro repressor's autoregulatory loop was thought to be the primary regulator of lambda plasmid replication initiation in Escherichia coli.
- Recent findings suggest lambda plasmids can be maintained without Cro function.
Purpose of the Study:
- To investigate lambda plasmid replication control in the absence of Cro repressor function.
- To explore the role of cell cycle regulation in lambda plasmid DNA synthesis.
Main Methods:
- Inactivation of the Cro repressor in lambda plasmids.
- Monitoring of lambda plasmid DNA synthesis and copy number.
- Analysis of replication initiation timing relative to the host cell cycle.
Main Results:
- Lambda plasmid DNA synthesis significantly increases upon Cro repressor inactivation but stabilizes at a constant level.
- Replication initiation becomes cell cycle-dependent in lambda plasmids lacking Cro function.
- The host DnaA protein is implicated in the cell-cycle-specific control of lambda cro- plasmid replication.
Conclusions:
- Lambda plasmids lacking Cro repressor function exhibit cell cycle-dependent replication initiation.
- The DnaA protein plays a role in this novel regulatory mechanism.
- The lambda cro- plasmid serves as a simplified model for studying DNA replication regulation within the cell cycle.