Replication of lambda plasmid DNA in the Escherichia coli cell cycle.
The Cro repressor autoregulatory loop has long been considered the main regulatory process in controlling lambda plasmid replication initiation in Escherichia coli. However, we found recently that lambda plasmids can be maintained at a constant copy number in the absence of Cro function. Here we demonstrate that shortly after inactivation of the Cro repressor, the synthesis of lambda plasmid DNA increases significantly but is then stabilized at a level similar to that observed in the presence of the Cro function. We found that replication initiation of lambda plasmids carrying a functional cro gene proceeds randomly in the host cell cycle, but in the absence of Cro function the replication initiation of lambda plasmid DNA appears to be cell cycle dependent. The host DnaA protein appears to be at least one of the factors involved in the cell-cycle-specific control of lambda cro- plasmid replication. Therefore, it seems that the lambda cro- plasmid may serve as an amazingly simple model for studies on the regulation of DNA replication in the cell cycle.
Herman-Antosiewicz
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A
Department of Molecular Biology, University of Gdańsk, Poland.
Wegrzyn
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G
D001426:Bacterial Proteins / Q000235:genetics; D010582:Bacteriophage lambda / Q000235:genetics*; D002453:Cell Cycle / Q000502:physiology*; D004261:DNA Replication / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D004926:Escherichia coli / Q000378:metabolism*; D018628:Gene Dosage; D007700:Kinetics; D010957:Plasmids / Q000235:genetics*; D012097:Repressor Proteins / Q000502:physiology; D013696:Temperature; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C066312:DnaA protein, Bacteria; D012097:Repressor Proteins; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins