This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Pierucci, O Articles by Helmstetter, C E Search for Related Content PubMed PubMed Citation Articles by Pierucci, O Articles by Helmstetter, C E

research-article

DnaA protein overproduction abolishes cell cycle specificity of DNA replication from oriC in Escherichia coli.

Department of Experimental Biology, Roswell Park Memorial Institute, Buffalo, New York 14263.

ABSTRACT

Initiation of DNA replication from oriC in Escherichia coli takes place at a specific time in the cell division cycle, whether the origin is located on a chromosome or a minichromosome, and requires participation of the product of the dnaA gene. The effects of overproduction of DnaA protein on the cell cycle specificity of the initiation event were determined by using minichromosome replication as the assay system. DnaA protein was overproduced by inducing the expression of plasmid-encoded dnaA genes under control of either the ptac or lambda pL promoter. Induction of DnaA protein synthesis caused a burst of minichromosome replication in cells at all ages in the division cycle. The magnitude of the burst was consistent with the initiation of one round of replication per minichromosome in all cells. The replication burst was followed by a period of reduced minichromosome replication, with the reduction being greater at 30 than at 41 degrees C. The results support the idea that the DnaA protein participates in oriC replication at a stage that is limiting for initiation. Excess DnaA protein enabled all cells to achieve the state required for initiation of DNA polymerization by either effecting or overriding the normal limiting process.

This article has been cited by other articles:

• Sibley, C. D., MacLellan, S. R., Finan, T. (2006). The Sinorhizobium meliloti chromosomal origin of replication. Microbiology 152: 443-455 [Abstract] [Full Text]