Escherichia coli dnaA gene function and bacteriophage λ replication

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Allele specificity of the Escherichia coli dnaA gene function in the replication of plasmids derived from bacteriophage λ has been demonstrated previously. Here, using a series of dnaA temperature-sensitive mutants, we investigated dnaA allele specificity of the replication of phages λP+ and λPts1πA66. We found that phage λP+ produces its progeny efficiently at 43°C irrespective of the dnaA allele, whereas λPts1πA66, which is unable to develop lytically in the dnaA+ host at this temperature, can replicate with different efficiency in certain dnaA mutants. Since the main role of DnaA in λ development seems to be stimulation of transcription from the p(R) promoter, we measured the activity of this promoter (using a p(R)-lacZ fusion) and the abundance of p(R)-derived transcripts (by Northern blotting analysis) in dnaA+ host and dnaA(ts) mutants at 30 and 43°C. We found significant differences in the activity of p(R) in various dnaA(ts) mutants at 30°C, which indicate different levels of stimulation of this promoter by products of particular dnaA alleles at permissive temperature. Differential levels of DnaA-mediated stimulation of p(R) in various dnaA(ts) mutants were also found at 43°C. Stimulation of the p(R) promoter by DnaA is necessary for both efficient production of the λ replication proteins, O and P, and effective transcriptional activation of oriλ. The differences in the efficiency of p(R) activation observed in dnaA mutants at 30 and 43°C can explain the mechanisms of allele specificity of dnaA gene function in the replication of bacteriophage λ and plasmids derived from this phage. Copyright (C) 1998 Federation of European Microbiological Societies.




Szalewska-Pałasz, A., Lemieszek, E., Pankiewicz, A., Wegrzyn, A., Helinski, D. R., & Wegrzyn, G. (1998). Escherichia coli dnaA gene function and bacteriophage λ replication. FEMS Microbiology Letters, 167(1), 27–32.

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