Competition for DNA polymerase III between the chromosome and the R-factor R1
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The R-factor R1 is normally present in a low number of copies per genome in Escherichia coli K12. This number may be incrased several-fold either by lowering the growth rate or by mutation (copy mutants); these two effects act synergistically. The effect of the copy number on growth rate was tested in a strain with a temperaturesensitive DNA-polymerase III (dnaE(ts)) using wild type and copy mutants of the R-factor R1. The presence of the copy mutant R1drd-19B2 increased the temperature-sensitivity by 1.5–2°C and reduced the growth rate at temperatures close to the maximum temperature. This growth rate reduction was greater the higher the number of R1 copies/genome. The results indicate that DNA-polymerase III is involved in the replication of the plasmid R1 and that R1 and the chromosome compete for the enzyme.
KeywordsEnzyme Growth Rate Escherichia Coli Rate Reduction Growth Rate Reduction
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- Bertani, G.: Studies on lysogenesis. I. The mode of phage liberation by lysogenic Escherichia coli. J. Bact. 62, 296–300 (1951)Google Scholar
- Engberg, B., Nordström, K.: Plasmid replication at different growth rates. Proc. Soc. gen. Microbiol. 1, 8 (1973)Google Scholar
- Grinstead, J., Saunders, J. R., Ingram, I. C., Sykes, R. B., Richmond, M. H.: Properties of an R factor which originated in Pseudomonas aeruginosa 1822. J. Bact. 110, 529–537 (1972)Google Scholar
- Nordström, K., Engberg, B.: Plasmid replication and cell division of Escherichia coli K12. Proc. Soc. gen. Microbiol. 1, 8–9 (1973).Google Scholar