Abstract
The capability to synthesize recA protein has been tested for Escherichia coli treated with mitomycin C. recA protein was assayed using an immunoradiometric assay (Paoletti, C., Salles, B., and Giacomoni, P. U. (1982) Biochimie 64, 239-246). Mitomycin C-treated wild type E. coli can express recA gene in a similar quantitative fashion, independently of the growth media used in this work; glucose did not inhibit induction of recA protein in cells growing in synthetic media. Wild type E. coli recovering from energy starvation displays a similar qualitative capability to induce the synthesis of recA protein independently of the stage of growth at which the cells are treated with the drug. At midexponential phase, the cells appear to have an enhanced capability to synthesize recA protein. The relationship between survival and capability to synthesize recA protein was explored for E. coli lex, rec, and/or uvr mutants, after treatment with mitomycin C. A good correlation was found, except for a recB mutant and for an ethidium-sensitive strain, both able to produce as much recA protein as the wild type but 100-fold more sensitive to the drug. A similarly satisfactory correlation was found when plotting the survival after UV irradiation versus the capability of synthetizing recA protein with the exception of an uvrA strain and of a lexA strain.
Highlights
Mitomycin C-treated wild type E. coli can express recA gene in a similar quantitative fashion, independently of the growth media used in this work; glucose did not inhibit induction of recA protein in cells growing in synthetic media
Wild type E. coli recovering from energy starvation displays a similar qualitative capability to induce the synthesis of recA protein independently of the stageof growth at which the cells artereated with thedrug
The results reported in this paper can be analyzed in the light of the experimental datafrom other laboratories aswell as in relationship to the theoretical model proposed for the content of recA protein 1 h after mitomycin C treatment. description of the induction of the functions involved in the
Summary
Which could be possibly attributed to the stage of growth in the induction of recA protein by mitomycin C as far as the. AeM=) 0.2 ( t = 0), glucose was added to a 1%final concentra- growth, as far as the time interval required for observing a tionand 5 minlater mitomycin C was addedto a final drop in survival is concerned These results seem to indicate concentration of 1 pg/ml. Cells were exponentially the lengthof the lag period and the maximlaevl el of induction grown in LB up to anAsso= 0.18-0.22 ( t = 0) and were added are concerned Another variable which might influence the expression of 1 h, samples were taken in order to determine the cellular recA gene is the stageof growth of the cells in the exponential viability in the drug-treated sample anidn the control, aws ell recA Protein and Survival with Mitomycin C.
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