| Autor: |
Marsden, Howard S., Pollard, Ernest C., Ginoza, William, Randall, Eleanor P. |
| Zdroj: |
Journal of Bacteriology; May 1974, Vol. 118 Issue: 2 p465-470, 6p |
| Abstrakt: |
When Escherichia colicells are gamma irradiated they degrade their deoxyribonucleic acid (DNA). The DNA of previously gamma-irradiated T4 phage is also degraded in infected cells. The amount of degradation is not only dependent on the dose but also on the genotype of the cell. The amount of degradation is less in cells carrying a recBor a recCmutation, suggesting that most of the DNA degradation is due to the recB+and recC+gene product (exonuclease V). In some strains a previous dose of ultraviolet (UV) light followed by incubation renders the cells resistant to DNA degradation after gamma irradiation. We have shown this inhibition to take place for infecting T4 phage also. By using six strains of E. coliselected for mutations in the genes recA, exr(or lex), and uvrB, we have been able to show that the preliminary UV treatment produces no change in recAand exrcells for both endogenous DNA degradation and the degradation of infecting irradiated T4 phage DNA, i.e., inhibition was not detected in these strains. On the other hand, wild-type cells and strains carrying mutations of uvrBshow inhibition in both types of experiments. Because the recAgene product and the exr+(lex+) gene product are necessary for the induction of prophage, it is possible that the phenomenon of inducible inhibition requires recA+and exr+presence. One interpretation of these results is that an inducible inhibitor may be controlled by the exrgene. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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