Photoreactivatiion, excision, and strand-rejoining repair in R factor-containing minicells of Escherichia coli K-12.
- 1 April 1972
- journal article
- Vol. 110 (1), 71-80
Abstract
Chromosomeless "minicells" are formed by misplaced cell fissions near the polar extremities of an Escherichia coli K-12 mutant strain. Resistance (R)-factor deoxyribonucleic acid (DNA) can be introduced into minicells by segregation from an R(+) (R64-11) derivative of the original mutant. We have assessed the ability of R(+) minicells to correct defects produced in their plasmid DNA by ultraviolet (UV) and gamma radiations. Minicells harboring plasmid DNA, in comparison with their repair-proficient minicell-producing parents, possess (i) an equal competence to rejoin single-strand breaks induced in DNA by gamma rays, (ii) a reduced capacity for the photoenzymatic repair of UV-induced pyrimidine dimers, and (iii) a total inability to excise dimers, apparently owing to a deficiency in UV-specific endonuclease activity responsible for mediating the initial incision step in excision repair. Assuming that the DNA repair properties of R(+) minicells reflect the concentration of repair enzymes located in the plasmid-containing polar caps of entire cells, these findings suggest that: (i) the enzymes responsible for rejoining single-strand breaks are distributed throughout the cell; (ii) photoreactivating enzyme molecules tend to be concentrated near bacterial DNA and to a lesser extent near plasmid DNA; and (iii) UV-specific endonuclease molecules are primarily confined to the central region of the E. coli cell and, thus, seldom segregate with R-factor DNA into minicells.This publication has 20 references indexed in Scilit:
- DNA Polymerase Required for Rapid Repair of X-ray—Induced DNA Strand Breaks in vivoScience, 1971
- Segregation of Transferable R Factors into Escherichia coli MinicellsNature, 1970
- Correlations between host-cell reactivation, ultraviolet reactivation and pyrimidine dimer excision in the DNA of bacteriophage λJournal of Molecular Biology, 1970
- DNA RepairAnnual Review of Biochemistry, 1968
- Enzymes Involved in the Early Stages of Repair of Ultraviolet-Irradiated DNAPublished by Cold Spring Harbor Laboratory ,1968
- The Properties of DNA Transferred to Minicells during ConjugationCold Spring Harbor Symposia on Quantitative Biology, 1968
- Rate of production of single-strand breaks in DNA by X-irradiation in situJournal of Molecular Biology, 1968
- Reconstruction in vivo of Irradiated Escherichia coli Deoxyribonucleic Acid; the Rejoining of Broken PiecesNature, 1966
- Resistance to the Bactericidal Effect of Ultraviolet Radiatic Conferred on Enterobacteria by the Colicine Factor collJournal of General Microbiology, 1965
- Sedimentation studies of the size and shape of DNAJournal of Molecular Biology, 1965