The effect of growth conditions on inducible, recA-dependent resistance to x rays in Escherichia coli
Escherichia coli cells grown to logarithmic phase in, and plated on, rich medium (yeast extract-nutrient broth) were more resistant to X rays, ultraviolet (uv) radiation, and methyl methanesulfonate (MMS) than cells grown in, and plated on, minimal medium. We have called this enhanced survival capability medium-dependent resistance (MDR). The magnitude of MDR observed after oxic X irradiation was greater than that observed after anoxic X irradiation, uv irradiation, or MMS treatment. MDR was not observed in stationary-phase cells with X or uv radiation. MDR was associated with an increased ability to repair X-ray-induced DNA single-strand breaks, and with reduced X-ray-induced DNA degradation and protein synthesis retardation. Postirradiation protein synthesis was concluded to be critical in allowing the high X-ray survival associated with MDR, because of the large radiosensitization caused by a postirradiation growth medium shift down or treatment with rifampicin (RIF). recA protein must be at least one of the proteins whose synthesis is critical to MDR, as judged by the absence of MDR or a RIF effect in X-irradiated recA and lexA mutants. The results with X-irradiated temperature-conditional recA cells suggest that it is only after cells have been damaged that the recA gene plays a role in MDR.
- Research Organization:
- Stanford Univ. School of Medicine, CA
- OSTI ID:
- 5742030
- Journal Information:
- Radiat. Res.; (United States), Vol. 93:2
- Country of Publication:
- United States
- Language:
- English
Similar Records
Recovery from ultraviolet light-induced inhibition of DNA synthesis requires umuDC gene products in recA718 mutant strains but not in recA+ strains of Escherichia coli
The mechanism of recA polA lethality: Suppression by RecA-independent recombination repair activated by the lexA(Def) mutation in Escherichia coli
Related Subjects
DNA
BIOLOGICAL RADIATION EFFECTS
ESCHERICHIA COLI
RADIOINDUCTION
RADIOSENSITIVITY
PROTEINS
BIOSYNTHESIS
BIOLOGICAL REPAIR
CELL CYCLE
CULTURE MEDIA
EXPERIMENTAL DATA
EXTREME ULTRAVIOLET RADIATION
METHYL METHANESULFONATE
MUTANTS
STRAND BREAKS
X RADIATION
BACTERIA
BIOLOGICAL EFFECTS
BIOLOGICAL RECOVERY
DATA
ELECTROMAGNETIC RADIATION
ESTERS
INFORMATION
IONIZING RADIATIONS
MICROORGANISMS
MUTAGENS
NUCLEIC ACIDS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
RADIATION EFFECTS
RADIATIONS
RECOVERY
REPAIR
SULFONIC ACID ESTERS
SYNTHESIS
ULTRAVIOLET RADIATION
560131* - Radiation Effects on Microorganisms- Basic Studies- (-1987)