Deoxyribonucleic acid repair in Escherichia coli mutants deficient in the 5'----3' exonuclease activity of deoxyribonucleic acid polymerase I and exonuclease VII

Journal Article · Sun May 01 00:00:00 EDT 1977 · J. Bacteriol.; (United States)

OSTI ID:5617916

Chase, J W; Masker, W E

A series of Escherichia coli strains deficient in the 5'----3' exonuclease activity associated with deoxyribonucleic acid (DNA) polymerase I (exonuclease VI) and exonuclease VII has been constructed. Both of these enzymes are capable of pyrimidine dimer excision in vitro. These strains were examined for conditional lethality, sensitivity to ultraviolet (UV) and X-irradiation, postirradiation DNA degradation, and ability to excise pyrimidine dimers. It was found that strains deficient in both exonuclease VI (polAex-) and exonuclease VII (xseA-) are significantly reduced in their ability to survive incubation at elevated temperature (43 degrees C) beyond the reduction previously observed for the polAex single mutants. The UV and X-ray sensitivity of the exonuclease VI-deficient strains was not increased by the addition of the xseA7 mutation. Mutants deficient in both enzymes are about as efficient as wild-type strains at excising dimers produced by up to 40 J/m2 UV. At higher doses strains containing only polAex- mutations show reduced ability to excise dimers; however, the interpretation of dimer excision data at these doses is complicated by extreme postirradiation DNA degradation in these strains. The additional deficiency in the polAex xseA7 double-mutant strains has no significant effect on either postirradiation DNA degradation or the apparent deficiency in dimer excision at high UV doses observed in polAex single mutants.

• Research Organization: Albert Einstein College of Medicine, Bronx, NY
• OSTI ID: 5617916
• Journal Information: J. Bacteriol.; (United States), Vol. 2
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ESCHERICHIA COLI
DNA REPAIR
MUTATIONS
RADIOSENSITIVITY
NUCLEASES
ENZYME ACTIVITY
DNA
MUTANTS
PYRIMIDINE DIMERS
ULTRAVIOLET RADIATION
X RADIATION
BACTERIA
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
ELECTROMAGNETIC RADIATION
ENZYMES
ESTERASES
HYDROLASES
IONIZING RADIATIONS
MICROORGANISMS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PHOSPHODIESTERASES
RADIATIONS
RECOVERY
REPAIR
560131* - Radiation Effects on Microorganisms- Basic Studies- (-1987)