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 04:00:00 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), Journal Name: J. Bacteriol.; (United States) Vol. 2; ISSN JOBAA
• Country of Publication: United States
• Language: English

Related Subjects

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