Pyrimidine dimer excision in Escherichia coli strains deficient in exonucleases V and VII and in the 5'. -->. 3' exonuclease of DNA polymerase I. [uv radiation]

Journal Article · Mon Jan 01 00:00:00 EST 1979 · J. Bacteriol.; (United States)

OSTI ID:6367374

Chase, J W ^[1]; Masker, W E; Murphy, J B

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1. Albert Einstein Coll. of Medicine, Bronx, NY

An isogenic series of Escherichia coli strains deficient in various combinations of three 5' ..-->.. 3' exonucleases (exonuclease V, exonuclease VII, and the 5' ..-->.. 3' exonuclease of DNA polymerase I) was constructed and examined for the ability to excise pyrimidine dimers after uv irradiation. Although the recB and recC mutations (deficient in exonuclease V) proved to be incompatible with the polA(Ex) mutation (deficient in the 5' ..-->.. 3' exonuclease of DNA polymerase I), it was possible to reduce the level of the recB,C exonuclease by the use of temperature-sensitivite recB270 recC271 mutants. It was found that, by employing strains deficient in exonuclease V, postirradiation DNA degradation could be reduced and dimer excision measurements could be facilitated. Mutants deficient in exonuclease V were found to excise dimers at a rate comparable to that of the wild type. Mutants deficient in exonuclease V and the 5' ..-->.. 3' exonuclease of DNA polymerase I are slightly slower than the wild type at removing dimers accumulated after doses in excess of 40 J/m/sup 2/. However, although strains with reduced levels of exonuclease VII excised dimers at the same rate as the wild type, the addition of an exonuclease VII deficiency to a strain with reduced levels of exonuclease V and the 5' ..-->.. 3' exonuclease of DNA polymerase I caused a marked decrease in the rate and extent of dimer excision. These observations support previous indications that the 5' ..-->.. 3' exonuclease of DNA polymerase I is important in dimer removal and also suggest a role for exonuclease VII in the excision repair process.

• OSTI ID: 6367374
• Journal Information: J. Bacteriol.; (United States), Vol. 137:1
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
DNA
BIOCHEMICAL REACTION KINETICS
ESCHERICHIA COLI
BIOLOGICAL RADIATION EFFECTS
NUCLEASES
POLYMERASES
MUTANTS
PYRIMIDINES
ULTRAVIOLET RADIATION
AZINES
BACTERIA
BIOLOGICAL EFFECTS
ELECTROMAGNETIC RADIATION
ENZYMES
HETEROCYCLIC COMPOUNDS
KINETICS
MICROORGANISMS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOSPHOTRANSFERASES
RADIATION EFFECTS
RADIATIONS
REACTION KINETICS
TRANSFERASES
560131* - Radiation Effects on Microorganisms- Basic Studies- (-1987)