Genetic and kinetic evidence for different types of postreplication repair in Escherichia coli B
The changes in molecular weight of deoxyribonucleic acid (DNA) synthesized after ultraviolet irradiation of Escherichia coli WP2/sub s/ uvrA, and strains additionally mutant at polA, exrA, recA, and exrA and polA loci, were examined by alkaline sucrose gradient centrifugation. In a repair-deficient uvrA recA strain, the frequency of breaks in newly synthesized DNA was equal to that for pyrimidine dimers in parental DNA. Measurements of the amounts and rates of postreplication repair of these breaks indicate that repair is two to three times faster when DNA polymerase I is present, although almost all breaks are repaired regardless of DNA polymerase I activity. Increased ultraviolet doses lead to an increase in the proportion of breaks remaining unrepaired in uvrA recA, uvrA exrA, and uvrA exrA polA strains. The numbers of unrepaired breaks resemble the numbers expected if repair of one lesion is prevented by proximity of a second lesion. (auth)
- Research Organization:
- Oak Ridge National Lab., TN
- NSA Number:
- NSA-33-000879
- OSTI ID:
- 4143449
- Journal Information:
- J. Bacteriol., v. 123, no. 1, pp. 154-161, Journal Name: J. Bacteriol., v. 123, no. 1, pp. 154-161; ISSN JOBAA
- Country of Publication:
- United States
- Language:
- English
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*ESCHERICHIA COLI-- BIOLOGICAL RADIATION EFFECTS
*STRAND BREAKS-- BIOLOGICAL REPAIR
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BIOSYNTHESIS
DOSE-RESPONSE RELATIONSHIPS
MOLECULAR WEIGHT
N48310* --Life Sciences--Radiation Effects on Microorganisms- -Basic Studies
POLYMERASES
RADIOINDUCTION
ULTRAVIOLET RADIATION