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J Bacteriol. 1970 July; 103(1): 49-54
Copyright © 1970 American Society for Microbiology. All Rights Reserved.

Repair of Radiation-Induced Damage in Escherichia coli II. Effect of rec and uvr Mutations on Radiosensitivity, and Repair of X-Ray-Induced Single-Strand Breaks in Deoxyribonucleic Acid¹

^a Department of Radiology, Stanford University School of Medicine, Stanford, California 94305

ABSTRACT

Strains of Escherichia coli K-12 mutant in the genes controlling excision repair (uvr) and genetic recombination (rec) have been studied with reference to their radiosensitivity and their ability to repair X-ray-induced single-strand breaks in deoxyribonucleic acid (DNA). Mutations in the rec genes appreciably increase the radiosensitivity of E. coli K-12, whereas uvr mutations produce little if any increase in radiosensitivity. For a given dose of X-rays, the yield of single-strand breaks has been shown by alkaline sucrose gradient studies to be largely independent of the presence of rec or uvr mutations. The rec⁺ cells (including those carrying the uvrB5 mutation) could efficiently rejoin X-ray-induced single-strand breaks in DNA, whereas recA56 mutants could not repair these breaks to any great extent. The recB21 and recC22 mutants showed some indication of repair capacity. From these studies, it is concluded that a correlation exists between the inability to repair single-strand breaks and the radiosensitivity of the rec mutants of E. coli K-12. This suggests that unrepaired single-strand breaks may be lethal lesions in E. coli.

¹ A preliminary account of this work was presented at the 14th Annual Meeting of the Biophysical Society, Baltimore, Md., February 1970.

This article has been cited by other articles:

• Town, C. D., Smith, K. C., Kaplan, H. S. (1971). DNA Polymerase Required for Rapid Repair of X-ray--Induced DNA Strand Breaks in vivo. Science 172: 851-854 [Abstract]