Enzymatic induction of DNA double-strand breaks in $gamma$-irradiated Escherichia coli K-12

Journal Article · Sat Nov 01 04:00:00 EST 1975 · Proc. Natl. Acad. Sci. U.S.A., v. 72, no. 11, pp. 4265-4269

DOI:https://doi.org/10.1073/pnas.72.11.4265· OSTI ID:4067350

Bonura, T; Smith, K C; Kaplan, H S

The polA1 mutation increases the sensitivity of E. coli K-12 to killing by $gamma$-irradiation in air by a factor of 2.9 and increases the yield of DNA double-strand breaks by a factor of 2.5. These additional DNA double-strand breaks appear to be due to the action of nucleases in the polA1 strain rather than to the rejoining of radiation-induced double-strand breaks in the pol$sup +$ strain. This conclusion is based upon the observation that $gamma$-irradiation at 3$sup 0$ did not affect the yield of DNA double-strand breaks in the pol$sup +$ strain, but decreased the yield in the polA1 strain by a factor of 2.2. Irradiation of the polA1 strain at 3$sup 0$ followed by incubation at 3$sup 0$ for 20 min before plating resulted in approximately a 1.5-fold increase in the D$sub 0$. The yield of DNA double-strand breaks was reduced by a factor of 1.5. The pol$sup +$ strain, however, did not show the protective effect of the low temperature incubation upon either survival or DNA double-strand breakage. We suggest that the increased yield of DNA double-strand breaks in the polA$sub 1$ strain may be the result of the unsuccessful excision repair of ionizing radiation-induced dna base damage. (auth)

• Research Organization: Stanford Univ., CA
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-023464
• OSTI ID: 4067350
• Journal Information: Proc. Natl. Acad. Sci. U.S.A., v. 72, no. 11, pp. 4265-4269, Journal Name: Proc. Natl. Acad. Sci. U.S.A., v. 72, no. 11, pp. 4265-4269; ISSN PNASA
• Country of Publication: United States
• Language: English

Related Subjects

*DNA-- STRAND BREAKS
*ESCHERICHIA COLI-- BIOLOGICAL RADIATION EFFECTS
*NUCLEASES-- BIOLOGICAL EFFECTS
560131* --Biomedical Sciences
Applied Studies--Radiation Effects--Radiation Effects on Microorganisms--Basic Studies
GAMMA RADIATION
MUTATIONS
N48310* --Life Sciences--Radiation Effects on Microorganisms- -Basic Studies
RADIOINDUCTION
SURVIVAL TIME