RecBC enzyme overproduction affects UV and gamma radiation survival of Deinococcus radiodurans

• Published in: DNA repair 2008, Vol.7 (1), p.40-47
• Main Authors: Khairnar, Nivedita P., Kamble, Vidya A., Misra, Hari S.
• Format: Article
• Language: English
• Subjects: Bacteriology; Base Sequence; Biological and medical sciences; Deinococcus; Deinococcus - enzymology; Deinococcus - genetics; Deinococcus - radiation effects; Deinococcus radiodurans; DNA Primers; DNA Repair; Escherichia coli; Exodeoxyribonuclease V - metabolism; Fundamental and applied biological sciences. Psychology; Gamma Rays; Growth, nutrition, cell differenciation; Kinetics; Microbiology; Molecular and cellular biology; Molecular genetics; Mutagenesis. Repair; Near-UV response; Radiation Tolerance; RecBC enzyme; Ultraviolet Rays
• ISSN: 1568-7864; 1568-7856
• DOI: 10.1016/j.dnarep.2007.07.007

Deinococcus radiodurans recovering from the effect of acute dose of gamma (γ) radiation shows a biphasic mechanism of DNA double strands breaks repair that involves an efficient homologous recombination. However, it shows higher sensitivity to near-UV (NUV) than Escherichia coli and lacks RecBC, a DNA strand break (DSB) repair enzyme in some bacteria. Recombinant Deinococcus expressing the recBC genes of E. coli showed nearly three-fold improvements in near-UV tolerance and nearly 2 log cycle reductions in wild type γ radiation resistance. RecBC over expression effect on radiation response of D. radiodurans was independent of indigenous RecD. Loss of γ radiation tolerance was attributed to the enhanced rate of in vivo degradation of radiation damaged DNA and delayed kinetics of DSB repair during post-irradiation recovery. RecBC expressing cells of Deinococcus showed wild type response to Far-UV. These results suggest that the overproduction of RecBC competes with the indigenous mechanism of γ radiation damaged DNA repair while it supports near-UV tolerance in D. radiodurans.