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Journal of Bacteriology, July 2007, p. 5101-5107, Vol. 189, No. 14
0021-9193/07/$08.00+0 doi:10.1128/JB.00409-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.
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Department of Chemistry and Biochemistry, and Program in Molecular and Cell Biology, University of Maryland, College Park, Maryland
Received 20 March 2007/ Accepted 4 May 2007
The bacterium Deinococcus radiodurans is resistant to extremely high levels of DNA-damaging agents such as UV light, ionizing radiation, and chemicals such as hydrogen peroxide and mitomycin C. The organism is able to repair large numbers of double-strand breaks caused by ionizing radiation, in spite of the lack of the RecBCD enzyme, which is essential for double-strand DNA break repair in Escherichia coli and many other bacteria. The D. radiodurans genome sequence indicates that the organism lacks recB and recC genes, but there is a gene encoding a protein with significant similarity to the RecD protein of E. coli and other bacteria. We have generated D. radiodurans strains with a disruption or deletion of the recD gene. The recD mutants are more sensitive than wild-type cells to irradiation with gamma rays and UV light and to treatment with hydrogen peroxide, but they are not sensitive to treatment with mitomycin C and methyl methanesulfonate. The recD mutants also show greater efficiency of transformation by exogenous homologous DNA. These results are the first indication that the D. radiodurans RecD protein has a role in DNA damage repair and/or homologous recombination in the organism.
Published ahead of print on 11 May 2007.
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