Repair of ionizing-radiation damage in the radiation resistant bacterium Deinococcus radiodurans.

Deinococcus radiodurans is extremely resistant to the lethal and mutagenic effects of ionizing-radiation and many other physical and chemical agents that damage DNA. This resistance is known to be due to D. radiodurans' extremely proficient DNA repair processes. However, little is known about the precise mechanisms employed by this organism to achieve its efficient repair. In the past two years there has been substantial progress in studies on the repair and tolerance of ionizing radiation damage. Areas of progress include: 1) studies on the importance of the deinococcal recA-gene in repair; 2) characterization of a large number of new ionizing radiation-sensitive strains; 3) newly discovered genetic loci with novel repair-related mutational phenotypes; 4) demonstration of efficient interplasmidic and interchromosomal recombination occurring postirradiation; and 5) recent speculations on the mechanisms of radiation resistance and the driving forces of natural selection for DNA damage resistance in D. radiodurans.