engleski

Deinococcus radiodurans: The Most Efficient DNA Repair Involves Coupled Replication and Recombination Processes

Bacterium Deinococcus radiodurans is one of the most radiation resistant organisms known. It can sustain extreme levels of ionizing radiation that induce several hundred double-stranded DNA breaks in its genome. The key to its radioresistance seems to be a highly efficient DNA repair, however, the molecular mechanism of accurate joining of the broken chromosomes is not yet understood. We have studied the mechanism of reconstitution of D. radiodurans genome after an exposure to gamma radiation shattering the genome down to about 25 kb fragments. We show that the highly efficient and accurate repair of fragmented D. radiodurans genome involves coupled DNA replication and recombination processes. A massive DNA polymerase I - dependent synthesis is required for the assembly of small chromosomal fragments into long linear intermediates which are subseqently matured by RecA-dependent homologous recombination into functional circular chromosomes.

Deinococcus radiodurans; gamma radiation; DNA repair; DNA replication; recombination

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