Features of DNA Helicase Encoded by the uvrD Gene of Deinococcus radiodurans R1 in Escherichia coli K-12 Cells

Reparative helicase II ofDeinococcus radioduransperforms an unexpected critical function in repair of double-strand DNA breaks through the mechanism of extended synthesis-dependent strand annealing (ESDSA), while it is considered as an optional participant in the RecF pathway of recombinational repair inEscherichia coli. A fragment of genomic DNA of the radioresistant bacteriumDeinococcus radioduranswith theuvrDgene encoding DNA helicase II, which is involved in excision repair of nucleotides, mismatch repair, and recombinational repair and replication, was cloned in the cells of the model object,Escherichia coliK-12. The pCR 2.1-uvrD(+)plasmid restores resistance to ultraviolet light of mutant cells ofEscherichia coliuvrD(-),helD(-), andrep(-)defective in reparative helicase II, helicase IV, and replicative helicase Rep, respectively, almost to the level of wild-type AB1157 anduvrD(+), and, to a lesser extent, the strain with a mutation in therecQgene encoding the key helicase of recombinational repair RecQ. The protective effect is also noticeable when strains with the plasmid are irradiated with gamma-rays. It is established thatDeinococcus radioduransUvrD helicase possesses broad possibilities.