PMID:19944654

Citation	Cao, Z, Mueller, CW and Julin, DA (2010) Analysis of the recJ gene and protein from Deinococcus radiodurans. DNA Repair (Amst.) 9:66-75
Abstract	The mechanism by which double-strand DNA breaks are repaired in the radiation-resistant bacterium Deinococcus radiodurans is not well understood. This organism lacks the RecBCD helicase/nuclease, which processes broken DNA ends in other bacteria. The RecF pathway is an alternative pathway for recombination and DNA repair in E. coli, when RecBCD is absent due to mutation, and D. radiodurans may rely on enzymes of this pathway for double-strand break repair. The RecJ exonuclease is thought to process broken DNA ends for the RecF pathway. We attempted to delete the recJ gene from D. radiodurans, using homologous recombination to replace the gene with a streptomycin-resistance cassette. We were unable to obtain a complete deletion mutant, in which the gene is deleted from all of the chromosome copies in this polyploid organism. Quantitative real-time PCR shows that the heterozygous mutants have a recJ gene copy that is ca. 10-30% that of the wild-type. Mutants with reduced recJ gene copy grow slowly and are more sensitive than wild-type to UV irradiation, gamma irradiation, and hydrogen peroxide. The mutants are as resistant as wild-type to methyl-methanesulfonate. The D. radiodurans RecJ protein was expressed in E. coli and purified under denaturing conditions. The re-folded protein has nuclease activity on single-stranded DNA with specificity similar to that of E. coli RecJ exonuclease.
Links	PubMed Online version:10.1016/j.dnarep.2009.10.009
Keywords	Bacterial Proteins/genetics; Bacterial Proteins/metabolism; DNA/metabolism; DNA Repair; Deinococcus/genetics; Deinococcus/growth & development; Deinococcus/metabolism; Deinococcus/radiation effects; Exodeoxyribonucleases/genetics; Exodeoxyribonucleases/metabolism; Gene Deletion; Gene Expression Regulation, Bacterial; Microbial Viability/radiation effects; Mutation; Phenotype; Protein Folding
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
DEIRD:D0EM60		GO:0008409: 5'-3' exonuclease activity	ECO:0000314:		F		Fig 7 or 8	complete CACAO 7709
DEIRD:D0EM60	enables	GO:0008409: 5'-3' exonuclease activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete

References

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