title: Preserving genome integrity: the DdrA protein of Deinococcus radiodurans R1.
abstract: The bacterium Deinococcus radiodurans can withstand extraordinary levels of ionizing radiation, reflecting an equally extraordinary capacity for DNA repair. The hypothetical gene product DR0423 has been implicated in the recovery of this organism from DNA damage, indicating that this protein is a novel component of the D. radiodurans DNA repair system. DR0423 is a homologue of the eukaryotic Rad52 protein. Following exposure to ionizing radiation, DR0423 expression is induced relative to an untreated control, and strains carrying a deletion of the DR0423 gene exhibit increased sensitivity to ionizing radiation. When recovering from ionizing-radiation-induced DNA damage in the absence of nutrients, wild-type D. radiodurans reassembles its genome while the mutant lacking DR0423 function does not. In vitro, the purified DR0423 protein binds to single-stranded DNA with an apparent affinity for 3' ends, and protects those ends from nuclease degradation. We propose that DR0423 is part of a DNA end-protection system that helps to preserve genome integrity following exposure to ionizing radiation. We designate the DR0423 protein as DNA damage response A protein.
authors.affiliation: Department of Biochemistry, University of Wisconsin, Madison, USA.
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Harris
authors.forename: Masashi
authors.initials: M
authors.lastname: Tanaka
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Saveliev
authors.forename: Edmond
authors.initials: E
authors.lastname: Jolivet
authors.forename: Ashlee M
authors.initials: AM
authors.lastname: Earl
authors.forename: Michael M
authors.initials: MM
authors.lastname: Cox
authors.forename: John R
authors.initials: JR
authors.lastname: Battista
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry / Q000235:genetics; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology; D034301:Deinococcus / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D005092:Exonucleases / Q000378:metabolism; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D016678:Genome; D016680:Genome, Bacterial; D016685:Mitomycin / Q000494:pharmacology; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D011839:Radiation, Ionizing; D011995:Recombination, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013045:Species Specificity
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C109737:DdrA protein, Klebsiella oxytoca; D012333:RNA, Messenger; D016685:Mitomycin; D004247:DNA; D005092:Exonucleases