title: Three tandem HRDC domains have synergistic effect on the RecQ functions in Deinococcus radiodurans.
abstract: The RecQ family of DNA helicases performs essential functions in the maintenance of genomic stability in all organisms. In Deinococcus radiodurans, DR1289 is a special member of RecQ family with unique arrangement of three tandem HRDC domains in the C-terminus. A dr1289 mutant is hypersensitive to gamma-irradiation, UV, H2O2 and mitomycin C. By complementing the dr1289 mutant with various domains of Dr1289 in vivo, we have determined that the helicase and all three HRDC domains are indispensable for complete DNA damage resistance. Using a continuous fluorescent dye-displacement assay, we investigated the optimal conditions for Dr1289 unwinding function at various concentrations of ATP and metal ions to show that the helicase activity is comparable to what observed in Escherichia coli RecQ. We also found that the helicase domain is necessary for the unwinding and ATPase activity and that the three tandem HRDC domains increase the efficiency of these activities. Based on these data, we propose that the C-terminus of Dr1289 has evolved in D. radiodurans to confront the types and amounts of DNA damage.
authors.affiliation: Institute of Nuclear-Agricultural Sciences, Zhejiang University, Hangzhou 310029, China.
authors.forename: Lifen
authors.initials: L
authors.lastname: Huang
authors.forename: Xiaoting
authors.initials: X
authors.lastname: Hua
authors.forename: Huiming
authors.initials: H
authors.lastname: Lu
authors.forename: Guanjun
authors.initials: G
authors.lastname: Gao
authors.forename: Bing
authors.initials: B
authors.lastname: Tian
authors.forename: Binghui
authors.initials: B
authors.lastname: Shen
authors.forename: Yuejin
authors.initials: Y
authors.lastname: Hua
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D004249:DNA Damage; D004260:DNA Repair / Q000235:genetics / Q000502:physiology; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D034301:Deinococcus / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D009154:Mutation; D010641:Phenotype; D010957:Plasmids / Q000235:genetics; D017434:Protein Structure, Tertiary; D011836:Radiation Tolerance / Q000235:genetics / Q000502:physiology; D053484:RecQ Helicases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D020080:Tandem Repeat Sequences
chemical_list: D004269:DNA, Bacterial; D011994:Recombinant Proteins; D000251:Adenosine Triphosphatases; D053484:RecQ Helicases