量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum and Radiological Science and Technology.
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Deinococcus radiodurans is a representative strain of the radioresistant bacteria characterized by extraordinary tolerance toward various DNA damaging agents such as ionizing radiation, ultraviolet rays and DNA cross-linkers. Following exposure to such agents, a number of genes which lack readily identifiable homologues among known proteins are induced. Of these, DdrA (DNA damage response A) is one of the most highly induced genes. However, the detailed function of DdrA in DNA repair mechanisms of D. radiodurans is not yet thoroughly understand. Sequence homology analysis revealed that D. radiodurans possesses a DdrA paralog, DdrAP, which is constitutively expressed in cells unlike DdrA. Although DdrAP is widely conserved in the member of genus Deinococcus, the function of DdrAP protein remains unclear. In this study, we constructed knockout strains for the DdrA-encoding gene (ddrA) and DdrAP-encoding gene (ddrAP) of D. radiodurans and investigated sensitivities of these mutant strains to DNA damaging agents and DNA replication inhibitors in order to gain an insight into the role of these genes in DNA repair mechanisms. Whereas ∆ddrA exhibited sensitivities to gamma rays, ultraviolet rays, and nalidixic acid, ∆ddrAP exhibited resistance to gamma rays, bleomycin, and novobiocin. Taking into consideration the result that ∆ddrAP exhibited a resistance to gamma rays and bleomycin, both of which produce DNA double strand breaks, and the fact that the DNA repair promoting protein PprA is interacted with DNA gyrase, DdrAP seems to involved in condensed nucleoid-dependent end joining, the double strand breaks repair mechanism in which PprA plays a crucial role in D. radiodurans.
Functional analysis of radiation-inducible protein DdrA and its paralog DdrAP in Deinococcus radiodurans
