Structural-functional analysis of the radiation-inducible protein DdrA and its paralog DdrAP

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K07730
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Applied microbiology
• Research Institution: Toyo University
• Principal Investigator: Narumi Issay 東洋大学, 生命科学部, 教授 (90343920)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: DNA修復 / 放射線抵抗性細菌 / DNA損傷誘導性 / ゲノム2本鎖切断修復

Outline of Final Research Achievements

The functional analyses of radiation-inducible protein DdrA and its paralog protein DdrAP from the radioresistant bacterium were carried out especially in terms of DNA repair. The ddrA deletion mutant showed a sensitivity to nalidixic acid. On the other hand, the ddrAP deletion mutant showed a resistance to novobiocin. These results suggest that DdrA and DdrAP proteins interact with the GyrA and GyrB subunits of topoisomerase, respectively, thereby, the interaction triggers a conformational change in topoisomerase, and changes the effects of topoisomerase inhibitors. The in vivo experiment using Western blot analysis and in vitro experiment using purified recombinant proteins revealed that a certain DdrA-degradative enzyme exists in crude cell extracts from the radioresistant bacterium, and it was suggested that DdrA protein avoids the cleavage activity of the DdrA-degradative enzyme by forming a heterocomplex with DdrAP protein.

Free Research Field

応用微生物学

Academic Significance and Societal Importance of the Research Achievements

放射線抵抗性細菌に特有のDNA修復機構である凝縮核様体依存性末端結合の構成要素としてこれまでに、PprAタンパク質、DNAトポイソメラーゼ、DNAリガーゼが明らかになっている。本研究によって、DdrAタンパク質及びDdrAPタンパク質は、DNAトポイソメラーゼと相互作用することが示唆され、CNDEJの構成要素として放射線抵抗性細菌が持つDNA損傷誘導性のDNA修復機構の一端を担うことが明らかになった。これらの構成要素の相互作用の詳細が明らかになれば、それらの相互作用を利用した新たな遺伝子工学試薬の開発にも繋がり、生命科学の新たな展開に貢献すると考えられる。