Regulation of DNA replication by G-quadruplex and its binding proteins

2020 Fiscal Year Final Research Report

• Project/Area Number: 17H01418
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Molecular biology
• Research Institution: Tokyo Metropolitan Institute of Medical Science
• Principal Investigator: MASAI Hisao 公益財団法人東京都医学総合研究所, 基礎医科学研究分野, 所長 (40229349)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 複製タイミング / クロマチンループ / 染色体高次構造 / 非相同末端結合 / 組換え修復 / ES細胞 / グアニン４重鎖DNA

Outline of Final Research Achievements

G-quadruplexes (G4) appear in both DNA and RNA, and are implicated in various biological reactions. We have studied their roles in regulation of DNA replication. Based on our long-standing studies on the second mode of DNA replication in E.coli, we hypothesized that replication can be initiated from RNA-DNA hybrids promiscuously generated on the genome. We show that G4/ RNA-DNA hybrid is efficiently formed upon transcription of G-rich DNA, and could serve as origins of DNA replication. One of the major initiation sites is located near terC, 180° opposite to the oriC, the primary origin, to which RecA and PriA, recombination and replication factor, respectively, essential for this mode replication, bind.
Conserved nuclear factor, Rif1, binds to G4 and regulates genome-wide replication timing. It does so by creating higher-order nuclear architecture near the nuclear periphery, which may be inhibitory for initiation. We have also clarified the functional domains of Rif1.

Free Research Field

分子生物学、生化学

Academic Significance and Societal Importance of the Research Achievements

生体のゲノム上にグアニン４重鎖構造が形成され、生物学的な重要な役割を果たすことが示されつつある。本研究では、G4の機能に関してRNA-DNA hybrid上に形成されるG4が複製開始のシグナルとなる事、G4結合因子がクロマチンループ形成により、複製開始を抑制するクロマチン高次構造を形成する事を示した。これらの発見はG4が担う新たな機能を明らかにするものであり、その分子基盤を解析することにより、これまで明らかになっていない、核酸の形が指令するゲノムの新規情報の解明に寄与する。また、得られた知見やG4結合リガンド等を用いて、G4を標的とした、制癌剤あるいは抗ウイルス剤の開発にも役立つであろう。