The regulation of initiation for chromosomal DNA replication by formation of G4 structure

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K06762
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 45010:Genetics-related
• Research Institution: Tokyo Metropolitan Institute of Medical Science
• Principal Investigator: TANAKA Taku 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, 主席研究員 (80425686)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: DNA複製 / RecA / PriA / 転写 / SDR / G4

Outline of Final Research Achievements

Recently, it is reported that G quadruplex (G4) structure involves in several nucleotide transactions. In Escherichia coli, stable DNA replication (SDR) can be initiated with a multi-replicon mode. Constitutive SDR (cSDR) activated in RNase HI-defective cells suggests roles of transcription in its initiation. oriT1 is identified in terminal region as novel origin candidate. oriT1 contains an uncharacterized open reading frame, ycjD, and canonical G quadruplex (G4)-forming sequences which are known to facilitate RNA-DNA hybrid formation upon transcription. Furthermore, the purified YcjD protein specifically binds to G4 in vitro. We also found that ectopic transcription can induce cSDR-like replication initiation and established minimum replicon which can be initiated replication by transcription dependent manner. These results suggest that forming of G4 is critical for initiation of transcription-dependent replication.

Free Research Field

分子生物学

Academic Significance and Societal Importance of the Research Achievements

DNA複製開始機構の解明は様々な疾患の原因究明と治療法確立に必須の課題であるが、分子間相互作用に基づく解析のみで解明することができない。G4の核酸代謝機構への関与は、DNAのかたちによる新たな制御機構の存在を示唆しており、真核細胞の複製機構の解明にブレークスルーをもたらすものである。真核生物のmulti-repliconの解明に、大腸菌SDRをモデルとして用いる発想は他になく、ユニークな結果を得られることを期待できる。本研究では、G4の転写に依存する複製開始を、転写誘導依存性複製開始機構を人工的に構築することで実現しており、新たな制御基盤の確立に重要な視点を提供する。