Study on the mechanisms of the chromatin formation on newly synthesized daughter strands: visualization and analyses of the chromatin formed on daughter strands using atomic force microscopy

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K06614
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 43050:Genome biology-related
• Research Institution: Saitama Medical University
• Principal Investigator: HIZUME Kohji 埼玉医科大学, 医学部, 講師 (10378846)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: DNA複製 / ヌクレオソーム / クロマチン / ヒストン

Outline of Final Research Achievements

Some of the proteins consisting of the replisomes, such as Dpb3-Dpb4 or Mcm2, have been reported as "histone chaperon." I performed the biochemical assay to test if these factors show the activity as histone chaperon, but neither Dpb3-Dpb4 nor Mcm2 N-terminal region (Mcm2N) didn't assemble nucleosomes from DNA and core histones. Next, I measured the interaction between Mcm2N and histones and found strong interaction of Mcm2N with H3-H4, as reported by some groups using human Mcm2 protein. Interestingly, I also found that Mcm2N does not interact with the reconstituted nucleosome, suggesting that Mcm2N can not access H3-H4 in a nucleosome. These results suggest that Mcm2N are involved in capturing histones released from template strands to provide them to newly synthesized strands but not involved in the dissociation of nucleosome on template strands.

Free Research Field

分子生物学

Academic Significance and Societal Importance of the Research Achievements

ヒストンを鋳型鎖から新生鎖に受け渡す複製因子は、ヒストンと十分な親和性で相互作用する必要があり、かつ、新生鎖に譲渡するためにその相互作用は一定条件で解消される必要もある。また、鋳型鎖から新生鎖への方向性をもって、ヒストンを移動させなければならない。本研究において検出されたMcm2Nとヒストンとの結合様式の解析を進めることで、例えば液-液相分離などで重要な“緩い結合”が、生理的な意義をもつ代表例として他の事例の解釈にも応用される知見となりうる。