| Project/Area Number |
08277104
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
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| Allocation Type | Single-year Grants |
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| Research Institution | Institute of Molecular Embryology and Genetics, Kumamoto University |
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Principal Investigator |
HIRAGA Sota Institute of Molecular Embryology and Genetics, Kumamoto University Professor, 発生医学研究センター, 教授 (40027321)
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| Co-Investigator(Kenkyū-buntansha) |
WACHI Masaaki Department of Bioengineeing, Tokyo Institute of Technology, Associate Professor, 生命理工学部, 助教授 (90192822)
OHYA Yoshikazu Graduate School of Science, University of Tokyo, Professor, 大学院・新領域創成科学研究科, 教授 (20183767)
OGURA Teru Institute of Molecular Embryology and Genetics, Kumamoto University Associate Professor, 発生医学研究センター, 助教授 (00158825)
NISHIMURA Akiko Genetic Strains Research Center, National Institute of Genetics, Associate Professor, 助教授 (20142002)
HORIUCHI Takashi National Institute for Basic Biology, Professor, 教授 (60108644)
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| Project Period (FY) |
1996 – 1999
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| Keywords | chromosome segregation / chromosome partitioning / control of replication initiation / cohesion of sister chromosomes / replication origin / DNA methylation / centromere / plasmid partitioning |
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| Research Abstract |
The ultimate goal of this research proposal is to understand molecular mechanisms of segregation of sister chromosomes in both prokaryotes and eukaryotes. During this research period, we have developed new cytological microscopy techniques to visualize specific proteins and DNA segments in small prokaryotic cells. Using these techniques, we have found as follows. The plasmid partition system, which is controlled by two plasmid gene products and the cis-acting site, determines subcellular locations of plasmid DNA molecules at the 1/4 and 3/4 cell positions prior to cell division. The replication origin oriC is replicated at the middle cell position and the sister chromosomes are cohesive with each other for an appropriate period of the generation time in E.coli. After releasing from the cohesion in the late period of replication, the oriC sister copies migrate to pole proximal ends of the nucleoid. Terminal DNA segments are located at division site before the cell divides. The subcellular localization of SeqA, which binds hemimethylated nascent DNA, supports the model 'translocating replication factories' in E.coli. The MukF-MukE-MukB protein complex of E.coli and the Smc protein of B.subtilis participate in segregation of sister chromosomes and maintenance of the folded chromosome structure. Three different regulatory mechanisms of replication initiation have been found in the E.coli ; hydrolysis of DnaA-binding ATP by DNA polymerase III, competitive inhibition of the binding of DnaA and the hemimethylated oriC region by SeqA, and trapping a large amount of DnaA in datA sister copies. In human chromosome, the centromere region and its DNA-protein complex were precisely analyzed. Specific proteins involved chromosome segregation and protein kinases involved in the M period were found in eukaryotes.
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