| Budget Amount *help |
¥3,830,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥330,000)
Fiscal Year 2007: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2006: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2005: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
The goal of the study is solution of molecular mechanisms on partition of bacterial chromosome and plasmid. We first analyzed cells of Escherichia coli by various cytological techniques and found that replication origin oriC, replication terminus ter, replication forks, and MukB clusters are localized in ordered manner in cell cycle. Furthermore, we examined precisely partition mechanism of F plasmid by immunofluorescence microscopy and FISH. Based on the results, we proposed the new hypothesis that the partition system of F plasmid is a reaction diffusion system of plasmid-coded SopA and SopB. SopA protein might be "activator" and SopB protein might be "inhibitor" in this system. SopA and SopB react each other, resulting in subcellular local positioning of SopB. The sopC region (centromere) of the plasmid binds specifically SopB, and plasmid DNA molecules locate in subcellular positions of high concentration of SopB. Additionally, we found that the partition system of E. coli chromosome is a reaction diffusion system mediated by at least 10 proteins involved SecA, SecY, AcpP and MukB. We named this system "POC (positioning of chromosome) system". In this system, SecA might be "activator" and SecY might be "inhibitor". These proteins react each other and diffuse within the cell, resulting in subcellular local positioning of these proteins. Other proteins of POC subordinate to the dynamics of SecA and SecY. DNA regions that bind specifically DNA binding proteins of POC localize in positions of high concentration of these DNA binding proteins. Thus, subcellular positions of the DNA regions are determined, therefore sister chromosomes are faithfully partitioned into both daughter cells upon cell division.
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