Control of Cell Division by Sex Factor F in Escherichia coli: Trigger protein and inhibitor protein encoded by the F plasmid.
| Project/Area Number |
63571047
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Biological pharmacy
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| Research Institution | Kyushu University |
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Principal Investigator |
HORIUCHI Tadao Kyushu University, Faculty of Pharmaceutical Sciences, Professor, 薬学部, 教授 (10037567)
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| Co-Investigator(Kenkyū-buntansha) |
MIKI Takeyoshi Kyushu University, Faculty of Pharmaceutical Sciences, Associate Professor, 薬学部, 助教授 (40037586)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1989: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1988: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | Escherichia coli / DNA replication / cell division / F factor / letA gene / letD gene / gel retardation analysis / DNA binding protein / Fプラスミド |
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| Research Abstract |
The F plasmid of Escherichia coli contains two genes, letA and letD, whose products are involved in the coupling between DNA replication of the F plasmid and cell division of the host bacteria. The letD gene product acts to inhibit cell division of the host bacteria, whereas the letA gene product acts to suppress the inhibitory activity of the letD gene product. When DNA replication of the F plasmid is blocked, expression of the letA gene is inhibited and as a result cells stop dividing.
To elucidate the mechanism that couples expression of the letA gene function with DNA replication of the F plasmid, we constructed mini-F plasmids containing promoterless lacZ gene downstream of the letA promoter and measured -galactosidase activities. The results showed that the letA and letD genes comprise an operon, and that expression of this operon is regulated negatively at the level of transcription by the letA and letD gene products, but not by DNA replication of the F plasmid either at the level of transcription or translation. In addition, we showed that the coupling between DNA replication of the F plasmid and cell division of the host bacteria is preserved even if promoter of this operon was replaced with the tac promoter. These observations suggest that expression of the letA function is regulated by DNA replication at a post-translational level.
As a first step to analyze this post-translational regulatory mechanism, we tried to search biochemical activities carried by LetA and LetD proteins. Using gel retardation analysis, we found that LetA protein binds to double stranded DNA indifferently to base sequence, and also obtained evidence that suggests LetA and LetD proteins, as a complex, binds to the promoter region of the letA, letD operon and that a protein encoded by the host chromosome plays indispensable role in this binding. Utilizing these features for assay of their activity, purification of LetA and LetD proteins is now under way.
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Report
(3 results)
Research Products
(9 results)
